Research Of Relationship Between Carbon Dioxide Net Exchange And Water Use Efficiency In Winter Wheat Field Ecosystem In Taiyuan Basin

Field ecosystem carbon pool as the major component of the terrestrial carbon pool was paid more and more attention over the recent years. Field ecosystem carbon cycle was disturbed directly by mankind's activities. A distinct characteristic of field ecosystem carbon cycle was carbon sink and source alternating occured. Through photosynthesis crops could fixate the energy and accumulate the organisms with two cycles of carbon and water. Water use efficiency is an important agronomical norm and linking to both carbon and water cycles. Eddy covariance method and chamber method are two mainstream methods to observate the carbon and water fluxes. In order to find the initial relationships between carbon and water fluxes, we used chamber method to measure fluxes at six different growing stages from erecting to ripening in a winter wheat crop ecosystem in Taiyuan basin and the related environmental factors also were observed at the same time. We found that1) There are apparently daily variation and seasonal variation to carbon fluxes. Both photosynthesis active radiation (PAR) and temperature (T) are the major factors to net ecosystem exchange (NEE) and there is a significant linear relation between NEE and PAR and T. The most significant relation is between NEE and PAR and canopy temperature (Tc) with a R2 of 0.739.2) During the observation stages, we found the carbon source and sink relations'rank is that:erecting> jointing> heading> booting ripening> grain filling.3) There is also a significant linear relations between photosynthesis active radiation (PAR) and temperature (T) and evaportranspiration (ET). Between ET and carbon fluxes have an apparent linear relation. As a result, PAR and T linking to both of the carbon and water fluxes.4) The water use efficiency (WUE) was calculated by two levels of NEE and GEP and they would be the references for water demand in a winter wheat field.