EPA 600/3-81-028
                                              April  1981
   PRODUCTION AND RELEASE  OF PLANT  MATERIAL
      IN BRACKISH AND  FRESHWATER WETLANDS
                     by
       Paul L.  Wolf and Donald Kinsey
 The University of Georgia Marine Institute
       Sapelo Island,  Georgia 31327
                 R80583310
               Project Officer
              Harold V.  Kibby
Corvallis Environmental Research Laboratory
      Environmental Protection Agency .
          Corvallis, Oregon 97330
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
     OFFICE OF RESEARCH AND DEVELOPMENT
    U.S. ENVIRONMENTAL PROTECTION AGENCY
          CORVALLIS, OREGON  97330

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
1. REPORT NO.
   EPA-60Q/3-81-Q28
                             2.
                                                           3.
ORD Report.
4. TITLE AND SUBTITLE
   Production and Release of  Plant Material in Brackish
   and Freshwater Wetlands
                                                           5. REPORT DATE
                                                                 April  1981
                          6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)

   Paul  L.  Wolf and Donald  Kinsey
                                                           8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND AOORESS

   The University of Georgia  Marine Institute
   Sapelo Island, Georgia  31327
                                                           10. PROGRAM ELEMENT NO.
                          11. CONTRACT/GRANT NO.


                             R80583310
12. SPONSORING AGENCY NAME AND AOORESS

   Environmental Research Laboratory
   Office of Research and Development
   U.S. Environmental Protection Agency
   Cnrvallis. Orpnnn Q733D	
                          13. TYPE OF REPORT AND PERIOD COVERED
                             final   4-78 to 4-79	
                          14. SPONSORING AGENCY COOE
                             EPA/600/02
1S. SUPPLEMENTARY NOTES
16. ABSTRACT
   Production, decomposition,  and transport of detritus were investigated  in  the fresh-
   water and brackish water wetlands of the Altamaha  River Delta, Georgia  from April  17
   1978. to 13 April  1979.   Maximum live standing  crop biomass of Spartina  cynosuroides,
   a brackish water  marsh  plant, was observed in  July(769 i 118 g dry wt m2).  Live
   material was absent  in  January.  Standing dead material ranged from a high  of 1800
   + 275 g dry wt m2 in November to a low of 158  +_ 57 in March.  The quantity  of fallen
   d"ead (litter) material  was  more constant throughout the year averaging  244  +_ 21 q do
   wt m2. Net aerial  primary productivity (NAPP)  of S_.  cynosuroides was 2029  g m2  yH
   with no differences  in  productivities of plots relative to the distance  from the
   riverbank because of minimal  tidal activity in the entire area. Maximum  live standing
   crop biomass of Zizaniopsis miliacea, a freshwater marsh plant, was obsterved in
   October (673 +_ 122 g dry wt m2). Live material  dropped to a low of 81 +_ 12  g dry wt
   m2 in March.  Standing  dead material ranged from a high of 870 +_ 222 g  dry  wt m2 in
   April  1978 to a low  of  308  +_ 101 in August. Aquatic respiration rates of standing anc
   fallen dead material  showed a pattern of swamp litter > Z_. miliacea > S_. cynosuroides
   Rates for marsh grasses were generally higher  in the spring dropping to  a  low in fall
   and winter. Rates in swamp  litter were much more variable without distinct  seasonal
   patterns.                                    .   .
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.lDENTIFIGRS/OPEN ENDED TERMS
                                                                                      'OUp
                                                                       iillation Resource
                           r?. '\5r;,.--t Sire
                           p • -<• ,v%;« "A
                           r.i..._-....:.2, ii H
                                                                        Pi
                                                                         1910?
18. DISTRIBUTION STATEMENT
   Release to public
                                              19. SECURITY CLASS (ThisReport)
                                                unclassified
                                                                         21. NO. OF PAGES
             20. SECURITY CLASS (Thispage)
              unclassified
                                                                         22. PRICE
EPA Form 2220-1 (9-73)

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                                 DISCLAIMER
     This report has been reviewed by the Corvallis Environmental Research
Laboratory, U. S. Environmental Protection Agency, and approved for publica-
tion.  Approval does not signify that the contents necessarily reflect the
views and policies of the U. S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
                                     ii

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                              EXECUTIVE SUMMARY
     Production,  decomposition,  and  transport  of  detritus were investigated
 in  the  freshwater and brackish water wetlands  of  the  Altamaha River Delta,
 GA,  from  17 April 1978  to  13 April 1979.  Maximum live  standing crop biomass
 of  Spartina cynosuroides,  a brackish water marsh  plant,  was  observed in July
 (769 ±  118 g  dry  wt m~z).  Live  material was absent in  January.   Standing
 dead material ranged from  a high of  1800 ± 275 g  dry  wt m~2  in November to  a
 low of  158 ±  57 in March.  The quantity of fallen dead  (litter)  material was
 more constant throughout the year averaging  244 ± 21  g  dry wt m~ .   Net
 aerial  primary productivity  (NAPP) of £. cynosuroides was 2029 g m~^ yr"^-
 with no differences in  productivities of plots relative to  the distance from
 the riverbank because of minimal tidal activity in the  entire area.

     Maximum  live standing crop  biomass of Zizaniopsis  miliacea. a  freshwater
 marsh plant,  was  observed  in October (673 ±  122 g dry wt m~2).  Live material
 dropped to a  low  of 81  ± 12  g  dry wt m~2 ia  March.  Standing dead material
 ranged  from a high of 870  ±  222  g dry wt m~2 in April,  1978, to a low of
 308 ±  101 in  August.  Fallen dead material had an annual average of 159 ± 71
 g dry wt  m~2.  NAPP for "L. miliacea  was  1478 g m~2 yr~l.  Productivities were
 higher  in creekbank plots  than in more inland  plots  (1824 and 1237  g m~2
 yr~l,  respectively) presumably because of longer  tidal  inundation times in
 the creekbank zone.  In both areas NAPP peaked between  April and May and was
 lowest  between November and  January. Leaf litter accumulation (primarily
 Nyssa  aquatica, Liquidambar  styraciflua. and Taxodium distichurn) was highest
 in November  (253  ± 19 g dry wt m-2)  and  lowest in spring and summer (18 ± 2g
 dry wt. m~2).

     Aquatic  respiration rates of standing and fallen dead  material showed  a
 pattern of swamp  litter >  _Z. miliacea  > J5. cynosuroides.   Rates for marsh
 grasses were  generally  higher  in the spring  dropping  to a  low in fall and
'winter.  Rates in swamp litter were  much more  variable  without distinct
 seasonal  patterns. Aejrial_respiration rates of dead  plant  material ranked
 Z.  miliacea  > swamp litter > J3.  cynosuroides.'   Fallen dead  marsh grass
 material  had  a higher  respiration rate than  standing  dead material, with the
 highest rates occurring during  the summer.   DOC leaching rates for  dead plant
 material  ranked swamp  litter > _Z. miliacea > ^. cynosuroides.  Seasonal pat-
 terns  of  leaching were  not evident in  the marsh grasses, nor were there
 differences between  fallen dead  and  standing dead materials.  Swamp litter
 had high  leaching rates in summer and  fall with low rates  during the winter
 months.
                                       iii

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     Weight losses in marsh grass litter bags ranked submerged > surface >
suspended with decomposition rates being higher in _Z. miliacea than _S.
cynosuroides.   Z_. miliacea surface litter at 11 months decreased to 14% of
the original weight while _§_. cynosuroides showed a decrease of only 40%.
Z_. miliacea submerged litter at 6 months had only 6% of the original
biomass, while ^. cynosuroides had 52% remaining.  Decomposition rates for
swamp litter were similar in both submerged and surface bags with the
greatest weight losses occurring between 1 and 6 months.

     Aquatic respiration rates of dead material from litter bags were higher
in more aquatic situations and were generally higher in the earlier stages
of decomposition with the highest rates observed in swamp litter.  Although
more variable, aerial respiration rates exhibited a pattern similar to that
of aquatic respiration.  DOC leaching rates for litter bag material ranked
^. cynosuroides > Z. miliacea > swamp litter.  Swamp litter had a negative
leaching rate indicating a possible uptake of carbon.  Submerged litter
leaching rates were higher in submerged and surface bags for S_. cynosuroides
while Z. miliacea suspended litter had the highest rate of leaching.

     Analyses of mineral composition data for litter bag material indicated
an accumulation of Ba, Fe, Na, N, Zn and P over an 11-month period while Al,
B, K, and Mg levels decreased.  Concentrations of Ca, Cu, Mn, and Sr re-
mained the same.  For most of the elements analyzed, levels were generally
higher in submerged and surface litter as compared to suspended material,
and litter bag material was highest in elemental concentration than plant
debris removed from the marsh surface.  Species differences in levels of
some elements were also demonstrated.

     Estimates of the quantity of carbon lost to the estuary as particulate
detritus were 372 and 147 g C m~^ y~^ from ^. cynosuroides and Z. miliacea
marshes, respectively.  However, the results for the swamp forest indicated
a possible import of carbon.

     This report^was submitted in fulfillment of Contract No. R805833010
by the University of Georgia Marine Institute under  the sponsorship of the
U. S. Environmental Protection Agency.  The report covers the period
20 April 1978, to 19 April 1979.
                                      iv

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                                 CONTENTS
Executive Summary .  "... '.  .  .  '.  \ ..........	   ±±±
Figures	    vi
Tables	   vii
Acknowledgments	    ix

     1.  Introduction 	      1
     2.  Conclusions and Recommendations	      3
     3.  Materials and Methods	      4
              Study Area	      4
              Detritus Production and Aerial Productivity 	      4
              Detritus Decay and Leaching Studies 	      6
              Litter Bag Studies	•	      6
     4.  Results and Discussion 	      8
              Detritus Production and Aerial Productivity 	      8
              Respiration and Leaching Studies	    13
              Litter Bag Studies (LBS)	    24
                   LBS - Weight Losses	    24
                   LBS - Aquatic Respiration	    25
                   LBS - Aerial Respiration	    25
                   LBS - Dissolved Organic Carbon (DOC) 	    26
                   LBS - Mineral Composition	    32
              Export Estimates	    40

References	    43
Appendices

     A.  Biomass, Aquatic Respiration, Aerial Respiration and DOC
              Leaching from Dead Plant Material  	    45
     B.  Biomass, Aquatic Respiration, Aerial Respiration, DOC
              Leaching and Elemental Composition of Litter Bag
              Material	    55

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                                 FIGURES


Number                                                                  Page

   1   Lower Altamaha River Delta	   5

   2   Mean dry weight of Spartina cynosure ides	   9

   3   Mean dry weight of Zizaniogsis miliacea	10

   4   Mean dry weight of leaf litter	11

   5   Aquatic respiration of fallen dead plant community in
          Spartina cynosuroides and Zizaniopsis miliacea 	  14

   6   Aquatic respiration of standing dead plant community in
          Spartina cynosuroides and Zizaniopsis miliacea 	  15

   7   Aquatic respiration of the dead plant community in
          swamp forest leaves	16

   8   Aerial respiration of the dead plant community in
          Spartina cynosuroides	17

   9   Aerial respiration of the dead plant community in
          Zizaniopsis miliacea 	  18

  10   Aerial respiration of the dead plant community in swamp
          forest leaves	19

  11   DOC released from dead Spartina cynosuroides	21

  12   DOC released from dead Zizaniopsis miliacea	  22

  13   DOC released from decomposing swamp forest leaves 	  23

  14   Aquatic respiration of litter bag material	29

  15   Aerial respiration of litter bag material 	  30

  16   DOC leaching of litter bag material	31

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                                  TABLES


Number

   1    Results of Duncan's Multiple Range Test on biomass, aquatic
           and aerial respiration and DOC leaching for litter bag
           material	   27

   2    Results of Duncan's Multiple Range Test on biomass, aquatic
           and aerial respiration and DOC leaching for litter bag
           material - pooled data	   28

   3    Results of Duncan's Multiple Range Test for elemental
           composition of litter bag material - pooled data	   33

   4    Results of Duncan's Multiple Range Test for elemental
           composition of Spartina cynosuroides litter bag material. .  .   36

   5    Results of Duncan's Multiple Range Test for elemental
           composition of Zizaniopsis miliacea litter bag material.  .  .    37

   6    Results of Duncan's Multiple Range test for elemental
           composition of swamp forest leaf litter bag material  ....    39

 A-l    Mean dry weight of marsh grass from clear cut plots	    46

 A-2    Mean dry weight of marsh grass from previous cut plots	    47

 A-3    Mean dry weight of leaf litter	    48

 A-4    Aquatic respiration of the attached dead plant community
           in two species of marsh grasses	    49

 A-5    Aquatic respiration of the attached dead plant community for
           three species of swamp forest leaves 	    50
                                                                             •
 A-6    Aerial respiration of the attached dead plant community  in
           two species of marsh grasses	    51

 A-7    Aerial respiration of the attached dead plant community  for
           three species of swamp forest leaves	    52

 A-8    DOC released  from dead plant parts for two species of marsh
           grasses	    53
                                     vii

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                              TABLES (Continued)


Number                                                         '          Page

 A-9    DOC released from three species of swamp  forest leaves	     54

 B-l    Biomass of litter bag material	     56

 B-2    Aquatic respiration of attached dead plant community in
           litter bag material	     57

 B-3    Aerial respiration of attached dead plant community in
           litter bag material	     58

 B-4    DOC leaching from litter bag material	'   59

 B-5    Mineral content of Spartina cynosureides  litter bag material. .     60

 B-6    Mineral content of Zizaniopsis miliacea litter bag material . .     63

 B-7    Mineral content of dead swamp forest leaf litter'bag material .     66
                                      viii

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                              ACKNOWLEDGMENTS
     The cooperation of the staff members of the University of Georgia
Marine Institute is gratefully appreciated.   We are particularly indebted
to Mr. Charles Durant for his duties as boat captain, navigator, cook,
historian, and general assistance in the scientific aspects of the study.

     The efforts of the following people are sincerely appreciated: Beth
Green, Phyllis Hawkins, Lucy Knowles, Mary Musselman, Thomas Pearson,
Steve Vozzo and Lebanon Valley College ecology students for their assis-
tance in field collections and laboratory analyses; Steve Vozzo for
preparing the figures; Mike Hardisky for conducting the .computer analyses;
and Mrs. Charlotte Rittle for her untiring service in the preparation of
the manuscript.

