The decomposition of dead wood on the forest floor alters ecosystem carbon and nitrogen cycling via its effect on soil chemistry and biotic activity. These processes are essential to the maintenance of key ecosystem functions including soil fertility and biodiversity. However, forests managed for timber production tend to have a lower volume of dead wood in comparison to unmanaged and mature forests. Canopy openings and woody debris were added to a maturing, even-aged, second-growth northern hardwood forest to enhance structural complexity and restore key ecosystem processes typically associated with late-successional forests. Our aim was to assess the direct and indirect effects of coarse woody debris (CWD) on organic matter mineralization by quantifying the potential production of extracellular enzymes by microbes and soil nutrient availability near and away from woody debris. Soils were sampled for potential enzyme activity assays near moderately and highly decayed wood in gap openings and closed canopy conditions during the 2017 growing season.
Results/Conclusions
Our analyses indicate seasonal variation in potential enzymatic activity involved in carbon degradation and phosphorous mineralization, and suggest a complex relationship among canopy opening conditions and wood decay status. Relative nutrient demand, computed from the ratio of enzyme activity related to carbon degradation and nitrogen mineralization, and nitrogen availability varied seasonally but were not affected by proximity to dead wood. Soil properties and nutrient availability also varied depending on canopy condition and the time of year. We are investigating the influence of microenvironments created by dead wood and canopy openings on microbial community composition and soil characteristics. These results will help in understanding the contribution of CWD to the forest floor and the influence of decaying wood characteristics on soil biotic activity. The presence of heterogeneously distributed woody debris of varying decay status may also be essential to maintaining and restoring ecosystem functions associated with nutrient cycling and microbial community dynamics in managed forests.