Effects Of Water And Nitrogen Control On Small And Medium-sized Animals In Desert Steppe Soil

Soil animals are important consumers and special decomposers in the ecosystem. Sensitive to the change of the environment, their differences in biology or community composition in soil ecosystem can reflect the subtle changes of environment; there-fore, they can be used as a soil animal indicator of soil environmental factors. Desert steppe is a kind of grassland which is over grassland, and the ecosystem is relatively weak. Global change on desert grassland soil animal behavior, distribution, abundance, and the size of the population and other kinds of relationships have different degrees of change, even causing the extinction of individual species. The article focuses on the Stipa Breviflora Desert Steppe as research object. Carried out the control of rainfall and nitrogen addition experiments to study the species, number and diversity of effects of water and nitrogen control on small and medium-sized animal in desert steppe soil, so it can provide biological evidence for desert steppe ecosystem to adapt and respond to changes in the environment.The results of this paper show that:1. From June to September, test plots were obtained small and medium-sized animal 9 orders,27 families,16 genera and a total of 44 taxa, of which the dominant group are Coleoptera-nose termite families, send mites-table engraved Acaridae, Collembola head springtails and Hymenoptera Formicidae, and its individual number accounts for 26.85% of the total number of individuals; among, common taxa 14 classes, Acariformes at most, a total of 8 families,16 genera, accounting for more than half of the total population, about 54.55%, followed by Parasiformes, Collem-bola and Isoptera, a total of 14 families, accounting for 31.82% of the total population, Thysanoptera, Diptera, Hemiptera, Coleoptera and Hymenoptera, at least, accounted for 13.63% of the total population. The communities of degrees from more to less as follows:Acariformes> Isoptera> Collembola> Parasiformes> Hymenopte-ra> Thysanoptera> Hemiptera> Diptera> Coleoptera.2. Nitrogen is beneficial to the increase of the desert grassland soil small and medium-sized animal species, decreasing and increasing rainfall do not significantly affect soil in June and July of small and medium-sized soil animals, and 0-10 cm soil layer increased more obviously in August; September, increasing rainfall and adding nitrogen (WN) increase to a great extent the 0-10cm layers of small and medium-sized soil animal species, increased 10 than control, increase of up to 250%.3. The small and medium-sized soil animals number of monthly dynamic soil in desert steppe is:increased relatively slowly in 6-7 month; a sharp increase in 7-8 month; 8-9 months of relatively stable value, it is 53.77/m2.Increasing rainfall, adding nitrogen, increasing rainfall and adding nitrogen all can increase the quantity of small and medium-sized soil animals, especially in the 0-10cm soil layer performance is more apparent in September.4. The diversity of small and medium-sized soil animals in desert steppe is not only related to rainfall and N application, which different water and nitrogen regulation, volatility changes in different months of small and medium-sized soil animals don’t agree with each other. However, increasing rainfall and adding nitrogen can maximize the diversity, evenness and richness of small and medium-sized soil animals in 8-9 month and increasing rainfall an greatly increase the dominance of small and medium-sized soil animals.5. The species, quantity and diversity of small and medium-sized soil animals in desert steppe and soil environmental factors are closely related, and the richness of soil total N, organic matter, moisture content was significant or extremely significant positive correlation, available P content significantly influences the species and quantities of soil in small animals, water content does not significantly change small and medium-sized soil animals.