     Finally, we wish to acknowledge the efforts of Dr. John Gallagher who
first initiated the Altamaha River Study in October, 1976; and Dr. Harold
Kibby, who served as the project officer.

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                                  SECTION 1

                               INTRODUCTION

     The Altamaha River Delta,  approximately 7 km south of Sapelo Island,
Georgia, is characterized by extensive brackish water marshes, freshwater
marshes, and river swamp hardwood forests.  Although there have been a few
studies of this freshwater to brackish water wetland system, processes within
these wetlands and their relationship to the more intensively studied saline
zones are poorly understood.  The food webs in this system like those of
saltwater marshes are predominantly based on detritus produced by the trees
and grasses (Wharton and Brinson, 1978).  Detrital productivity contributes
to invertebrate and vertebrate production and is potential food for export to
other components of the coastal system.  The rivers associated with the
marshes and forests may be point sources of inorganic nutrients and organic
compounds for the salt marshes along the coast.  Windora, Dunstan and Gardner
(1975) have shown that river flow could contribute 20% of the inorganic
nitrogen needed by marsh plants.  Organic nitrogen compounds are also pre-
sent in river flow (Dunstan and Atkinson, 1976).  Brinson (1977) however,
reported that, in some cases, swamp forest areas may act as nutrient sinks.
It appears that any alterations in this system which cause a change in the
amount, quality, and timing of detrital productivity, and a modification in
nutrient transport patterns could have an effect on productivity at the
primary and secondary levels within the system.  Wharton (1970) reported
that channelization and damming projects in freshwater areas have resulted
in severe damage with little or no recovery even after a relatively long
period of time.  Furthermore, large quantities of detritus and nutrients are
probably.processed in the saline Iportion of the coast since there is a net
flow of water from fresh to saline areas.  Without information on detrital
productivity and the associated nutrient flux in the freshwater and brackish
water wetlands, it would .be impossible to predict the impact of alterations
of these wetlands on the adjacent estuarine.

     In October, 1976, investigators from the University of Georgia Marine
Institute, Sapelo Island, Georgia, initiated studies which focused on the
detrital and microbial processes in three types of wetlands (swamp, fresh-
water marshes, and brackish water marshes) in the Altamaha River system.
These studies provided some information on potential detritus production,
detrital decay rates, and movement of  detritus between freshwater wetlands
and the adjacent estuary.  A preliminary evaluation of the data indicated a
need for further work in this area before conclusions could be made
concerning the interaction of freshwater, brackish water and saline systems.
Even if research would show that the dynamics in the freshwater areas do not
result  in a significant input into the already-rich coastal area, the timing

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and placement of the input, the composition of the material, or the pulsing
action during high water flow may be critical to the organic nutrition of
coastal areas.  For example, the river system seems ideally designed to
release materials into the adjacent ecosystems in pulses, whereas flow from
the salt marshes dominated by semi-diurnal tides would be more uniform and
rhythmic.

     The main objective of the proposed research was to continue the work on
the Altamaha River system.  Specifically, we attempted to answer the
following questions:

     1.  How much detritus is produced in the wetland types?

     2.  How fast does the detritus decay and what is the leaching rate
         of organic compounds into the water from the dead and dying
         leaves?

     3.  What is the quantity of detritus released into the river and
         transported to the estuary?

     4.  What are the chemical characteristics of the detritus from the
         river wetlands?

     Although the results of our research should enable the various agencies
concerned with ecosystem management to assess the advantages and disadvan-
tages of any alterations in coastal freshwater and brackish water ecosystems,
it is apparent that further studies are necessary for a more complete
understanding of these systems and their relation to the more saline coastal
areas.

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                                 SECTION 2

                      CONCLUSIONS AND RECOMMENDATIONS
     The results of this study indicate that the brackish water marshes and
freshwater marshes are areas of relatively high productivity which make
significant contributions of particulate detritus, organic compounds, and
inorganic nutrients to the coastal estuarine system.  The role of the
freshwater swamp forest has not been as clearly defined.  There are indica-
tions that these swamp forest areas may be "importers" rather than
"exporters" of carbon and other nutrients.  Clearly, there is a need for
further work in these sensitive wetlands - particularly in the freshwater
marshes and swamps.  Specifically, the following projects and/or studies are
recommended:

     1)  Underground biomass should be determined in the. Zizaniopsis
         miliacea marsh to give a more accurate assessment of net
         primary productivity and potential detritus production.

     2)  Studies on _Z. miliacea should be expanded to include stands
         in what were formerly areas of rice culture.  These old rice
         fields occupy approximately 2544 ha in the Altamaha River Delta.
         The present study included only stands of _Z. miliacea in a rela-
         tively narrow zone (182 ha) along river and creekbanks.

     3)  A more intensive litter bag study should be initiated whereby
         more bags are utilized and samples are collected much more
         frequently.  The results of this study would provide more
         accurate information on decomposition rates and nutrient
         exchanges.

     4)  The quantities of plant materials (live and dead) consumed by
         marsh and swamp fauna should be determined.

     5)  Finally, and perhaps most importantly, elevational data and
         information on tidal amplitude and frequency of inundation are
         needed for these areas.  These data are needed to quantify
         more accurately the transport of detritus and nutrients to and
         from these areas, and will enable us to establish more clearly
         the relationships between the various type of coastal wetlands.

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                                  SECTION 3

                            MATERIALS AND METHODS
STUDY AKEA

     The general study area was situated in the Altamaha River Delta
approximately 16 km north of Brunswick, GA.  Sampling sites (Figure 1) were
located in Spartina cynosuroides, a brackish water (0-15 U/00) marsh on the
south side of Broughten Island; in Zizaniopsis miliacea, a predominantly
freshwater marsh bordering the north side of Hammersmith Creek, a tributary
of the Altamaha River; and in two forested areas dominated by Nyssa aquatica,
Taxodium distichum, and Liquidambar styraciflua.  The forested area was
located approximately 26 ra from the creekbank on the north side of Hammer-
smith Creek adjacent to the Z_. miliacea productivity plots.  This area,
designated Riverbend, is subject to flooding only on extremely high tidal
conditions.  The other area, designated freshwater swamp, was situated on the
south side of Hammersmith Creek approximately 0.5 km west of Riverbend.  This
area was flooded much more frequently than the Riverbend site.  Nine collec-
tions were made at approximately 6-week intervals between 17 April 1978 and
13 April 1979.

DETRITUS PRODUCTION AND AERIAL PRODUCTIVITY

     The question of how much detritus is produced was approached by
measuring the calculating net aerial primary productivity (NAPP) and the
production of dead plant material.  Changes in dead marsh plant biomass
during each sampling interval were measured utilizing the paired.plots method
of Wiegert and Evans (1964) as modified by Lomnicki et al. (1968).  In the
_S. cynosuroides marsh, six plots were placed at 6 m intervals on a transect
from riverbank to the higher marsh dominated by Iva frutescens.  Similarly,
eight plots were placed at 3 m intervals in the Z. miliacea marsh on a
transect from creekbank to the hardwood forest.  At both sites, plant
material in each 0.5 m^ plot was clear cut (Clear Cut Plots), and bagged,
after which fallen 'dead material (litter) was removed from the marsh surface
and bagged.  In an 0.5 nr area adjacent to each of the clear cut plots, all
of the dead material was removed and discarded.  These plots were designated
as previous cut plots.  At the next sampling interval, approximately six
weeks later, the previous cut plots were clear cut and the plant material was
bagged.  Following the collection at each sampling period, the plots were
advanced approximately 1 m, and the process of establishing paired plots was
repeated.  Marsh grass was returned to the laboratory where it was sorted
into live .and dead material, oven dried at 60° C and massed to the nearest
gram.  Litter was washed over a No. 18 brass sieve, oven dried at 60° C, and

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Figure 1.   The Lower Altamaha River Delta, Georgia,
           showing sampling sices.   Sroughton Island, 1;
           Riverbend, 2;  Freshwater Swamp, 3; and Reese
           Island, 4.

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massed to Che nearest gram.

     Net aerial primary productivity was calculated with the formula
NAPP = AG 4- M, where AG = change in live plant biomass during the time in-
terval (Lomnicki et al.,  1968).  In summing the marsh grass productivities
during each time interval to arrive at annual NAPP, negative values were
treated as zero productivities.

     In each of the two forested areas 12 plastic trash containers  (0.1 m
in surface area) were mounted on poles to catch material falling from the
trees.  At each collection the material was harvested, bagged, and  returned
to the laboratory where it was oven dried at 60° C and massed to the nearest
0.1 gram.

DETRITUS DECAY AND LEACHING STUDIES

     At each collection,  samples of standing dead marsh plant material,
fallen dead marsh plant material, and fallen leaves from the swamp  forest
were returned to the laboratory for respiration (aerial and aquatic) and
leaching studies.  Aquatic and aerial respiration rates of the attached dead
plant community from each of the plant types were determined as described by
Gallagher and Pfeiffer (1977); release of dissolved organic carbon  (DOC) from
the dead plant parts was measured according to Gallagher, Pfeiffer  and
Pomeroy  (1976).

LITTER BAG STUDIES

     Further information on detritus decay rates was  obtained through litter
bag studies utilizing a modification of Brinson (1977).  Standing dead
material from two marsh sites and fallen leaves from  the river swamp forest
were obtained and air dried in a greenhouse.  Dried marsh plant material
(100 g each) was placed in 120 x 30 cm fiberglass litter bags (1.5  mm mesh
size) and returned to Altamaha River Delta.  Bags containing Z_. miliacea
standing dead were located at the productivity collection site.  Because the
S^. cynosuroides collection site had a history of frequent burnings  each
spring, bags containing that material were located in a _S. cynosuroides marsh
1  km NE of the productivity collection site.  At the  two sites, 18  bags each
were suspended on wooden stakes above the marsh surface to simulate decay of
standing dead, secured on the marsh surface to simulate decay of fallen dead,
and submerged in the water adjacent to the marsh site to simulate decay of
dead plant material after it is washed into the river and creek.  Air dried
swamp leaf litter  (20  g each) was placed in 36 x 18 cm fiberglass litter bags
(1.5 mm mesh size), returned to the swamp forest where 18 bags each were
placed on the forest floor which was free of standing surface water at the
time of placement, and submerged in the water of a narrow canal connecting
the creek with the swamp forest area.  To simulate decay rates in more saline
water after material from the marshes and swamp forests had been transported
to the estuary, 18 litter bags each with dead plant material from the two
marsh sites  (100 g each) and the swamp forest  (20 g each) were submerged in a
tidal creek adjacent to the University of Georgia Marine Institute  facilities
on Sapelo Island.  Six bags were retrieved from each  of the treatment areas

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(suspended, surface, submerged) at each location at one, six, and eleven-
month intervals.   Following retrieval, plant material was air dried and
massed to the nearest gram (marsh grass) and 0.1 gram (swamp leaf litter).
Leaching and respiration measurements were made on representative litter
samples from each of the treatments at each location.  Samples of litter bag
plant material and litter collected from the marsh and swamp surfaces at each
retrieval were oven dried at 60° C and ground in a Wiley mill (40 mesh
screen).  Spectographic analyses of P, K, Ca, Mg, Mn, Fe, B, Cu, Zn, Al, Sr,
Ba, and Ma; and determinations of total N were conducted by the Soil Testing
and Plant Analysis Laboratory, Athens, GA.

     Statistical analyses were accomplished using the Statistical Analysis
Computer Systems Program (SAS) (Barr et al., 1976).  Duncan's Multiple Range
test was used to evaluate statistical differences in decomposition, respira-
tion, leaching and mineral composition of litter bag materials.

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                                 SECTION 4

                            RESULTS AND DISCUSSION


DETRITUS PRODUCTION AND AERIAL PRODUCTIVITY

     _S_.  cynosuroides living biomass for clear cut plots ranged from a high of
769 ± 98 g dry wt ra~2 in July to a low of zero in January (Figure 2).  Stand-
ing dead biomass peaked in November (1800 ± 275 g dry wt m~2) and reached a
low in March (158 ± 57 g dry wt m~2).   However, the latter figure does not
represent the amount of standing dead material usually present in early
spring because fire swept through the area destroying much of the dead ma-
terial prior to the March, 1979 collection.  In March, 1978, a year in which
the marsh was not burned, standing dead biomass averaged 1087 ± 104 g dry wt
m~2, and in April, 1978 the amount was 970 ± 94 compared .to 215 g dry wt m~2
for April, 1979.  Fire caused a decrease in litter biomass (88 ± 21 g m~2) in
March, 1979 compared to 427 ± 33 in March, 1978.  With the exception of the
unusually low amount of litter present at the March collection, litter bio-
mass was relatively constant throughout the year.

     Z.  miliacea living biomass for clear cut plots reached a maximum in
October and a low in March (Figure 3).  Unlike J3. cynosuroides, _Z. miliacea
apparently does not experience a complete "die-back" each growing season.
Live material was collected at each sampling throughout this study during a
two-year period preceding the present study.  Standing dead biomass was high-
est in April, 1978 and lowest in August.  Variations in litter biomass were
not as pronounced as in live and standing dead material.

     Leaf litter accumulations at the forest sites were highest in November
with the lowest accumulation occurring in April and July at Riverbend and the
freshwater swamp site, respectively (Figure 4).

     Net aerial primary productivity for S_. cynosuroides was 2029 g dry weight
m~2 yr~l with a turnover time of 2.64.  Turnover time is equal to productivity
divided by the maximum live biomass.  NAPP reached a maximum between 17 April
and 30 May 1978 (472 g m~2) and was lowest between 9 January and 5 March 1979
(9 g m~2).  Odum and Fanning (1973) reported an NAPP of 2092 g dry wt m~2 yr"1
for _S_. cynosuroides on the south shore of Rabbit Island in the Altamaha River.
However, they did not use the Lomnicki method for calculating productivity
and therefore comparisons between the two figures may not be feasible.
Linthurst and Reimold (1978) reported NAPP for S_. cynosuroides in the

-------
1900


1800


1700


1600


1500
   r

1300
                  -o LIVE

                 —• STANDING DEAD

                     LITTER
   S.E.-1275
                                                   SE.'i362
      20     60     100     140
  17 APR   30 MAY  IOJUL  MAUG
   1978
                                   IBO
                                  I60CT
                                   -2
220    260     300    340    380
28NOV   9 JAN      5 MAR   13 APR
        1979
Figure 2.  Mean dry weight  (g m *" ±  S.E.) of  Spartina cynoauroidea
            from clear  cut plots in the Altamaha River Delta.

