Definition of wetland-dry grassland ecotone and vegetation stability in the Nanhaizi wetland in Yanchi, Ningxia

To determine vegetation community diversity and stability in different habitat regions of the Nanhaizi wetland in Yanchi County, Ningxia Autonomous Region, vegetation surveys were conducted in July 2016. Firstly, the moving split-window technique was applied to the quantitative determination of ecotone. According to the result, the research area was divided into wetland regions, ecotone, and arid regions. Then, diversity indexes (species diversity index, community dominant concentration index, community evenness index, and species richness index) were used to analyse plant community diversity of different habitat regions in different transect lines. The M.Godron stability determination method was used to analyse plant community stability in different habitats. The results showed: 1) The ecotone boundary could be clearly delineated with six quadrats of east and west transect lines, and eight quadrats of south and north transect lines. 2) Species diversity index, community evenness index, and community dominant concentration index of the four transect lines all followed the order of ecotone>arid region>wet region, whereas the species richness index was ordered as wet region>arid region>ecotone. 3) As compared to that of the other two habitat regions, the ecotone had the highest stability of vegetation, but the least species. The M.Godron stability followed the order of wet region>arid region>ecotone. The research showed that the moving split-window technique could be used to quantitatively determine small-scale wetland-grassland ecotones.By analysing the data and making comparisons, we found a negative correlation between vegetation diversity and stability.