United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas NV 89193-3478
Research and Development
EPA/620/SR-93/016 July 1994
w EPA Project Summary
Environmental Monitoring and
Assessment Program: Arid
Ecosystems 1993
Implementation Plan—Colorado
Plateau Plot Design Pilot Study
William G. Kepner
This implementation plan describes
the basis for activities planned during
1993 in the southeastern Utah portion
of the Colorado Plateau. Ecological in-
terpretation of information gathered on
monitoring sites requires plot configu-
rations that provide sufficient area! sup-
port to capture the characteristics of
the biological communities. The study
objective and approach of the 1993 pi-
lot study are to determine the sampling
support area and optimum plot size for
selected indicator measurements (spec-
tral properties, vegetation composition
and abundance, and soil properties).
Plot size variance and configuration re-
lationships along with cost of data col-
lection in terms of available resources,
e.g., time and money, will be used for
optimal plot design evaluations.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory, Las Vegas, NV, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The U.S. Environmental Protection
Agency (EPA), in collaboration with other
federal agencies, states, research insti-
tutes, and university systems, has initi-
ated the Environmental Monitoring and
Assessment Program (EMAP) to develop
a long-term approach to assess and peri-
odically document the condition of eco-
logical resources at the regional and na-
tional scales and to develop innovative
methods for anticipating emerging prob-
lems before they reach crisis proportions.
The goals of EMAP are to monitor and
assess the condition of U.S. ecological
resources and to contribute to decisions
on environmental protection and manage-
ment.
To accomplish its goals and objectives,
EMAP has established eight ecosystem
monitoring and research groups (i.e., es-
tuaries, coastal waters, Great Lakes, sur-
face waters, forests, agroeco.systems, arid
ecosystems, and landscape ecology) and
seven cross-system program groups (i.e.,
design and statistics, quality assurance,
information management, landscape char-
acterization, indicators, methods and lo-
gistics, and assessment and reporting).
This implementation plan describes the
basis for activities planned during 1993 by
the EMAP arid ecosystems monitoring and
research group.
Arid ecosystems, as defined by EMAP,
are terrestrial systems characterized by a
climatic regime where potential evapo-
transpiration exceeds precipitation, annual
precipitation ranges from <5 to 60 cm,
and daily and seasonal temperatures range
from -40 to 50°C. The vegetation in arid
ecosystems is dominated by woody pe-
rennials, graminoids, succulents, and
drought-resistant trees. Physiognomy is
generally low-form and canopies typically
open. Arid ecosystems include associated
riparian communities; however, intensively
managed agriculture, such as irrigated
farmlands, is excluded even though it may
occur in the same climatic region.
The EMAP Arid Ecosystems include
• arid, semiarid, and subhumid regions of
the United States and occupy much of the
Printed on Recycled Paper
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land surface area (excluding high-eleva-
tion forests) west of 95° W longitude.
EMAP-Arid is one of three EMAP Terres-
trial Resource Groups that are progres-
sively interacting in activities as the pro-
gram matures.
The objectives of the EMAP Arid Eco-
systems resource monitoring and research
group (EMAP-Arid} parallel those estab-
lished for EMAP. It is the intent and pur-
pose of EMAP-Arid to measure and report
on the extent, condition and trends of re-
source classes (i.e., arid subpopulations)
within the blogeographical provinces of
nearctte and neotropical North America
that occur within arid, semiarid, and
subhumid climatic regimes. A number of
pilot and demonstration projects will be
required in the next few years to develop
indicators of the condition of arid ecosys-
tems and measurement procedures prior
to achieving full implementation.
Environmental indicators are being de-
veloped to collectively describe the condi-
tion of an arid ecosystem. Indicators "com-
mon" to the EMAP Terrestrial Resource
Groups will be fostered by the EMAP-Arid
group. The operating strategy is model
based and identifies regional issues and
assessment questions, links them with so-
cietal values that have biological relevance,
and identifies indicators that, when mea-
sured and integrated, can evaluate the
status and trends in the condition of arid
ecosystems. Issues that have been identi-
fied as regionally important in arid eco-
systems are desertification, livestock graz-
ing, biodiversity, water resource manage-
ment, air quality, and global climatic
change. Three societal values are cur-
rently identified as significant to arid eco-
systems and have served to focus the
conceptual development of the monitoring
and research strategy for EMAP-Arid, es-
pecially relative to the selection and use
of indicators. These values are
• Biological integrity—species compo-
sition and structure (abundance and
spatial arrangement) of biotic and abi-
otic elements and their associated
functions (ecological processes at
various levels (i.e., genetic, species,
population, community, ecosystem,
and landscape) of biological organi-
zation.
• Aesthetics—broadly defined as at-
tributes that affect human perception
and appreciation of the environment.
• Productivity—the quantity and quality
of ecological and nonconsumptive ser-
vices or products provided by arid
resources and their capacity for long-
term maintenance.
