Use of the Index of Biotic Integrity to Assess the Impact of Land Management Activities on Low Order Streams in Northern Idaho

摘要

The Index of Biotic Integrity (IBI) was adapted to the faunal characteristics of northern Idaho headwater streams. Stream biota was sampled from June 1987 through September 1987. The original Index of Biotic Integrity, as developed for midwestern U.S. streams, was unsuitable for use in northern Idaho. Only four of the 12 metrics included in the original IBI reflected changes in the biotic integrity of northern Idaho streams. The original IBI, although significantly correlated with measures of stream quality, was too insensitive and classified lower quality streams as being in 'good to excellent' health. The original IBI was modified to contain eight metrics to reflect the health of the fish, amphibian, and aquatic macroinvertebrate communities. Also, expectation criteria of three metrics were adjusted for relative stream size. The modified IBI seems to adequately assess the health of northern Idaho headwater streams. The modified IBI detected changes in stream health, as index scores were significantly correlated with road density and percent harvest of the drainages. Also, the modified IBI was more highly correlated with measures of impact and less significantly with the measures of stream size than Shannon diversity of fishes by biomass of numbers, the Index of Well Being, Brillouin diversity of both fishes and aquatic macroinvertebrates. The modified Index of Biotic Integrity offers managers a technique to evaluate stream health with limited vertebrate and invertebrate sampling. Because the index was developed from data collected in northern Idaho streams with generally nonerosive rock types, the authors do not know how well this index would classify stream health in other regions of Idaho or other streams in the Pacific Northwest.