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FUNCTIONAL ASSESSMENT OF ALASKA PEATLANDS IN COOK INLET BASIN
REGION 10 REGIONAL APPLIED RESEARCH EFFORT (RARE)
Background
Peatlands are organic soil wetlands that are
underlain by peat, which is partially
decomposed vegetation. Peat develops
when the rate of plant growth exceeds decay
and commonly accumulates 1 mm annually.
The Cook Inlet Basin ecoregion of south
central Alaska contains many wetlands.
Most of these wetlands are peatlands and
nearly all are still pristine. Some are
extensive as shown in the picture below
taken in the Kalifornski Flats on the Kenai
Peninsula.
The majority of Alaska's population lives
within this ecoregion, in Anchorage and the
Matanuska-Susitna Borough (MSB) to the
north and in the Kenai Peninsula Borough to
the south. All three areas are experiencing
population growth, with the MSB the most
rapidly developing. Our aim has been to
help environmental managers in this
ecoregion to look at the classification of
their wetlands, understand functions of the
peatlands, and have measures to determine
the impact of human activities.
Approach
Specific goals of this project included
quantifying wetland hydrologic functions,
comparing different classification systems of
wetlands, measuring arsenic concentrations
in wetland pore waters, and determining
nutrient demands in peat using rates of
microbial extracellular enzyme activity
(EE A).
Results
Peatlands were found to contribute 55 % of
the water for summer dry-season baseflow
to a tributary of the Anchor River, an
important anadromous fishery. Many of the
peatlands in this watershed are fens with
respect to vegetation and pH but are
ombrotrophic hydrologically. Like the small
watershed measured and modeled here, most
peatlands in this ecoregion probably provide
discharge to adjacent streams.
The Cook Inlet Classification (CIC), a
wetland classification system developed for
this region (Gracz 2012), was found to
perform better at grouping biological and
physical variables than a hydrogeomorphic
wetland classification developed in another
region. The CIC uses hydrologic and
geomorphologic features as well as
vegetation to type wetlands.
Arsenic was found in measurable
(>1.3 jig/L) quantiti es in 60 % of pore water
samples from intact peat. Indeed, 30 % of
the 27 wetlands sampled had >10 |ig/L
which is the EPA standard for arsenic in
drinking water. The source of the arsenic is
presumed to be natural, not anthropogenic.
1
U.S. Environmental Protection Agency
Office of Research and Development
E P A/600/F-15/089
August 2015

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The microbial EEA methods tested various
substrates including simple sugars, amino
acids, a phospho-monoester, and polycyclic
phenols. EEA rates in peat samples
demonstrated nitrogen and phosphorus
limitations within the peat along vertical
profiles in the wetlands; P-limitation was
present mostly in the upper peat layers.
Chemical ratios of C, N and P in the peat
were not as reliable measures of resource
constraints in these peatland soils as were
EEA. The EEA rates also demonstrated the
tight coupling of microbial N and P
acquisition to recalcitrant organic carbon
breakdown, i.e., C compounds that are more
resistant to decomposition, as seen in data of
the following graphic figure.
In this figure phenol oxidase enzyme
activity (EA), which represents the potential
rate of utilization of a recalcitrant organic C
compound, normalizes the significant
relationship between an organic C
breakdown (by P-glucosidase EA) and
phosphorus acquisition (by phosphatase
EA).
services such as providing source water for
fishable streams, drinking water, habitat for
wildlife, and C storage and C accumulation
in the peat. The qualitative and quantitative
methods help environmental managers know
what to expect of natural peatlands in this
region. With this information, we can better
achieve goals to protect wetlands from
disturbance or loss of ecological services.
Citations
Gracz, Michael B. (2012) Wetland Classification and
Mapping of the Cook Inlet Basin Alaska. Kenai
Watershed Forum http://cookinletwetlands.info/
Contacts
Mary F. Moffett
Research Ecologist
ord/nheerl"
Mid-Continent Ecology Division
Duluth. MN
218-529-5174
moffett.mary@epa.gov
Brace Duncan
Regional Science Liaison
Region 10
Seattle. WA
206-553-0218
duncan.brace@epa.gov
Matthew LaCroix
Biologist
Region 10
Alaska Operations Office
Anchorage, AK
907-271-1480
lacroix.matthew@epa.gov
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