that usually characterize these 
environments. 
As with forest lands, natural and 
human-caused changes in rangeland 
habitats can affect fish and wildlife 
diversity. For example, grazing by 
domestic livestock affects the amount 
and type of forage left for wildlife, and 
it affects riparian habitat for fish. In 
total over recent decades, there have 
been minor declines in the area of 
rangeland. 
Wetlands—Wetlands are at the 
transition between land and water 
areas. Of existing wetland habitats, 74 
percent are under private ownerships 
with the remaining acreage distributed 
among Federal, State, and local 
jurisdictions (fig. 30). Wetlands are 
among the most productive of 
ecological systems. This inherent 
productivity sustains nearly one-third 
of the Nation’s threatened and 
endangered species, provides nursery 
and spawning grounds for 60 to 90 
percent of U.S. commercial fish 
catches, provides breeding and 
wintering grounds for millions of 
waterfowl and shore birds, and 
supports numerous other species of 
birds, mammals and reptiles. Wetlands 
are used for commercial fishing and 
trapping, nonconsumptive recreation 
and study, waterfowl hunting, 
recreational fishing, and other 
activities. 
Because of their inherent productivity, 
some wetlands have been drained and 
used for various types of commodity 
production. Conversions to these other 
uses have contributed to a net decline 
in the area of wetlands from an original 
area exceeding 200 million acres to 
about 100 million acres today. 
Local, State, and Federal agencies have 
been promoting wetland conservation 
and restoration programs. For example, 
the Food Security Act of 1985 has 
greatly reduced the incentive for some 
wetland conversion by making 
ineligible for price supports and other 
publicly provided benefits any person 
who produces an agricultural 
Figure 30—Wetlands are among the most productive ecological systems. 
commodity on wetland converted after 
passage of the legislation. 
Flowing Waters and Associated 
Impoundments—The condition of 
flowing waters and associated 
impoundments affects the wildlife and 
fisheries resource. About 80 percent of 
the Nation’s flowing waters have 
problems with fish habitat, or 
composition of the fish community 
related to water quantity or quality. 
Water quality is affected by turbidity, 
high temperature, nutrient surplus, 
toxic substances, and dissolved 
oxygen. Some of these problems result 
from soil and vegetative manipulation 
associated with agriculture, forestry, 
and other human activities. 
Agricultural Lands—Because of the 
large areas involved, agricultural 
cropping significantly affects fish and 
wildlife populations. Across the 
country, land used for crops declined 
between the late 1940’s and early 
1970’s but increased through the early 
1980’s. Changes in farming practices 
associated with increased cropping 
adversely affect wildlife populations. 
For example, the continuation of 
fencerow-to-fencerow farming would 
eliminate in the affected areas much of 
the nesting, feeding, and winter cover 
that wildlife need for survival. One 
way to make farming practices 
consistent with wildlife habitat is to 
make farmers aware that wildlife can 
be managed as a crop capable of 
generating income. In this way, the 
marketplace could provide incentives 
for making provisions for wildlife 
habitat a normal part of agricultural 
cropping. Conversion of surplus 
cropland to permanent cover under the 
Conservation Reserve Program should 
improve habitat conditions for some 
species in some regions. 