-------
  1100

  1000


   900


N  600
l

 E  700


f 600
 *

I" S0°

" 400


   300

   200


   100
                                    o	o LIVE

                                    •	• STANDING DEAD

                                             LITTER
           I
                  I
      20     66     100    140
   17 APR  3OMAY  IOJUL   I4AUG
    1978
                                    I BO
                                   I6OCT
                                   -2
220    260     300    340    380
2QNOV   9 JAN      5 MAR  13 APR
         1979
Figure  3.   Mean dry weight  (g  m   ±  S.E.) of  Zizaniopsis miliacea
            from clear  cut plots in the  Altamaha River  Delta.

-------
  180

  170


  160

  150

  140

  130


  120


l

_ 100
-C

I  90


£  80

o-  70

   60

   50




   30

   20

   10
•	• RIVERBEND

o	o FRESHWATER SWAMP
    20     6O     JOO     J40
17 APR   30 MAY   IOJUL  I4AUG
 1978
                                   180
                                  I6OCT
                                     -2
                           220     260
                           28NOV   9 JAN
300   340     380
   5 MAR  13 APR
  Figure 4.   Mean dry  weight  (g ra " ±  S.E.) of  leaf litter at  two
               forest  locations  in the Alt amaha  River Delta.

-------
 Itamaha River Delta ranging from 1742 to 6039 g dry wt m~2 yr~l depending on
 he technique used for calculating NAPP.   The Lomnicki method was not used
 or calculating NAPP in their study.   However, Linthurst and Reimold, using
 he method of Smalley (1958) reported an  NAPP of 2789 with a turnover time of
 ,.3.   When we calculated NAPP by the Smalley method we obtained an NAPP of
 '33 g dry wt m~2 with a turnover time of  2.3.  The possible explanation for
 :he rather sizable difference in NAPP between the two areas is that the
 Sroughton Island collection site was higher in elevation than the Linthurst-
 leimold site.  Although elevations were not measured in the present study, it
 /as readily apparent that our area was higher and drier than the Linthurst-
 teimold area.  Comparing the maximum living biomass between the two areas,
 -inthurst and Reimold reported a maximum of 2177 g m~^ whereas we found a
 naximum of only 769 g m~2.   As a further check on living biomass, in July,
 L978, we collected 5, 0.5 m^ samples of S_. cynosuroides from the site where
 the litter bags had been placed.  For that area we obtained a mean of
 1395 ± 228 g m~2, a figure almost twice as high as the value for Broughton
 Island.  Again, elevation was not measured, but it was obvious that the Reese
 Island area was lower and subject to more frequent tidal inundation.  Odum
 and Fanning  (1973), and others, have shown that creekbank _S. cynosuroides is
much more productive than more inland areas, presumably because of more tidal
 influence in the lower areas.  For comparison, we arbitrarily divided the
 collection site into two zones - a lower zone consisting of 3 pairs of plots
within 18 m of the riverbank, and a higher zone of 3 pairs of plots between
 19 and 30 m from the creekbank.  NAPP in the lower and higher zones were
 2048 and 1896 g dry weight m~2 yr~^-, respectively.  Thus our area appears to
 be more homogeneous than the areas studied by Odum and Fanning.  It should be
 noted that in the collection site, Spartina  alterniflora was the dominant
 plant on the riverbank, occupying a zone approximately 3 m wide.

     Productivity in the Broughton Island area may have been adversely
 affected by  fire which swept through the collection site in February, 1979.
 Although, standing live material is normally absent in late winter and early
 spring, dead material biomass is usually very high at that time of the year.
 As a result of the  fire, a  significant reduction in biomass of dead material
 was observed in the March collection.  This  reduction effectively lowered
 the NAPP value for  that time period.  The Linthurst-Reimold and Odum-Fanning
 NAPP values  for ^.  cynosuroides cited previously represent data for stands
 which had not been burned during the course  of the study period.

     NAPP for Z. miliacea was 1478 g dry weight m~2 yr~^ with a turnover  time
 of 2.37.  Maximum NAPP was  observed between  17 April and 30 May 1978  (351 g
 m~-) and dropped to  zero for the period between 28 November 1978 and  9
 January 1979.  To determine differences between creekbank NAPP and NAPP
 farther inland we divided the collection site into two zones - one  zone con-
 sisting of  a series of 4 paired plots within 12 m of the creekbank; the other
 zone a series of 4  paired plots between 13 and 24 m from the creekbank.  NAPP
 values were  1824 and 1237 g dry weight m~2 yr~^ for creekbank and inland
 zones,  respectively.  Presumably the higher  NAPP in the creekbank zone is a
 result of more tidal activity in this area (Odum and Fanning, 1973).  To
 properly assess the potential contribution of the marshes  to the detritus
 food web, data on elevation and tidal inundation are needed for both  areas.
                                    12

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RESPIRATION AND LEACHING STUDIES

     la J5.  cynosuroides Cbe attached dead community on the fallen dead had a
higher respiration rate than that of standing dead (Figures 5 and 6).
Generally,  respiration rates were higher in the spring, somewhat reduced
during the summer reaching a low in October, and maintained a low rate until
early spring when a significant increase occurred.

     Aquatic respiration rates in the £. miliacea marsh followed the same
pattern as that in S_. cynosuroides (Figures 5 and 6).  However, the rates in
Z. miliacea were somewhat higher, with the highest rates being observed in
the standing dead community.  Because of the frequent  flooding at the River-
bend site, the standing dead community was subjected to inundation for a
larger period of time than the similar community at Broughton Island, which
conceivably could have resulted in higher respiration  rates.  Incubation
temperatures, which ranged from a low of 8° C in January to a high of 27° C
in July, did not appear to have an effect on the pattern of respiration rates.
It is more likely that the previous history of the dead material was the most
important factor in the development of the microbial community and concomi-
tant respiratory rates.  Aquatic respiration rates for the swamp forest leaf
community were, generally, significantly higher than the rates observed for
the two marsh communities  (Figure 7).  Among the  three species of tree leaves
studied, Taxodium distichum showed the highest mean respiratory rate for the
entire year (238 ± 90 ug C g~l dry wt hr"*) while Liquidambar styraciflua
showed the lowest rate (121 ± 27).  The highest rate recorded for Taxodium
was almost an order of magnitude higher than that recorded for marsh grass.
The reasons for these differences are not clear,  although it may be related
to nutrient mediated events in the two environments.

     In S.. cynosuroides. aerial respiration of the standing dead microbial
community was fairly constant during  the entire year with the exception of a
peak in October (Figure 8).  The fallen dead community generally had a higher
respiration rate showing a  relatively low rate in the  spring and early summer,
a fairly constant higher rate during  late summer, fall, and winter, and a
return to a lower rate in  early spring.  The differences in respiration rates
between the fallen dead and standing  dead communities  may be related to a
larger microbial biomass on the fallen  dead material and/or differences in
nutrient content.  Likewise, at Rlverbend in _Z. miliacea,  the standing dead
community had a relatively  low, constant respiration rate  (Figure 9), while
the  fallen dead community  had a much  higher rate  at each sampling period and  ,
was much more variable.  However, the annual cycle was different in  that the
lower  rates were observed  in November and January, rather  then early spring.

     Aerial respiration data for  the  microbial community on swamp forest
leaves are difficult  to interpret.  Over the entire year, Nyssa aquatica and
Taxodium distichum communities had similar  respiration rates, which were
considerably higher  than the L. styraciflua community  (Figure 10).  I.
distichum microbial  aerial  respiration  exhibited  a pattern of higher rates
for  late spring and  summer, a reduction in  fall and winter with the lowest
rate occurring in April.   The JN.  aquatica community showed an increase in
respiration rates from early spring  through July  with  a peak in August, a
drop in October to early summer levels, and a series of high and low values

                                      13

-------
o
•f
>.
u
•O
T
v
o
9
        ~55	60    155
     17 APR  30 MAY   to ML  HAUG
      1976
13 APR
   Figure 5.  Aquatic  respiration (yg C g~  dry wt h~  ±  S.E.)
              of attached  dead plant community in fallen  dead
              material from Broughton Island (Spartina
              cynoauroides)  and Riverbend (Zizaniopaia millacea).
              Incubation time,  3.5 h.

-------
  I
  o»
  o
  o>
  a.
140

130

120

MO

100

90

60

70

60

50

40

30

20

10
                              -• BROUGHTON ISLAND

                              -o RIVERBEND
                                      T A
                                               \
          20    60    100   HO
       17APR 30MAY IOJUL HAUG
        1978
                          ISO  220   260   300   340   380
                          I60CT  28NOV  9JAN    5MAR  13APR
                                    .   1979
Figure 6.
                                        -1
                                               -1
      Aquatic  respiration  (\ig  C g   dry wt h   ± S.E.) of
      attached dead plant  community in standing dead material
      from Broughton Island  (Spartina cynosuroides) and Riverbend
      (Zizaniopsis miliacea).  Incubation time,  3.5 h.

-------
    692




Ic   400

1.  350
i
>.  300
•o
7   250
o»
«J   200

*•  150

    100


     50
                            a-	o Nysso aqualica

                            •	• Liquidambar styraciflua

                                    Taxodium dislichum
100
         20     60
      17 APR  30 MAY   IOJUL
       1978
   I4AUG
140
 160
I60CT
220
28NOV
260
 9 JAN
 1979
300    340     380
   5 MAR  13 APR
   Figure 7.   Aquatic respiration  (pg C  g   dry wt h    ± S.E.) of
                the attached  dead plant community for three species
                of swamp forest leaves.  Incubation time,  3.5  h.

-------
I
fi
.9"
 »

•o

T
 o
u
 CP
 0.
90

80

70

60

50

40

30

20

10
        20     60     100    140
    I/APR   30MAY   IOJUL  MAUG
     1978
                                        -« FALLEN DEAD
	O STANDING DEAD
                               180
                               I6OCT
     220    260
     28 NOV    9 JAN
             1979
300    340    380
   5 MAR  13 APR
  Figure  8.
                                          -1
                                                   -1
          Aerial respiration (pg  C g   dry wt  h ** ± S.E.)  of
          the  attached  dead plant community  in fallen  and  standing
          dead Spartina cynosuroidea.   Incubation time,  3  h.

-------
CO
                                                                         « FALLEN DEAD
                                                                     	o STANDING DEAD
                                   2O     60     100     140
                               17 APR  30 MAY  IOJUL  I4AUG
                                1978
 180
16 OCT
220    260
2B NOV  9 JAN
        1979
                                       300    340    380
                                           5 MAR   13 APR
                              Figure 9.
                                                                     -1
                                       ,-1
Aerial  respiration  (pg C g   dry  wt h A ± S.E.)  of the
attached  dead plant  community in  fallen and standing dead
Zizaniopsls miliacea.   Incubation time, 3 h.

-------
I
.e
 o
 '5


 •o

7
                                                       Nysso oquotica

                                                       Liquidombor slyrocrflua

                                                       Taxodium distichum
         20     60     100    140
     17 APR  30 MAY   IOJUL  14 AUG
      1978
 ISO
I6OCT
220
26 NOV
260
9 JAN
1979
300    340    360
    5 MAR  13 APR
  Figure 10.   Aerial  respiration (pg  C g    dry wt h    ± S.E.) of  the
                attached dead plant community for three species of  swamp
                forest  leaves.   Incubation time, 3 h.

-------
for the remainder of the year.  The L. styraciflua community, however, had a
more constant rate with the exception of a lower and higher rate in July and
October, respectively.  Without further speculation, we conclude that these
variations reflect only species differences.

     In j>. cynosuroides and Z. miliacea marshes seasonal patterns in DOC
leaching rates are not apparent (Figures 11 and 12).  For both species of
grasses there are no significant differences in the rate of leaching between
fallen dead and standing dead averaged over the entire year.  However, Z.
miliacea had a rate approximately 100 vg C g~"l dry weight h~^- higher than _S.
cynosuroides which may have been a result of longer inundation times for the
Z_. miliacea marshes.

     T_. distichum showed a definite increase in DOC release from May through
August 1978 with a decline to a low in January, 1979 and then an increase
through March and April of 1979 (Figure 13).  L. styraflua exhibited a
similar pattern except that the highest rate was observed in October, 1978,
with a subsequent decline to a low in March, 1979, followed by an increase
in April.  N_. aquatica, on the other hand, had levels of DOC significantly
lower than the other two species over the entire year.  Seasonal trends in
leaching rates were not as apparent as the patterns of leaching observed in
the other two species.  DOC leaching rates for N:. aquatica in this study for
a 3 hr period were comparable to DOC rates for the same species reported by
Brinson  (1977).  Leaching rates for the 3 species of the leaves were
significantly higher than those of the marsh grasses.

     As  indicated above, respiration and leaching rates were quite variable,
and although we have not fully identified the factors causing these variations
we might suggest probable causes.  Marsh grass and swamp forest leaf litter
were removed randomly from the marsh surfaces and forest floor. Consequently,
data relative to residence times in these areas and times of tidal inundation
were not available.  Obviously, the age of the material and length of exposure
to tidal inundation would have had   significant effects on the rates.  In
addition, the proportion of leaves and stems in the sample may have affected
dead plant microbial community respiration rates and DOC releases (Gallagher
et al.,  1976).  Because no attempts were made to ensure equal masses of stems
and leaves at each collection, it is  conceivable that the disproportionate
representation of these components would have caused the rather wide
variations observed in this study.  Furthermore, we would expect less
variations in rates among newly fallen leaves and standing dead material com-
pared  to  aged stems.  Data for aerial respiration and DOC leaching rates over
the entire year showed less variations in standing dead (predominantly leaves)
compared  to  fallen dead (a mixture of leaves and stems).  Also, aquatic
respiration  rates for _S. cynosuroides standing dead were less variable than
for the  fallen dead material.  However, in Z_, miliacea, standing dead material
had a wider  variation in aquatic respiration rates  than did the fallen dead.
Thus,  for a  more accurate assessment of respiration and leaching rates, more
information  relative  to the age of the material and tidal inundation times
should be obtained, and in marsh grasses, measurements should be made separa-
tely on  stems and leaves.
                                     2U

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                             7OO
                             600
500
to
                           l
                           .c


                           o
                           0>


                           o 300


                           CT
                           3.



