取样尺度效应对滇西北地区种子植物物种多样性纬度分布格局的影响

Effects of sampling scale on latitudinal patterns of species diversity in seed plants in northwestern Yunnan,China

滇西北地区是全球25个生物多样性保护热点地区之一,是验证生物多样性理论的理想场所。为探索取样尺度效应对植物物种多样性纬度分布格局的影响,我们探讨了不同取样尺度下滇西北地区种子植物物种多样性的纬度分布格局及其影响因子。我们利用野外考察数据和文献资料建立了群落尺度下的源数据集和区域尺度(县域尺度)下的源数据集,共建立、收集了68个植物群落样方和26个县域的种子植物物种丰富度;采用二元相关性和多元逐步回归分析植物物种多样性纬度分布格局与气候、地理因子间的关系。结果表明,从南到北,物种多样性在群落尺度下呈单调递减格局,在区域尺度下反而呈线性递增趋势;在群落尺度下受到热量因子的显著影响,在区域尺度下主要受单位面积海拔高差的影响。这一结果在一定程度上表明了取样的尺度效应对物种多样性纬度分布格局的显著影响。了解滇西北地区植物多样性的热点区域,应该基于不同取样尺度下的分析,以消除或减少植物多样性保护的盲点。在今后的相关研究中,应关注不同的取样尺度下多样性的纬度分布格局可能的表现形式及其内在机制,这或许可以减少或消除相关研究中的争议或不一致。

Different latitudinal patterns of species diversity were given in previous studies and therefore mechanisms have been put forward to explain these patterns. However, there were significant discrepancies among related case studies. To test the effects of sampling scale on interpreting these discrepancies, we explored latitudinal patterns of species diversity at regional and community scales in northwestern Yunnan. Based on literature data as well as our field investigations, community and regional datasets were established, including the species richness of 68 plots at the community scale and that of seed plants in 26 counties at the regional scale, respectively. Based on these two datasets, the relationship between species richness and alti- tudinal gradient, as well as climatic and geographical factors, was analyzed using bivariate correlations analysis and stepwise regression. Our results showed that plant species diversity decreased with increasing latitude at the community scale, which was mainly correlated with the thermal factor. Contrarily, an increas- ing trend was observed with the increase of latitude at the regional scale, which was mainly due to altitude difference per unit of area. The results demonstrate the influence of sampling scales on the estimation of plant species diversity distribution. In conclusion, when determining the hotspots of plant diversity in northwestern Yunnan, we should analyze the data collected at different sampling scales to eliminate blind spots in biodiversity protection.