Effects of Plant Species on Soil Properties in the Ecosystem Restoration - A Case Study in the Dry Valley of the Upper Minjiang River

Biodiversity pattern impacts effects on the soil properties on different scales, and contrarily soil characteristics influence biodiversity. Changes in the abundance of species - especially those that influence water and nutrient dynamics, trophic interactions - affect the structure and functioning of ecosystems. It is very important to reveal their close relationships for understanding the process of ecosystems. As an ecological sensitive region in Yangtze River, the shrub community biogeochemistry of arid valley in Upper Minjiang River caused much attention. We investigated the detailed plant biodiversity, topography and different soil properties along six typical shrub line-transects at three sites in the valley. To discern the complex relationships of plant and soil, different multivariate statistical analysis techniques were used at different spatial scales. The results showed different soil properties were significantly relative to community features at different scales and principle component analysis screened that available nitrogen (AN) was a sensitive factor for the shrub communities. Multivariate linear regression revealed that shrub coverage, height and herb species had quantitative linear relationships with AN content. Further study of biodiversity and soil properties showed that soil organic matter (OM), total nitrogen (TN) and AN had high relationship with the deduced plant alpha-diversity index. To elucidate the effects of species change on the soil properties, we compared the similarity index and the nutrient variation index we brought out using two methods. The results showed species change could explain variation of soil properties and they had certain cause-effect relation along the slope catena and in the arid dry valley. Thus, it is possible to identify potential mechanism of soils response to variation in plant diversity, with implications for resource management.