                             ZOO
                             100
                                                                 •	•  FALLEN DEAD

                                                                          STANDING DEAD
                                                                                    y
17 APR  30 MAY
 1978
    100
IOJUL   I4AUG
                                                      T4O~
                                ISO
                                I60CT

                                                                                            i
                                                                   2SNOV
9 JAN
 1979
                                                      5 MAR  13 APR
                              Figure 11.
                                                                 -1
                                                 -1
              DOC released (ug C g  " dry wt h " ± S.E.)  from
              fallen and  standing dead Spartina cynosuroides.
              Incubation  time, 3 h.

-------
N>
                          1000 •
                           900 -
                                                                          • FALLEN DEAD
                                                                           STANDING DEAD
                                 20     60     100     HO    180    22O    260    300    340    380
                             17 APR  30 MAY  10 JUL  I4AUG      I60CT   28NOV  9 JAN      5 MAR  13APR
                              1978                                         1979

                              Figure 12.  DOC released (pg C g~   dry wt  h~   ± S.E.)  from
                                           fallen and standing  dead Zlzanlopsla mlllacea.
                                           Incubation time, 3 h.

-------
ro
u>
                                                                                     Nysso oquolico

                                                                                     Liquidombor slyracifkia

                                                                                     Toxodium distichum
                                                                                                   /
                                 I
                                       20     60     100    140
                                   17 APR   30 MAY  IOJUL   I4AUG
                                    1978
 ieo
I6OCT
220
28NOV
9 JAN
 1979
300    340     380
    5 MAR  13 APR
                              Figure 13.   DOC released  (  g C g      S.E.) from three species of
                                            decomposing swamp forest leaves.   Incubation  time,  3 h.

-------
LBS - WEIGHT LOSSES

     In the _S. cyuosuroides marshes, suspended litter showed the slowest rate
of decomposition (Tables 1 and 2).   Significant weight losses did not appear
until the 11-month collection.  However, surface litter decomposed rather
rapidly, showing a 31% weight loss at 6 months and a 60% loss at 11 months.
The submerged litter experienced a significant weight loss during the first
month (16%) and a subsequent loss of 32% at the 6-month collection.  Litter
submerged in salt water showed a pattern similar to that of other submerged
bags at the 1-month collection.  Rates of decay for suspended, surface, and
submerged litter are expressed in the following formulae:

            suspended (11 months) y =  99.5 - 0.74X
            surface   (11 months) y = 100.3 - 0.18X
            submerged ( 6 months) y =  96.5 - 0.2SX,
            where y = percent remaining at'time X,
            and X = time in days.

     Decomposition rates for _Z. miliacea litter follow the same general
trends as those for ^. cynosuroides litter - submerged > surface > suspended.
However, the rates in ^. miliacea are greater than those in £. cynosuroides.
Suspended litter showed a 58% decrease at 6 months without a further signifi-
cant decrease at 11 months.  Surface bags exhibited a 17% decrease at 1 month
and a 72% decrease at 6 months with an 86% decrease at 11 months.  The
greatest magnitude of decomposition was observed in the submerged bags - a
19% decrease in biomass at 1 month with a 94% decrease at 6 months.  In fact,
only one of six bags contained litter at the 6-months collection period.
Thus, the decrease in biomass was indeed dramatic between the 1-month and
6-months collection periods.  Linear regression equations depicting decompo-
sition rates  for the three types of litter are as follows:

            suspended (11 months) y = 94.8 - 0.19X
            surface   (11 months) y =• 93.5 - 0.27X
            submerged (11 months) ? = 98.5 - 0.52X

Thus, suspended Z. miliacea litter had  a decay rate comparable to ^.
cynosuroides  surface litter, while _Z. miliacea surface litter had  a rate
comparable  to the ^. cynosuroides submerged litter.  The submerged _Z. miliacea
decay rate was approximately  twice that of ^. cynosuroides submerged litter.
The more rapid decay rates observed for Z. miliacea suspended and  surface
litter  are probably related to the longer  time of tidal inundation in the
freshwater marshes.  The rather wide difference in weight losses between the
two types of  submerged marsh  grass litter  cannot be fully explained at this
time.  We suggest  that differences in current velocity and composition of  the
grasses are factors.  _Z. miliacea has a higher water  content than JS.
cynosuroides  (73 and 67% respectively).

     Swamp  forest  leaf litter  showed significant decreases in weights at each
time interval with the greatest  losses  occurring between one and six months
(45%).  Following  the 6-months collection, only another 10% decrease occurred.
A significant difference in the  rate of decomposition between surface litter
                                     24

-------
and submerged litter was not observed as is illustrated in the following
linear regression equations:

            surface   (11 months) y - 89.1 - 0.25X
            submerged (11 months) y = 93.5 - 0.25X

The similarity in decomposition rates is probably related to the fact the sur-
face bags were inundated for long periods of time during the study.  At each
of the collections, the surface bags were covered with approximately 25 cm of
water which indicated that surface and submerged bags were exposed to the same
general environmental conditions.

LBS - AQUATIC RESPIRATION

     Respiration rates for the three types of saltwater submerged litter were
significantly higher than in all other treatments (Figure 14; Tables 1 and 2).
This is somewhat surprising in that Gallagher (1977) reported lower rates for
similar material suspended in saltwater as compared to freshwater.  In the
latter work, material had been submerged for a period of only 7 days which may
account, in part, for the differences observed.   The aquatic respiration rate
in suspended litter was significantly lower than in surface and submerged
litter in both species of marsh grasses.  No significant.differences were ob-
served between surface and submerged litter for the three types of litter.

     In comparing aquatic respiration rates between species (Table 2), swamp
litter showed a significantly higher rate  (81 yg C g~l hr~l) than did S_.
cynosureides (48 yg C g,"  hr~l) and Z. miliacea (42 ug C g~l hr~l) litter.
In combining aquatic respiratory data for  all types of litter, saltwater sub-
merged litter had the highest rates, suspended litter the lowest rates, with
surface and submerged litter having similar, intermediate rates.

     For £. cynosuroides and Z., miliacea combined aquatic respiratory rates
for all types of litter were significantly higher at 1 month than at 6 months,
with no differences between 6 months and 11 months.  The combined respiratory
rate for swamp litter was significantly higher at 1 and 6 months than at 11
months with no significant differences between 1 month and 6 months.  Briefly
summarizing the above material, aquatic respiratory rates were higher in more
aquatic situations  (excluding the saltwater treatment) and were generally
higher in  the earlier stages of decomposition.

LBS - AERIAL RESPIRATION

     Generally, aerial respiration rates were higher in the earlier stages of
decomposition as is indicated when comparing the combined rates of all litter
types, or when comparing the rates of each type to  time  (Tables 1 and 2 and
Figure 15).  Rates were significantly higher at 1 month with no significant
differences between 6 and 11 months.

     Unlike the situation for aquatic respiration,  swamp litter exhibited the
lowest aerial respiratory rate with Z. miliacea showing the highest rate.
However, in comparing types of litter (all species) saltwater litter had the

-------
highest rate followed in decreasing order (all significant differences) by
submerged, surface and suspended litter.

     In comparing respiratory rates for litter representing each species, the
trend observed above is not as pronounced.  For _S. cynosuroides both salt-
water and on-site submerged litter had higher aquatic respiration rates than
suspended and surface litter but did not differ from each other.  However,
surface litter had a significantly higher rate than suspended litter.  For Z_.
miliacea, saltwater litter exhibited a significantly higher rate than the
other three types, submerged was higher than surface and suspended, but no
differences occurred between the latter two types.  In swamp litter, salt-
water submerged aerial respiratory rates were significantly higher than
surface submerged rates while surface rates were higher than submerged rates.
Thus, while the pattern for aerial respiration generally resembles that of
aquatic respiration, more variation occurred within the individual species.

LBS - DISSOLVED ORGANIC CARBON  (DOC)

     When comparing the combined DOC leaching rates for all litter types, the
following trends were noted (Tables 1 and 2, and Figure 16).  As was observed
for respiration rates (aquatic  and aerial), leaching rates were generally
higher in the earlier stages of decomposition.  _S_. cynosuroides litter had
significantly higher leaching rates than Z_, miliacea and' swamp litter, while
Z. miliacea was significantly higher than swamp litter.  Surprisingly, swamp
litter showed a net negative leaching rate which indicates an uptake of car-
bon.  Ac  this point, we cannot  explain these results.  When comparing types
of litter for all species involved, suspended material had a higher  rate  than
all other types with no significant differences in rates between the other
types.  This is also somewhat surprising, since we would have expected higher
leaching  rates in the submerged and surface litter.  In terms of individual
species,  however, _S. cynosuroides on-site submerged litter showed a  signifi-
cantly higher leaching rate than the other types.  Suspended, surface, and
saltwater submerged litter did  not differ in DOC leaching.  In Z. miliacea,
DOC leaching rates were significantly higher for suspended litter with no
differences occurring between the other types.  DOC leaching rates of swamp
forest leaf litter in surface and submerged bags did not differ significantly.
Many negative values were recorded which may indicate an uptake of DOC by the
material.

     Comparisons of mean aquatic respiration, aerial respiration, and DOC
leaching  rates of litter bag material for the three collection periods to
rates  for material  (standing dead and fallen dead) from "natural areas"
averaged  over the entire year show the  following patterns.  For both species
of marsh  grasses, aquatic respiration rates were similar for litter  bag
material, fallen dead, and standing dead.  Aerial respiration rates  for _S.
cynosuroides litter were higher than those of fallen dead and standing dead.
In Z_. miliacea, litter bag material and fallen dead aerial respiration rates
were similar and significantly  higher than standing dead rates.  DOC leaching
rates were  similar in all _S. cynosuroides material, but Z_. miliacea  litter bag
material  had a rate approximately 21/2 times lower than that of fallen dead
and  standing dead grass.
                                      26

-------
ISJ
      TABLE 1.  RESULTS OF DUNCAN'S MULTIPLE  RANGE TEST   FOR TIME  AND TYPE DIFFERENCES IN MEAN BIOMASS (WT),
          AQUATIC RESPIRATION (AQUA), AERIAL  RESPIRATION  (AER),  AND DOC LEACHING (DOC) FOR TWO SPECIES
              OF MARSH GRASSES AND SWAMP FOREST LEAVES ENCLOSED  IN LITTER BAGS SUSPENDED (SUS),
                         SURFACE (SUR), SUBMERGED (SUB) AND  SALTWATER TREATED (SALT)t
Spartina cynosuroides
TIME
0
1 month
6 months
11 months

0
1 month
6 months
11 months

0
1 month
6 months
11 months
WT

89b
74 c
55d

lOOa
86b
30 c
25c

20a
16b
6c
4d
AER

61a
31b
26b


84 a
43c
60b


56a
22b
19b
AQUA

70a
19b
2 Ob


7 la
34b
21b


114a
90a
24b
DOC

527a
109b
-177c
Zizanlopsis

181a
131a
296a
Swamp

- la
-32a
-49a
TYPE
SUS
SUR
SUB
SALT
millacea
SUS
SUR
SUB
SALT
Litter
SUR
SUB
SALT

WT
90a
77c
84b
93a

70b
62c
62c
94a

lie
12b
18c

AER
lie
44b
74 a
63a

47c
51c
85b
124a

34b
29c
58a

AQUA
13c
37b
44b
14 3a

7c
46b
65b
14 la

83b
53b
16 3a

DOC
261b
288b
692a
118b

322a
92b
75b
153b

lla
Sab
-58b

        Means  with the same letters are not significantly different

        Wt  in  grams dry weight; AER, AQUA and DOC in pg C g~  dry weight h~

-------
TABLE 2.  RESULTS OF DUNCAN'S MULTIPLE RANGE TEST  FOR TIME, SPECIES, AND TYPE
     DIFFERENCES IN MEAN BIOMASS (WT), AERIAL RESPIRATION  (AER), AQUATIC
           RESPIRATION (AQUA), AND DOC LEACHING (DOC) FOR  SPARTINA
            CYNOSUROIDES (SCYN), ZIZANIOPSIS MILIACEA (SMILI), AND
               SWAMP FOREST LITTER BAG MATERIAL - POOLED DATAt

TIME
0
1 month
6 months
11 months
SPEC
SCYN
ZMILI
SWAMP
TYPE
SUS
SUR
SUB
SALT
WT

77a
67b
37c
29d

85a
70b
13c

80a
49c
47c
65b
AER


67a
33b
35b

43b
65a
35c

32d
43c
55b
81a
AQUA


82a
43b
22c

42b
48b
81 a

lOc
55b
54b
149a
DOC


250a
81b
-60c

330a
16 5b
-18c

290a
135b
15 8b
87b
   Means with the same letter are not significantly  different

 r  WT in grams dry weight; AER, AQUA, and DOC  in  ug  C  g~   dry weight  h~
                                     28

-------
                                                                                      Swamp Forest leaves
N>
135
130
105
!c 90
I
» 75
>»
TJ
- 60
e»
° 45
i»
a.
30
15
0
-15



















S. cynosuroides








fin


































16 1 6 II 1 6 II
SUB SUS SUR
-
-






Z. mUlocea
.

-





















1 6
SUB

















n














— a 	
1 6 II 1 6 II
SUS SUR









- — .
-
-






























1






























6 II 1 6 II
SUB SUR
                                                                  -1
-1
                           Figure  14.   Aquatic respiration (ug C g   dry wt  h  """  ±  S.E.)  of  the
                                       attached dead plant community from  dead plant  material
                                       enclosed in suspended  (SUS), surface  (SUR),  on-site sub-
                                       merged (SUB), and saltwater submerged (SAL)  litter bags.
                                       Incubation time, 3 h.

-------
ui
O
                             120


                             (OS
~  90
 f

 !7
 >»
 * GO
                           o
                             45
                             30
                              15
                                      S. cyno*urold««
                                        Z. mlllacto
                                            Swamp Forttl
                                                                          1
                                 I 6
                                  SUB
               I 6 II
               SUS
I  6  II
SUR
I 6
SUB
I  6 II
SUS
I  6 II
SUR
I 6 II
SUB
I  6 II
SUR
                           Figure 15.  Aerial respiration (pg C g~  dry wt h~  ± S.E.) of  the
                                       attached dead plant  community from dead plant material
                                       enclosed in suspended  (SUS), surface (SUR), on-slte
                                       submerged  (SUB),  and saltwater submerged (SAL) litter
                                       bags.  Incubation time,  3 h.

-------

eoo

700
!c 600
i 500
af
>. 400
7 300
o>
u 200
*• 100
S.


