北亚热带常绿阔叶林凋落物生产量及其与林分因子的关系

凋落物是森林生产力的重要组成部分.为了探讨凋落物生产特点及其与林分结构的关系,为亚热带常绿阔叶林可持续经营提供依据,在安徽省祁门县查湾自然保护区亚热带常绿阔叶林2种不同林分分别设立3个固定样地,共6个,进行林分结构调查并对凋落物生产量进行为期1a（2014年6月至2015年5月）的监测.结果表明：该地区凋落物生产量为5.95-9.70t·hm^-2·a^-1,除落果外,不同林分质量差异不显著（P〉0.05）.林分因子与凋落物量的相关性分析结果显示：凋落物总量、落叶与林分胸高断面积呈显著正相关（P〈0.05）.落果量与优势树种的平均胸径及其胸高断面积呈现显著正相关（P〈0.05）,与多样性指数、均匀度指数、林分密度呈现极显著负相关（P〈0.01）.木质凋落物与林分结构参数均无显著相关性（P〉0.05）.节律上,样地P1和样地P2凋落物总量与落叶表现为双峰型;样地P3凋落物总量与落叶表现不规则型;样地P4,样地P5和样地P6凋落物总量与落叶表现单峰型.不同林分落叶养分比较发现：氮、钙差异显著（P〈0.05）,磷差异极显著（P〈0.01）.养分年归还量分别为碳2.7-4.7t·hm^-2·a^-1,氮75.75-105.58kg·m^-2·a^-1,磷2.07-3.67kg·m^-2·a^-1,钾16.54-41.80kg·hm^-2·a^-1,钙74.61-109.91kg·hm^-2·a^-1,镁17.95-29.48kg·m^-2·a^-1.落叶、落果、碎屑物占各元素归还量的71.17%-95.75%。

Effects of Chinese Fir，Loblolly Pine and Deciduous Oak Forests on Nutrient States of Soils in Northern Subtro－pics of China

This paper deals with a study on the effects of Chinese fir, loblolly pine and deciduous oak forests on thenutrient status of soils in northern subtropics of China, adopting the principle of forest ecology in the caseof similar climate and soil type. The experimental area was situated in the Xiashu Experimental Centre ofForest, where the soil is yellow-brown soil derived from siliceous slope wash. Sample plots of these 3 standswere established to study the nutrient status in litter, the amount of nutrient uptake by roots, the quantityof nutrient output by percolating water outside the deep layer of soil, and the seasonal dynamics of availablenutrient in surface soil. It was shown that the intensity of nutrient cycling in soil under deciduous oak wasthe highest, and the effect of oak in improving soil fertility was the best. The result of improving soil fertilityby Chinese fir was the most inferior, though the intensity of nutrient cycling under that stand was higherthan that under loblolly pine stand. The influence of loblolly pine on the improvement of soil fertility wasbetter than that of Chinese fir, in spite of its lowest intensity of nutrient cycling.