Responses of benthic macroinvertebrates in small intermittent streams to silvicultural practices

We examined macroinvertebrate communities in small (0.1-1.0 m(2)) pools of intermittent streams (always containing some water but without perennial flow) with small watersheds (2-6 ha) subjected to five types of forest harvest to assess potential impacts of the different harvest methods. Buffer strips 10 m wide were left on each side of the streams. Each harvest treatment was coupled with a similar unharvested reference stand. An incomplete block design included three 0.05 m(2) vacuum samples from each treatment paired with three from the adjacent references. There was a high degree of similarity among references for parameters other than taxonomic composition (e.g. macroinvertebrate density, number of species, Shannon diversity, functional groups, etc.). Statistically significant differences were found between references and treatments and among harvest methods but the responses varied among response variables (density, Shannon-Weiner diversity, species composition), different species assemblages (all invertebrates, chironomids, Ephemeroptera-Plecoptera-Trichoptera [EPT], isopods), and functional group categories (shredders, collector-gatherers). We collected 56 taxa, 7-16 per site, with low community similarity (mean Jaccard's = 0.18, mean Bray-Curtis percent dissimilarity = 81). The most severe harvest treatments resulted in the highest diversities of total invertebrates in these small spring pool communities.