Soluble Organic and Inorganic Nutrient Fluxes in Clearcut and Mature Deciduous Forests

Abstract

The mechanisms by which forest ecosystems retain or lose soluble inorganic nutrients after disturbance are well known, but substantial amounts of soluble organic nutrients may also be released from cut vegetation. Our objective was to compare the leaching of dissolved organic and inorganic nutrients in cut and mature forest stands and to develop hypotheses about factors controlling the retention of soluble organic nutrients after disturbance. Solution chemistry was measured for 2 yr after clearcutting a small area in the surrounding undisturbed deciduous forest on a reference watershed at the Coweeta Hydrologic Laboratory in the Appalachian Mountains. Concentrations of dissolved organic C (DOC) and N (DON) in slash leachate were 2.6 to 3.2 times the concentrations in throughfall from undisturbed forest. Concentrations in forest floor, A horizon, and B horizon solutions from cut plots were 1.2 to 3.8 times those from undisturbed forest. Dissolved organic P (DOP) concentrations in cut plots were 3.1 and 3.6 times those of uncut plots in solutions from slash and forest floor, respectively, but did not differ in mineral soil. Fluxes of DOC, DON, and DOP in all strata were greater in cut plots than uncut plots. Fluxes of DON were greater than those of ammonium plus nitrate N in all strata of both cut and uncut plots. We hypothesize that the wellrecognized retention mechanisms for inorganic nutrients combine with equilibrium adsorption of dissolved organic matter to efficiently buffer against leaching of both soluble inorganic and organic nutrients after clearcutting.

Dissolved organic carbon dynamics in a UK podzolic moorland catchment: linking storm hydrochemistry, flow path analysis and sorption experiments

“…This concept is consistent with our laboratory batch results (Fig. 8), but contrasts with field observations such as that of Qualls et al (2000) who noted a near complete removal of DOC on contact with subsoils in a forested catchment. The laboratory sorption experiments showed the potential for podzol subsoils to dramatically change the composition, but not necessarily the concentration, of DOC transported from the site of production in organic surface soils to streams under conditions in situations where waters contact subsoils.…”

Maintenance of terrestrial nutrient loss signatures during in‐stream transport

“…We used data for small streams in the desert southwest, Arizona, USA (sites 5, 6, 7, and 25 in Grimm et al [1981] We also assessed potential groundwater nutrients by collecting original samples from point-source hill-slope surface waters (seeps and springs, n ¼ 10) and mixing wells placed into stream sediments (n ¼ 80) following Brookshire et al (2005) and through the use of piezometers (n ¼ 4, at Noland Divide) and published values for spring, soil lysimeter, and riparian well water (Grimm et al 1981, Mulholland 1992, Qualls et al 2000, Van Miegroet et al 2001, Yeakley et al 2003. We further explored the implications of in-stream nutrient removal for watershed nutrient balance (atmospheric input minus stream output) at sites for which long-term inorganic N budgets have been constructed and across which deposition varies from ;5 to 32 kg NÁha …”

Controls on fluxes and export of dissolved organic carbon in grasslands with contrasting soil types

“…DOC export and translocation through the soil profile DOC fluxes largely depend on the measurement depth since DOC concentrations are continuously decreasing from the organic layer to the subsoil (e.g. Qualls et al 2000). To quantify the DOC export of an ecosystem a below ground system border has to be defined, such as the border between the subsoil horizon and the bedrock as it is used in our study.…”