U.S. Department of the Interior

U.S. Geological Survey

The Gap Analysis Program (GAP) is 

a program for identifying the degree to 

which native species and natural communities are represented in present-day 

conservation lands. Those areas where 

unique biological communities and conservation lands do not overlap constitute 

gaps in our conservation effort. 

GAP aids in the protection of biodiversity through a regional assessment of 

the conservation status of native species 

and natural land-cover types. This 

assessment provides a practical approach 

based on available data to identify potential conservation areas and strategies. 

GAP is a preliminary step to the more 

focused, local studies needed to establish 

boundaries for potential biodiversity 

management areas. GAP is conducted as 

state-level projects and is coordinated by 

the U.S. Geological Survey (USGS) 

Biological Resources Discipline 

(BRD). It is a cooperative effort among 

regional, state, and Federal agencies 

and private groups.

Ohio GAP

In Ohio, the U.S. Geological Survey, 

The Ohio State University, and the 

Ohio Department of Natural Resources, 

Division of Wildlife, are cooperating 

on the GAP analysis. The Ohio GAP 

program, one of fifty, has terrestrial and 

aquatic components that include all terrestrial vertebrates, fish, crayfish, and a 

set of aquatic macroinvertebrates 

(fig. 1). 

Additionally, through an Ohio Lake 

Erie Protection Fund grant, Ohio GAP 

is doing an analysis on wetlands within 

the Lake Erie Basin. This work allows 

the terrestrial and aquatic components 

Figure 1. Numerous species can be found in Ohio. Some of these are, clockwise (starting at right): New River crayfish, Cambarus sciotensis, Yellow Warbler, Dendroica petechia, Racer, Coluber constrictor, Orangethroat darter, Etheostoma spectabile, Northern 

spring peeper, Pseudacris crucifer. (Photos reproduced with permission.)

What is the Ohio Gap Analysis Program (GAP)?

USGS Fact Sheet FS-093-01

August 2001

In cooperation with The Ohio State University, Ohio Department of Natural Resources, and Ohio Lake Erie Protection Fund

Box 1

National GAP

The mission of the National Gap Analysis Program is to provide regional assessment of 

the conservation status of native vertebrate species and natural land-cover types and 

to facilitate the application of this information to land-management activities. This is 

accomplished through the following five objectives:

1. Map the land cover of the United States.

2. Map predicted distributions of vertebrate species for the United States.

3. Document the representation of vertebrate species and land-cover types

 in areas managed for the long-term maintenance of biodiversity.

4. Provide this information to the public and to those entities charged with

 land-use research, policy, planning, and management.

5. Build institutional cooperation in the application

 of this information to state and regional 

 management activities.

These objectives can be used as a conservation tool to 

• identify and map areas of species richness,

• determine and map the conservation status of

 lands comprising these areas, and

• identify the “gaps” between areas of high species 

 richness and conservation lands.

 http://www.gap.uidaho.edu
of GAP to be integrated to produce an 

ecosystem-based conservation tool for 

wetlands, the unique areas between land 

and water. The Wetland GAP will be 

concurrent with the two other Ohio GAP 

projects. 

Terrestrial Setting

Five natural ecoregions in Ohio have 

been defined by soil type, vegetation, 

and topography: (1) Huron/Erie Lake 

Plain, (2) Eastern Corn Belt Plain, (3) 

Erie/ Ontario Lake Plain, (4) Interior 

Plateau, and (5) Western Allegheny Plateau. These divisions are used by many 

state and Federal agencies for land-use 

planning and management, as well as for 

biological assessments.

The Huron/Erie Lake Plain, a former 

lakebed in northwestern Ohio, consists 

of silty, poorly drained soils. Important 

remnant ecosystems found here include 

the Great Black Swamp, a large forested 

wetland that was converted to cropland 

at the turn of the last century, and the 

Oak Openings, a dune and swale ecosystem.

The Eastern Cornbelt Plain extends 

from central Ohio westward into Indiana. What once comprised beech-maple 

forests with scattered prairie openings is 

now prime agricultural land in Ohio.

The Interior Plateau in the southwestern corner of Ohio is a transitional area 

between the Western Allegheny Plateau 

and the Eastern Corn Belt Plain. Primarily agricultural in the west, the landscape becomes increasingly forested 

towards the east. Historically, forest 

openings contained prairie species and 

cedar barrens.

The Erie/Ontario Lake Plain, the 

home of most of Ohio’s industry, occupies the northeast corner of the State. 

Many isolated wetlands (bogs, fens, and 

forested swamps) containing rare northern plant species are found in this part of 

the State.

Box 2

Why is GAP important?

Loss of Biodiversity

Biological diversity, or biodiversity, 

refers to the variety of living things in 

an ecosystem. Biodiversity can be 

defined at three hierarchical levels: 

genetic, species, and ecosystem. 

