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Threats to Biological Diversity
Benefits of Indiana's Biological Diversity


Generally, the qualification of a natural area is the lack of disturbance by humans. Since few if any areas exist in Indiana that are totally undisturbed, it is instead necessary to consider how long an area has gone undisturbed relative to other areas. A broad definition of a natural area is cited in the Natural Resources Inventory prepared by the Indiana Department of Natural Resources in 1976, "any outdoor site that contains an unusual biological, geological, or scenic feature or else illustrates common principles of ecology uncommonly well."
17 Another definition of natural resource areas is set forth by the Indiana General Assembly for the purposes of protection by the State of Indiana as: "those of land, water, or both land and water" that either (1) retain or have reestablished their "natural character," although that character need not be undisturbed; or (2) have scientific or educational value and either have unusual flora or fauna or have biotic, geological, scenic, or paleontological features.18

The rich diversity of Indiana's natural resources drew settlers to Indiana and supported prosperity. The abundant sand, a variety of fish, hard timber, plentiful wildlife, clean water, and the fruits of various species of vegetation sustained life for the early pioneers, and provided prosperity as a result their use. However as humans utilized these resources to build an economic future, humans were simultaneously compromising the base for that diversity.19 We "live in a landscape made up of natural systems which sustain us. If we degrade those systems, we degrade the quality of our own lives."20

Biological diversity is the "assortment of habitats and natural regions, the diversity among species, and the genetic variation within each species. It is the foundation of the ecological processes that make life possible, and it makes natural communities resilient to disturbances such as floods, tornadoes, pest infestation and human alteration of habitat."21

There are several reasons for conserving biological diversity (or "biodiversity"). These reasons are generally described as: (1) Loss of diversity weakens entire natural systems; every species plays a role in maintaining this system. (2) More specifically, only a few species are used as a food source. Wild strains of these species are a critical genetic reservoir of new variations to prevent spread of pests and diseases. In addition every species is a potential source of medicine. (3) Humans depend on healthy ecosystems for air, water, and food. Further, the economy depends on a healthy ecosystem as well. (4) The species and natural systems are intrinsically valuable simply due to their existence.22

In 1980, the market value of prescription drugs from higher plants was estimated at over $3 billion. Organic alkaloids, a class of chemical compounds used in medicines, are found in an estimated 20% of plant species. Yet only two percent of plant species have been screened for these compounds.23 Approximately 25% of the prescription drugs currently marketed in the United State are based on chemicals derived from wild plants. Indiana has contributed to the development of medicines from plants located in Northwest Indiana. An example is the yellow wild indigo, a state threatened plant species, currently being used in research to treat the AIDS virus. The plant is only found in black oak savannas in Northwest Indiana. The Nature Conservancy has compiled a list of examples of plant and animal species utilities in an unpublished report: Utility of Diversity Summaries: March 1981 to February 1989.24

Threats to Biological Diversity

The most serious threats to biological diversity in Indiana include: (1) habitat loss and fragmentation; (2) habitat degradation; and (3) the spread of exotic species.25 The direct loss of habitat for plants and animals can be attributed to a variety of human activities. These activities include conversion of lands and waters from prairie, forest, or wetland for agricultural use; or filling wetlands of destruction of dunes for industrial or residential developments. Habitat fragmentation is a significant threat to biological diversity where ever human activities are present. Habitat fragmentation has been described as the"process whereby large continuous areas of habitat are reduced in areas and separated into discrete parcels." These discrete parcels become fragments of habitat, isolated from other areas of similar habitat by a modified landscape. Fragmentation can occur as a result of habitat being divided by roads, railroads, canals, power lines, or fences. Fragmentation can lead to rapid loss of species due to a barrier to the normal processes of dispersal and colonization.

Habitat degradation can lead to a reduction in biological diversity. Water quality in rivers and lakes has over the years become degraded due to siltation resulting from urban and agricultural activities, pollution from discharges of municipalities, industries and agriculture, and runoff containing chemicals from highways and fields. Wildlife and riparian habitats have been degraded through means such as the manipulation of waterways for flood controls and draining of low lands for agriculture and development.


Natural communities depend upon the natural cycles of floods and rely on wetlands to purify the water in which they live and provide vegetation for food and nesting.

Plants and animals are often restricted in their ability to move to other areas. In some instances, species are transported by people for use as game fish, cultivation, and breeding. In other cases, species have been introduced inadvertently on ships and vehicles. The majority of "exotic" species do not become established, however, because they are transplanted in areas where their natural predators do not exist, they may have an advantage over native species in an area. Once established, they directly influence the native species through competition for resources, predation, or the actual alteration of the native habitat. In Northwest Indiana purple loosestrife and the common reed (Phragmites) have invaded wetlands and drastically altered the natural plant communities.

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