In response to the Federal Water Pollution Control Act (a.k.a., Clean Water Act) of 1972, forestry best management practices (BMPs) were developed and subsequently implemented to address NPS pollution during forest management. BMP guidelines vary by state and can be nonregulatory, quasi-regulatory, or regulatory. To determine how effective the guidelines for protecting water quality are, research literature relating to BMP effectiveness was evaluated. Forestry BMP effectiveness studies are often site or region specific. Therefore, BMP research in the United States was divided into three regions: northern, southern, and western. Thirty research studies were reviewed for the southern region with the majority being conducted in the Piedmont and Coastal Plain physiographic regions. The Western region had thirty-one studies, most of which were in the Pacific Border physiographic region. The northern region had twenty studies primarily in the northeastern states. Forestry BMP effectiveness research generally focused on forest water quality from timber harvesting, site preparation, forest road construction and maintenance, stream crossings, and other categories of forest operations. The literature indicates that forestry BMPs protect water quality when constructed correctly and in adequate numbers. Forestry BMP effectiveness studies allow state forestry BMP programs to evaluate progress in reducing non-point source pollution and achieving water quality goals established under the Clean Water Act (CWA). Furthermore, states have used research findings to change BMPs and improve their guidelines. Although forestry BMPs have been proven to protect water quality, they are still being refined to enhance their performance.

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The influence of clear and partial cut harvests on belowground nutrient cycling processes was examined on the Pearl River floodplain, Mississippi. Foci exambted by this study included fine root biomass and detritus, fine root production, fine root nutrient contents, soil respiration rates, and microbial biomass C, N, and P during the first year post-harvest. Both the clearcut and partial cut initially reduced fine root biomass; however, fine root biomass levels within each treatment did not differ at this study's conclusion. Bimonthly fine root production within both the clearcut and partial cut declined initially following harvest; however, net primary production was greatest within the clearcut, followed by the partial cut, and lowest within the control. Soil respiration rates showed strong seasonal trends; however, increased soil respiration rates within the clearcut and partial cut were not found until almost 1 yr post-harvest. Decreased microbial biomass C levels were observed following both harvests. Only the clearcut treatment significantly reduced microbial biomass N. No treatment effects were found regarding microbial biomass P. Herbaceous and woody vegetation recolonization was vigorous within the clearcut and partial cut harvests, strongly influencing fine root production levels and soil respiration rates. It appears that fine roots from naturally recolonizing vegetation play a large role in belowground C storage following disturbance. The rapid increases in fine root production and biomass following both silvictdtnral methods indicates that, within these ecosystems, the negative in0uences of harvesting on belowground C and nutrient pools may be short lived.

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