Why is the diversity of life important? Genetic diversity ensures the 

resilience and productivity of natural 

and agricultural ecosystems on which 

we depend for food, medicines, and 

raw materials. Species diversity 

ensures a supply of biological “workers” for ecological tasks: animals 

renew soil fertility, decompose 

wastes, and pollinate crops and natural vegetation, whereas plants are 

useful in erosion control, watershed 

protection (by countering droughts 

and floods), wastewater management, noise abatement, and air-pollution control 

(Murphy, 1988). Ecosystem diversity ensures that large-scale biotic systems interact to purify our air and water, control and stabilize the climate, and cycle nutrients. 

Despite these and other benefits of biodiversity, species are disappearing at an 

alarming rate. The United States contains approximately 4 percent of the world’s 

known reptile species, 5 percent of the amphibians, 7 to 8 percent of the freshwater fish, 9 percent of the mammals, and 8 percent of the birds (World Resources 

Institute, the United Nations Environment Programme, the United Nations Development Programme, and the World Bank, 1999). The Nature Conservancy estimates 

that about one-third of U.S. plant and animal species, about 6,500 species, are at 

risk of extinction (Stein and Flack, 1997). Animal species in Ohio are included in 

this potential risk of extinction (table 1).

Habitat Loss in Ohio

Habitat loss in Ohio is a major concern. The leading cause of loss of biodiversity is habitat destruction (Stein and Flack, 1997). Several kinds of human activities that most likely will lead to habitat loss include large-scale corporate farming, 

urban development, logging, grazing, mining, road building, water development, 

introduction of nonnative species, pollution, fire suppression, and recreation.

Among the 50 states, Ohio is ranked 7th in population with 11,256,654 people 

(U.S. Census Bureau, 2000) and 34th in land area with 41,330 mi2 (Ohio Historical 

Society, 1999). Ohio has approximately 73,000 farms covering 15 million acres 

(Ohio Agricultural Statistics Service, 1998). The State produces an estimated 300 

to 400 million board feet of timber each year (Ohio Agricultural Industry, 2001). 

There are 113,435 miles of highway in Ohio (Ohio Historical Society, 1999), which 

is, for its size, more than any other state (Key to the City, 2001).

Sources: U.S. Fish and Wildlife Service, 2001; Ohio Department of Natural Resources, Division of Wildlife, written 

commun., 2001

Table 1. Federal or State endangered, threatened, special interest, and species of 

concern in Ohio

Endangered Threatened Special 

interest

Species of 

concern

State Federal State Federal State Federal

Mammals 061 0 0 8 3

Birds 29 1 3 1 6 10

Reptiles 05 0 1 2 10 7

Amphibians 050 0 0 2 0

Fish 24 1 13 0 9 8

Mollusks 27 6 4 0 6 9

Dragonflies 090 0 0 0 2

Crayfish 000 1 0 2 0

Butterflies 072 1 0 3 3

Moths 14 0 4 0 3 3

Beetles 031 2 0 6 5
The Western Allegheny Plateau, containing most of the public lands and forests in Ohio, occupies the southeastern 

part of the State. This unglaciated region 

is characterized by steep valleys, ridges, 

and many interesting geological formations. Coal mining and timber harvesting are the main land uses in this part of 

the State.

Historically, Ohio’s landscape comprised a diverse array of ecosystems. 

Although 95 percent forested, the 

remainder of the State included 5 million 

acres of various wetland types (bogs, 

fens, and marshes). In addition, nearly 

1,000 mi2 (square miles) of prairies and 

grasslands occupied large forest openings at the time of settlement.

Today, few undisturbed prairies, wetlands, and forests remain. Since the late 

1700s, Ohio has undergone drastic 

changes in land use, which have resulted 

in a mosaic landscape consisting mainly 

of agriculture, suburban/urban areas, and 

fragmented woodlands. 

Aquatic Setting

Ohio is a water-rich state with more 

than 3,300 named streams and an even 

larger number of small, unnamed 

streams. Ohio has 44,000 miles of continuously flowing streams, 376 mi2 of 

inland water, and 3,499 mi2 of Lake 

Erie, providing Ohio with a diversity of 

freshwater species. Lake Erie is the 11th 

largest freshwater lake in the world and 

has the most productive fishery in all the 

U.S. Great Lakes. The health of the 

Lake Erie fishery depends on the health 

of the streams flowing into the Lake. 

The Ohio River drainage basin, which 

contains more than 400 miles of waterways, is approximately 22,720 mi2 

within Ohio’s borders. The Ohio River 

is the boundary for six states and is a 

major transportation corridor.

Ohio’s aquatic resources are subject 

to many conflicting and competing uses, 

thus posing some of the State’s most 

pressing ecological problems. Approximately 52 species of fish, 53 species of 

mussels, and 3 species of crayfish are 

listed on the State level as extinct, extirpated, of special interest, endangered, or 

threatened (Dave Risley, Ohio Department of Natural Resources, written commun., 2001). Problems facing Ohio’s 

aquatic resources include the loss of 90 

percent of Ohio’s original wetlands to 

urban and agricultural use, the destruction of riverine habitat through the building of more than 60,000 dams, water 

withdrawal, land-use alteration (resulting 

in decreased water quality and alteration 

of flow), pollution, and the introduction 

of nonnative species. These problems 

will continue to put pressure on streams, 

rivers, and remaining natural wetland 

habitats in Ohio.

