若尔盖高原湿地景观与环境要素的DCCA多元相关分析

Analysis on Relationship between Wetland Landscape and Environmental Factors in Zoige Plateau Based on DCCA

以9个指标反映若尔盖高原湿地生境的环境特征,在ArcGIS 9.2平台下进行随机样方布设,采用DCCA排序方法定量分析湿地景观与环境要素之间的关系。结果表明:(1)排序前2轴累计解释了湿地景观与环境要素关系的79.4%,表明其具有有效的目标研究显示度;(2)沿地形指数所近似表达的水分状况梯度,研究区各景观类型具有明显的分异特征,地形指数所反映的降水再分配是影响该区湿地景观空间分布的核心过程;(3)海拔高程与坡度、地形指数,以及气温之间具有极显著相关性,地形不仅决定了区域总体上的水热分异格局,同时影响局部范围内的水分留存和涵养能力,是影响该区湿地景观的基本因素。

Nine indices,such as elevation,topographical index,precipitation,temperature,soil,etc,were used to define the environmental characteristics of wetland habitats in Zoige Plateau.Based on ArcGIS 9.2 platform,scatter quadrats were randomly generated,sample-environmental factors matrix and sample-landscape structure matrix were obtained through spatial analysis module.And then,a DCCA was used to quantitatively analyze the roles of the environmental factors and their effects on the spatial distribution of wetland landscape.The results suggest that： 1） the first two DCCA axes explained 79.4% of the relationships between environmental influence and wetland distribution,suggesting that DCCA was an effective analysis technique at landscape scale.2） There is no evident correlationship（-0.2117,1st axis;0.0348,2nd axis） between precipitation and wetland distribution,meanwhile,various wetland landscapes changed obviously along the moisture gradient（0.8003,P0.001,1st axis）,which was represented approximately by topographical index.Precipitation redistribution by topography and geomorphology was core process in formation of wetland landscape spatial distribution.3） Elevation significantly correlated to slope,topographical index and annual average temperature,suggesting that not only the spatial differentiation of hydrothermal regime but also the water conservation ability in local area were deeply influenced by terrain.Terrain was the basic influence factor of wetland landscape in the study area.4） The 2nd DCCA axis was mainly composed of soil type（0.6029,P0.01） and the distance to road（-0.4322,P0.05）.These two factors had important impact on wetland landscape of Zoige Plateau.Above all,applying DCCA which is widely used in quantitative ecology areas for multivariate analysis is helpful to understand the relations between wetland distribution and environmental factors at landscape scale in Zoige Plateau.And topographical index is an effective indicator in delineating the moisture differentiation and wetland distribution.