-
-
_

•
-

-
-


















cymxuroidet










1










•
—












1 6 II 1 6 II
SUB SUS






















































350
300
250

200
ISO

100
50











Z. mlllocea


.

•
-

-
-
1 6 II
SUR











































—














16 1 6 II
SUB SUS













—



















Swamp Fore it

100
75

50
25
n
1 6 II
SUR -25



-50
-75

leaves
"
•

-
-
-41
-
- 1 6 II 1
SUB






W

6 II
SUR
Figure 16.   DOC released (pg C g~  dry we h~  ± S.E.)  from dead plant
            parts enclosed in suspended (SUS), surface (SUR),  on-site
            submerged (SUB) and saltwater submerged (SAL)  litter bags.
            Incubation time, 3 h.

-------
     Aerial respiration rates of swamp litter bags material was similar to
the rates of fallen leaves.  Aquatic respiration rates of litter bag material
were much lower than rates for the three species of the leaves utilized in
this study.  Mean DOC leaching rates for litter bag material, a composite of
fallen leaves representing several species of trees, was -18 ug C g~l hr~l.
Rates for fallen leaves representing N^ aquatica, _L. styraciflua, and T.
distichurn, were 541, 794, and 675 yg C g~i hr"1, respectively,  Obviously,
confining the swamp litter in bags served to reduce the leaching rates.  The
causes of these reductions are not known, and a repeat of the experiment
would be helpful to determine whether the reduction was real or simply a
result of experimental error.

LBS - MINERAL COMPOSITION

     Swamp litter had significantly higher concentrations of P, Ca, Mg, N,
Mn, Fe, Al, B, Cu, Sr, and Ba (Table 3).  For the above elements, ^.
cynosuroides and _Z. miliacea were similar in concentrations with the excep-
tion of P, N, and Ba which were significantly higher in J3.. cynosuroides than
2^. miliacea.  7^.  miliacea had significantly higher concentrations of Zn  than
did S_. cynosuroides with no differences in levels between Z_. miliacea and
swamp litter, and no difference between swamp litter and J3. cynosuroides.  ^.
cynosuroides had a significantly higher level of Na than.the other two  types
with no differences occurring between swamp litter and Z_. miliacea.  Marsh
grasses and swamp litter did not differ significantly in K levels.

     When pooled data  (Table 3, all treatments, all species) were compared  to
time, the  following five trends were noted:

     1)  significant increases in P concentrations at 6 months;
         no significant decreases at 11 months; 11-month levels
         somewhat higher than 1-month level

     2)  significant increases of Ca, Cu, Mn, and Sr at 6 months;
         further significant decreases at 11 months to 1-month
         levels

     3)  significant increases of Ba, Fe, Na, and N at 6 months;
         no  further changes at 11 months; 6 and 11-month levels
         significantly higher than  1-month level

     4)  no  changes in Zn  between 1 month and 6 months; increases
         at  11  months  to a level significantly higher than at 1
         month

     5)  significant decreases of K, Mg, Al, and B at 11 months;
         6 and  11-month levels significantly lower  than 1-month
         levels

Thus, at  the end of the 11-month period,  levels of Ba, Fe, Na, N, Zn and  P
represent  elemental accumulations while K, Mg, Al and B levels indicate
losses.  No  significant changes appeared  to have occurred in  concentrations
of Ca, Cu, Mn,  and Sr.

                                     32

-------
UJ
LJ
      TABLE 3.  RESULTS OF DUNCAN'S MULTIPLE RANGE TEST  FOR TIME, SPECIES AND TYPE DIFFERENCES (POOLED DATA)
           FOR MEAN ELEMENTAL COMPOSITION OF SPARTINA CYNOSUROIDES  (SCYN), ZIZANIOPSIS MILIACEA  (ZMILI),
                  AND SWAMP FOREST LEAF (SWAMP) LITTER BAG MATERIAL - SUSPENDED (SUS), SURFACE (SUR),
                                  SUBMERGED (SUB) AND SALTWATER TREATED  (SALT) I"

TIME
1 month
6 months
11 months
SPEC
SCYN
ZMILI
SWAMP
TYPE
SUS
SUR
SUB
SALT
P

.0959b
.U89a
.1078ab

.0676c
.09665
.1659a

.0622c
.1087b
.1296a
.1372a
K

.0899a
.0329b
.0183b

.0516a
.0604a
,0558a

.0276b
.0364b
.0463b
.1887a
Ca

.5330b
.8363a
.6086b

.2974b
.3943b
1.3952a

. 3051d
.7480b
.8878a
.5239c
Mg

.1936a
.1523b
.1180b

.1438b
.1537b
.2007a

.1015b
.1237b
.1253b
.4775a
N

.82b
1..29a
1.27a

.76c
1.13b
1.39a

.8867b
1.1967a
1.1429a
,8978b
Mn

lllOb
1758a
994b

576b
94 Ib
2597a

383d
1052c
1839b
2652a
Fe

3980b
5257a
6405a

2602b
3827b
9365a

1655c
5922ab
6925a
4801b
Al

6304a
5077b
4383b

4377b
4962b
7566a

2583c
5531b
6352b
9484a
                                                                                              (Continued)

-------
TABLE  3.   (Continued)
                                        Cu
Sr
lia
Na
TIME
1 month
6 months
11 months
SPEC
SCYN
2MILI
SWAMP
TYPE
SUS
SUR
SUB
SALT

20.82a
9.91b
7.04b

8.32b
7.01b
31.06a

4.97c
8.75b
9.06b
59.23a

4.215b
5.400a
4.684b

3.001b
3.177b
8.734a

2.500c
4.973b
6.461a
4.785b

49. 4b
294. Ib
690. 2a

39. 3b
449. 2a
317. 2ab

579a
192a
15 7a
37a

38.92b
53.93a
41.36b

25.42b
29.90b
85.56a

18.51d
45.12c
55.35b
69.74a

46.92b
97.09a
75.50a

13.72c
43.79b
170. 94a

26.92b
90.16a
107. 89a
13.03b

194b
1393a
413a

1099a
376b
269b

958a
748ab
268b
116b
   Means with the same letter are not significantly different
t  P, K, Ca, Mg, N, in %; others in PPM

-------
     Comparison of mineral content among suspended,  surface, on-site sub-
merged, and saltwater litter showed that K, Mg, Mn,  Sr, Al and B levels were
significantly higher in saltwater submerged litter than in other types. When
saltwater submerged litter is excluded from the comparisons, the following
trends were noted.  No differences in levels of K, Mg, and Zn were noted. For
?, Ca, Mn, Cu, and Sr concentrations in on-site submerged > surface > suspen-
ded.   N, Fe, Al, B, and Ba levels were equally higher in submerged and
surface litter than, in suspended litter.  Generally, surface litter was
intermediate in elemental concentrations, with suspended material usually
having the lowest concentrations with the exception of Na which was signifi-
cantly higher in suspended material.

     The patterns of elemental composition for .S_.  cynosuroides, _Z. miliacea,
and swamp litter vary somewhat from those observed above.  When comparing _S.
cynosuroides litter concentrations at the collection periods, three general
patterns were noted (Table 4).  P, K, Al, and Cu showed steady decreases
through time until 11-month levels were significantly lower than 1-month
levels.  Ca, Mn, Sr, Ba, Na, and Fe concentrations increased between 1 and 6
months followed by a decrease between 6 and 11 months to levels characteris-
tic of the 1-month collection.  N levels followed the latter pattern with the
exception that although the 11-month value was lower than the 6-month value,
it was significantly higher than the 1-month concentration.  B, Mg, and Zn
concentrations did not differ significantly with time.

     In ^. cynosuroides, elemental concentrations were highest in saltwater
and/or on-site submerged litter.  K, Mg, Mn, Al, and B concentrations were
highest in saltwater treated litter.  In comparing only suspended, surface,
and on-site submerged litter the following relationships were noted.  K, B,
Zn, Mg, and Mn did not differ significantly.  For P and N, on-site
submerged > surface > suspended; on-site submerged litter levels of Ca, Cu,
Ba, and Sr were higher than surface and suspended; and Al and Fe levels for
surface and submerged were higher than suspended.  Only in Na levels were
higher levels seen for surface and suspended litter as compared to submerged
litter.  It appears that elemental accumulation was accelerated in the more
aquatic conditions.

     No significant changes in P, Mn, Al, Ba, and Na concentrations in _Z.
miliacea occurred during the 11-month study period  (Table 5).  Although Ca
and Sr levels were significantly higher at 6 months, further decreases
occurred so that  11-month levels were similar to 1-month levels.  B, K, and
Mg concentrations at the 11-month collection were significantly lower  than at
the 1-month collection.  Cu, Fe, N, and Zn showed significant increases at 11
months with Cu  and N accumulating more rapidly than Fe and Zn.  As in £.
cynosuroides, Z_.  miliacea saltwater submerged litter was higher in K, Mg, Mn
and B  levels.   In addition, Sr was significantly higher in the saltwater
treatment.  Comparing only suspended, surface, and on-site submerged litter
showed again  that suspended material was generally lower in elemental  concen-
trations than the other two types.  No significant differences in concentra-
tions  of B, Ba, Ca, Mn, Na, and Zn were observed between the three types of
litter.  Al, Cu,  Fe, and P levels were similar in submerged and surface bags
with both being higher in concentration then suspended litter.  Submerged

-------
   TABLE  4.  RESULTS  OF DUNCAN'S  MULTIPLE RANGE TEST  FOR TIME AND TYPE DIFFERENCES
              COMPOSITION  OF SPARTINA CYNOSUROIDES LITTER BAG MATERIAL - SUSPENDED
                     SURFACE (SUR),  SUBMERGED (SUB),  AND SALTWATER TREATED (SALT)t
IN MEAN ELEMENTAL
(SUS),

TIME
1 month
6 months
11 months

1 month
6 months
11 months

TYPE
SUS
SUR
SUB
SALT

SUS
SUR
SUB
SALT
P K

.0661b .0806a
.8777a . 383b
.0441c .0114c
_B
8. 26a
10.23a
5.90a
L K

.0388c .0313b
.0593b .0359b
.1058a .0500b
.0933a .1566a
B
6.29b
7.91b
5.31a
21.00a
Ca

.2217b
.4686a
.2207b
Cu
3.35a
3.64a
1.45b
Ca.

.2121b
.2749b
.4584a
.2705b
Cu
2.23b
2.72b
4.35a
3.21b
Mg

. 1508a
.1525a
.1181a
Zn
30.45a
46.27a
47.84a
M&

. 1166b
.1218b
.1326b
.3048a
lo. •
40.99a
36.87a
46.87a
27.23a
N

,57c
I.Ola
.82b
Sr
20.14b
38.87a
18.07b
_N

.65c
.77b
.95a
.64c
Sr
14. lie
23.05bc
38.42a
36. 7 lab
Mn

473. 8b
1093. la
90. 9b
JJa
10.23b
25.13a
5.51b
Mn

114b
202b
-
lllOa
M
4.87b
11.64b
31.28a
8.46b
Fe Al

2604ab 5033a
3475a 4431ab
1435b 2995b
Na
277. 6b
2396. 6a
996. Sab
Fe Al

607b 1322c
2717a 4056b
4220a 5398b
4343a 11449a
M
1253ab
1856a
39 8b
77b
*
   Means with the same letter are not significantly different
t  P, K, Ca, Mg, N, in %; others in PPM

-------
  TABLE  5.   RESULTS OF DUNCAN'S MULTIPLE RANGE TEST  FOR TIME AND TYPE DIFFERENCES IN MEAN ELEhflilNTAL
                COMPOSITION OF ZIZANIOPSIS MILIACEA LITTER BAG MATERIAL - SUSPENDED (SUS),
                       SURFACE (SUR),  SUBMERGED (SUB), AND SALTWATER TREATED (SALT)t

TIME
1 month
6 months
11 months

1 month
6 months
11 months

TYPE
SUS
SUR
SUB
SALT

SUS
SUR
SUB
SALT
*
Means with the
P K

.0874a .1053a
.1025a .0217b
.0874a .Ol56b
B
9.98a
5.20b
3.18c
' J? K

,089b .0247c
. 1095a .0281c
.0860ab .0414b
. L2iOa 0.2950a
K
. . 3.92b
3.68b
2.58b
31.71a
same letter are not sig
Ca

.3474b
.4832a
. 3847ab
Cu
2.61b
3.97a
3.38a
Ca

.3795a
.4400a
.2742a
.4391a
^u
2. 72b
3.77a
3.01ab
3. lOab
nif icantly
Mg

.1943a
.1325b
.0971c
•
Zn
29. Ib
105. 9b
1690. Oa
Mg

.0894b
.1053b
.0579c
.6089a
Zn
1099a
109a
34 a
18a
different
N

.81b
1.36a
l.Sla
ll
25.92b
35.55a
31.25ab
N.

1.08b
1.37a
0.82b
0.91b
Sjr
22.02c
32.52b
14.26c
63.90a

Mn

1043a
951a
758a
Ba
37.28a
47.94a
51.97a
Mn

59 8b
931b
612b
2449a
Ba
44.56a
53.29a
46.05a
10.50b

Fe Al

3260b 5309a
3909ab 4551a
4864a 4748a
M
105a
105 2 a
130a
Fe _/a

2494c 3592b
5349a 59lla
4918ab 5801a
261lbc 5840a
Ma
721a
180a
164a
28a

t  1', K, Ca, Mg, N, in %; others in PPM

-------
litter was clearly higher in K concentration,  while surface litter was
significantly higher than both suspended and submerged litter.  Significantly
lower concentrations of Mg were recorded for submerged material.

     Patterns of elemental accumulation and loss in swamp litter appeared to
be more clearly established than those of the marsh grasses (Table 6).  Fe,
P, and Cu showed significantly higher levels at 11 months than at 1 month
with accumulation being most rapid for P and Cu.  Al, B, K, and Mg levels
were significantly lower at 11 months than at 1 month with losses occurring
more rapidly for B, K, and Mg.  Initial accumulation at 6 months followed by
losses at 11 months to 1-month levels were observed for Ba, Ca, Mn, N, Na,
Sr, and Zn.  Brinson (1977) reported accumulations of Ca and Fe in swamp
forest leaves with losses of K and Mg.  He, however, showed also an accumula-
tion of N and a strong accumulation of P followed by a loss.  We also showed
accumulation of N and P, however, the P levels remained higher than the 1
month level and N accumulation was followed by a loss.

