Aquatic arthropods and forestry: effects of large-scale land use on aquatic systems in Nearctic temperate regions

Aquatic arthropods can be affected by forest management through increased amounts of light, discharge, and sediment runoff, alteration of the supply of basal resources, changes in the supply of large wood, temperature modifications, and food-web effects. This syndrome of alterations varies geographically in magnitude, and the specific details depend on initial biotic and abiotic conditions, local topography, climate, and the particular management practices used. Impacts on standing water appear to be subtle, and most attention has focussed on streams, where changes are often more obvious. The intensity of any changes in processes affecting aquatic arthropods depends, in part, on the proximity of logging to the shoreline and the proportion of watershed harvested, and also on the condition and frequency of forest access roads crossing or near water bodies. Some groups of species are particularly vulnerable, but others, particularly generalist species such as some Baetis Leach (Ephemeroptera: Baetidae) and some Chironomidae (Diptera), appear to benefit from harvesting. In general, outcomes of harvesting near streams are temporary increases in production and abundance but reductions in diversity. Impacts on all trophic levels, especially in streams, can occur from forest harvesting. The primary tool for mitigating these impacts is the use of riparian buffers, but there are still major uncertainties about the effectiveness of specific widths and configurations of buffers and their use for additional types of disturbance.