Effects Of Increased Rainfall Amount On Ground Vegetation And Arthropod Community In A Desertified Steppe Region

Taking the natural sandy grassland in desert steppe of Ningxia as a subject, an investigation on soil, vegetation, and arthropods properties were carried out in the sites with increased precipitation by20%,40%,60%and100%.(1) The rainfall pattern changed strongly from July to September. There was no significant difference in soil, vegetation, and arthropods properties among treatments in spring and summer, suggesting the similarity and viability of experimental setup.(2) There was a significant positive correlation between the abundance of herbs and soil moisture in the spring. Along with increased precipitation, positive responses of plant species richness, density and height increased significantly. Appropriate precipitation also significantly reduced the biomass of weeds.(3) The ground arthropods responded slowly to precipitation. The density of arthropods was higher in spring than in summer and in autumn. There was a significant positive correlation between the arthropod groups and plant density, richness, height. The lowest biomass of arthropods was found in the autumn in comparison to the spring and summer. Increased precipitation reduced the difference of biomass of ground arthropods between in spring and in summer. Ground arthropod diversities in summer and autumn were significantly higher than in spring. There was a significant positive correlation between community diversity and soil moisture.(4) Ground arthropod communities included predatory group, coprophagous group, saprophagous group, parasitic group, omnivorous group and herbivorous group. A marked impact of summer-precipitation treatment was found on the ground arthropod communities. The number of taxa density and richness of functional groups under increased precipitation (40%, and60%) in the summer and autumn showed that the two indices of herbivorous and saprophagous arthropods were markedly lower, while those of predatory arthropods were markedly higher in comparison to the other treatments.(5) All the results suggested that the effect of precipitation experimental setup on vegetation and arthropods properties should take into account the seasonal changes. Vegetation and arthropods properties were both affected by season and treatment. The vegetation and arthropod communities had different responses to increased precipitation in desertified steppe.