     Forest leaf litter showed no significant differences in nutrient levels
between surface and submerged litter.  This is not surprising, since, as
stated earlier, the environmental conditions, at least time of inundation,
were similar.  In comparing the three treatments, saltwater submerged litter
showed accumulation of Al, B, K, Mn, P, and Sr, with losses of Ba, Ca, Mg, N,
and Zn.  No differences were observed between Cu, Fe, and Ba levels.

     Specific comparisons of mineral content of litter bag material to
natural litter removed from the marsh surfaces at each collection are diffi-
cult to make.  The material collected from the marsh surface was more
heterogeneous in composition because it consisted of stem and leaves in
various stages of decomposition.  Presumably, litter bag material was more
homogeneous because standing dead marsh grass material at the same stage of
decomposition was used for the litter bags.  In addition, only one sample of
marsh litter material was analyzed for mineral composition, making statisti-
cal comparisons virtually impossible.  Nevertheless, some generalizations can
be made in comparing suspended, surface, and on-site submerged litter to
natural litter for the two species of marsh grasses.  Comparisons were not
made for swamp forest leaf litter.

     Al, Cu, Fe, Mg, Mn, N, Na, Sr, and Zn levels were lower in natural litter
than in litter bag material.  Qualitatively, the differences ranged from
somewhat lower to much lower.  Al and Fe were particularly outstanding in that
concentrations of these elements were, in some cases, two orders of magnitude
lower in natural litter.  Ca  and B levels were more variable but generally
similar in concentration in the four types of litter.  K levels were lower in
j>. cynosuroides litter but higher in _Z. miliacea litter.  P concentrations
showed definite similarities  to suspended litter levels in ^. cynosuroides
while being  lower in concentration than surface and submerged material.  In
Z. miliacea, however, K levels in natural litter were more similar to surface
litter levels at 1 month with no differences at 6 and 11 months.  Thus, it
appears that,  for many of the elements analyzed, enclosure in litter bags re-
sulted in  an accumulation of  minerals leading to an elevation of concentra-
tions over natural levels.  The causes of these increases are not clear.  The
                                      38

-------
  TABLE  6.  RESULTS  OF DUNCAN'S  MULTIPLE RANGE TEST
             COMPOSITION  OF SWAMP  FOKES'f LEAF LITTER
                     SURFACE (.SUR),  SUBMERGED (.SUB),
FOR TIME AiND TYPE DIFFERENCES IN MEAN ELEMENTAL
BAG MATERIAL - SUSPENDED (SUS),
SALTWATER TREATED (SALT)t

TIME
1 month
6 months
11 months

1 month
6 months
11 months

TYPE
SUR
SUB
SALT

SUR
SUB
SALT
P K

.1469b .0818a
.1800a .0387b
.1836a .0298b
B
52.03a
14.62b
13.06b
P K

.1574b .0454b
.1637b .0456b
.1974a .1146a
B
14.65b
• 14.31b
125. OOa
Ca

1. 195b
1.739a
1.343b
Cu
7.51b
9.41a
10.13a
Ca

1.533a
1.440a
.862b
Cu
8.42a
9. 34a
8.05a
Mg

.2498a
,1751b
.1431b
Zn
101. 6b
686. 7a
261. 7b
MB

.1442b
.1451b
.5187a
la
431. 4a
286.0ab
57. 7b
N

1.18b
1.58a
1.53b
Sjr
81.26b
95.45a
81.42ab
N

1.45a
1.41a
1.14b
s*.
79.75b
83.45b
108. 61a
Mn

2045b
3812a
2131b
Ba
108. 7b
250. 4a
187. 8ab
Mn

2025b
2564b
4398a
Ba
205. 6a
188. 5a
20. Ib
Fe

6775b
9207b
14217a
Na
201. 4b
453. 7a
169. Ob
Fe

9700a
9707a
7447a
Na
330. 8a
209. Oa
243. 7a
Al

9327a
6553ab
5612b




Al

6627b
7273ab
11164a




   Means with the same letter are not significantly  different
t  P, K, Ca, Mg, N, in %; others in PPM

-------
litter enclosed in bags may act Co remove suspended sediments from water
flowing through the bags and thus, through adsorption on the smaller particles
of marsh grass, increase nutrient levels.  On the other hand, the increases
may be a reflection of a more rapid loss of organic matter than minerals from
the litter.  This, however, would not explain why natural litter levels are
usually lower than the litter bag material unless one assumes that natural
litter is continually "recruiting" material from the standing dead material
and thus significant accumulations of elements do not occur.

EXPORT ESTIMATES

     To estimate the quantity of organic material transported to the estuary,
we modified a series of equations developed by Gallagher (1977).  The
equations are based on the model of carbon fixation and subsequent losses as
shown in the following diagram:
                                     respiration
                                                respiration
                                                             T
net ~
primary '
m
living
plant (G)
mortality ^
(M) . ^
standing
dead
plant (SD)
frag-
ment a- N
tion (F) '
fallen
dead
(FD)
lost
^ to the
^ estuary
(T.TT.I
                                      leaching
                                                 leaching
where P
AG + M, AG = G    - G.;  ASD
AFD
and T., and T  = harvest at beginning and end of time interval, respectively.

Decomposition of standing dead and fallen dead (litter) marsh plant material
was calculated with the following equations:
DE
  SD
DE
  FD
where,

DE,,n = Decomposition  (respiration and leaching) of standing dead during time
       interval,

DE..™ = Decomposition  (respiration and leaching) of fallen dead during time
       interval,

t  = time submerged during time interval,
                                     40

-------
t  = time emergent during time interval,
 3
SD1 = rate of leaching of DOC from the standing dead community,

SD  = submerged or aquatic respiration of the standing dead community,

SD  = emergent or aerial respiration rate of the standing dead community,
  &
FD, = rate of leaching of DOC from the fallen dead community,

FD  = submerged or aquatic respiration rate of the fallen dead community, and

FD  = emergent or aerial respiration rate of the fallen dead community.
  3.
After calculating decomposition, export was estimated with the following
equations:

     F = ASD + M - DE  , and
                     o U

     LIE = AFD + F - DEFD.

     Export values were determined for each time interval and then summed to
yield total export of organic matter for the entire time period.  It was
assumed that the dry weight of plant material was about 50% carbon.  Using a
2% tidal inundation time for the _S. cynosuroides marsh, the equation yielded
an export of 372 g C m~2 yr~^.  In the _Z. miliacea marsh, a 5% inundation time
for standing dead and a 10% inundation time for fallen dead yielded an annual
export rate of 147 g C m~2.  These export values account for 37% and 20% of
net annual primary productivity for ^. cynosuroides and _Z. miliacea, respec-
tively.  The lower export value for the _Z. miliacea marsh can be explained,
in part, by the higher respiration and leaching rates in this area and by the
greater proportion of time the freshwater marsh is exposed to tidal inunda-
tion,  Thus, more carbon is lost through respiration and leaching resulting
in less being available for export as detritus.  Nevertheless, it is apparent
that both marsh areas are making significant contributions to the estuarine
system.  Values for carbon export from S_. cynosuroides and Z_. miliacea marshes
have not been reported.  However, Teal  (1962) estimated that 45% of tall form
Spartina alterniflora net annual primary productivity is removed by tidal
action before it can be utilized by marsh consumers.  Odum and Fanning (1973)
reported export values of 25% and 8% of net annual primary productivity  for
tall form and short form _S. alterniflora, respectively.  Thus the values
reported in this study are comparable to estimates for tall form _S.
alterniflora.

     Although the equations shown above were formulated to estimate export
from marsh areas, we attempted to utilize them in calculating the potential
export of carbon from the swamp forest areas.  Combining leaf litter fall from
the two  forest collection sites (Figure 4), and assuming a 50% tidal inunda-
tion time, the data show a negative export of carbon  (-211 g C m~- yr~^)
which may indicate a transport of carbon into these areas.  Positive values
for carbon export were obtained only for the April-May collection period
                                     41

-------
(6 g C m~2)  and the August-October period (42 g C ra~2).   The latter value is
associated with relatively large quantities of leaf litter fall during this
time period, whereas the former value is probably related to lower rates of
respiration and leaching during this time period resulting in more carbon
available for transport in plant material.  Thus it appears that the forest
swamp areas may act as a sink not only in the accumulation of some nutrients
ns shown in this study and by Brinsin (1977), but also as a recipient of
carbon.   A more accurate account of tidal inundation time will enable us to
refine these estimates.
                                     42

-------
                                REFERENCES
Barr, A.  J.,  J.  H.  Goodnight, J.  P.  Sail, and J. T. Helwig.  1976.  A User's
     Guide Co SAS 76.   SAS Institute, Inc., Raleigh, North Carolina.

Brinson,  M.  M.  1977.   Decomposition and nutrient exchange of litter in an
     alluvial swamp forest.  Ecology 58:601-609.

Dunstan,  W.  M. ,  and L. P. Atkinson.   1976.  Sources of new nitrogen for the
     South Atlantic Bight.  Pages 69-78 in M. Wiley, ed., Uses, stresses and
     adaptation to the estuary.  Vol. I.  Estuarine Processes.  Academic
     Press,  Inc.  New York.

Gallagher, J. L., W.  J. Pfeiffer, and L. R. Pomeroy.  1976.  Leaching and
     microbial utilization of dissolved organic carbon from leaves of
     Spartina alterniflora.  Estuarine Coastal Marine Sci. 4:467-471.

Gallagher, J. L. and W. J. Pfeiffer.  1977.  Aquatic metabolism of the
     communities associated with attached dead shoots of salt marsh plants.
     Limnolg. Oceanogr. 22:562-565.

Gallagher, J. L.  1977.  Detritus dynamics and microbial aspects of food webs
     in river swamp wetlands and adjacent estuarine waters.  Progress Report
     for Office of Planning and Budget, Atlanta, Georgia.  35 pp.

Linthurst, R. A., and R. J. Reimold,  1978.  Estimated net aerial primary
     productivity for selected angiosperms in Maine, Delaware, and Georgia.
     Ecology 59:945-955.
   *
Lomnicki, A., E. Bandola,  and K.  Jankowska.  1968.  Modification of the
     Wiegert-Evans method  for estimations of net primary production.
     Ecology 49:147-149.

Odum, E.  P. ,  and Marsha E. Fanning.   1973.  Comparison of the productivity
     of Spartina alterniflora and Spartina cynosuroides in Georgia coastal
     marshes.  Bull.  G. Acad. Sc. 31: 1-12.

Smalley,  A.  E.  1958.   The role of two invertebrate populations, Littorina
     irrorata and Occhelium fidicinum in the energy flow of a salt marsh
     ecosystem.   Ph.D. Thesis.  University of Georgia, Athens.  126 pp.
                                     43

-------
Teal, J. M.  1962.  Energy flow in Che salt marsh ecosystem of Georgia.
     Ecology 43:614-624.

Wharton, C. H.  1970.  The southern river swamp — a multiple use  environ-
     ment.  Georgia State University, Atlanta, Georgia.

Wiegert, R. G., and F. C. Evans.  1964.  Primary production and  the
     disappearance of dead vegetation on an old field in Southeastern
     Michigan.  Ecology 45: 49-63.

Windom, H. L., W. H. Dunstan, and W. S. Gardner.  1975.  River input of
     inorganic phosphorus and nitrogen to the southeastern salt  marsh
     environment.  Pages 309-313 _in F. G. Howell, J. B. Gentry,  and M. H.
     Smith, eds.  Mineral cycling in southeastern ecosystems.  U.S. Energy
     Research  and Development Administration, Washington, D.C.
                                     44

-------
APPENDIX A - BIOMASS, AQUATIC RESPIRATION, AERIAL
RESPIRATION, AND DOC LEACHING FOR STANDING DEAD AND
FALLEN DEAD IN TWO SPECIES OF MARSH GRASS, AND FOR
SWAMP FOREST LEAVES.
                        45

-------
          TAHLE A-l.
MEAN DRY WEIGHT (g m~2 ± S.E.) OF TWO  SPECIES  OF MARSH GRASSES (N=6 AND N=8,
RESPECTIVELY) IN CLEAR CUT PLOTS FROM  THE  ALTAMAHA RIVER DELTA
cr*
Spartina cynosuroides
Da te
17 Apr
30 May
10 Jul
14 Aug
16 Oct
28 Nov
9 Jan
5 Mar
13 Apr
Live
1978
1978
1978
1978
1978
1978
1979
1979
1979
216
582
769
682
584
173
0
9
218
±
±
±
±
±
±

•t
+
69
57
118
107
94
44

2
49
Standing
920
676
828
837
1105
1800
1530
158
215
±
±
±
±
±
t
±
±
±
Zlzaniopsls

17 Apr
30 May
10 Jul
14 Aug
16 Oct
28 Nov
9 Jan
5 Mar
13 Apr

1978
1978
1978
1978
1978
1978
1979
1979
1979

179
357
459
593
623
426
222
81
135

±
t
±
+
±
+
l
±
±

44
93
61
157
122
60
41
12
13

870
506
368
308
393
521
332
426
465

±
±
±
±
±
±
±
±
±
Dead
94
53
147
194
114
275
362
57
38
miliacea

222
138
101
24
51
76
39
61
65
Litter
276 ±
246 ±
316 ±
228 +
244 ±
256 ±
273 ±
88 ±
269 ±


235 ±
254 ±
106 ±
77 ±
129 ±
96 ±
168 ±
216 ±
147 ±
44
69
63
40
15
53
57
21
84


62
61
27
13
22
21
15
8
11
Total llioniass
1412
1504
1913
1747
1105
2229
1803
255
702


1284
1117
933
978
1145
1043
722
723
747
± 126
± 87
± 201
± 297
± 193
l 320
± 405
± 42
± 137


± 321
± 276
± 199
± 178
± 168
± 117
± 67
i 77
± 73

-------
TABLE A-2.  MEAN DRY WEIGHT (g ra   ± S.E.) OF TWO SPECIES OF MARSH GRASSES
          (N=6, AND N=8, RESPECTIVELY) IN PREVIOUS CUT PLOTS FROM
                         THE ALTAMAHA RIVER DELTA
Spartina cynosuroides
Date
30 May 1978
10 Jul 1978
14 Aug 1978
16 Occ 1978
28 Nov 1978
9 Jan 1979
5 Mar 1979
'13 Apr 1979
Live
682 ± 96
596 ± 80
764 ± 98
593 ± 140
287 ± 33
0
Plots destroyed.
118 ± 23
Total Dead
106 ± 14
209 ± 35
305 ± 33
335 ± 73
638 ± 51
408 ± 81
by fire
5 ± 1
Total Biomass
788 ± 98
805 ± 96
1069 ± 100
928 ± 187
925 ± 79
408 ± 81

