环境梯度下蒙古栎群落的物种多样性特征

The species diversity characteristics comparison of Quercus mongolica community along environmental gradient factors

通过样地法研究了东北地区处于不同经度、纬度和海拔的 13个地点蒙古栎群落的物种丰富度、Gini指数、PIE指数、Shannon指数和 Pielou指数 ,利用相关和回归的统计方法分析了不同地点物种的丰富度指数、Simpson多样性指数和 Shannon多样性指数与各地所处的经度、纬度和海拔的关系。结果发现 :不仅不同地点 (较大尺度 )的物种丰富度和多样性指数均有差异 ,即使在相同的地点 (较小尺度 ) ,物种丰富度及多样性指数也有差异 ,有时还具有很大的差异 ,呈现空间异质性分布的特征 ;因为影响这些多样性指数的环境因子更加复杂 ,不仅受经度、纬度和海拔的影响 ,也受地形、群落的年龄、干扰史等多种生态因子影响。不同地点的物种丰富度与海拔和纬度都具有明显的相关性 (p<0 .0 5 ) ,物种丰富度随海拔和纬度的升高而降低 ,依据显著度的大小可以推测物种丰富度与海拔的相关性比与纬度的相关性更密切 ;蒙古栎群落不同类群的植物种的丰富度具有不同的分布格局 ,木本植物的丰富度与当地纬度具有明显的相关性 (p<0 .0 5 ) ,而与所在地的海拔没有显著的关系 (p>0 .0 5 ) ,而草本植物受海拔的影响更显著 (p<0 .0 5 ) ,而与纬度之间没有显著的关系 (p>0 .0 5 )。群落的 Gini指数、PIE指数、Shannon指数和Pielou指数未发现与海?

Diversity of Quercus mongolica communities was investigated in 13 sites across northeastern China which differed in latitude, altitude and longitude. Field investigations were conducted. Measurements were conducted from the north edge of Q. mongolica range (Huma, Heilongjiang Province) to the south end (Baishilazi, Liaoning Province). The geographic position (including latitude, longitude and altitude) of each site was recorded, and plants in the tree layer (including all mature trees, saplings and seedlings), the shrub layer and the herb layer were sampled using plots measuring 20m×20m, 10m×10m and 10m×10m, respectively. Species richness, Pielou′s index of evenness, the probability of species encounter, as well as Shannon-Wiener and Gini diversity indices were calculated for each plot in each site. Relationships between species richness or the diversity indices and the environmental factors (such as latitude, longitude and altitude) for the whole fields and different structural groups were analyzed. We found that the spatial distribution of species richness and species diversity of Q.mongolica communities showed great heterogeneity in different sites, to the extent that species richness and species diversity of some plots within sites differed. This indicates that these diversity indices may be affected not only by latitude and altitude, but also by topographical factors such as slope, soil, age of communities and disturbance.The correlation and regression analysis showed that species richness significantly related to altitude and latitude, decreasing as altitude and latitude increased. Additionally, patterns of plant species richness differed between plants structural groups. Woody species richness related closely and negatively with latitude, as did herb species richness with altitude. No significant relationship was found between woody species richness and altitude or between herb species richness and latitude. Taken together, this suggests that the species richness of vascular plants may more closely relate to altitude than to latitude. Neither the Gini diversity index, Shannon-Weiner diversity index and nor PIE closely correlated with latitude, longitude or altitude. Altitude and latitude are indirect environmental variables indicative of average temperature, and can drive gradients in species richness. Different patterns of species richness along these environmental gradients exist for different structural groups perhaps due to the fact that woody plant distribution is sensitive to large-scale environmental factors such as latitude, while the distribution of herbaceous plants is sensitive to local-scale environmental factors such as altitude.CCA ordination among diversity indices and environmental factors also support above conclusions.