: Changes in Soil Carbon, Nitrogen, Enzyme Activities, and Bacterial Population in Forest Soils Following Sawlog Harvest.

Summary:

Demand for wood products, the rising interest in bio-fuel production, and a global interest in soils as a carbon sink requires additional understanding of forest harvest impacts on soil quality (biological, chemical, and physical indicators). Therefore, the objective of this study is to investigate changes in soil quality indicators during a two year period following sawlog harvest on soils with differing nutrient status. Research is being conducted at the Missouri Ozark Forest Ecosystem Project (MOFEP), a long-term experimental site, located in mixed hardwood forests of southeast Missouri. The MOFEP site consists of nine compartments (each ca. 400 ha) in a randomized complete block design. Harvest treatments at MOFEP consist of clear-cutting (CC), single-tree selection (STS), and no harvest controls (NH) each replicated in triplicate. Pre- and post- harvest soil samples are collected at depths of 0 – 10 cm and 10 – 20 cm from low and medium nutrient status soils within each compartment.  To quantify soil carbon and nitrogen pools and fractions, total organic carbon (TOC) and nitrogen (TN), active C (KMnO₄ oxidizable carbon), and water extractable carbon and nitrogen (WEOC/WEN) are being analyzed. Activities of the soil enzymes β-glucosidase and β-glucosaminidase are being determined as indicators of soil biological change, and water stable aggregate analysis will be used to quantify a change in physical soil properties.  The results from two pre-harvest and three post-harvest sampling events will be presented.  This work will advance our understanding of soil quality changes immediately following CC and STS, and ultimately ensure that forest regeneration methods used on marginal soils is sustainable.