Niche characteristics of main shrub populations in the arid valley of the Minjiang River,southwestern China

The arid valley of the Minjiang River located in southwestern China is an ecological fragile transition zone from the Tibetan Plateau to Sichuan Basin.This paper reported a field study on characteristics of shrub populations niche in the area to provide a scientific base for vegetation restoration and management. Niche breadths and overlaps of 20 main shrub populations along gradients of soil moisture, soil pH, available K, available P and total N were analyzed using Levins and Schoener indices. Onosma farrerii, Caryopteris terniflora, Sorphora vicifolia, Lespedeza floribunda and Bauhinia faberi had higher niche breadth and adaptability to environment and played a vital role in maintaining the diversity and stability of plant community; each population had different niche breadth in different resource dimensions.It showed that different populations had different ability of using resources and they had different ecological adaptability. The sum of niche breadth of all populations in different resource dimensions was as the following:soil pH > total N >soil moisture> available K > available P. It indicated that the ability of populations using available K and available P was lower than that of soil moisture, populations with high niche breadth also had high niche overlap, but not all species with low niche breadth had low niche overlap.