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以15年生杉木低效林为研究对象,设计间伐强度为20%(T20)、30%(T30)、40%(T40)及未间伐(T0)4种间伐处理,探讨间伐2年后杉木林下生物多样性及土壤养分的变化,并采用改进层次分析法对间伐成效进行综合评价。结果表明:(1)间伐对林下植物生长具有积极的促进作用,有效提高林分的生物多样性,且林下植物种类、灌木层Simpson指数和Shannon-Weiner指数随着间伐强度增大而增加,T0、T20、T30和T40处理林下分别出现0种、12种、14种和16种植物;(2)间伐有利于改善土壤养分状况,间伐后杉木林土壤有机质含量、全磷含量、全钾含量和水解氮含量增幅依次为2.20~38.08 g·kg-1、0.19~0.98 g·kg-1、6.36~13.99 g·kg-1和19.13~154.19 mg·kg-1;(3)综合评价得到T0、T20、T30和T40处理的间伐成效指数值依次为0.294、0.503、0.724和0.732,说明T30、T40处理的间伐成效要明显好于T20处理。因此,建议对密度较大的杉木低效林按照30%~40%的株数间伐强度进行间伐改造,并保留阔叶树种,以形成多树种、结构比较稳定、生态和经济效益更高的针阔混交林,实现可持续经营。
The 15-year-old Chinese fir inefficient forest was used as the research object to design the thinning intensity of 20% (T20), 30% (T30), 40% (T40) and no thinning (T0) Biodiversity and soil nutrient changes were evaluated. The improved AHP was used to evaluate the effect of thinning. The results showed that: (1) The thinning had a positive effect on the growth of plant undergrowth, and effectively increased the biodiversity of the stand. The plant species, shrub layer Simpson index and Shannon-Weiner index increased with the increase of thinning intensity , 0, 12, 14 and 16 plants under T0, T20, T30 and T40 treatments respectively. (2) Thinning was beneficial to the improvement of soil nutrient status, soil organic matter content and total phosphorus content of Chinese fir plantation after thinning Potassium content and hydrolyzed nitrogen content increased from 2.20 to 38.08 g · kg -1, from 1.19 to 0.98 g · kg -1, from 1.63 to 13.99 g · kg -1 and from 19.13 to 154.19 mg · kg -1, respectively. (3) Comprehensive evaluation The thinning efficiency indices T0, T20, T30 and T40 were 0.294, 0.503, 0.724 and 0.732, respectively, indicating that the effect of thinning on T30 and T40 was significantly better than that on T20. Therefore, it is suggested that thinning of the Chinese fir inefficient forest with density of 30% ~ 40% should be carried out with thinning, and broad-leaved species should be preserved to form multi-tree species with stable structure and high ecological and economic benefits. Forest, to achieve sustainable management.