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CAS Workshop on Ecosystem Succession Theory and Practice of Ecological Restoration The wave-shape of vegetation and material exchange
along ecotone between oasis and desert Wang Genxuan
Gao Xiaowei Chen
Dongliang Wei Xiaoping (State key
laboratory of arid agroecology, Lanzhou University, Lanzhou 730000,
China) Abstract:
The vegetation and material and energy flux along the ecotone
between oasis and desert was very important for the steady and
sustainable development of arid desert ecosystem. There are
remarkable water gradient in the soil and air along ecotone between
oasis and desert. In the oasis, there are the water potential are
very high (near 0) at 1m depth under the ground and the vapor
pressure deficit( VPD) are very low at the 2m high and 3 o’clock
afternoon in the growth season. This gradient was maintained by the
diffusion of water molecules from oasis to the desert through soil
and air along the ecotone. The wave-shape pattern of the vegetation
along the ecotone was remarkable compared with the relative steady
pattern in the oasis and desert. The coverage of vegetation is near
100 in the irrigated farmland during the plant growth season in
summer in the oasis. The coverage changed fluctuantly when the
sample was located in the ecotone and outside the irrigated land.
The average of the coverage decreased gradually along the ecotone
from oasis to desert. The wave-shape of the coverage in desert was
less notable than in ecotone because the coverage was too small to
show the wave-shape in the desert. The flux of material and energy
through the surface of soil-plant-atmosphere was direct proportional
with the coverage along the ecotone. Key words:
vegetation; desert; ecotone; water and CO2 flux
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