Greater Yellowstone Network
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|Debinski, D. M. and C. Swanson. 2004. Terrestrial Insects as a Vital Sign in the Greater Yellowstone Network.
|Insects play many vital roles in ecosystems; their environmental services are as varied as Class Insecta itself. These diverse services include pollination, seed dispersal, soil profile modification, connecting plants and vertebrates in food webs, nutrient cycling, and acting as natural biological control agents.
Insects are ideal organisms to monitor because their biological cycles are well known, they can be maintained in the field or the lab at low cost, they are easy to breed, have modest food requirements, high reproductive rates, short life spans, a high mobility level in the environment, and display a high sensitivity and quick responses to change.
The suitability of insects as ecological monitors is well known; their populations have been used to document long term changes in habitats (Turin & de Boer, 1988) and fossil records of insect communities have been used to construct climate histories (Atkinson et al., 1987).
Insect populations are responsive to changes in micro- and macrohabitat, including chemical pollution, habitat fragmentation, ecological disruption, and climate change (Kremen et al., 1993). Chemical pollution, a significant problem in ecosystems where humans are present, usually affects the total numbers and biomass of insect populations.
In response to the habitat changes caused by fragmentation, insect communities and movement patterns change. Ecological disruptions such as fire, tropic cascades, logging, and the introduction of exotic species may also cause huge fluctuations in community composition. The warmer, drier conditions expected in the Greater Yellowstone Ecosystem with global climate change (Romme & Turner, 1991) may significantly affect insects with specialized habitat requirements.
Insect movement patterns and community composition are expected to change along with the climatic conditions. It is important to remember that insect populations are capable of huge interannual fluctuations; therefore a population explosion of one species or a decrease of another is not necessarily an indication that major changes are underway.
However, the loss of a subset of this community if continued over the course of many years, a major change in geographic distribution patterns, or a downward turn in many species that exhibit similar sensitivities would be cause for concern.
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