间伐强度对杉木林下植物物种多样性和结构组成的影响

Effects of Understory Plant Species Diversity and Composition in Cunninghamia lanceolata Plantations with Different Thinning Intensity

关键词:  物种多样性  杉木人工林  间伐强度  主成分分析(PCA)  南亚热带

Key words:  species diversity  Cunninghamia lanceolata plantation  thinning intensity  principal component analysis (PCA)  south subtropics

摘要:

[目的]研究营林措施对杉木(Cunninghamia lanceolata)林下植被的多样性影响及其关键控制因素,从本质上解释人工林下植被变化的调控机制。[方法]以3种不同间伐强度(强度:74%,中度:50%和弱度:34%)的杉木人工林为研究对象,采用野外调查和室内分析相结合的方法,重点探究间伐强度对林下植物物种丰富度和多样性的影响,以及林下植物物种组成与生境因子之间的关系及其重要控制因子。[结果]间伐8 a后,杉木林下灌木层的物种丰富度和多样性没有发生明显变化,但间伐措施能明显改变灌木层的物种组成,这种效应在中度间伐和强度间伐的杉木林中表现尤为突出;间伐不仅能显著改变杉木林下草本层的物种丰富度和Whittaker β多样性,而且也能明显改变草本层的物种组成,这种作用在强度间伐的杉木林中最强;冗余分析(RDA)结果揭示了土壤碳氮比和乔木胸高断面积是影响杉木林下灌木层物种变化的最主要因子,而影响林下草本层物种组成的最显著因子为土壤有机碳含量和乔木胸高断面积。[结论]间伐措施,特别是高强度的间伐措施能显著改变灌木层的物种组成,以及草本层的多样性和物种组成,可能对杉木人工林的生态过程和林木生长产生一定影响。

Abstract:

[Objective] Investigating the effects and key control factors of silvicultural measures on plant species diversity of understory in Cunninghamia lanceolata plantations was conducted in order to demonstrate the mechanisms of vegetation changes in understory of plantation.[Methods] This study focused on exploring the effects of plant species diversity and composition in Cunninghamia lanceolata plantations with different thinning intensity (High:74%, Middle:50% and Low:34%).Also, the relationship between understory plant species composition and environmental factors, and its key controlling factors were determined by combining field investigations and laboratory analysis.[Results] The species richness and diversity of shrub layer were not changed significantly with different thinning intensity, but the composition of plant species in shrub layer changed significantly after thinning 8 years, which appeared stronger especially in the moderate and high intensity thinning.In addition, thinning not only significantly changed plant species richness and Whittaker β diversity, but also changed the species composition significantly in herbaceous layer, which appeared strongest in high intensity thinning;Redundancy analysis suggested that soil C/N and tree basal area were the most important factors determining shrub layer plant distribution, while soil organic carbon and tree basal area were the most important factors determining herb layer plant species composition.[Conclusion] High intensity thinning significantly changed the composition of species in shrub layer, and species diversity and composition in herb layer.These change may finally influence the ecological processes and tree growth in Cunninghamia lanceolata plantations.