123 ± 22
Zizaniopsis miliacea

30 May 1978
10 Jul 1978
14 Aug 1978
16 Oct 1978
28 Nov 1978
9 Jan 1979
5 Mar 1979
13 Apr 1979

212 ± 64
490 ±47
468 ± 70
601 ± 186
453 ± 14
146 ± 16
70 ± 9
139 ± 15

17.2 ±32
193 ± 38
98 ± 16
209 ± 58
252 ± 75
178 ± 26
300 ± 47
66 ± 11

384 ± 80
683 ± 67
566 ± 80
810 ± 243
705 ± 89
324 ± 37
370 ± 57
205 ± 22
                                    47

-------
TABLE A-3
MEAN DRY WEIGHT (g m~2 ± S.E.) OF LEAP LITTER AT TOO FOREST
 LOCATIONS (N=12) IN THE ALTAMAKA RIVER DELTA
Date
                              River bend
                                             Freshwater Swamp
17 Apr
30 May
10 Jul
14 Aug
16 Oct
28 Nov
 9 Jan
 5 Mar
13 Apr
       1978
       1978
       197S
       1978
       1973
       1978
       1979
       1979
       1979
                             10.1 ±  0.9
                             29.9 ± 10.6
                             20.8 ±  5.2
                             23.9 ±  3.5
                            114. S ± 17.3
                            120.1 ± 18.0
                             27.7 ±  5.1
                             35.8 ± 11.6
                             15.8 ±  3.4
                                               23.12 ±  3.1
                                               24.30 ±  3.8
                                                8.20 ±  1.2
                                               12.30 ±  3.5
                                               76.40 ±  11.1
                                              152.80 ±  18.8
                                               46.90 ±  6.2
                                               23.90 ±  3.4
                                               17.30 ±  2.6
                      48

-------
TABLE A-
AQUATIC RESPIRATION" (MS c g ' DRY WEIGHT h L ± S.E.) OF ATTACHED DEAD PLANT' COMMUNITY
       IN TWO SPECIES OF MARSH GRASSES IN THE ALTAMAIIA RIVER DELTA
Spartina c]

Date
18 Apr
30 May
10 Jul
14 Aug
16 Oct
29 Nov
9 Jan
5 Mar
13 Apr


1978
1978
1978
1978
1978
1978
1979
1979
1979

Fallen
82 ±
50 ±
55 ±
31 t
8 ±
29 ±
25 ±
9 ±
51 ±

Dead
.12
7
20
1
4
6
4
3
4
^nosuroides



Standing Dead

27
63
55
13
21
15
9
41

±
±
±
±
±
±
±
±

3
26
17
7
4
3
1
5
Zizariiopsis miliacea


Fallen
41
36
44
54
9
30
26
23
94
+
t
±
±
±
J;
±
±
±

Dead
4
8
15
14
5
9
2
4
18


Standing Dead

10
1
55
29
59
94
12
126

± 2
± 3
± 3
± 7
± 1.4
± 16
± 5
± 11
 Incubation time,  3.5 h; N=3.

-------
Ul
o
       TAHLE  A-5.   AQUATIC RliSPIRATION* (|jg C g  l  DRY  WEIGHT h *~ ± S.l::.) OF ATTACHED DEAD PLANT  COMMUNITY

                      FOR THREE SPECIES OF SWAMP FOREST  LEAVES IN THE ALTAMAHA RIVER DELTA
     Da to
Nyssn aquatlea
Liquldanihar styracitlua
TaxodLum distichuin

18
30
10
14
16
30
9
5
13

Apr
May
.Itil
Aug
Oct
Nov
Jan
Mar
Apr
•T: — i.-;v.i:

1978
1978
1978
1978
1978
1978
1979
1979
1979

125
63
79
126
153
335
189
46
277

t
±
i
±
±
±
±
±
±

9
2
4
6
30
21
26
9
28

95
77
190
92
236
243
81
24
47

±
±
±
±
+
±
±
±
±

16
30
53
22
56
17
14
1
11

383
160
161
296
97
892
59
31
62

± 78
± 7
± 18
t 30
± 14
t 72
± 2
± 5
± 3
       Incubation  time,  3 h;  N=3.

-------
TABLE A-6.
                                       -1
                                          -1
AERIAL RESPIRATION  (ug C g " DRY WEIGHT-h " t S.E.) OF AIT ACHED  DEAD PLANT  COMMUNITY
     IN TWO SPECIES OF MARSH GRASSES FROM THE ALTAMAHA RIVER DELTA
Spartina cynosuroides

Date
17 Apr
30 May
10 Jul
14 Aug
16 Oct
30 Nov
9 Jan
5 Mar
13 Apr



Fallen Dead
1978
1978
1978
1978
1978
1978
1979
1979
1979
. 4
11
6
28
22
25
18
28
1
± 1 (6)
± 0.6 (6)
± 1
i 5
± 3
i 1
± 2
± 2
± 0.1 (6)


Standing
1
1
0.8
-4
24
2
1
6
1
± 0.
± 0.
± 0.
± 2
± 1
± 0.
± 0.
t 1
± 0.

Dead
3 (6)
5 (6)
2


4
1

3 (6)

Zizaniopsis

Fallen Dead
72 ±
81 t
132 ±
82 i
106 ±
25 ±
28 ±
64 ±
55 ±
5 (6)
3 (6)
31
12
4
i
2
3
1
miliacea




Standing Dead
1
9
8
-4
3
2
14
5
1
+
+
±
±
±
±
±
±
±
0.
1
2
1
2
0.
1
1
0.
4 (6)
(6)


(8)
4 (7)

(7)
2
 Incubation time,  3 h;  N=9, unless otherwise indicated.

-------
Ul
NJ
       TABLK A-7.  AEE<1AL  RESl-'IRATION" (jJg C g J DRY WEIGHT h  l  ±  S.E.)  OF AIT ACHED DEAD PLANT COMMUNITY
                       FOR  THREE  SPECIES OF SWAMP FOREST LEAVES IN  THE ALTAMAHA RIVER DELTA
Date

1.7 Apr
30 May
10 Jul
1.4 Aug
16 Oct
30 Nov
9 Jan
5 Mar
13 Apr


1978
1978
1978
1978
1978
1978
1979
1979
1979
Nyssn

1 ±
18 ±
24 ±
142 ±
16 ±
110 ±
35 ±
68 ±
26 ±
acj^uatica

0.4
1
4
28
5
7
7
5
7

(6)
(6)


(7)

(8)
(6)
•
Liquidambar styraciflua

26
16
1
68
16
12
26
11
2

±
±
+
±
±
+
+
±
±

8
2
0.3
7
2
0.3
2
2
0.2

(6)
(6)
(8)

(10)
(6)

(8)
(7)
Taxodium distichum

2 t
114 ±
45 ±
133 ±
27 ±
49 ±
29 ±
35 ±
5 ±

0.5
20
7
11
7
3
1
2
1

(6)
(6)
(10)




(8)
(7)
        Incubation time, 3 h; N=9,  unless otherwise noted.

-------
OJ
        TABLE A-8.   DOC RELEASED  (pg C g   DRY WEIGHT h   ± S-E.) FROM DEAD PLANT PARTS FOR TWO SPECIES
                                 OF MARSH GRASSES FROM THE ALTAMAHA RIVER DELTA
Spartina cynosuroides

Date
17 Apr
30 May
10 -lul
14 Aug
16 Oct
30 Nov
9 Jan
5 Mar
13 Apr



Fallen Dead
1978
1978
1978
1978
1978
1978
1979
1979
1979
435 ± 18
573 ±83
552 ± 31
262 ± 48
290 ± 26

169 ± 18
335 ± 16
247 ± 32
(7)



(7)

(A)
(3)
(8)



Standing Dead
425 ±
364 ±
379 ±
448 1
265 ±
501 ±
127 ±
142
304 ±
33
92
44
54
37
67
21

24
(6)



(6)
(3)
(7)
(1)


Zizaniopsis


Fallen Dead
201 ±
183 ±
313 ±
769 ±
954 ±
109 ±
346 ±
532
246 ±
15
3
25
71
49
24
126

24
(8)


(8)
(5)
(4)
(3)
(1)

millacea



Standing Dead
594 ± 71
468 !: 12
441 ± 36
230 ± 41
628 ± 27
322 ± 65
107
270 ± 52
731 ± 62
(7)

(8)

(8)
(4)
(1)
(3)

        fncubation  time,  3 hr; N=9,  unless  otherwise  indicated.

-------
TABLE A-9.   DOC RELEASED
                             g C g l DRY WEIGHT h 1 ± S.E.)  FROM THREE  SPECIES OF SWAMl1  FOREST
                          LEAVES COLLECTED IN THE ALTAMAHA RIVER DELTA
Date
1.7
30
10
14
16
30
9
5
13
Apr
May
.Tu.1
Aug
Oct
Nov
.Ian
Mar
Apr
Nyssa aquatica
1978
1978
1978
1978
1978
1978
1979
1979
1979

660 ±
94 ±
746 ±
390 t
289 ±
842 ±
299 l
199 ±
1349 ±

104
20
78
77
41
46
25
46
143


(5)
(8)

(8)
(2)
(3)
(3)
(6)
Liquldambar styraciflua

398 ±
22 ±
927 ±
342 ±
2570 ±
2183 ±
356 i
72
272 ±

33
11
35
40
249
219
143

4

'
(6)

(6)
(8)
(3)
(2)
(1)
(5)
Taxodium

179 ±
224 ±
1578 ±
2054 ±
1308 ±
316 ±
-22
25 ±
409 ±
distich urn
9
37
135
113
175
41

5
47


(8)

(8)
(2)
(1)
(3)
(7)
Incubation time, 3 h; N=9, unless otherwise indicated.

-------
APPENDIX B - BIOMASS, AQUATIC RESPIRATION, AERIAL
RESPIRATION, DOC LEACHING AND ELEMENTAL COMPOSITION
OF LITTER BAG PLANT MATERIAL FOR TWO SPECIES OF
MARSH GRASSES AND SWAMP FOREST LEAVES.
                         55

-------
     TABLE B-l.  WEIGHT OF DECOMPOSING MARSH GRASS AND SWAMP FOREST LEAVES   (g DRY WEIGHT  1  S.E.)
      FROM LITTER BAGS AT FOUR LOCATIONS IN THE ALTAMAHA RIVER DELTA AT THREE COLLECTION PERIODS'!"

1 month
                                                           6 months
11 months
Sp art ina cynosuroides
Suspended
Surface
Submerged
Saltwater
Zizaniopsis miliacea
Suspended
Surface
Submerged
Saltwater
Forest Leaves
Surface
Submerged
Saltwater

96. ± 1.0
95 ± 1.0
84 ± 1.0
82 ± 2.0 (A)

93 ± 1.0
83 ± 0.4 (5)
81 ± 2.0 (4)
88 ± 3.0 (6)

16 ±0.4
17 ± 1.0
16 ± 2.0

92
69
52


42
28
6


7
4


± 0.3
± 0.2
± 1 (3)


± 4.0
± 3.0 (4)
± 6.0


± 0.6
± 0.4

                                                                                     38 ±  5.0    (5)
                                                                                     14 ±  2.0    (4)
                                                                                      5 ± 0.8
                                                                                      3 ± 0.6    (5)
   Initial weight of marsh grass   = lOOg/bag
   Initial weight of forest leaves =  /Og/bag

I   N=fa,  unless otherwise indicated

-------
  TABLE B-2.  AQUATIC RESPIRATION   (|Jg C g    DRY WEIGHT h    ±  S.E.)  OF ATTACHED DEAD PLANT COMMUNITY
     l-'KOM DEAD PLANT PARTS ENCLOSED IN SUSPENDED (SUS), SURFACE (SUR),  SUBMERGED (SUB)  LITTER BAGS
                     AT THE COLLECTION SITE AND SUBMERGED  BAGS IN  SALTWATER (SAL)
1 month
Spartina cynosuroides
SUB
SUS
SUR
SAL
Zi zaniopsis miliacea
SUB
SUS
SUR
SAL
Forest Leaves
SUB
SUR
SAL

62 ±
15 ±
61 ±
143 ±

63 ±
20 ±
59 ±
141 ±

93 ±
85 ±
163 ±

7
5
25
19

3
10
10
13

12
19
21
6 months 11 months

27 t 3
13 ± 13 11 i 3
19 ±5 26 1 7


66 ± 24
-2 ± 10 15 ± 2
51 ± 23 28 ± 3


47 ± 17 18 ± 4
133 ±56 30 ± 8

*
   Incubation time, 3.5 h; N=3.

-------
          TABLE  B-3.   AERIAL RESPIRATION (»Jg C g   DRY WEIGHT h   ± S.E.) OF ATTACHED DEAD PLANT
               COMMUNITY  FROM DEAD PLANT PARTS ENCLOSED IN SUSPENDED (SUS),  SURFACE (SUR),
                     SUBMERGED (SITU)  LITTER BAGS AT THE COLLECTION SITE, AND SUBMERGED
                                          BAGS IN SALTWATER (SAL)
CO
Spartina cynosuroldes
          SUli
          SUS
          SUR
          SAL

ZtzaniopsJ.3 miliacea
          SUB
          SUS
          SUR
          SAL

Lorest Leaves
          SUB
          SUR
          SAL
I 1
119 ±
3 ±
62 ±
63 ±
121 ±
31 ±
73 ±
124 ±
49 ±
58 ±
58 t
no ri lh
5
.04 (7)
5
3
6 (6)
5
3
3
3 (8)
2 (10)
6
6 months
38 ± 3 (8)
17 ± 2 (6)
34 ± 2

60 ± 2
46 ± 3
21 ± 3

20 ± 1 (10)
24 ± 1

11 months

13 ± 2 (8)
36 ± 4


63 ± 2
57 ± 3 (8)

21 1 1
17 ± 2

       Incubation time, 3h; N=9,  unless otherwise  indicated.