The EMAP-Arid group has elected to
develop its first research indicators rela-
tive to productivity and biological integrity,
significant social concerns relating to the
critical issues of desertification 'and cli-
mate change in western North American
landscapes. Various measures, attributes,
and indices are being evaluated as indi-
cators related to specific indicator catego-
ries. Three indicator categories of arid eco-
system condition (spectral properties, veg-
etation composition and abundance, and
soil properties) were tested during the sum-
mer of 1992 in the southeastern Utah
portion of the Colorado Plateau. The 1993
activities will concentrate on the develop-
ment of optimal field plot sampling de-
signs from which to obtain measurements
for the three indicator categories .evalu-
ated in the 1992 Pilot Study.
Study Objective and Approach
The study objective and approach of
the 1993 EMAP-Arid pilot study is to de-
termine the sampling support area and
optimum plot size for selected indicator
measurements. Interpretation of ecologi-
cal condition at EMAP-Arid monitoring sites
requires an adequate representation of
the vegetation and soils communities at a
site. A number of criteria have been used,
by researchers to determine the minimum
plot size and shape required to adequately
describe an area. The measurement of
variables for indicators on EMAP-Arid
monitoring sites is intended to reflect the
status of plant and soil communities
present in the sampled resource commu-
nity. Thus, it is important that the sam-
pling support area is of a sufficient size to
adequately characterize those indicator
variables for the plant and soil communi-
ties under consideration. The approach to
determining the EMAP-Arid indicator sam-
pling support area and plot design will be
based to some extent on the research
conducted by others. However, the EMAP-
Arid survey requirements for sampling plots
will differ from other studies in several
facets. The sampling plots will have to
serve as monitoring sites for a multiplicity
of measurements with the potential for
repeated visits to the site over decades.
Complete census of the plots may be nei-
ther feasible nor desirable under these
circumstances. They must be set up with
minimal disturbance to the measurement
areas. The number, of plots or replicate
samples at the site for monitoring pur-
poses will be the number required for
specified confidence estimates in the sur-
vey. Thus, questions of replicatipn block-
ing with different treatments on the plots
within blocks as in experimental trials are
not relevant to the survey.
The field sampling areas required for
this study will be coordinated and inte-
grated by the three indicator groups. Large
macroplots estimated to be larger than
the indicator sampling support area will
be established at each site and inten-
sively sampled. Each macroplot will be
selected so that it is in a single landscape
unit. These macroplots will be established
in three biomes (in parallel EMAP terms,
these are research types)—desertscrub,
woodland, and grassland. The macroplots
will be the basis for a uniformity sampling
trial at each site. Plots of varying configu-
rations can be crafted from the uniformity
sampling trial on the macroplot to evalu-
ate their qualitative and quantitative prop-
erties. Each macroplot is subdivided into
a rectangular array of basic sampling units.
The area within a basic unit required for a
particular measurement will vary with the
type of indicator category measurement.
The measurement areas may be small
quadrats for vegetation cover measures,
a soil sample, or spectral reading area.
The measurement taken in these areas
will be sufficient to represent the charac-
teristics of the basic unit. The arrange-
ment of measurement areas, relative to
one another within the basic units, will be
set up to accommodate sampling logistics
that are anticipated at a monitoring site
for future surveys.
The goal is to have a cost-efficient sam-
pling strategy that is sufficient to provide
an adequate description of the vegetation
and soils community at the site. The rela-
tionship between properties of indicator
parameters and the plot size and shape
will be established and estimated for all
measurements most critical to the quanti-
fiable indicators identified for EMAP-Arid
monitoring. A final plot design operation-
ally feasible for indicator measurement
purposes in a future EMAP-Arid demon-
stration survey will be determined from
data collected in 1993 on these large
macroplots.
Study sites for 1993 were selected to
represent readily observable differences
in biome and productivity combinations;
however, every possible combination is
not represented because of time and cost
constraints. The desert scrub biome is the
most extensive biome in the Great Basin
biogeographic region. Low-, medium-, and
(medium) high-producing sites were se-
lected to represent this major biome. A
medium producing grassland and high-
producing pinyon-juniper site were also
selected. Low-producing grassland and
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pinyon-juniper sites are rare in the Great
Basin biogeographic province.
Macroplot Design
Ecological interpretation of information
gathered on monitoring sites requires plot
configurations that provide sufficient areal
support to capture the characteristics of
the biological communities. The general
1993 macroplot design to determine the
sample support area and optimum plot
design is shown in Figure 1. Plot size
variance and configuration relationships
along with cost of data collection in terms
of available resources, e.g., time and
money, will be used for optimal plot de-
sign evaluations. Optimal plot design will
be determined empirically for all important
indicator measurements via uniformity
sampling trials with nested plot designs
on three EMAP-Arid formation types or
biomes, i.e., desert scrub, grassland, and
conifer woodland (pinyon-juniper). This
study needs to precede or coincide with
indicator development before undertaking
projects at the survey demonstration level.
