Ecoinformatics and Soil-Plant Formations - New Ecoinformatics Tools in Environmental Science: Applications and Decision-making - page 688

Fig. 8.16 Carbon cycle in the forest ecosystem

decomposition are described by linear or exponential models. Velocities of the
biomass dying are modeled by linear models. In general, the choice of model forms
to parameterize the carbon cycle depends on the existing database about forest
ecosystem parameters and characteristics. Below, the speci c models are

considered.
Photosynthesis is described by the equations:

A 6i ¼ b i u i ðÞW i ðÞ f i x ð h i ðÞ; ð i ¼ 1 ; 2 Þ

A 63 ¼ b 3 u 3 ð T ÞW 3 ð E Þ f 3 ð x 5 Þ h 3 ð w Þnð x 3 Þ;

where ʲ i (i=1, 2, 3) are the coef cients that re fl ect a dependence of photosynthesis

on the vegetation type; and φ i φi(T) is the dependence of photosynthesis on the

temperature T under the forest canopy. Functions ʨ i ,f i and h i reflect the photo-
synthesis dependence on illumination, mineral salts and moisture. Function

ʾ
characterizes a dependence of photosynthesis on the biomass of trees. The other
functions have the following view:

i ¼ 1 ; 2 ; W i ðÞ ¼exp ða i E Þ

u i ðÞ ¼1 þðd i = 100 Þ T T opt ð Þ; u 3 ðÞ ¼1 þðd 3 = 100 Þ T T A ; opt ð i ¼ 1 ; 2 ; 3 Þ;

=r i g

Þ c ;

f i x ðÞ ¼exp a i = x 5 ð Þ ð i ¼ 2 ; 3 Þ; f 1 x ðÞ ¼1 ; h i ðÞ ¼exp f b i ½w w A ; opt w opt ð i ¼ 1 ; 2 ; 3 Þ; n x ðÞ ¼x 3 = x 3A ð

where are constants; T opt and T A,opt are optimal

temperatures under the forest canopy and in the free atmosphere for photosynthesis,
respectively; w opt and w A,opt are optimal humidity under the forest canopy and in
free atmosphere for photosynthesis, respectively.
Carbon

ʴ i , a i , ʱ i ,b i , ˃ i (i=1, 2, 3) and ʳ

fluxes from vegetation tiers of the forest ecosystem are described by the
following models:

fl

a i4 ¼ k i x i ð i ¼ 1 ; 2 Þ; a 34 ¼ k 3 x 3 = ½1 þ d ð T T A Þ;

where k i (i=1, 2, 3) are the proportionality coef cients.