间伐对近天然落叶松+云杉+冷杉混交林凋落物特征的影响

Effects of thinning on litter characteristics of semi-natural Larix olgensis + Picea asperata + Abies nephrolepis mixed forests

为探讨间伐对近天然落叶松＋云杉＋冷杉混交林凋落物特征的长期影响,对吉林省汪清林业局金沟岭林场间伐强度分别为0（对照）、20%、30%和40%4种处理的20块样地进行土壤和凋落物样品的采集和测定,分析不同间伐处理间凋落物特征及其与土壤养分间的相关性。结果表明：1）近天然落叶松＋云杉＋冷杉混交林凋落物现存量为51.44-181.60 t/hm^2,持水量为20.33-47.27 t/hm^2,凋落物C与N质量比介于61-72之间,其N、P和K质量分数在不同间伐强度间呈现不同顺序,C质量分数随间伐强度增加逐渐增大;但不同间伐强度之间的凋落物现存量、持水率和养分质量分数差异不显著（P〉0.05）。2）凋落物的现存量、持水量及养分质量分数与土壤养分全量的相关性在不同间伐强度的近天然落叶松＋云杉＋冷杉混交林间表现出一定的相似性,表明间伐不对凋落物特征与土壤养分相关性构成主要影响。3）间伐27年后,不同间伐强度间凋落物特征差异不显著,这可能是由于间伐时间较长,间伐的影响逐渐减弱所致。

We collected soil and litter samples from twenty plots of semi-natural Larix olgensis-Picea asperata-Abies nephrolepis mixed forests under four thinning intensities（ 0（ control）,20%,30% and40%） in Jingoulin Forest Farm,Jilin Province,in order to assess long-term effects of thinning on litter characteristics. The correlations between litter characteristics and soil nutrients were analyzed. The results are shown as follows： 1） The standing crop of litter in semi-natural L. olgensis-P. asperata-A.nephrolepis mixed forests was 51. 44-181. 60 t / hm^2,the water holding capacity of litter was 20. 33-47. 27 t / hm^2,and the litter C： N ratio ranged between 61 and 72. Concentrations of litter N,P and K showed different orders under different thinning intensities and litter C concentration gradually increased with thinning intensity; however,there were no significant differences in standing crop,water holding capacity and nutrient concentration of litters under different thinning intensities（ P 0. 05）. 2）Correlations between litter characteristics and soil nutrients showed certain similarity under different thinning intensities,indicating that thinning intensity was not the main affecting factor. 3） Twenty-seven years after thinning,no significant differences were observed in litter characteristics under varying thinning intensities,showing no long-term thinning effects in our study.