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Determine the functions
ˆ
i
, G
i
, f
i
, H
i
, and
ˇ
:
u
i
T
ðÞ
¼1
þðd
i
=
100
Þ
T
M
T
Y
ð
Þ;
ð
i ¼ 1
;
2
Þ; u
3
T
ðÞ
¼1
þðd
3
=
100
Þ
T
M
T
A
ð
Þ;
G
3
X
ðÞ
exp
ða
i
X
3
Þ;
ð
i ¼ 1
;
2
;
3
Þ;
f
1
X
ðÞ
1
;
f
i
X
ðÞ
¼exp
a
i
=
ð
X
5
Þ;
ð
i ¼ 2
;
3
Þ;
(
)
2
c
;
W
A
W
Y
r
i
X
3
X
3A
H
i
ð
W
Þ
¼exp
b
i
W
ð
i ¼ 1
;
;
3
Þ; vð
X
3
Þ
¼
2
where T
У
and T
A
are atmospheric temperatures in tundra and taiga, respectively,
ʴ
i
(i = 1, 2, 3) are indicators of variability of the annual biomass increment with an
increasing temperature beneath the canopy by 1
°
C;
ʱ
i
, a
i
, b
i
,
ʺ
, and
ʳ ∈
(0,1) are
constant coef
cients; W
A
and W
Y
are soil moisture in taiga and tundra, respectively;
k
i
(i = 1, 2, 3) are the proportionality coef
(0,1) is the share of the forest
cover transforming into dead organic matter of soil as a result of decomposition.
To parameterize the atmospheric temperature beneath the tree canopy, it is
supposed that it cannot be below the environmental temperature T, increases with
the mass of trees up to some level X
3
= 0.5
cients;
˃∈
ʲ
2
/
ʲ
1
, and then decreases:
8
<
:
f
ð
X
3
Þ;
1
f
ð
X
3
Þ
T
A
=
T
;
T
M
ð
X
3
;
T
Þ
¼T
T
A
=
T
;
f
ð
X
3
Þ
[
T
A
=
T
;
1
;
f
ð
X
3
Þ
\
1
;
where
f
ð
X
3
Þ
¼1
b
1
X
3
þ b
2
X
3
;
cients.
The model described above can be used as an independent unit of the global
model, providing a transformation of the spatial structure in Fig.
1.23
and speci-
fying the local elements of the model of the water balance on the territory described
in Krapivin and Kondratyev (2002). For real application of the model, its param-
eters should be estimated with a concrete attachment to geographical latitude.
ʲ
1
and
ʲ
2
are positive coef
8.4 Wild
res as Components of Global Ecodynamics
8.4.1 Fires and Forest Ecosystem
Fires play a substantial role in the formation of forest ecosystems. Moreover, it can
be stated that they are an integral element of their development. Fire in a forest can
be caused either by a lightning stroke or anthropogenically. From available esti-
mates, the frequency of lightning strokes in tropical forests reaches 50 per km
2
annually. In the moderate-zone forests this quantity is less and constitutes 2
-
5
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