不同林龄红锥人工林林下植被物种多样性恢复动态

Restoration dynamics of understory species diversity in Castanopsis hystrix plantations at different ages

为了解林下植被物种多样性随林龄的恢复轨迹,在广东省龙眼洞林场采用空间替代时间的方法,选取以相同方式经营的6个林龄序列(10、15、20、25、30和34年)的红锥(Castanopsis hystrix)人工林为研究对象,利用α和β多样性指数分析物种多样性随着林龄的变化趋势.结果显示:(1)共发现植物32科45属51种,其中灌木层物种有23科33属39种,草本层有9科12属12种.(2)灌木层和草本层的物种丰富度随着林龄的变化趋势类似,呈现先增加后下降的趋势;Simpson优势度指数和Shannon-Wiener多样性指数随着林龄的增加呈现先增加后下降的趋势,其中灌木层和草本层Simpson优势度指数的最大值均出现在20年的林龄;灌木层和草本层的Pielou均匀度指数表现较为平稳.(3)草本层植被群落的Jaccard相似性指数和Morisita-Horn相似性指数沿恢复轨迹呈下降趋势,且草本层植被的Jaccard相似性指数和Morisita-Horn相似性指数呈显著正相关.上述结果表明不同林龄红锥人工林林下植被物种多样性变化在扰动后的恢复过程中呈现非线性关系,与传统观点一致.未来该红锥人工林林下植被随着恢复时间会维持一个较为稳定的状态.

The temporal and spatial responses of species diversity are important ecological issues.However,the influence of different restoration times on the diversity of understory species remains unclear.This study aims to explore the diversity of undergrowth vegetation in Castanopsis hystrix plantations with different forest ages and increase our understanding of the restoration process and stability of the understory vegetation and optimize forest management.We selected C.hystrix plantations with six age series of 10,15,20,25,30,and 34 years located at Longyandong Forest Farm in Guangdong Province.Theαandβdiversity indices were used to analyze the variation trend of species diversity with different forest ages.(1)There were 32 families,45 genera,and 51 species of understory vegetation under the six age groups.Among them,the shrub layer vegetation had 23 families,33 genera,and 39 species,and the herb layer had 9 families,12 genera,and 12 species.(2)The species richness of the shrub and herb layers increased first and then decreased with increasing forest age.With increasing forest age,the Simpson dominance index and Shannon–Wiener diversity index of the shrub and herb layers showed a similar recovery trajectory with an increasing and then decreasing trend.The maximum value of the Simpson dominance index of the shrub and herb layers was observed in the 20-year-old forest.The Pielou evenness index of the shrub layer showed a smooth and stable pattern of change with increasing forests age.(3)The Jaccard similarity index and Morisita-Horn similarity index of herb layer vegetation decreased with the recovery process after disturbance,in addition,the Jaccard similarity index and Morisita–Horn similarity index of the herb layer vegetation were significantly positively correlated.We concluded that the understory vegetation diversity in different ages of C.hystrix plantations showed a nonlinear relationship in the recovery process after disturbance,which was consistent with the prevalent view.The understory vegetation of C.hystrix plantations will remain relatively stable over time in the future.