不同氮含量华北落叶松叶凋落物在不同间伐强度林内氮释放规律研究  

Nitrogen releasing dynamics of needle litter affected by thinning intensity and litter N content in a Larix principisrupprechtii plantation

作　　者：王巍伟[1] 吕瑞恒[1,2] 刘勇[1] 陈晓[1] 李国雷[1] 

机构地区：[1]北京林业大学省部共建森林培育与保护教育部重点实验室 [2]新疆塔里木大学植物科学学院

出　　处：《北京林业大学学报》2014年第3期63-68,共6页Journal of Beijing Forestry University

基　　金：国家自然科学基金项目(30972353);高等学校博士学科点专项科研基金项目(20090014110011)

摘　　要：以不同间伐强度下华北落叶松叶凋落物为研究对象,根据氮含量将凋落物分为不同类型,采用轮置分解法,探讨间伐强度和凋落物类型两因素对华北落叶松人工林叶凋落物氮释放年变化规律、氮净积累量和氮净释放量的影响。结果显示:1)在一定间伐强度范围内,华北落叶松叶凋落物氮含量随间伐强度增大而增加,在极轻度(I)、轻度(II)、中度(III)和强度(IV)间伐林下分别为(0.128±0.01)g、(0.210±0.02)g、(0.233±0.02)g和(0.125±0.01)g。2)凋落物类型影响凋落物氮释放年变化规律,其中低氮凋落物表现为"积累—释放—积累",而中氮和高氮凋落物大体上表现为"释放—积累—释放"。3)凋落物类型对氮净释放量有显著影响(P<0.05),中氮和高氮凋落物的氮净释放量显著高于低氮凋落物;间伐强度对氮净释放量无显著影响。4)间伐强度和凋落物类型均对凋落物氮净积累量有显著影响,且两因素间存在明显的交互作用(P<0.05),其中低氮凋落物氮净积累量显著高于中氮和高氮凋落物,且中度间伐有利于低氮凋落物氮积累,不利于中氮和高氮凋落物氮积累。因此,适度的间伐有利于提高华北落叶松叶凋落物氮含量,进而提高氮净释放量,促进养分循环。This experiment investigated the effects on nitrogen （N） releasing dynamics of needle litter from a Larix principis-rupprechtii plantation with different N content resulting from varied thinning intensities. The needle litter was divided into different types according to its N content. The litter with different N content was put back into the forest floor of 4 sites of varied thinning intensities to separately investigate the impact of micro-climatic conditions and litter properties on litter decomposition. The N content of L. principis-rupprechtii litter increased by thinning of the plantation, from （0. 128 ± 0.01 ） g with very light thinning, to（0. 210 ±0. 02）g with light thinning, （0. 233 ±0. 02）g with medium thinning, and（0. 125 ± 0.01 ）g with heavy thinning. Litter types with different N contents influenced N decomposition dynamics. Decomposition of litter with medium and high N content followed a pattern of ＂release-accumulation- release＂ of N, but litter with a low N content followed an ＂accumulation-release-accumulation＂ pattern. The different litter types influenced the N net release in litter during decomposition, with medium and high N litter releasing more N than that in low N litter. Thinning intensity had no significant effects on the N net release. The different litter types and thinning intensity had an effect on the accumulation of N in litter during decomposition, with low N litter accumulating more N than that in medium and high N litter. There was an interaction between thinning intensity and litter types affecting N net accumulation. Medium thinning decreased litter N accumulation and heavy thinning significantly increased the N net release from high N litter during decomposition. Our results suggest that moderate thinning could increase N content in the needles of L. principis-rupprechtii, thus increase the N net release and promote nutrient cycling.

关 键 词：华北落叶松 叶凋落物 间伐强度 轮置分解 氮释放 

分 类 号：S791.22[农业科学—林木遗传育种] S725[农业科学—林学]