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Precipitation and Streamwater Chemistry in an Undisturbed Forested Watershed in New Hampshire

Martin, C. Wayne
Ecology 1979 v.60 no.1 pp. 36-42
Picea, biogeochemistry, calcium, cations, forest succession, forested watersheds, growing season, hardwood forests, humans, logging, nitrates, nitrogen, nutrient uptake, nutrients, old-growth forests, seasonal variation, soil water, streams, sulfates, trees, weathering, New England region, New Hampshire
Precipitation and streamwater from the Bowl, a watershed in central New Hampshire, were analyzed chemically during 1973 and 1974. The Bowl, covered by a northern hardwood forest with spruce and fir at higher elevations, has never been logged or otherwise disturbed by humans. Calcium, sulfate, and nitrogen ions dominated stream chemistry. The biogeochemistry of the cations seemed to be regulated more by precipitation, soil—water movement, and chemical weathering reactions than by forest succession. Nitrate concentrations remained nearly constant, at °2.5 mg/l throughout the study, with no apparent seasonal fluctuations; in contrast, nitrate concentrations in the stream draining a nearby 55—yr—old forest definitely declined during the growing season. Nitrate budgets indicated a net loss of this important plant nutrient from both watersheds. However, a net accumulation of ammonium was sufficient to give a net increase of total N in both watersheds. These data do not support the hypothesis of Vitousek and Reiners that old—growth forests may reach a point of no net growth and no net uptake of nutrients. Mixed deciduous—coniferous forests in New England, free from human disturbances, may reach an age where they become prone to natural disturbances that create a mosaic of similar—aged group of trees, each group having differing abilities to accumulate nutrients.