南岭南坡中段不同群落林下幼树的生物多样性及分布

Biodiversities and Distribution Patterns of Saplings in Different Forest Communities in the Nanling Mountain,Southern China

2008年中国南方特大冰雪灾害对南岭森林生态系统产生严重的影响，冰雪灾害4a后通过对南岭树木园内不同群落类型林下幼树的调查，分析不同群落林下幼树生物多样性和分布的差异。结果表明：林下幼树胸径主要集中分布在0．6～1．8cm间，使群落垂直分层现象更为明显；各群落林下幼树物种的丰富度（S）显著（P〉0．05）大于乔木物种的，林下幼树的pielou均匀度指数（J）基本处于0．5～0．6间，与乔木层无显著差异，乔木层物种丰富度和分布均匀度直接影响林下幼树的生物多样性指标；不同群落类型林下幼树数量分布表现出明显的差异，落叶阔叶林林下幼树株数平均8870株·hm-2，常绿阔叶林林下幼树株数平均7160株·hm-2，针阔混交林林下幼树株数平均5920株·hm-2，其中，鸭公树幼树分别占30．O％，13．3％、9．5％。减去鸭公树种子萌发产生的幼树外，不同群落类型林下幼树株数差异并不显著（P〉0．05），动物传播使外源性树种鸭公树的种子在不同群落间散布，而以南酸枣为主要优势种的落叶阔叶林能够引入更多的种子。不同群落林下幼树均呈现聚集分布，其中，大规模聚集的鸭公树和牛耳枫在落叶阔叶林中趋于Poisson分布，而群落内部乔木树种通过种子散布萌发和根蘖萌条产生的幼苗，聚集强度较大。

The ice storm in 2008 had serious impact on forest ecosystems in Nanling Mountain. Almost all kinds of plantations and natural forests were subjected to varying degrees of influence. By investigating the understory sap- lings of different communities in the Nanling Arboretum 4 years after the storm occurred to depict the sapling biodi- versity and its distribution patterns. The results showed that the seed germinating and root sucker sprouting made each community structure emerged a more significant stratification. There were significant differences of reserved seedlings and saplings among different communities ： 8 870 per hm2 in deciduous broad-leaved forest （DBF） , 7 160 per hm2 in evergreen broad-leaved forest （EBF） and 5 920 per hm2 in coniferous and broad-leaved mixed forest （MF）. The diameter at breast height （DBH） distribution of understory saplings focused broad - leaved mixed forest （MF）. The diameter at breast height（DBH） distribution of understory saplings focused in 0. 6--1.8 cm, and had amaximal DBH of 1.0 cm. While DBH ranged from 1.8--3.0 cm, the sapling amount of EBF was slightly different from that of DBH and MF, the former was more than the latter, there were few understory saplings with DBH be- tween 3.0--5.0 cm in these communities, which presents that the community structure had no significant stratifica- tion and the ice storm ing software SPSS 21. contributed to the regeneration and succession of different communities. Using of data process- 0 to analysis the difference and correlation of biodiversity index between conopy trees and un- derstory splings, there was no significant difference of biodiversity index among different community canopy trees, but the understory splings. The sapling species richness （S） was significantly higher than tree species, and the Pielou index（J）of understory saplings and canopy tree species was basically between 0.5----0. 6, which had no sig- nificant differences. The canopy species composition and uniformity of distribution affected the distribution of under- story saplings. The variance mean ratio （V/m） was applied to measure the distribution pattern of the dominant spe- cies of understory saplings in different communities. The results indicated that all of dominant sapling species of each community appeared aggregated distribution. Among them saplings through seeds （by some canopy species spreading） germinating and root suckering occurred often gather greater strength. Neolitsea chui （K = 18. 584） and Daphniphyllum calycinum （K = 9. 792 5 ） approach Poisson distribution in DBF which Choerospondias axillaris as the dominant species. The interspeeific association of Choerospondias axillaris and Neolitsea chui could be obtained by interspecifie link analysis.