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About the productivity function P(C,N,T)

The productivity of the vegetation is a function of C, N, and T alone. As in [9] we assume that the productivity function P(C,N,T) can be presented in the multiplicative form (accordingly with Liebig's principle):
equation88
where tex2html_wrap_inline1365 is the maximum productivity of the vegetation and tex2html_wrap_inline1367, tex2html_wrap_inline1369 are functions: tex2html_wrap_inline1371. Here tex2html_wrap_inline1373 is a unimodular function: tex2html_wrap_inline1375 (see Fig. 2),

  figure93
Figure 2: Function tex2html_wrap_inline1373 describing the dependence of productivity on temperature T.

according to [10], the function tex2html_wrap_inline1381 is a monotonous increasing function with saturation (see Fig. 3).

  figure100
Figure 3: Function tex2html_wrap_inline1381 describing the dependence of productivity on carbon content C in the atmosphere.

The function tex2html_wrap_inline1387 is a monotonous increasing function, tending to one when tex2html_wrap_inline1389 (as in Fig. 3). Since C=A-N then the product tex2html_wrap_inline1393 can be presented in the form tex2html_wrap_inline1395 for fixed A(t) (see Fig. 4).

  figure107
Figure 4: The function tex2html_wrap_inline1399 as a function of N.

The function tex2html_wrap_inline1403 is a unimodular function where tex2html_wrap_inline1405. It is defined in the interval tex2html_wrap_inline1407.


next up previous
Next: About the function and Up: The model: Formulation and Previous: The model: Formulation and

Werner von Bloh (Data & Computation)
Thu Jul 13 11:24:58 MEST 2000