南岭国家级自然保护区林下植物分布的地形相关性

以南岭国家级自然保护区山地森林群落林下植物为研究对象，探讨地形因子对林下植物分布的影响。该区3个海拔高度下的山地常绿阔叶林林下植物组成丰富，但个体多度在样方中的分布存在很大的空间异质性。在9000m^2的样地中设置的450个4m^2小样方，共记录到林下维管植物255种，隶属于95科、181属，总的物种个体多度为18203株。多响应置换过程（MRPP）分析表明，坡向和海拔（p〈0．0001）及坡度（p〈0．05）这3个地形因子对林下植被分布有显著的影响，其影响程度大小排序为：海拔〉坡向〉坡度。指示种分析（ISA）进一步确定了不同地形条件下具有显著指示值（IV≥50）的指示种。本项研究表明林下植物的空间分布会同时受到多个地形因子的影响，因此需综合各因子间的相互作用全面考虑；同时，MRPP结合ISA对于揭示群落植物分布的空间异质性及其与环境因子作用的相互关系、生物多样性保育、森林恢复以及造林引种等方面均有着重要的理论意义和实践价值。

Topographic Correlates of Understory Plant Species Distribution in Nanling National Nature Reserve, Guangdong

Effect of topographic factors on the distribution of understory plant species was investigated in the montane forest communities in Nanling National Nature Reserve, Guangdong, China. The montane evergreen broadleaved forest communities sampled from 3 elevations had diverse species composition and abundance, but with great heterogeneity in spatial distribution. 255 vascular plant species from the understory ,with a total abundance of 3228 stems, were recorded in 450 subplots（4 m^2each）within the total plot area of 9000 m^2 ,which belonged to 95 families and 181 genera. The result of Multi-Response Permutation Procedures （MRPP） showed that aspect, elevation （p 〈 0. 0001 ） and slope （p 〈 0. 05 ） had a significant influence on the distribution of understory species, with the magnitude of influence in the following order： elevation 〉 aspect 〉 slope. Furthermore, Indicator Species Analysis （ISA） identified the indicator species with a significant indicator value ≥50 under different topographic conditions. This study indicated that a community might be affected by several topographic factors in the meantime. Therefore interactions and compensation among topographic factors should be taken into account when assessing the effect of a single topographic factor on the spatial patterns of understory vegetation. The two statistical programs, MRPP and ISA, are robust in demonstrating relations of spatial heterogeneity of plant distribution to environmental factors, and in identifying indicator species, which has significant implications for plant biodiversity conservation, forest restoration, and silvicultural applications.