Ecological analysis of subalpine meadow in Yunding Mountain,Shanxi

Based on the field investigation of community plots,two-way indicator species analysis(TWINSPAN) and detrended correspondence analysis(DCA) were applied to analyse the ecological relationships on subalpine meadow communities in Yunding Mountain,Shanxi province.It was showed that:(1)five meadow communities of 36 samples located in different altitudes were recognized by TWINSPAN and characteristics of the communities were described respectively,including distribution of dominant species and relationship with environmental factors.All results were confirmed by the two-dimensional ordination diagram of DCA.(2)The environmental variables,such as altitude,grazing intensity,moisture and heating conditions,were the major environmental factors affecting community's change.The results of DCA ordination showed that the five meadow communities had their different distributions along their environmental gradient.The first axis and the second axis of DCA reflect the gradient of elevation,grazing intensity and soil water conditions of the communities.(3) The distribution patterns of dominant species were highly similar to that of the communities.With the increase of the altitude,Kobresia bellardii,Carex lanceolata,Festuca ovina and Taraxacum mongolicum gradually took the dominant status on the communities,which showed that community distribution patterns were coordinate to the zonal vegetation distribution patterns due to the increase of elevation and the decrease of human interruption.(4)The difference in species diversity of the community had close correlation mainly to the specific evenness and grazing intensity,meanwhile,also had close correlation to the meadow habitat.Species diversity of the meadow distributing in the semi-sunny slope,semi-shady slope,shady slope and high altitude area,due to its better water supply and temperature environment,was much richer than that on the sunny slope and low altitude area.Also habitat conditions degraded because of intensive grazing.Meanwhile,species diversity plays an important role in the development and distribution of the meadow communities.(5) Grazing has an obvious interruption effect on the succession of subalpine meadow communities in Yunding Mountain,which has validated the previous researchers' opinions.