Geography Reference
In-Depth Information
Simulated effects of afforestation on albedo in Jiangxi Province (magnified by 10
-3
)
Table 5.2
Month
DB
DN
EB
EN
Mean
Std.
Mean
Std.
Mean
Std.
Mean
Std.
Jan
11.31
30.52
3.59
27.43
-7.61
28.73
-7.61
28.73
Feb
11.56
30.37
3.75
27.17
-7.57
28.36
-7.56
28.39
Mar
11.51
31.18
3.70
28.05
-7.71
29.26
-7.71
29.25
Apr
11.75
27.83
3.93
24.15
-6.57
25.03
-6.57
25.03
May
12.05
22.80
4.24
17.93
-4.78
18.16
-4.78
18.16
Jun
12.35
20.04
4.54
13.99
-3.58
13.54
-3.58
13.54
Jul
12.34
19.75
4.52
13.59
-3.47
13.12
-3.47
13.12
Aug
12.33
19.92
4.52
13.84
-3.54
13.39
-3.54
13.39
Sep
12.31
20.44
4.49
14.60
-3.77
14.27
-3.77
14.27
Oct
11.80
24.03
3.99
19.62
-5.31
20.22
-5.31
20.22
Nov
11.58
27.10
3.77
23.40
-6.40
24.40
-6.40
24.40
Dec
11.26
28.63
3.57
25.42
-7.10
26.62
-7.08
26.63
complex effects of expansion of the evergreen needleleaf forests under the scenario
of EN, which makes the monthly average temperature decrease from May to
September and increase from October to April (Table
5.1
). On the whole, the
variation of the monthly average temperature change under the scenarios of DN,
EB, and EN is similar to that of under the scenario of DB.
Afforestation can affect the monthly average temperature via multiple ways
such as albedo, potential evapotranspiration, and leaf area index. Considering the
plentiful water and heat resources in Jiangxi province, albedo is most likely to be
the principal cause resulting in the monthly average temperature changes. The
changes of albedo under all the four scenarios are provided to help to identify the
reasons of monthly average temperature changes (Table
5.2
). A larger increase in
albedo shows a severer decrease trend in monthly average temperature. It implies
that the cooling effect is due to the low surface net radiation caused by high albedo
under the scenarios of DB and DN. And on the contrary, the declines of albedo
under the scenarios of EB and EN may be the major causes of monthly average
temperature increase in Jiangxi Province. The variation of monthly average tem-
perature change also has a convergence trend with that of albedo change. The
correlation coefficient of monthly average temperature change and albedo change
reaches -0.77, which also implies that the temperature changes are mainly derived
from the changes of albedo driven by afforestation.
The effects of afforestation on the monthly average precipitation are more
significant than that on the monthly average temperature. The precipitation in
Jiangxi Province will decrease greatly in the summer under the scenarios of DB
and DN (Table
5.3
). Under the scenario of DB, the monthly average precipitation
will decrease by 10.63, 11.50, and 8.63 mm in June, July, and August, respec-
tively. Although the decrement of the monthly average precipitation is smaller
than that of under the scenario of DN, it still reaches 10.42 mm in July. The
drought effects of the deciduous forest expansion will last throughout the year
