Soil Solution Chemistry and Nutrient Flux in Missouri Ozark Highland Soils Under Mixed Hardwood Forests.

Changes in soil solution chemistry and nutrient flux as a result of forest regeneration methods may disproportionately affect forest soils. Forested ecosystems underlain by highly weathered soils with inherently low nutrient supply capacity may be more vulnerable to decreased soil fertility due to the forest harvest management practices than soils with high nutrient supply capacity. The objective of this study is to quantify soil solution chemistry changes in Ozark Highland soils located in southern Missouri before and after timber harvest, and to elucidate differences in soil solution chemistry between different nutrient status soils. Starting in 2010, soil solution chemistry and nutrient flux is being monitored at Missouri Ozark Forest Ecosystem Project (MOFEP) sites in low and medium nutrient status soils managed using three regeneration methods: (1) clearcutting (CC); (2) single tree selection (STS); and (3) no-harvest management (NHM). Throughfall and soil solution samples collected with zero-tension solution samplers (15 and 40 cm depths) will be analyzed for pH and electrical conductivity, and concentrations of cations (Ca²⁺, K⁺, Mg²⁺, Na⁺, NH₄⁺), anions (Cl^-, NO₃^-, SO₄^2-, PO₄^3-), dissolved organic carbon, and total nitrogen. Cumulative ion flux through the system is being captured using ion exchange resin samplers (15 and 40 cm depths). Pre-harvest solution sampling on a weekly or biweekly basis has been initiated. Ion exchange resin samplers have been installed and will be removed and analyzed on a seasonal basis.  Solution sampling will continue in this manner through forest harvest in 2011. Data will be analyzed to investigate differences between treatments, soil, and depth before and after treatment. Study results will aid in the development of forest management policies that ensure sustainable use of Missouri Ozark forests.