Study Of Components Of Carbon Cycle In Temperate Meadow Steppe

Grassland ecosystem is the important component of the terrestrial ecosystem, plays an important rolein the carbon cycle in terrestrial ecosystem. Temperate Meadow Steppe is an important part of thegrassland ecosystem and a large carbon reservoir. In under the trend of global warming, WhetherTemperate Meadow Steppe will become the carbon source or sink, has a significant role in nationalpolicy, also has the vital significance to the study of grassland ecosystem carbon assessment and carboncycle. The study was done using a variety of methods in the the Stipa baicalensis Meadow Steppe in theHulunbeir, Inner Mongolia. Temperate meadow steppe carbon cycle components were analyzed.Based on the measurement of NEE with eddy covariance system from Jan.2009to Dem.2010, theauthors analyzed the characteristics of ecosystem CO2flux in the the Stipa baicalensis Meadow Steppein the Hulunbeir, Inner Mongolia. The results were as follows: There was a single uptake peak with themaximum CO2uptake peak among9:00a.m.-13:00p.m. in growing season. There were distinct seasonalvariations with an inverted W-shape during the growing season, and the ecosystem was a CO2source inthe non-growing season. The night net ecosystem CO2exchange was correlated exponentially with thesoil temperature on daily-scale level, except for W≤0.19in2009. The ecosystem was a carbon sink in2009and2010. Accumulated NEE were-211.25and-74.54gC·m-2,respectively, during the growingseason, and annual accumulated NEE were-181.67and-66.38gC·m-2, respectively, in2009and2010.Based on the measurement of soil CO2evolution with the Li-8150(Li-COR, Inc, Lincoln, NE, USA)from Jun.2009to Jun.2010, the authors analyzed the characteristics of the soil CO2flux from the Stipabaicalensis Meadow Steppe in the Hulunbeir, Inner Mongolia. The results were as follows: The dailydynamics of soil respiration rate in this study area presented a peak curve in growing season. And thesoil respiration in this study area had obviously seasonal dynamics. The relationship of soil respirationwith soil temperature and soil water content could be better expressed with linear or exponential-powerequation. Using the Van’t Hoff exponential equation to fit soil respiration and soil temperature, theresults showed that they all had good exponential regression relationships in growing season and innon-growing season. The effect of soil temperature on soil respiration was more sensitive innon-growing season than that in growing season. From the observed and simulated values the annualsoil CO2flux was488.47and507.20gC·m-2·a-1in2009and2010. The contribution of soil respiration ingrowing season to the annual soil CO2flux was about90%.Based on a static opaque chamber method and root exclusion method from Jun. to Sep.2013, theauthors analyzed the characteristics of the soil CO2flux and its components from the Stipa baicalensisMeadow Steppe in the Hulunbeir, Inner Mongolia. The results were as follows: The daily dynamics ofsoil respiration, soil microorganism respiration and soil root respiration in this study area presented apeak curve in growing season. The soil root respiration in this study area had obviously seasonaldynamics showed as a bimodal curve in growing season, similar with the dynamics of soil respiration.Soil respiration and soil microorganism respiration showed a significant exponential regression with 5cm and10cm soil temperature. The contribution of root respiration to total soil respiration obviouslychanged in the growing season, and the proportion was varied from27.65%-50%with the mean valueof51.85%. Total soil respiration, total soil microorganism respiration and total root respiration were579.07,257.44and321.62gC·m-2, respectively.