Niche characteristics of dominant plant populations in grassland of loess hilly region of China with different management styles

In order to understand the response of niche characteristics of different plant communities to different management methods, five different managed grasslands including enclosure(E), lightly grazing(G), fertilization(F), clipping(C) and deratization(D) were investigated at YangQingChuang valley in Loess Hilly Region, China. Niche breadth and overlap indices were used to measure the niche characteristic of dominant plant populations, based on the field survey data got by “quadrat method”. The results showed that: The niche breadths of Lespedeza davurica, Artemisia sacrorum, Leymus secalinus, Artemisia scoparia and Poa sphondylodes which appeared in five treatments of the grasslands were larger than other species. The rank ordering between niche breadth in every population and total population were different in different management methods. Species which had the biggest niche breadth value in E, G, F, C and D were Lespedeza davurica, Leymus secalinus, Viola philippica, Lespedeza davurica, Artemisia scoparia respectively. And the number of species which had the niche breadth value greater than four in E, G, F, C and D were seven, six, three, three and three respectively. The order of niche overlap was as follows: E>G>F>C>D. In addition, the results demonstrated that there had no linear relationship between the niche overlap and niche breadth of tested species in the grasslands at four management styles except F. Niche analysis indicated that the E and G management styles resulted in the demand for resources tended to be the same between different populations. And different populations can coexist between each other by competition to facilitate the community succession. On the other hand, F, C and D management styles resulted in few individual plant species with strong competitiveness which destroyed the competition mechanism of grassland ecosystem and had negative effects of vegetation restoration. From the perspective of forages development, E, F and C management styles, are advantageous to superior forage grass progress.