The Study Of Evapotranspiration Of Community And Populations During Succession

Applying means of connecting LI-LI-6262 CO₂/H₂O analyzer to the chamber, this paper studied on the characters of evapotranspiration of community and populations in three different succession phases( in the enclosed plot , in the new enclosed plot, outside the enclosure plot)across a day and growing season in typical steppe July and August 2004. Analysing the relationships between evapotranspiration and their environments by statistic means, we get such conclusions: 1 , In three different succession plots, the curves of diurnal variation of evapotranspiration of populations and community have two types: one peak and two peaks in the middle ten days of July. In the last ten-day of July and the whole August, the curves of diurnal variation of evapotranspiration of populations and community almost take on only one type: one peak; 2, The total evapotranspiration of community in the daytime vary with the growth season. Outside the enclosure, The difference of total evapotranspiration of community in the daytime is most distinct. The difference of total evapotranspiration of community in the daytime in the enclosure is least; 3, In three different succession phases , the populations are different which are most correlated with community. outside the enclosure plot, Cleistogenes squarrosa hasthe most correlation with community. In the new enclosed plot, Leymus chinensis has the most correlation with community. In the enclosed plot, Stipa grandis has the most correlation with community; 4* The sequence of total evapotranspiration of community in three different plot is: community in the enclosure plot > community outside the enclosure plot > community in the new enclosure plot; 5* The total transpiration of A .michnoi Roshev. is the most in whole measuring period; 6n The transpiration Leymus chinensis and Stipa grandis have the remarkable correlation with their biomass. A .michnoi Roshev., Cleistogenes squarrosa and Artemisia frigid have not remarkable correlation with their biomass.7> Light intensity and temperature are the two important environmental factors affecting evapotranspiration of populations and community. Let light intensity and temperature as independent variables and evapotranspiration as dependant one , establish models among them in order to calculate evapotranspiration of the whole growth season across the region.