-------
          TABU:  11-4.   DOC'  RELEASED  (ug  c  g    DRY WEIGHT  h    ±  S.E.)  FROM DEAD  PLANT  PARTS  ENCLOSED  IN
             SUSPENDED (SUS),  SURFACE  (SUR),  SUBMERGED  (SUB)  LITTER BAGS  AT THE COLLECTION  SITE  AND
                                            SUBMERGED IN  SALTWATER (SAL)
Ul
VO

Spartina cynosuroidcs
SUB
SUS
SUR
SAL
Zizaniopsis mlliacea
SUB
. SUS
SUR
SAL
Forest Leaves
SUB
SUR
SAL
I (i

733 ±
473 ±
718 ±
78 ±

139 ±
- 332 ±
100 ±
153 ±

-65 ±
57 ±
-4 ±
nonth

37
205
119 (8)
20

11
9
13
26

4
14
14
6 months 11 months

203 ± 120 (2) 137 ± 27 (2)
123 ± 25 203 ± 98 (3)
73 ± 10 287 ± 145 (2)


-4 ± 28
312 ± 82 (7) 296 (1)
70 ± 23 270 ± 52 (3)


-27 ± 29 (8) -37 ± 85 (4)
-28 ± 10 (7) -27 ± 24 (4)

       Incubation time, 3 h; N=9, unless otherwise indicated.

-------
      TABLE B-5.  MINERAL CONTENT  OF SPARTINA CYNOSUROIDES STANDING DEAD ENCLOSED IN SUSPENDED  (SUS),
           SURFACE (SUR) AND SUBMERGED (SUB) LITTER BAGS AT THE COLLECTION SITE; SUBMERGED MATERIAL
                 IN SALTWATER (SAL); AND FALLEN DEAD MATERIAL  (LIT) COLLECTED FROM THE MARSH
                                   SURFACE AT EACH SAMPLING PERIODt
cr>
o

1 month
SUS
SUR
SUB
SAL
LIT
6 months
SUS
SUR
SUB
LIT
11 months
SUS
SUR
P

.035 ±
.050 ±
.081 ±
.093 ±
.038

.038 ±
.080 ±
.125 ±
.053

.041 ±
.048 ±


.007
.001
.011
.008


.009
.001
.002


.004
.006
K

.048 ±
.046 ±
.072 ±
.157 ±
.058

.035 ±
.047 ±
.027 ±
.014

<.008
.014 ±
Ca

.012
.014
.006
.015


.006
.003
.005



.004

.169 ±
.238 ±
.209 ±
.270 ±
.086

.181 ±
.415 ±
.708 ±
.222

.270 ±
.172 ±

.002
.015
.025
.026


.015
.029
.133


.•105
.029
Mg

.079 ±
.089 ±
.131 ±
.305 ±
.0543

.164 ±
.168 ±
.134 ±
.096

.128 ±
.109 ±

.003
.003
.004
.031


.022
.042
.004


.018
.003

0.
0.
0.
0.
0.

0.
0.
1.
0.

0.
0.

46
47
69
64
54

73
98
21
68

77
86
N

± 0.01
± 0.03
± 0.06
± 0.06


± 0.03
± 0.13
± 0.05


± 0.01
± 0.05
                                                                                               (Continued)

-------
     TABLE B-5.  (Continued)
                        Mn
Fe
Al
Cu
cr»
1 month
SUS
SUR
SUB
SAL
LIT
6 months
SUS
SUR
SUB
LIT
11 months
SUS
SUR

157.8 ±
183.3 ±
444.0 ±
1110 ±
222.2

87.9 ±
322.2 ±
2527 ±
251.9

81.1 ±
100.6 ±

39.3
11.9
87.9
351


11.7
99.1
468


16.7
42.1

364 ±
1651 ±
4057 ±
• 4343 ±
73

503 ±
4200 ±
4383 ±
114

570 ±
2299 ±

24.4
507
521
237


165
1052
758


87
1430

479 ±
2342 ±
5862 ±
11449 ±
34

2527 ±
5701 ±
4935 ±
73

1865 ±
4125 ±

55
863
270
454


490
209
783


1215
774

3.
3.
5.
21.
4.

8.
14.
5.
6.

5.
6.

13 ±
33 ±
58 ±
00 ±
31

36 ±
35 ±
04 ±
92

75 ±
04 ±

0.38
0.24
0.37
2.07


5.64
5.41
0.27


0.86
0.69

2.66
3.13
4.38
3.21
3.21

2.43
3.75
4.31
1.80

1.61
1.29

± 0.59
± 0.42
± 0.33
± 0.72


± 0.15
± 0.41
± 0.08


± 0.13
± 0.12
                                                                                                  (Continued)

-------
     TABLE B-5.   (Concluded)
                             Zn
Sr
Ba
Na
cr>
N)
1 month
SUS
SUR
SUB
SAL
LIT
6 months
SUS
SUR
SUB
LIT
11 months
SUS
SUR

24.
33.
36.
27.
37.

'44.
42.
57.
7.

61.
34.

28 ±
62 ±
67 ±
23 ±
34

85 ±
91 ±
07 ±
56

61 ±
07 ±

1.82
4.46
5.60
2.23


7.00
16.07
1.93


14.45
13.44

8.
16.
19.
36.
2.

16.
35.
57.
11.

18.
17.

18 ±
00 ±
67 ±
71 ±
19

00 ±
35 ±
18 ±
65

34 ±
80 ±

0.56
1.97
3.78
1.84


3.41
3.99
12.14


8.13
4.14

5.
12.
14.
8.
2.

2.
5.
48.
2.

5.
5.

46 ± 0.
48 ± 1.
51 ± 1.
46 ± 0.
64

97 ± 0.
24 ± 0.
05 ± 3.
56

42 ± 0.
61 ± 1.

27
42
89
28


47
21
56


94
15

343.30
273.90
416.70
76.73
92.90

4580
4769
379.00
-

385.50
1913

± 53.80
± 13.90
± 25.00
± 5.40


± 691
± 211
± 37.00


± 44.60
± 82
        P,  K, Ca, Mg, N  in %±S.E.;  Mn,  Fe,  Al,  B,  Cu,  Zn,  Sr,  Ba,  Na in PPHtS.E.

    t   N=3 for all values except LIT,  where  N=l.

-------
TABLE B-6.  MINERAL CONTENT  OF ZIZANIOPSIS MILIACEA STANDING DEAD ENCLOSED IN SUSPENDED
     (SUS), SURFACE (SUR),  AND SUBMERGED (SUB) LITTER BAGS AT TOE COLLECTION SITE;
         SUBMERGED MATERIAL IN SALTWATER (SAL); AND FALLEN DEAD MATERIAL (LIT)
               COLLECTED FROM THE MARSH SURFACE AT EACH SAMPLING PERIOD"!'

1 month
SUS
SUR
SUB
SAL
LIT
6 months
SUS
SUR
SUB
LIT
11 months
SUS
SUR
LIT
1'

0.079 ± 0.006
0.064 ± 0.002
0.086 ± 0.007
0.121 ± 0.010
0.063

0.097 ± 0.014
0.132 ± 0.004
0.140
0.047

0.084 ± 0.013
0.132 ± 0.009
0.108
K

0.046 ± 0.001
0.038 ± 0.002
0.414 ± 0.001
0.295 ± 0.008
0.088

0.020 ± 0.006
0.021 ± 0.004
0.016
0.048

<.008
0.023 ± 0.002
0.080
Ca

0.358 ± 0.022
0.639 ± 0.002
0.086 ± 0.007
0.439 ± 0.046
0.331

0.481 ± 0.061
0.592 ± 0.119
0.507
0.834

0.354 ±.0.032
0.416 ± 0.022
0.247
Mg

0.054 ± 0.001
0.056 ± 0.004
0.058 ± 0.003
0.609 ± 0.013
0.038

0.118 ± 0.015
0.133 ± 0.005
0.073
0.059

0.067 ± 0.008
0.127 ± 0.001
0.050
N

0.78 ±
0.74 ±
0.82 ±
0.91 ±
0.75

1.29 ±
1.65 ±
0.13
0.84

1.29 ±
1. 72 ±
0.88


0.02
0.02
0.05
0.04


0.06
0.08



0.11
0.04

                                                                                    (Continued)

-------
TABLE B-6.  (Continued)
                   Mn
Fe
Al
Cu
1 month
SUS
SUR
SUB
SAL
LIT
6 months
SUS
SUR
.SUB
LIT
11 months
SUS
SUR
LIT

601.9 ±
512.8 ±
611.6 ±
2449 ±
299

690.0 ±
1057 ±
3875
223

679.8 ±
1222 ±
504

25.2
30.1
44.3
279


82.3
329



104.6
675


2062 ±
3448 ±
4918 ±
2611 ±
546

3143 ±
5754 ±
7165
300

2884 ±
6844 ±
548

583
417
879
202


1183
652



1155
577


4047 ±
5548 ±
5800 ±
5840 ±
620

4098 ±
5841 ±
5558
61

3151 ±
6345 ±
755

336
733
771
281


1646
480



1266
144


3.04
2.59
2.58
31.71
2.37

3.83
4.50
3.27
3.98

2.40
3.97
2.45

± 0.
± 0.
± 0.
± 0.


± 0.
± 0.



±.0.
± 0.


18
12
10
33


66
39



43
16


2.17 ±
2.17 ±
3.01 ±
3.10 ±
1.72

3.71 ±
4.78 ±
5.20
1.43

2.39 ±
4.37 ±
1.27

0.11
0.19
0.35
0.22


0.55
0.24



0.37
0.12

                                                                                            (Continued)

-------
Ul
     TABLE  B-6.   (Concluded)

                             Zn                   Sr                     Ba                     Na
1 month
SUS
SUR
SUB
SAL
LIT
6 months
SUS
SUR
SUB
LIT
11 months
SUS
SUR
LIT

36.
27.
34.
18.
16.

90.
145.
169
7.

3227
152.
16.

4. ± 2.3
6 ± 2.4
3, ± 3.6
1 ± 1.51
5

5 ± 3.4
3 ± 23.9

9

± 1840
7 ± 21.3
8

12.
12.
14.
63.
10.

33.
44.
22.
15.

22.
40.
2.

70 ±
70 ±
26 ±
90 ±
07

68 ±
39 ±
66
46

14 ±
36 ±
74

1.87
2.56
2.16
2.15


3.65
2.71



4.27
2.22


48.
44.
46.
10.
30.

46.
64.
102.
25.

52.
51.
• 23.

52 ±
07 ±
05 ±
50 ±
78

54 ±
47 ±
70
91

62 ±
32 ±
11

4.22
0.86
5.00
0.69


5.20
7.20



10.50
7.71


108.
120.
164.
28.
75.

257.
229.
209.
35.

71.
189.
902.

7
1
3
83
4

3
3
9
8

4
3
1

± 8.8
± 10.2
± 12.4
± 2.26


± 33.1
± 24.1



± 13.5
± 12.1

       P, K, Ca, Mg, N in %±S.E.; Mn, Fe, Al, B, Cu, Zn, Sr, Ba, Na in PPM±S.E.
    t  N=3 for all values except LIT, where N=l.

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TABLE B-7.   MINERAL CONTENT  OF DEAD SWAMP FOREST LEAVES ENCLOSED IN SURFACE (SUR),  AND SUBMERGED
     (SUB)  LITTER BAOS AT THE COLLECTION STIE; AND DEAD LEAVES SUBMERGED IN SALT WATER (SAL)t

1



6


11



month
SUB
SUR
SAL
mon t hs
SUB
SUR
months
SUB
SUR
P

0.128 ±
0.115 ±
0.197 ±

0.174 ±
0.186 ±

0.202 ±
0.171 ±


0.006
0.010
0.012

0.002
0.010

0.024
0.006


0/062
0.068
0.115

0.033
0.045

0.040
0.023
K

± 0.005
± 0.005
± 0.004

± 0.009
± 0.012

± 0.009
± 0.004


1.344
1.380
0.862

1.594
1..883

1.352
1.336
Ca

± 0.048
± 0.019
± 0.037

± 0.161
± 0.361

± 0.142
± 0.075


0.114
0.117
0.519

0.173
0.177

0.150
0.138
Mg

± 0.009
± 0.005
± 0.004

± 0.009
± 0.011

± 0.002
± 0.004


1.21
1.20
1.14

1.52
1.63

1.55
1.51
N

± 0.01
± 0.15
± 0.06

± 0.01
± 0.04

± 0.20
± 0.06
                                                                                        (Continued)

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TABLE R-7.  (Continued)




                  Mn
Fe
Al
Cu
1



6


11


month
sun
SUR
SAL
months
SUB
SUR
months
SUB
SUR

1010 ±
727 ±
4398 ±

3733 ±
3892 ±

3144 ±
1456 ±

155
27
450

67 4
828

650
733

8347 ±
4530 ±
7447 ±

7094 ±
11319 ±

15665 ±
13252 ±

2540
330
416

161
1700

1173
1126

10868 ±
5949 ±
11164 ±

4782 ±
8325 ±

5619 ±
5608 ±

2765
318
513

365
1872

151
37

14.61
16.49
125.00

13.80
15.45

14.62
12.01

± 1.00
± 1.28
±9.36

± 0.82
± 0.98

± 0.94
± 0.74

7.49
7.00
8.05

10.02
8.79

11.10
9.48

± 0.65
±0.23
± 0.43

± 0.88
± 0.31

± 0.94
± 1.13
                                                                                            (Continued)

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TABLE H-7.  (Concluded)

                         Zn                    Sr                      Ba                     Na
j. month
SUB
SUR
SAL
6 months
SUB
SUR
11 months
cr>
oo SUB
SUR

134.
113.
57.

455.
918.

259.
263.

1 ±
0 ±
7 ±

3 ±
0 ±

4 ±
2

1.8
17.2
8.7

62.2
244

75.2


69
65
108

96
94

85
75

. 38 i
.80 ±
.60 ±

.00 ±
.90 ±

.80 ±
.50 ±

5.21
0.88
8.50

11.10
5.80

2.70
7.50

154.
151.
20.

202.
298.

218.
167.

3 ±
5 ±
1 ±

6 ±
0 ±

7 ±
1 ±

7.22
2.17
1.74

26.00
101.60

11.60
9.70

182.9 l
177.7 ±
249.7 ±

282.1 ±
631.9 ±

148.4 ±
182.8 ±

2.07
2.74
34.60

94.00
269.50

19.30
8.30
   P, K, Ca, Mg, N In %±S.E.;  Mn, Fe, Al,  B,  Cu,  Zn,  Sr,  Ba,  Na In PPM±S.E.
t  N=3 for all values.

-------