Stand and soil responses of a loblolly pine plantation to midrotation fertilization and vegetation control.

摘要

This study was conducted in a 14-year-old midrotation loblolly pine ( Pinus taeda L.) plantation to assess the effects of fertilization and vegetation control (a) on soil net nitrogen mineralization, (b) litter decomposition and (c) foliar nutrient concentrations and use, and vegetation growth. Fertilization (none, 224 kg ha−1 N plus 56 kg ha−1 P) and vegetation control (none, complete) treatments were applied in a 2x2 factorial design in March 1998. Soil net nitrogen mineralization was assessed by monthly field and laboratory incubations, litter decomposition and nutrient (N, P K, Ca, Mg, S, Mn, Zn, B, Cu) release dynamics were determined by the litterbag method, foliar nutrient use of pines and hardwoods was estimated from litterfall and foliar nutrient concentrations, and growth was determined based on annual measurements of diameter and height. Field net N mineralization rates were 19, 18, 31, and 78 kg ha−1 yr−1 for control (C, no treatment), fertilization (F), vegetation control (VC), and vegetation control plus fertilization (VC+F) treatments, respectively. Relative treatments responses were similar in the laboratory incubations. Litter mass loss during decomposition was reduced by 9% after 32 months by vegetation control, and fertilization had no effect. The mobility of the nutrients was as follows: Cu≤N≤S