Fertilization intensifies drought stress: Water use and stomatal conductance of Pinus taeda in a midrotation fertilization and throughfall reduction experiment

摘要: While mid-rotation fertilization increases productivity in many southern pine forests, it remains unclear what impact such management may have on stand water use. We examined the of nutrient and availability stem volume, leaf area, transpiration per unit ground area (EC) canopy conductance (GS) a plantation during its 8th 9th growing seasons. Treatments consisted factorial combination throughfall reduction (30% versus ambient) (a complete suite essential nutrients) beginning April 2012. Overall, our results indicate that despite unusually high rainfall study period lack index (LAI) response, both EC GS decreased response to reduction. Fertilization increased volume increment 21% 2013. Treatment differences were greatest season 2013, when was average 19%, 13% 29% lower (D), (F) combined treatment (FD) than control (C), respectively. The responses volumetric soil content (VWC) F associated with decrease relative C at VWC. Decreases D VWC, but little change observed FD resulted from these two factors. pattern different treatments suggests structural or physiological changes underlie this possibly fine root hydraulic conductivity. In short term, led large use efficiency production, which could suggest greater resiliency minor stress. However, impacts long-term sensitivity drought remain concern, as triggered by comparable magnitude 30% exclusion reductions found treatment.