The Response Of Soil Properties To Experimental Warming And Nitrogen Addition In Desert Steppe

Changes of climate and nitrogen deposition can profoundly influence the terrestrial ecosystem, including carbon cycling, which may lead a consequent feedback to climate change. Grassland is one of most widely distribute vegetation type, and it is the vastest ecosystem in China, coving40%land of China. In grassland, carbon of ecosystem is mostly concentrated in the soil, and its carbon activity occurs mainly in soil, too. In present, most researches of soil respiration are about typical grassland and meadow grassland, few about desert grassland. To make a better understanding of the response of soil respiration in desert steppe to the global change, a field experiment was conducted in the desert grassland in northern China. We found:(1) Warming elevated soil temperature obviously, but the effect fades with the depth of soil.(2) Warming and nitrogen addition didn’t change the soil moisture obviously, and the variation of soil moisture is mainly caused by the variation of precipitation.(3) Warming and nitrogen addition didn’t change the soil total nitrogen, total phosphorus, available phosphorus, total potassium and available potassium obviously.(4) Warming and nitrogen addition didn’t change the soil pH value.(5) There was obvious variation of soil seasonal dynamic, and the soil seasonal dynamic correlate with precipitation and10cm soil moisture obviously, but not correlate with temperature obviously. Warming, nitrogen addition and their interaction did not change soil respiration seasonal dynamic obviously.(6) During experiment, no matter control, warming, nitrogen addition and their interaction, the daily soil respiration dynamic showed a monopeak curve. At the warm time of the day. soil respiration rate was high, but at the cool time of the day, soil respiration rate was low.(7) Warming and nitrogen addition didn’t change soil organic carbon (SOC) obviously. And soil organic carbon (SOC) was not correlate with soil respiration significantly.(8) Warming and nitrogen addition didn’t change underground biomass obviously. Underground biomass was correlate with soil respiration significantly. The correlation coefficient of10cm depth underground biomass and soil respiration was as high as0.62, which showed significantly correlation between underground biomass and soil respiration.