弃管杉木林杉木数量与群落物种多样性间的关系

森林群落物种多样性格局和动态一直是生态学的研究热点，人工林弃管后演替进程中物种多样性变化也很值得研究。杉木(Cunninghamia lanceolata)作为我国南方林区人工栽培最广、经济价值最高的用材树种之一，其人工林分布面积很大，通常群落结构简单、物种多样性低，然而群落中杉木数量如何影响植物物种多样性，迄今缺乏研究。在浙江省自然保护区内，选择不同疏伐强度和弃管时间的杉木人工林，建立了6个1 hm~2长期动态监测样地，在10 m×10 m、20 m×20 m、50 m×50 m和100 m×100 m尺度下，探究群落物种多样性(物种丰富度、Simpson指数、Shannon-Wiener指数和Pielou均匀度指数)的变化规律，分析杉木数量(多度和相对多度)对物种多样性的影响。结果显示：弃管前对杉木林的疏伐强度越高，演替恢复后的群落物种多样性越高。相同疏伐程度下，物种多样性随演替时间的延长有先升高后降低的趋势。取样尺度小于100 m×100 m时，杉木数量与物种多样性呈极显著负相关；100 m×100 m尺度下仅杉木相对多度与3种多样性指数呈显著负相关，杉木多度与各物种多样性均无显...

Relationship between the number of Cunninghamia lanceolata and community species diversity in abandoned Chinese fir forests

The pattern and dynamics of forest community species diversity have always been the research focus of ecology,and the change of species diversity in the succession process of abandoned plantations is also worth studying.The Chinese fir(Cunninghamia lanceolata)is one of the most widely cultivated woods with the highest economic value in the southern forest region of China.This plantation usually has a simple community structure,low species diversity,and poor stress resistance.As for the community in subtropical area,many scholars have studied and discussed the community characteristics of the Chinese fir forests in different forest ages or different thinning intensities,but how the number of the Chinese fir in the community affects the plant species diversity is lack of research so far.In this study,6 one-hectare long-term dynamic monitoring plots were established at the abandoned Chinese fir forest with different thinning intensities and abandoned time in four nature reserves of Zhejiang Province.Each woody plant with DBH(diameter at breast height)≥1 cm was investigated,and the species name,DBH,height and coordinates were recorded.The community species diversity(species richness,Simpson index,Shannon-Wiener index and Pielou′s evenness index)was investigated at the scales of 10 m×10 m,20 m×20 m,50 m×50 m,and 100 m×100 m.The distribution pattern and correlation between the number(abundance and relative abundance)of the Chinese fir and species diversity were analyzed.The results showed that the higher the thinning intensity of the Chinese fir forest before abandonment,the higher the species diversity of the community after succession.Under the same thinning intensity,the species diversity firstly increased and then decreased during succession.When the sampling scale was less than 100 m×100 m,the number of the Chinese fir was negatively correlated with species diversity.Under the scale of 100 m×100 m,only the relative abundance of the Chinese fir was negatively correlated with the three diversity indices(Simpson index,Shannon-Wiener index and Pielou′s evenness index),but there was no significant correlation between the abundance of the Chinese fir and species richness.The values of the three diversity indices in each community were consistent,but had no correlation with species richness.In a word,when the relative abundance of the Chinese fir was less than 30%,the community usually had relatively high species diversity.