oElPA
United States
Environmental Protection
Agency
An Ecological and Habitat
Vulnerability	A
Arkansas' White River Basin
Project Overview
In the summer of 2000, the U.S. EPA's Office of
Research and Development was requested to collabo-
rate in a U.S. EPA Region 6 Regional Applied Research
Effort (RARE). The primary goal of this RARE is to
utilize current science and technology to improve the
assessment capabilities of ecological and habitat vul-
nerability in the White River Basin (Arkansas). This
RARE is also being conducted in the relevant sur-
rounding areas of the Lower Mississippi River Valley
and builds upon the results of U.S. EPA's ecological
assessment of the Louisiana Tensas River (EPA/600/R-
99/016).
Project Geographical Coverage
The risk of surface water impairment as a result of land
cover configuration and change potential was assessed
and reported for the White River's drainage basin (left,
A), bounded by the U.S. Geological Survey Hydrologic
Unit Codes (HUCs) 0802 and 1101. The risk of habitat
damage or loss as a result of land cover change was
assessed and reported for the "Omernik" Mississippi
Alluvial Valley (MAV) Ecoregion (left, B), which
includes a portion of HUC 0802. A portion of
Arkansas' Lower White River Basin (left, C), which
includes a 9,000 square kilometer sub-region of the
MAV Ecoregion, was utilized to test habitat vulnerabil-
ity methodologies at a relatively fine scale. The fine-
scale study area (left, C) was selected in conjunction
with the U.S. Fish & Wildlife Service and Regional EPA
scientists, such that the White River National Wildlife
Refuge (NWR), Cache River NWR, and Bald Knob
NWR (Arkansas) were included. These three National
Wildlife Refuges contain a large proportion of the last-
remaining bottomland hardwood swamps of the
Mississippi River Valley.
Project Goals and Approach
HABITAT VULNERABILITY ASSESSMENTS:
•	Create GIS models of habitat suitability for plant
species, animal species, and guilds using published
Habitat Suitability Index (U.S. Fish & Wildlife
Service) and life history documentation
•	Utilize fundamental ecological principles of habitat
patch dynamics to determine vulnerability to loss
or degradation
•	Utilize land cover gradients in the Lower White
River Basin and MAV Ecoregion to model current
and future landscape change scenarios
WATER QUALITY VULNERABILITY
ASSESSMENTS:
•	Utilize landscape-ecological metrics (e.g., percent
forest cover) and land cover gradients among
watersheds in the White River Basin to determine
water quality impairment vulnerability
•	Validate modeled relationships between land-
scape-ecological condition and surface water
quality using the National Water Quality
Assessment Program (U.S. Geological Survey)
water chemistry data

-------
An Ecological and Habitat Vulnerability
Assessment of Arkansas' White River Basin
Habitat Vulnerability Assessment Parameter
Overview: U.S. FWS Habitat Suitability Index factors
for mallard duck (below, left), black bear, least tern,
and wetland plants; habitat patch area; habitat patch
perimeter; habitat interior-to-edge ratio; habitat shape
indices; unified patch index; current human population
density; future human population density; road
indices; unified human disturbance index; and a uni-
fied vulnerability index (below, left)
Water Quality Vulnerability Assessment
Parameter Overview (measured among HUCs
and within riparian zones): percent forest cover;
largest forest patch proportion of watershed; mean for-
est patch area; largest forest patch area; percent crop
agriculture; percent pasture; percent total agriculture
(below, right); percent barren land; percent urban and
built-up; percent wetland; percent human-use; percent
natural land cover; and percent agriculture on steep
slopes
For Further Information, contact:
Ric Lopez, Ph.D. or Daniel T. Heggem
U.S. EPA National Exposure Research Laboratory
Environmental Sciences Division/ ORD
944 E. Harmon Ave.
Las Vegas, NV 89119
Pel: (702) 798-2394 or (702) 798-2278
FAX : (702) 798-2692
E-mail: lopez.ricardo@epa.gov or
heggem. daniel@epa. gov
http:// www.epa.gov/nerlesdl/land-sci/staff, htm
Vi
(< -3 Std. Dev.) = Greatest Habitat Vulnerability
(-3 to -2 Std. Dev.)
(-2 to -1 Std. Dev.)
(-1 to 0 Std. Dev.)
(0 to 1 Std. Dev.)
(1 to 2 Std. Dev.)
(2 to 3 Std. Dev.)
(> 3 Std. Dev.) = Least Habitat Vulnerability
S
HUC Percent Total Agriculture
^8-30
¦ 30 - 46
46-61
J 61 - 76
H 76 - 92
30 0 30 60 90 120 150 180 210 240 Kilometers
For this effort and other NERL science projects, visit our website at http://www.epa.gov/nerl
NOVEMBER 2002

-------