Macroplot sampling areas are designed
for vegetation, harvester ants, spectral
properties, and soils.
Indicators
The EMAP indicators are being devel-
oped as characteristics of the environ-
ment that, when measured, quantify the
magnitude of stress, habitat characteris-
tics, degree of exposure to stressors, or
the degree of ecological response to an
exposure. Indicators serve as the basis
for quantification of the assessment end-
points (i.e., the actual measurements to
be made). In the 1993 EMAP-Arid Colo-
rado Plateau Plot Design Pilot Study, the
same three indicator categories and mea-
surements used in the 1992 pilot will be
studied to determine the optimum plot size
for each. The three indicator categories
are vegetation composition and abun-
dance, spectral properties, and soil prop-
erties.
The composition, structure, and abun-
dance of vegetation have been recognized,
Soils/Vegetation/Spectral Macroplot Design
Enter/Exit
Veg/Spectral
Here
180M
1. Trees/Veg Sampling
Sequence
3. X = Basic Soil Unit
(36 Samples)
®= Auger Samples
(9 Samples)
4. Tree Plot
15m
5m
Grasses/Forbes
(576 Readings)
5.
Spectral N Shrubs/Ants
(1440 Readings) (288 Readings)
«— Enter/Exit
Veg/Spectral Here
Figure 1. Macroplot design for soils, vegetation, and spectral properties indicators.
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as useful indicators of environmentally in-
duced changes in arid vegetation. The
proposed measurements for the determi-
nation of these indicators are estimation
of (1) the percent cover and (2) the height
of the green vegetation on the site by
species. Together these measurements
can provide an index of leaf area and
serve as sensitive indicators of change in
biological condition at the organism, popu-
lation, community, and ecosystem levels.
Electromagnetic radiation provides in-
formation about the physical and chemi-
cal properties of materials. While the spec-
tral reflectance properties of objects tend
to be wavelength dependent, the determi-
nation of these relationships is critical for
characterizing or discriminating the objects.
Vegetation, soils, and other materials have
spectral responses that are a function of a
diverse array of properties of those mate-
rials. These properties might include mois-
ture content, shadowing, and presence of
other materials. Nevertheless, the overall
spectral response of a material is largely
a function of the material itself. Spectral
measurements will be made to determine
if vegetation condition and soil properties
can be related to spectral signatures col-
lected by satellite, hand-held spectrom-
eters, or both. Ground spectra will be col-
lected using a portable field spectrometer.
The 1993 Plot Design Pilot Study wilt fo-
cus on correlating the spectral reflectance
measured on the ground with that deter-
mined from various satellite platforms to
estimate vegetation and soils features.
Selected soil properties will be mea-
sured in the field and lab as indicators of
soil erosion, productivity, and moisture-
plant growth indices. Local soil charac-
teristics and soil surface and subsurface
samples wpl be obtained using established
methods from the U.S. Soil Conservation
Service. Local soil characteristics will be
used to evaluate type of soil and to calcu-
late an erosion index. Surface physical
and chemical soil attributes are obtained
from samples collected at the surface.
Surface soil properties are one of the first
attributes to respond to natural and an-
thropogenic stress. Deep soil profile ob-
servations will be collected to classify the
soil. Most of the measured soil properties
provide baseline data that would only be
resampled if notable changes occurred in
other indicators. The data can then be
used for comparison extrapolation and in-
terpolation of long-term change.
The following research questions will
be assessed in addressing the 1993
EMAP-Arid objective:
t.What is the relationship between indi-
cator measurement properties and the
size and shape of plot for selected
vegetation, soils, and spectral indica-
tor measures?
2. What are the costs associated with
setting up and sampling basic units
for measuring the selected vegeta-
tion, soils, and spectral indicator cat-
egories?
3. What are the sizes and shapes of
plots that maximize the amount of
information per unit cost for the se-
lected vegetation, soils, and spectral
indicator measures?
4. What are the effects of spatial corre-
lation patterns, if they exist, on the
choice of plot size and shape?
5. How similar are the variances and
correlation patterns across EMAP-Arid
subpopulation formation types?
The U.S. Environmental Protection
Agency (EPA), through its Office of Re-
search and Development (ORD), funded
and collaborated in the research described
here. It has been peer reviewed by the
Agency and approved as an EPA publica-
tion. Mention of trade names or commer-
cial products does not constitute endorse-
ment or recommendation for use.
u.S. GOVERNMENT PRINTING OFFICE: 1994 - 550-M7/80279
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The EPA author, William G. Kepner, is with the Environmental Monitoring Systems
Laboratory, Las Vegas, NV 89193-3478.
Daniel T. Heggem is the EPA Project Officer (see below).
The complete report, entitled "Environmental Monitoring and Assessment Program:
Arid'Ecosystems 1993 Implementation Plan—Colorado Plateau Plot Design Pilot
Study," (Order No. PB94-165339; Cost: $19.50; subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Las Vegas, NV 89193-3478
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
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EPA/620/SR-93/016
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