Effects of Disturbance on Niche Breadth, Overlap, and Differentiation of Dominant Plant Species in Napa Plateau Wetland, Shangri-la

Ecological niches remain central to explaining community structure, and niche-based studies have helped us to better understand species interactions, distributions, coexistence and the associated mechanisms. However, most of these studies focus on terrestrial plants, and few studies have explicitly quantified niche parameters of plateau wetland plants. Also, although understanding the effects of disturbance on niche breadth and overlap is vital to developing a basic understanding of species dynamics, response strategies and distribution patterns, few studies have tested explicitly disturbance effects at different seasons. Our study sites are set up in Napa Wetland, Shangri-la, located at the southeastern margin of the Tibetan Plateau. Recently, wetland loss and degradation has become a serious local problem, mainly due to three types of disturbance, tourist trampling, anthropological grass removal, and pig forage. The main purpose of our study is to investigate the effects of different types of disturbance on niche parameters of dominant wetland plant species. We chose research sites under different disturbance regimes, and surveyed selected sites during May, July and October in 2011, with 3 replicates for each disturbance regime. Our results showed that there was a seasonal variation in species niche breadth under different disturbance regimes. Similarly, niche overlap and niche differentiation also altered with seasonal changes, with the lowest niche overlap and the highest niche differentiation occurring in spring and fall, whereas the highest niche overlap and the lowest niche differentiation occurring in summer. Our results thus provide important information in regard to plant community composition, structure and dynamics in Napa Wetland under different disturbance regimes, and help to further explore the mechanisms by which dominant wetland species coexist, and their response patterns to varying disturbance forms in the long term.