Sweeney, B. W. 1993. Proceedings of the Academy of Natural Sciences of Philadelphia 144:291–340.
The presence or absence of trees on land adjacent to stream channels is shown to significantly affect the structure and function of macroinvertebrate communities in White Clay Creek, a Piedmont stream in southeastern Pennsylvania. Low order forested tributaries are about 2.5x wider than deforested streams and have more benthic surface area in the form of inorganic (sand, gravel, cobble) and organic (tree roots, leaf litter, wood, etc.) substrates for macroinvertebrate colonization. Streamside forests affect food quality and quantity for macroinvertebrates directly through inputs of particulate food (leaf litter, soils, wood, etc.) and indirectly by affecting the structure and productivity of the microbial (algae, bacteria) food web through shading and modifying the levels of dissolved organic carbon and nutrients. Deforestation eliminates shading and can result in a 2–5°C warming of small streams which is shown to greatly affect important life history characteristics of macroinvertebrates (e.g. growth rate, survivorship, adult size and fecundity, timing of reproduction). The effect of native versus foreign tree species in streamside areas is discussed within the context of stream recovery and restoration. A spatial protocol for planting streamside forests as buffers for mitigating non-point pollution is reviewed and recommendations concerning the details (site preparation, seedling size and species, weed abatement, use of tree shelters, etc.) of streamside reforestation are given.