No abstract

Undisturbed forested watersheds are generally recognized as a primary source of high‐quality water. The physical and chemical nature of these waters fluctuate constantly in response to natural stresses but are most influenced by man's activities. Three major forest land management activities—timber harvesting, fertilization, and herbiciding—which may have an adverse affect on water quality are reviewed. In general, research results indicate that nutrient losses, particularly nitrogen, following forest clearcutting are small to negligible. Similarly, forest fertilization studies indicate that nitrogen concentrations in streams are not drastically increased. Large areal applications of selected herbicides in the West have demonstrated that, if carefully applied, they can be used without impairment of water quality.

A field study of five coal surface mine sites reclaimed with sewage sludge and one site reclaimed by conventional methods (chemical fertilizer) was conducted to assess the effects of sludge amendments and time on populations of bacteria, fungi, and actinomycetes, and on microbial respiration and organic matter decomposition. The sludge‐amended sites ranged in age from 1 to 5 yr following sludge application at rates of 120 to 134 Mg ha−1 (dry wt. basis). All sites were planted to grass and legume cover. Populations of aerobic heterotrophic bacteria, fungi, and Nitrobacter, and soil respiration rate, were highest on the 1‐yr‐old site due to the high organic matter input. On the four older sites, values decreased, but remained within the ranges reported for undisturbed soils. Actinomycete populations peaked on the 3‐ and 4‐yr‐old sites, while populations of Nitrosomonas were not related to the age of the site. Decomposition rate was lowest on the 1‐yr‐old site, and increased significantly with site age. As measured by microbial populations and activity, ecosystem recovery on the sludge‐amended sites appeared to be occurring at a more rapid rate than on the fertilizer‐amended site, which after 5 yr, exhibited sparse microbial populations and low activity. The microbial populations in the sludge‐amended spoil were not adversely affected by the heavy metals applied in the sludge, when compared with populations of soil microbes reported for undisturbed soils.

Average annual and seasonal runoff and daily mean discharges at selected flow durations of 137 watersheds in the northeast United States totaling less than 100 square miles were related to selected climatic, topographic, and land‐use variables. The most influential variables on annual and seasonal discharges, in descending order, were precipitation, percentage of watershed area in forest cover, elevation, latitude, July mean maximum temperature, and percentage of swamp. Isohyetal precipitation was more highly correlated with average annual runoff than precipitation values from stations closest to the watersheds. The degree of correlation of average annual runoff with average annual precipitation in nonmountainous physiographic units was related to the distance between the precipitation station and the center of the watershed. The proportion of forest cover was correlated positively with runoff, its influence very likely integrating a number of environmental factors that would tend to produce greater runoff.

No abstract