Sustainability of High Intensity Forest Management with Respect to Water QuaIity and Site Nutrient Reserves
Ensuring sustainability of intensively managed woody crops requires determining soil and water quality effects using a combination of field data and modeling projections. Plot- and catchrnent-scale research, models, and meta-analyses are addressing nutrient availability, site quality, and measures to increase short-rotation woody crop (SRWC) productivity and site sustainability. Plot-scale (0.5 ha) research began in 1995 in MS, AL, and TN to compare woody and agricultural crops. In 1997, the plot scale expanded to catchment-scale SRWCs plantings (20-40 ha) on International Paper lands in South Carolina. Water quality, erosion, runoff, soil quality, and nutrient cycling are being quantified with production of SRWCs. Combined literature, meta-analyses, field data, and models (NuCM and WATRCOM) are identifying mechanisms to enhance soil carbon, fertilizer and water-use efficiency, and site sustainability, while minimizing nutrient and soil losses. Data and literature analyses demonstrate that soil cover, rates and timing of nutrient application, rainfall timing and intensity, and plant growth are keys to minimizing runoff, erosion, and nutrient transport while maximizing productivity. In SC, decreases in soil water potassium and phosphorus are indicative of previous agricultural fertilization; while increased extractable aluminum reflects increasing site acidification. Modeling simulations and water level management at the SC site are demonstrating mechanisms to enhance tree growth.