Abstract:

The paper, a synthesis based on data from our own investigation on Stipa baicalensis steppe for the period 1986-1988, deals with the relationships among biotic and abiotic factors at community ecology level. Analysis is applied to aboveground net primary production (ANPP), the energy source for livestock production process, with respect to accumulated temperature(≥5℃)(X1),rainfall in the growth season of the steppe plants (X2),and content of organic matter of surface soil (X3), which are the abotic variables most often used to explain variation in ANPP.

The models predicting ANPP in Stipa baicalensis steppe were structured in term of X1, X2, and X3. The predictive power of the models was found to be very high, and the models were successfully validated in three cases with an independent data set.

The prediction model that gave the best fit in Stipa baicalensis steppe was

Y 528.1328 + 12.1948X1 +82.5701001X2 +57.1987X3 + 12.6375X1X2

- 6.1265X1X3 + 28.0875X2X3 - 36.1774X12 - 31.4429X22- 26.2633X32

We have also made, in detail, the analysis of the relationships among ANPP and 3 ecological factors. ANPP was responsive to all of 3 ecological factors discussed in the paper. Action intensity, which has an effect upon ANPP, can be indicated by a contribution rate. The contribution rates of X1,X2, and X3 were 1.069, 2.0513 and 1.8889, respectively.