模拟外源性氮磷对马占相思凋落叶分解及土壤生化特性的影响

Effects of Nitrogen and Phosphorus Additions on Leaf Litter Decomposition and Soil Biochemical Characteristics in an Acacia mangium Plantation

[目的]研究外源性氮和磷对马占相思凋落叶的分解速率、分解过程中N、P、K含量和土壤生化特性的影响,以便为森林土壤养分管理提供参考。[方法]以广东省云勇林场马占相思林下凋落叶为试验材料,采用尼龙网袋分解法,设置对照(CK)、施N(10 g·m^(-2))、施P(5 g·m^(-2))、施N+P(N 10 g·m^(-2)+P 5 g·m^(-2))4种处理,每隔3个月取样1次,并测定凋落叶残留量和N、P、K含量。[结果]表明:施N、P和N+P处理对马占相思凋落叶的分解均为促进作用。各处理马占相思凋落叶的N含量在分解过程中大致保持稳定,施P和N+P处理的凋落叶P含量在分解过程中总体呈波动性上升,而各处理的凋落叶K含量变化规律不明显。施N、P和N+P处理提高了马占相思林土壤的有机质和全N含量,促进脲酶、磷酸酶及过氧化氢酶的活性。[结论]施N、P和N+P处理促进了马占相思凋落叶的分解,有利于马占相思林的养分循环。

[ Objective] To study the effects of nitrogen and phosphorus additions on leaf litter decomposition, nutri- ent dynamics and soil biochemical characteristics during the decomposition process in a Acacia mangium plantation in order to understand the mechanism of influence of nitrogen and phosphorus on leaf litter decomposition of A. man- glum and forest soil nutrient management. [ Method] Leaf litter decomposition of the A. mangium plantation in Yu- nyong Forest Farm was investigated using litter bag method. N and P additions were designed in four treatments： the control, N addition （N 10 g ·m^-2）, P addition （P5g·m^-2） , and N ＋P addition （N 10g · m^-2＋P5g · m^-2）. It was sampled in a three-month interval and then the remaining leaf litter and N, P, K contents were analyzed. [ Result ] The N, P and N ＋ P additions improved leaf litter decomposition. The N content of leaf litter with the four treatments remained stable. The P content of leaf litter with P and N ＋ P additions tended to increase and were grea- ter than their initial value during litter decomposition process. The K content of leaf litter with the tour treatments changed irregularly. The N, P and N ＋ P additions significantly increased soil organic matter and total N contents and improved activities of soil urease, acid phosphatase and catalase. [ Conclusion ] N, P and N ＋ P additions ac- celerated leaf litter decomposition of the A. mangium, which improved the nutrient cycling of A. mangium planta-tion.