The Regulation Of Temperature And Water On Ecosystem Respiration Of A Subtropical Plantations

With the tendency of global warming, more and more attention should be paied to CO2flux. Terrestrial ecosystem is the habitat of human beings, it is relevant with the production and life of people. Thus the study of carbon circulating in terrestrial ecosystem turns into the key point. As the main part of terrestrial ecosystem, forest plays an important role in controlling the climate change. Eddy covariance is a micrometeorological technique that allows a non-invasive measurement of the exchange of CO2between the atmosphere and a several hectare area of forest, shrubland, or grassland on the ecosystem scale and provides new platform to quantify and compare the magnitudes and dynamics of annual ecosystem carbon and water balance.At present, estimating of ecosystem respiration using statistics method is widely used, and can be classified in those that using only night-time data for the estimation of ecosystem respiration and those that exploiting daytime data using light-response curves, sometimes with both day and night-time data, for example stable carbon isotopes, correlation analysis and artificial neural network.The carbon balance has been affected by altered precipitation patterns caused by global climate changes. The carbon sequestrated by terrestrial ecosystems returns to the atmosphere mainly through respiration, of which temperature and water are two essential factors in regulating ecosystem respiration(Reco). Seasonal drought caused by the imbalance of heat and rain according to ChinaFLUX Qianyanzhou Subtropical plantations site provides natural experimental conditions to investigate the regulation of temperature and water on ecosystem respiration. Based on the Eddy covariance and conventional meteorological data collected from this ecosystem from2003to2010, this study analyzes the response of ecosystem respiration to temperature and soil water content, and explores the effects of temperature or both temperature and soil water content on ecosystem respiration seasonality and annual respiration. The study shows that the seasonal variations of ecosystem respiration is mainly controlled by soil temperature, and Reco is an exponential function of soil temperature. Only under drought condition can soil water content play a significant role in regulation. With only temperature taken into account, the ecosystem respiration rate at the reference temperature (Rref) was significantly affected by soil water content; while with only the conditions of temperature and soil taken into account, the ecosystem respiration under reference temperature was not affected by soil water content. There was no evident difference between considering temperature alone and both temperature and soil water content, the ecosystem respiration amount was1289.4±73.9gC m-2a-1. But the seasonal variations of ecosystem respiration had significant differences between2003and2010whether a seasonal drought existed or not.