坡面尺度上地貌对α生物多样性的影响

为了解地貌在坡面尺度上对α生物多样性的影响,采用主观采样法在陕北吴起县合家沟流域不同地貌部位进行了样地调查.利用SPSS16.0统计软件先后对各地貌部位物种组成及各物种的重要值、地形因子要素间、地形因子和群落α多样性之间分别做了聚类分析、相关分析和多元回归分析.结果表明:(1)地貌部位相似的群落聚类在一起,说明地形因子是影响物种组成、群落结构、生态系统等的重要因素.(2)海拔和坡位,坡向和坡度,地形指数和海拔、坡位、坡形之间的Pearson 相关系数均大于0.8,双尾显著性检验概率小于0.05.(3)影响α生物多样性指标香农-维纳指数的地形因子按重要性从大到小依次是:坡位、坡向、海拔、坡形、坡度、地形指数,进一步分析得出在黄土高原丘陵沟壑区,沟沿线、光照、土壤水分和养分在影响α生物多样性指标上依次递减.(4)通过多元线形回归检验,得出坡位、坡向、坡形、海拔这四个地形因子与群落α生物多样性关系密切,建立的回归模型显著性检验可信度大,与样本数据的拟合度高.各地形因子数据归一处理后的回归方程为:香农-维纳指数=2.417-0.581×坡形-1.333×坡位+1.449×海拔+0.631×坡向.地形地貌特征在黄土丘陵区表现明显,研究它对生物多样性的影响可为该区植被恢复提供参考,但由于调查样地尺度较小,在应用推广上尚待进一步研究.

Effects of landforms on a biodiversity in slope scale

In order to understand topographic effect to a biological diversity in slope scale.samples were investigated by subjective sampling method in different topography positions of Hejiagou Basin,Wuqi County in Northern Shannxi Provice. Meanwhile, it have been respectively analysed of Cluster, Correlation and Multiple Regression on the species composition and their values, terrain elements, terrain factor and community a diversity of every topography positions by SPSS 16.0. The result showed:(1)The communities of similar topography positions clustered, and it indicated mat the terrain had a significant effect on species composition, community structure and ecosystem.(2)The Pearson correlation coefficients between altitude and slope position, aspect and slope gradient, as well as the topographic index and aititude, slope position, slope shape respectively were more than 0.8. The probability of 2-tailed significance test was less than 0.05.(3)The order of terrain factors which influenced the Shannon-Wiener index was slope position, aspect, altitude, slope shape, slope gradient and topographic index according to its importance. The further analysis indicated that the shoulder line of valley, sunlight, soil moisture and nutrient declined by order in importance fonxbiological diversity.(4)Through the multivariate linear regression equation test, there existed significant correlation between 4 topographic indexes(slope position, aspect, slope shape, altitude) and community a biodiversity. The significance test reliability of regression model was high, as well as the fitting degree with sample data. The terrain factors being normalized, the regression equation was: Shannon-Wiener index=2.417 -0.581×slope shape- 1.333×slope position+1.449×altitude+0.631×aspect. Topography and landform character displayed more obvious in loess hilly region, mere were some reference value to vegetation restoration in the region. However, it required further study in the application pending due to smaller-scale sample survey.