Reciprocal Relationships between Topography, Soil Moisture, and Native Vegetation Patterns in the Loess Hilly Region, China

In loess hill landscapes, the pattern of vegetation affects movement of water and soil across the landscapes at multiple scales; likewise topography and soil moisture influence the structure of the plant community. At smaller scales, soil moisture is heterogeneous. Small-scale heterogeneity has a large impact on the performance of individual plants, and therefore it influences the structure and dynamics of plant populations and communities. These relationships must be studied in order to gain an understanding of the ecosystem dynamics. We investigated at the slope scale the community structure of natural grassland on the Loess Plateau. The study site had been fenced off for more than 20 years. We selected 14 topography, soil moisture, and community structure metrics. Through the use of multivariate statistics (principle component analysis and cluster analysis) and canonical correlation analysis, we explain the complex relationships between topography, soil moisture and community structure. Three community types were identified by cluster analysis, distinguished by significant differences in elevation, slope, soil moisture at the 20-140cm depth, species richness, and Shannon-Wiener index. Correlation analysis indicated that elevation impacted community coverage, and slope position and slope aspect affected biodiversity of the plant community. Elevation and slope position influenced soil moisture at 0-300cm depth, while the biodiversity of the plant community had a reciprocal relationship with soil moisture at 0-100cm depth.