Figure 2. Breeding Bird Species Richness based upon location data from the 

Ohio Breeding Bird Atlas (Peterjohn and Rice, 1991).

Box 3

Terrestrial Methods

Ohio Terrestrial GAP is generating range 

maps using a hexagon sampling grid created 

by the U.S. Environmental Protection Agency 

(USEPA) as part of standard GAP procedure 

(fig. 2). More detailed species distributions are 

being modeled within the hexagons where particular species are known to live. To conduct a 

GAP analysis, scientists create digital maps 

representing existing natural vegetation, predicted distributions of native vertebrate species, and current protected lands, using 

geographic information systems (GIS) and 

remote-sensing technology. These maps will 

be superimposed to analyze the elements 

(individual species, species-rich areas, and 

vegetation-cover types) that are underrepresented in areas designated for the management and protection of biodiversity.

 

 

Figure 3. Ohio’s major drainage basins.
Products

To aid in the protection, restoration, 

and conservation of terrestrial and 

aquatic habitats, GAP produces maps 

(Boxes 3 and 4) that identify ecologically valuable areas. Maps of vegetation, 

stream and wetlands classifications, 

biodiversity, and conservation status 

made available to state and local agencies charged with land-use, transportation, and development planning will help 

promote conservation prior to development. The GAP approach provides a 

useful planning tool to protect common 

species, while they are still common, as 

well as to protect rare species by identifying critical habitats.

 The planned products of Ohio GAP 

can be used by State and Federal agencies, as well as local and regional planning authorities. Uses of GAP data 

include wildlife management, ecosystem restoration, county planning, landuse planning by private corporations, 

basic research, generation of options for 

conservation-area designations, and 

environmental assessments.

References Cited

Key to the City, 2001, Ohio facts and 

links: accessed May 30, 2001, at 

URL http://www.pe.net/~rksnow/

ohlinks.htm.

Murphy, D. D., 1988, Challenges to biological diversity in urban areas, in

Wilson, E.O., ed., Biodiversity: 

Washington, D.C., National Academy Press, p. 71-76.

Ohio Agricultural Industry, 2001, Quick 

facts: accessed May 30, 2001, at 

URL http://www.state.oh.us/agr/

quickag.html.

Ohio Agricultural Statistics Service, 

1998, 1998 Ohio agricultural statistics: U.S. Department of Agriculture, table 7.

Ohio Historical Society, 1999, Ohio’s 

Geography: Ohio History Central—

Natural Ohio, accessed April 3, 

2001, at URL http://www.ohiokids.org/ohc/nature/geograph/

index.html.

Peterjohn, B.G., and Rice, D.L., 1991, 

The Ohio breeding bird atlas: Ohio 

Department of Natural Resources, 

Division of Natural Areas and Preserves.

Stein, B.A., and Flack, S.R., 1997, 1997 

species report card, The state of 

U.S. plants and animals: Arlington, 

Va., The Nature Conservancy, p. 8.

U.S. Census Bureau, 2000, County population estimates for July 1, 1999, 

and population change for July 1, 

1998, to July 1, 1999: accessed May 

30, 2001, at URL http://www.census.gov/population/estimates/

county/co-99-1/99C1_39.txt

World Resources Institute, the United 

Nations Environment Programme, 

the United Nations Development 

Programme, and the World Bank, 

1999, World resources 1998-99: 

Oxford Press, 384 p.

For more information, 

please contact:

Ohio GAP Coordinator

U.S. Geological Survey

6480 Doubletree Avenue

Columbus, OH 43229

Phone: (614) 430 - 7700

Internet: http://oh.water.usgs.gov/ohgap/

ohgap.html

By: S. Alex. Covert, Melissa Haltuch, and 

Troy Wilson

Box 4

Aquatic Methods

Ohio Aquatic GAP is generating a 

1:100,000-scale digital map layer of 

riverine habitats for approximately 

3,300 named streams in Ohio. To 

map riverine habitats, scientists are 

using landscape features that remain 

relatively constant through time, such 

as major drainage basins (fig. 3). By 

identifying stream types based on 

habitat and determining their rarity 

and conservation status, GAP 

researchers can develop conservation priorities for Ohio’s rivers. Once 

conservation gaps based on habitat 

have been determined, the researchers will use distribution data for all 

known species of fish (fig. 4) and 

crayfish, as well as selected macroinvertebrates, to predict these species distributions in each riverine 

habitat.

Figure 4. Ohio distribution of pumpkinseed sunfish (blue dots) from 

Ohio GAP fish database. The red dots represent fish-collection sites 

where pumpkinseed sunfish were not observed.