人为干扰对风水林群落林下木本植物组成和多样性的影响

华南地区的风水林是乡村聚落的一种特色林分, 具有守护村庄的象征意义。在过去的数百年中, 风水林在乡村的社会文化习俗的影响下而受到保护, 对当地的生物多样性保育有着重要作用。为揭示人为干扰对风水林的影响, 我们选择广东省东莞市大岭山镇同一林分起源的3个具有相似地形的风水林, 研究了在不同干扰强度下其林下木本植物种类组成和物种多样性。多响应置换过程(multi-response permutation procedures, MRPP)分析表明, 人为干扰显著改变了风水林林下木本植物组成(P = 0.001, A = 0.3886), 沿着干扰由弱至强的梯度呈现出中生性植物减少、阳生性植物递增的趋势。多样性指数变化趋势为重度干扰＞中度干扰＞轻度干扰, 但没有表现出统计学意义上的差异(P＞0.05)。随着干扰强度的增大, 3个风水林群落相互间的林下物种相似性降低, 物种替代率呈增加趋势。双向聚类分析较好地反映出林下物种因受不同人为干扰强度影响而表现出在空间分布上的差异。指示种分析进一步确定了不同干扰强度下具有显著指示值(IV ≥60)的指示种。综合分析表明, 人为干扰有利于阳性物种在风水林内定居生长, 并明显地改变了林下木本植物组成, 但未能引起物种多样性的显著差异。此外, 找出对人为干扰产生关键生态响应的林下指示种, 对增进风水林的生物多样性保育以及生态系统管理有着重要的理论意义和实践价值。

Effects of human disturbance on understory woody species composition and diversity in fengshui forests

In southern China, fengshui forests are distinctive woodlands that are treated as a protective barrier behind rural villages. Likely due to their socio-cultural importance to indigenous people, these forests have been conserved over the past several hundred years and play a significant role in conservation of local biodiversity. To reveal the effects of human disturbance on fengshui forests, we compared the species composition and diversity of understory woody plants among three fengshui forests with similar topographic situation and identical origin under different degrees of disturbance intensity in Dalingshan Town of Dongguan City, Guangdong Province. The low, medium and high disturbance level of fengshui forest stands were identified according to impact factors such as road length, agricultural land, residential area, factory area, cutting degree and garbage cover. Multi-response permutation procedures (MRPP) analysis showed that the composition of understory woody species (P = 0.001, A = 0.3886) differed among forest stands. Meanwhile, the proportion of mesophytes decreased with disturbance and the proportion of heliophytes increased. Though not statistically significant (P > 0.05), diversity indices consistently showed the following trend: high disturbance > medium disturbance > low disturbance. Jaccard coefficients of understory species similarity among the three fengshui stands declined with increasing intensity of human disturbance, indicating that species replacement occurred. Two-way cluster analysis of the relationships between plant species and forest stands indicated that the spatial distribution of understory species differed among stands. Indicator species analysis (ISA) identified species that were indicative (importance value >60) of the three forest stands studied, and therefore potential indicators of different disturbance regimes. We conclude that human disturbance of fengshui forests appeared to alter understory species composition, and favor the establishment and growth of heliophytes, but failed to affect species diversity. Furthermore, identification of candidate understory indicators which capture key ecological responses to human disturbance may have significant implications for improving biodiversity conservation and ecosystem management of fengshui forests.