Soluble organic and inorganic nutrient fluxes in clearcut and mature deciduous forests

Abstract

ABSTRACT nitrification due to a high C/N ratio in litter (Vitousek et al., 1979), temporary sorption on ion exchange sitesThe mechanisms by which forest ecosystems retain or lose soluble (Vitousek et al., 1979) and in the case of P, fixation orinorganic nutrients after disturbance are well known, but substantial amounts of soluble organic nutrients may also be released from cut sorption on soil (Wood et al., 1984; Walbridge et al., vegetation. Our objective was to compare the leaching of dissolved 1991). The increase in water flux from the root zone organic and inorganic nutrients in cut and mature forest stands and to due to cutting and the concomitant reduction in evapo-develop hypotheses about factors controlling the retention of soluble transpiration also plays an important role in controlling organic nutrients after disturbance. Solution chemistry was measured the leaching of nutrients (Likens and Bormann, 1995). for 2 yr after clearcutting a small area in the surrounding undisturbed The factors which control the leaching of organic nutri-deciduous forest on a reference watershed at the Coweeta Hydrologic ents after clearcutting or other disturbances, however,Laboratory in the Appalachian Mountains. Concentrations of dis-have not been extensively investigated.solved organic C (DOC) and N (DON) in slash leachate were 2.6 to Dissolved organic N is the major form of N in stream-3.2 times the concentrations in throughfall from undisturbed forest. water draining from many mature forest watershedsConcentrations in forest floor, A horizon, and B horizon solutions from cut plots were 1.2 to 3.8 times those from undisturbed forest. (Sollins and McCorison, 1981; Hedin et al., 1995). In