浙江九龙山香果树群落乔木层物种的多样性格局

Species Diversity Pattern of Arbor Layer Species in Emmenopterys henryi Communities in Jiulongshan, Zhejiang Province

摘要:

为了解香果树(Emmenopterys henryi)群落的物种多样性及其驱动因素，在浙江九龙山自然保护区建立了35个以香果树为中心15 m半径的样圆，调查样圆内胸径2.5 cm以上的乔木层树木的物种和胸径。通过线性混合效应模型分析α多样性与海拔、坡向、香果树胸高断面积的关系，通过Mantel检验和方差分解分析样地间距离、海拔、坡向和香果树胸高断面积差异对β多样性的影响。结果表明，九龙山香果树群落乔木层物种丰富(50科96属145种)，且以落叶或半常绿树种占优势; 样地乔木层Shannon-Wiener指数为2.37~3.40，Simpson指数为0.86~0.94；群落乔木层α多样性随海拔升高呈先升高后下降的变化趋势，但与样地坡向和香果树胸高断面积无关；群落乔木层Sorenson指数为0.15~0.95，物种周转组分对群落β多样性的贡献达74.88%；样地间地理距离与乔木层β多样性及其组分呈显著正相关，样地间海拔差异与其乔木层β多样性及其物种丰富度差异组分呈显著正相关，而样地间香果树胸高断面积差异仅与物种周转组分显著正相关；样地地理距离对于乔木层β多样性及其组分具有最高的解释度(23%~29%)，海拔差异对于乔木层β多样性也有较高的解释度(16%)。因此，九龙山香果树群落乔木层的α多样性主要受海拔影响，而β多样性及其组分受扩散限制、生境过滤或香果树-伴生种互作等因素的影响。

关键词:α多样性;β多样性;珍稀植物;海拔;空间距离

Abstract:

To understand the changes in species diversity of Emmenopterys henryi community and its driving factors, 35 sample circles with a 15 m radius centered on an E. henryi tree were set up in the Jiulongshan National Nature Reserve, Zhejiang Province. The species and diameter at breast height (DBH) of arbor layer trees (i.e. woody plants with a DBH more than 2.5 cm) within the sample circles were investigated. The relationship between α diversity of arbor layer trees and altitude, and slope aspect, and DBH of E. henryi in each sample circle were analyzed by linear mixed model, and the influences of spatial structure, altitude, and slope aspect, and DBH of E. henryi on β diversity were studied using the mantel test and variation partition analyses. The results showed that the number of species in arbor layer of E. henryi communities was rich, with 145 woody species belonging to 98 genera and 50 families, and dominated by deciduous or semi-evergreen species. The Shannon-Wiener index ranged from 2.37 to 3.40 and the Simpson index from 0.86 to 0.94. The α diversity indices increased at first then decreased with elevation, and neither related to the slope aspect nor DBH of E. henryi. The Sorenson index of community pairs ranged from 0.15 to 0.95 and the contribution of turnover components to the total β diversity of arbor layer was 74.88%. The geographical distance between sample circles was significantly positively correlated with β diversity and its components of arbor layer trees; while the altitude difference between sample circles was significantly positively correlated with β diversity and species-richness difference of arbor layer trees. The DBH difference of E. henryi between sample circles was only positively correlated with species turnover of arbor layer trees. The geographical distance of the sample circles is the likeliest explanation for β diversity and its two components (23%–29%) of arbor layer trees. The altitude difference is also a probable explanation for β diversity of arbor layer trees (16%). Therefore, α diversity of arbor layer trees in the E. henryi community in Jiulongshan was mainly affected by altitude, while β diversity and its two components of arbor layer trees were affected by dispersal limitation, habitat filtering, and interspecific interaction between E. henryi and associated species.

Key words:α-diversity;β-diversity;Rare species;Altitude;Spatial distance