Temperature Induced Changes In Soil Solution Chemistry Following Timber Harvest: A Column Simulation Study.

Mixed hardwood systems at the Missouri Ozark Forest Ecosystem Project (MOFEP) site in southern Missouri are harvested using clearcutting (CC) and single-tree selection (STS) regeneration methods. Soil temperature data collected before and after a previous harvest event demonstrated increases in soil temperature under both regeneration methods with greater temperatures occurring in CC sites. The objective of this work is to identify the effects of temperature changes following harvest events on soil solution chemistry.  Three soils present at MOFEP were selected based on relative nutrient status as indicated by subsoil percent base saturation (BS): low, ≤ 20 % BS; medium, 20 – 50 % BS; and high, ≥ 50 % BS.  Field replicated sampling sites were identified in non-harvested stands based on available soil characterization data. Soil samples were collected from the 0 – 10 cm depth, air-dried, and passed through a 2-mm sieve. Soils were repacked into 7.5 cm (diameter) x 10 cm (length) columns at a soil bulk density of 1.4 g cm^-3.  Columns incubated in constant temperature rooms at 21, 23, and 26 ^oC were leached weekly with synthetic precipitation over the course of three months.  Preliminary data investigating differences in solution pH, electrical conductivity, total nitrogen, dissolved organic carbon, base cation, and anion concentrations will be presented.  Comparison of results with ongoing field studies monitoring soil solution chemistry will also be included.