Geoscience Reference
In-Depth Information
Table 6.1 Comparison of the ecosystem characteristics for acid and no acid tundra
The tundra ecosystem characteristics
Acid medium
No acid medium
PH of the upper mineral horizon
6.9
5.2
Average height of the vegetation canopy (cm)
3.9
6.5
Leaf area index (m
2
/m
2
)
0.5
0.84
Mossy cover (%)
65
79
NDVI
0.28
0.41
O-horizon thickness
11
21
Part of the area without vegetation (%)
7.5
0.8
flux from the soil (MJ/m
2
/day) 3.13 1.83
Depth of soil thaw (cm) 52 39
Total net primary production (mgCO
2
-C/m
2
/day) 940 1,820
Net CO
2
absorption 670 950
Respiration losses 270 870
CH
4
extraction (mgCH
4
/m
2
/day) 69 449
Organic carbon content in the metric layer (kg C/m
3
) 0 8
Calcium storage in active soil layer (mole(+)/m
3
)
Heat
fl
400
35
all, carbon dioxide. In particular, Table
6.1
shows that division of the tundra soil
into acid and no acid, in
uences on this assessment. Study of arctic ecosystems and
their role in biogeochemical cycles is realized in framework of series scienti
fl
c
programs between of which LAII (Land-Atmosphere-Ice Interactions) and ATLAS
(Arctic Transitions in the Land-Atmosphere System) are notable for investigation of
fl
fluxes of water, energy and GHGs in the Arctic as well as for mapping the spectral
re
ection and zonal boundaries between ecosystems.
An important step forward in studying the Arctic environment is the Climate and
Cryosphere (CliC) Project (Allison et al. 2001). The term
fl
“
cryosphere
”
describes
those portions of the Earth
is surface, where water is in solid form. This includes all
kinds of ice and snow and frozen ground, such as permafrost. The main components
of the cryosphere are snow, river and lake ice, sea ice, glaciers and ice caps, ice
shelves, ice sheets, and frozen ground. In terms of the ice mass and its heat capacity,
the cryosphere is the second largest component of the climate system (after the
ocean). Its in
'
uence for climate variability and change is based on physical prop-
erties, such as its high surface reflectivity (albedo) and the latent heat associated
with phase changes, which have a strong impact on the surface energy balance.
The cryosphere is an important part of the global climate system. It is strongly
fl
in
uences
each of these properties. It also has an effect on the exchange of heat and moisture
between the Earth
fl
uenced by temperature, solar radiation and precipitation, and, in turn, in
fl
'
s surface (land or sea) and the atmosphere, on clouds, on river
fl
flow (hydrology), and on atmospheric and oceanic circulation. Parts of the cryo-
sphere are strongly in
uenced by changes in climate. The cryosphere may therefore
act as an early indicator of both natural and human-induced climate changes.
The cryosphere on land stores about 75 % of the world
fl
s freshwater. The
volumes of the Greenland and Antarctic Ice Sheets are equivalent to approximately
'
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