The Impact Of Simulated Climate Change On The Ecosystems Characteristics And Carbon Exchangeof Stipakrylovii Steppe In Inner Mongolia

In this paper, We used OTC (open top chambers)to simulate warmingand precipitation enhancement in the whole growing season of 2013 and 2014(May-September).Investigating the affect of changes in temperature and precipitation to ecosystem characteristics and the carbon exchange, will help to determine the grassland ecosystem carbon storage capacity in the future climate change conditions, clear the impact of climate change on grassland ecosystem productivity, biodiversity, and provide scientific support ofthe Inner Mongolia steppe adapting to future climate change and sustainable development of grassland animal husbandry. The mainconclusions as follow:(1)In the growing season, the air temperature of control temperature and T is greater than control temperature and precipitation enhancement, the temperature increased range of control temperature is generally less than 2.5℃, reached 3.6℃ only during August; the temperature increased range of temperature was between 2.56～3.81℃; the average in night the lowest of air temperature of controltemperature and precipitation enhancement were higher than other treatments. The soil temperatures increment of surface (0-10 cm) fluctuated around 0℃ and the controltemperature and precipitation enhancement’s increased biggest, higher than other treatments, the maximum in early of June and the end of July, up to 8.5℃; the soil temperatures 10-30cm of almost below 0℃.The increment of soil moisture was no consistency rules, only precipitation enhancement is higher than temperature treatment.(2)The number of species occurring in the community increased in precipitation enhancement,the important values of Leymus chinensis increased in controltemperature and precipitation enhancement; the community density and community biomass increased in precipitation enhancement, the community height increased in controltemperature and precipitation enhancement;the communities diversity and evenness were not significantly different in temperature and precipitation enhancement.(3)The decomposed standing dead of Leymus chinensis is less than Stipa krylovii and the decomposedamount of litterwas maximum. The decomposedamount, control is the highest, controltemperature and precipitation enhancement is the lowest, the simulation of climate change inhibited on litter decomposition.The microbialnumber was highest in precipitation enhancement on July, lowest in controltemperature and precipitation enhancement on August, lowest inTon September. There were no significant differencesof soil organic carbon content、total nitrogen and available nitrogen under different treatments, only 10-20cm, available nitrogen treatment in precipitation enhancement is significantly lower than control and temperature.(4)Precipitation enhancement promoted NEE, GEP and ET, warming inhibited;NEE, GEP and ET reached a peak in June 27 and July 8;photosynthetic efficiency of Leymus chinensis and Stipa krylovii reached the highest on August 7;temperature increasing help increase photosynthetic rate f Leymus chinensis and Stipa krylovii, the moisture increasing affect adversely to the photosynthetic rate.(5)Ecosystem respiration rate under each treatment reached a peak at 12:00 in June, at 9:00 in July and August; temperature increasing increased soil respiration rate, moisture increasing reduced.Suitable hydrothermal conditions are an important factor for regulating photosynthesis s and soil respiration of Stipa krylovii steppe.Temperature risingas mainly climate change characteristicin Inner Mongolia Stipa krylovii steppe will further drought, will not help the carbon budget of Stipa krylovii steppe.