摘要
通过不同海拔高度的样带调查来研究香溪河流域河岸植物群落物种丰富度格局 ,并探讨河岸带中生物多样性维持的生态学机制。结果表明 :河岸植物群落总的物种丰富度、乔木层物种丰富度和草本层物种丰富度沿海拔梯度均表现出相似的格局特征 ,利用抛物线方程进行拟合 ,物种丰富度与海拔之间有显著的相关性。灌木层物种丰富度和藤本植物物种丰富度格局特征不明显 ,且物种丰富度与坡度相关。在流域尺度上 ,海拔对物种丰富度有着重要的控制作用 ;在局部尺度上 ,季节性洪水干扰导致的空间异质性和小地形对群落的生物多样性有着重要的影响。研究结果支持关于总的物种多样性在原始河流的中间河段将达到最大值的预测。
There are two approaches adressing the relationships between environmental factors and biodiversity, namely, experimental manipulation of number of species within a community and survey of biodiversity along a natural gradient at large scale. In this study, we employed the latter method to investigate the variability of species richness along the altitude gradient in the Xiangxi River Watershed. Xiangxi River originates in the southern slope of Mt. Shennongjia of western Hubei, and runs for 94km into the Yangtze River. Its mean discharge is 65.5m 3/s. From high to low elevation, vegetation types along the river are composed of needle-leaved forest, needle- and broad-leaved mixed forest, evergreen and deciduous broad-leaved mixed forest, and evergreen broad-leaved forest. In 2000, we sampled 40 plots, each with the size of 100m×10m and 100m apart from its neighboring plots along the gradient of altitude. In each plot, plant species richness was gauged by counting all species present, and environmental factors including slope, aspect, altitude, breadth of stream and height above stream were also recorded. Statistical analysis demonstrated that total species richness (Y 1), arborous species richness (Y 2) and herbaceous species richness (Y 3) were significantly related to altitude. The relationships could be fitted into the parabola function, Y 1=-0.00001X 2+0.0357X+6.0921(R 2=0.536, p<0.01), Y 2= -0.000004X 2 +0.012X-1.5709 (R 2=0.577, P<0.01), Y 3=-0.000003X 2+0.0105X+5.5894 (R 2=0.324, P<0.05), respectively. The highest species richness occurred in the transitional zone between mountain evergreen forest and deciduous broad-leaved forest at the altitude of 1500~1800m. There were great variations of shrub and liana species richness from plot to plot, but no significant relationships with altitude were found at watershed scale. This study indicated that , at large scale, altitude plays an important role in species richness, and spatial heterogeneity resulting from seasonal flooding and attributable to micro-landform determines the species diversity at a small (local ) scale. The results support the prediction that overall species diversity reaches a peak in the midreaches of a pristine river.
出处
《生态学报》
CAS
CSCD
北大核心
2002年第5期629-635,共7页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目 ( 30 0 70 1 5 3
39970 1 2 3)
关键词
湖北
神农架
香溪河流域
河岸带
植物群落
物种丰富度
Xiangxi River Watershed
riparian zone
plant community
species richness
pattern
