The Responses Of The Plant Community Characteristics And CO₂ Flux To Water And Nitrogen In Stipa Breviflora Steppe

With the rapid development of human activities and industrial, increasing concentrations of greenhouse gases, leading to the gradual warming of the global climate, and changed the terrestrial ecosystem carbon and nitrogen cycle. Grassland ecosystem carbon and nitrogen cycles as an important part of the global carbon and nitrogen cycles, lawn has a significant impact on global climate change. Desert steppe grasslands of Inner Mongolia is an important component, accounting for 10.7% of the total area of grassland. Poor stability desert grassland, water and nitrogen is the main limiting factor of the ecosystem productivity.This article is breviflora desert steppe for the study, simulation of global nitrogen deposition and precipitation changes, Setting WN, W, RN, R, N,CK 6 treatments, analysis of the seasonal variation changes under different water and nitrogen condition on community characteristics and ecosystem carbon exchange, diurnal variation and its relationship with biotic, abiotic factors, reveals the water and nitrogen control breviflora desert Grassland and carbon exchange. We made the following conclusions:(1) Controlled precipitation and nitrogen addition has changed the composition of plant communities and important values.(2) Precipitation treatment significantly increased the diversity of desert steppe species and evenness (P<0.05); Save the rain N treatments, improve the rich desert grassland species richness and dominance; precipitation N treatments, help to reduce Community ecological dominance.(3) Addition of nitrogen significantly increased the aboveground biomass (P<0.05).(4) Under Different Water and Nitrogen net carbon exchange NEE, consistent ecology breathing ER, ecosystem primary productivity GEP seasonal dynamics trend did not change the law of the desert steppe ecosystem gas exchange. The whole growing season, the breviflora desert steppe NEE, ER, GEP showed a single peak curve, the maximum in vigorous plant growth season (July-August). (5) W, N, WN treatment increased NEE, ER, GEP. Under N treatment, ecosystem gas exchange is maximized. R, NEE RN under treatment, ER, GEP decreased. (6) Dynamic change of day desert steppe in mid-August period of vigorous growth ecosystem carbon exchange, Inner Mongolia breviflora desert steppe ecosystem carbon exchange for the period of performance for the total carbon sink.(7) Ecosystem gas exchange NEE, ER, GEP and 10cm soil moisture was significantly positively correlated,10cm soil temperature and ER showed a significant positive correlation.