Effects Of Simulated Warming On Active Soil Organic Carbon And Nitrogen Of The Alpine Timberline

Changes in soil temperature and water caused by climate warming would affect the soil micro environment,and then affected matter and nutrient cycling in the ecosystem.The ecological environment in the timberline ecotone is sensitive to climate warming.Soil organic carbon and nitrogen play an important role in the matter and nutrient cycling of the ecosystem.Active soil organic carbon and nitrogen play a very important role in maintaining the forest ecosystem nutrient balance;and it is the most obvious and quick to response to soil quality changes,and provide the main microbial energy and nutrients for microbes.At present,there are many studies on the effects of climate warming on soil active organic carbon and nitrogen in high latitudes and high altitudes,but the results are not the same.How would climate warming effect on soil active organic carbon and nitrogen in timberline ecotone in western Sichuan Province?Therefore,in order to learn the effects of climate warming on soil active organic carbon and nitrogen,we set up open-top chamber to simulated warming on active soil organic carbon and nitrogen of the alpine timberline in timberline ecotone in western Sichuan Province.The purpose of this study was to learn the effects of climate warming on soil active organic carbon and nitrogen.In the first year,the average temperature of soil organic layer increased by 0.49?;in the second year the average temperature of soil organic layer increased by 0.71?.In the first year,the annual average temperature of the mineral soil layer increased by 0.34?;in the second year the average temperature of soil organic layer increased by 0.50?.In the second year air temperature increased by 1.03?.Warming has no significant effect on soil microbial biomass carbon and nitrogen in the two soil layers.Sampling time had a significant effect on soil microbial biomass carbon and nitrogen in the two soil layers.Soil microbial biomass carbon and nitrogen was significantly correlated with soil total carbon,total nitrogen,total phosphorus,soluble inorganic carbon.Soil microbial biomass carbon and nitrogen were significantly correlated with soil soluble carbon,nitrogen and phosphorus,water content and pH.Soil organic layer soil microbial biomass carbon is higher than mineral soil layer.Warming has no significant effect on soil soluble organic nitrogen in soil organic layer,and no significant effect on soil soluble organic carbon in the mineral soil layer.Warming had a significant effect on soil soluble organic nitrogen in the mineral soil layer.Warming had a significant effect on soil soluble organic carbon in soil organic layer.Sampling time significantly affected soil soluble organic nitrogen in two soil layers.There was a significant correlation between soil dissolved organic carbon and soil total carbon,soluble inorganic carbon.Soil soluble organic carbon had significant correlation with soil soluble carbon,nitrogen and phosphorus,water content,temperature and pH.Soil soluble organic nitrogen had significant correlation with total carbon,total nitrogen,soil soluble carbon,nitrogen and phosphorus,and water content.Soil organic layer soil soluble organic carbon and nitrogen content is higher than mineral soil layer.Soil soluble organic carbon and nitrogen in the early growing season is lower than the other seasons.Warming has significant effect on NO₃^--N in two soil layers;warming had no significant effect on soil NH₄⁺-N and soil soluble carbon,nitrogen and phosphorus.There was a significant correlation between NH₄⁺-N and soil total carbon,total phosphorus and water content.NO₃^--N had significant correlation with soil total carbon,total nitrogen,total phosphorus,pH and water content.Soil soluble carbon,nitrogen and phosphorus had significant correlation with soil total carbon,total nitrogen,total phosphorus,pH and water content.In summary,simulated warming increased soil temperature in the two soil layers.Simulated warming had a significant effect on of NO₃^--N in two soil layers and has no significant effect on soil microbial biomass carbon and nitrogen Simulated warming in soil organic layers had a significant effect on soil soluble organic carbon.This indicates that the response of soil active organic carbon and nitrogen to simulated warming is not consistent.In the future,global warming may affect the soil carbon and nitrogen processes and carbon and nitrogen cycle in the ecosystem.In the short term,the simulated warming did not significantly affect the soil organic carbon and nitrogen content,but with the global warming,it may change the soil microbial community structure to affect the soil carbon and nitrogen cycle.