Leaching of dissolved organic carbon, dissolved organic nitrogen, and other solutes from coarse woody debris and litter in a mixed forest in New York State

Abstract

Coarse woody debris (CWD) may play a role in nutrient cycling in temperate forests through the leaching of solutes, including dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), to the underlying soil. These fluxes need to be considered in element budget calculations, and have the potential to influence microbial activity, soil development, and other processes in the underlying soil, but studies on leaching from CWD are rare. In this study, we collected throughfall, litter leachate, and CWD leachate in situ at a young mixed lowland forest in NY State, USA over one year. We measured the concentrations of DOC, DON, NH 4 + , NO 3 À , dissolved organic sulfur, SO 4 2À , Cl À , Al, Ca, K, Mg, Na, and P, estimated the flux of these solutes in throughfall, and measured the cover of CWD to gain some insight into possible fluxes from CWD. Concentrations of DOC were much higher in CWD leachate than in throughfall or litter leachate (15 vs. 0.7 and 1.6 mM, respectively), and greater than reported values for other leachates from within forested ecosystems. Other solutes showed a similar pattern, with inorganic N being an exception. Our results suggest that microsite scale fluxes of DOC from CWD may be An high relative to throughfall and litter leaching fluxes, but since CWD covered a relatively small fraction (2%) of the forest floor in our study, ecosystem scale fluxes from CWD may be negligible for this site. Soil directly beneath CWD may be influenced by CWD leaching, in terms of soil organic matter, microbial activity, and N availability. Concentrations of some metals showed correlations to DOC concentrations, highlighting the possibility of complexation by DOM. Several solute concentrations in throughfall, including DOC, showed positive correlations to mean air temperature, and fewer showed positive correlations in litter leachate, while negative correlations were observed to precipitation, suggesting both biological and hydrologic control of solute concentrations.

Logging residues and ground vegetation in nutrient dynamics of a clear-cut boreal forest

“…Part of the carbon and other nutrients can be released as dissolved organic forms (Vestgarden 2001, Hafner et al 2005. In boreal forests, the decomposition process is mainly carried out by fungi and bacteria (Persson et al 1980), which produce degrading enzymes (Killham 1994).…”

Wood-soil interactions in soil bioengineering slope stabilization works

“…Standard error of mean is reported (n=6). cal, chemical and biochemical properties of the underlying soil was reported by several studies (Busse 1994, Kayahara et al 1996, Krzyszowska-Waitkus & Vance 1999, Spears et al 2003, Hafner et al 2005, Zalamea et al 2007, Kappes et al 2007) however, to our knowledge, no specific investigations have been done on wooden-work deterioration ef fects on soil biological features. Thus, our results represent a new field of research ai med to assess the environmental impact of soil bioengineering works.…”

“…Several studies report increase of microbial biomass C:N ratio and denitrification activity (Hafner et al 2005), increase of microbial biomass C and of microbial quotient (qmic -Busse 1994), increase of non symbiotic N-fixing bacteria (Hendrickson 1994). Conversely, Zalamea-Bustillo 2005 did not find any dif ference in soil microbial biomass size in soils under decomposing logs when compa red to control soils.…”

“…A lack of effect on soil moisture can be related to the early decay stage of the logs; in fact, Harmon & Sexton 1995 reported that a high degree of decay, particularly with degradation of sapwood and heartwood, allows higher infiltration ra tes of water thus modifying soil humidity. Kayahara et al (1996) and Hafner et al (2005) reported higher C:N ratios in the soil under decomposing wood, due to increases in total C coupled with decreases of total N and indicating that decaying wood can re present a source of recalcitrant organic mat ter. We did not observe significant variations of soil C and N content and of the C:N ratio.…”

“…Some studies found higher C (carbon) and N (nitrogen) percentages in soil under decaying wood, but did not observe changes in the C:N ratios (Kayahara et al 1996), while Hafner et al (2005) reported hi gher C:N ratio beneath decaying logs.…”