Effects of Human Disturbances on Plant Community of the Yellow River Wetland and its Mechanisms.

In order to analyze the different types of influence of human disturbance on plant communities in the Yellow River wetland and the relevant mechanisms, three wetlands in Zhengzhou section which were respectively affected by agricultural planting, reservoir construction and building construction, were selected after conducting a large number of field investigations. After measuring the plant communities and related environmental factors, redundancy analysis was carried out based on human pressure index evaluation system. The results showed that the whole wetland plant community showed an obvious degradation trend, and the function of productivity maintenance decreased. For the sample land with different types of human disturbance, the severity of human disturbance varied from the disturbance caused by reservoir construction to agricultural planting, and building construction. With intensification of the severity of human disturbance, the similarity coefficients of plant communities in different wetlands declined successively, and the species richness index of wetland in Bird Nature Reserve and Taipingzhuang North wetland decreased by 15. 98% and 37. 05%, respectively, compared with the Taohuayu wetland, indicating that the overall construction of wetland plant communities gradually became simpler. Among the many factors causing wetland degradation, the change of ammonium nitrogen content in soil had a significant negative correlation with species diversity index and species evenness index, and was one of the main reasons for wetland plant degradation. [ABSTRACT FROM AUTHOR]