8095

• UCREFRP Catalog Number: 8095
• Author: National Research Council.
• Title: Impacts of Emerging Agricultural Trends on Fish and Wildlife Habitat.
• USFW Year: 1982.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

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moose. The migration westward brought a drastic modification of
pralrle habitat to the detriment of some wildlife (bison, elk, and
pronghorn) and to the benefit of others (rodents and lagomorphs).
These early changes were gradual in relation to the rate of
transformation brought on by the advent of mechanized agriculture. In
the early periods, wildlife had time to adapt to "changing conditions
. . . [or] . . . to retreat to nearby undisturbed areas. But [modern]
agriculture in America rapidly affected vast areas . . . giving most
wildlife species no time to adapt and no place to retreat" (Brokaw
1978).
Modern agricultural technology, together with economic forces, has
favored large contiguous fields devoted to single crops. The
increasingly efficient drainage of lowlands, improved varieties of
crops capable of growing on marginal soils, increased and more
efficient use of fertilizer and pesticides, and development of
irrigation have expanded cropland at the expense of natural
ecosystems. The variety of habitat essential to wildlife is now often
lacking. Species that responded positively to earlier patterns of
agriculture have now declined. The ring-necked pheasant is an
excellent example: the large pheasant populations typical in the
Midwest and Northern plains 30 years ago have dwindled rapidly with
the intensification of agricultural operations.
Many specific agricultural and forestry land use practices affect
the potential of an area to support wildlife. A unit of land planted
to row crops or grain and plowed immediately after harvest results in
poor habitat for most wildlife. If the same unit is cropped using
conservation tillage practices or is used for pasture, it becomes more
attractive to several species. Crop and forest diversity, plant
spacing, presence of weeds, spillage of harvested crops, crop and
forest residues, timing of farming and silvicultural operations, field
size, and distribution of fields in relation to one another and to
uncultivated bottomlands, woodlots, and similar areas that are
relatively undisturbed all determine the attractiveness of an area to
wildlife. Often, small changes in land use practices can result in
major differences in the amount of habitat available to wildlife.
Other practices result in changes in the quality of aquatic
habitats. Silt from erosion and runoff from organic wastes,
fertilizers, and chemicals, as well as such techniques as irrigation,
channelization, ponding, and cutting on steep slopes, affect aquatic
systems and hence the species diversity of fish and wildlife dependent
on these habitats.
SOme practices that increase agricultural production enhance fish
and wildlife habitats; others are detrimental. For example,
diversifying crop and tree species may increase yields and build soil
texture and fertility and at the same time create wildlife habitats
far superior to those of similar areas that support single-species
crops. Erosion control often directly and indirectly improves
terrestrial habitats and protects water quality while benefiting
agricultural production. Fall plowing, double cropping, extensive
clearcutting, and increased use of herbicides aid production, but
usually at the expense of wildlife habitat.