The Effect Of Simulated Warming And N Addition On Ecosystem Gas Exchange In Inner Mongolia Desert Steppe

Human activities have resulted in enrichment of greenhouse gases in the atmosphere and altered the global cycle of nitrogen (N). As consequences human activities, both Earth’s surface temperature and atmospheric N deposition have increased over the past two centuries, and the increasing could profoundly influence global carbon (C) cycling. As one of the most important terrestrial biomes, grassland accounts for approximately40%in of the Earth’s land area, and approximately1/3the organic carbon of terrestrial ecosystem was storage in grassland ecosystems. Therefore, the effect of climate warming on grassland ecosystem will directly decide global C and N cycle. The study relies on the experimental base of Inner Mongolia Siziwang Banner desert steppe pastoral Academy as a research platform, what temperature and nitrogen increase may influence the ecosystem gas exchange were studied, and clarified the control factors of CO2releasing and absorbing, this would provided basic material for budgeting the global carbon balance and estimating the potential effects of global change. The results showed that:No significance difference was found for soil moisture and above-ground biomass by both warming and N addition (P＞0.05); N addition significantly increased ecosystem net C exchange (NEE), ecosystem respiration (ER) and gross ecosystem productivity (GEP), but the increase of GEP was higher than increase of ER during the growing season, leading a net C sink status during the study; Seasonal mean NEE, ER and GEP had linear correlations with biotic (peak aboveground biomass) and abiotic (soil temperature and soil moisture). N addition significantly increased net C storage during the growing season, whereas the warming had no significant effect on NEE in a short term.