干旱区生态环境知识资源中心

Vegetation cover on sand dunes mainly depends on wind power (drift potential-DP) and precipitation. When this cover decreases below a minimal percentage, dunes will start moving. It is therefore necessary to study the effects of DP and precipitation on contemporary dune activity in order to predict likely future dune mobility in the coming decades. We concentrate on the future activity of the currently fixed dune fields of the Kalahari and the Australian deserts. These sand seas include the largest areas of stabilized dunes in the world, and changes in their mobility have significant economic implications. Global maps of DP are introduced, based on real and reanalysis data. Analyses of two global circulation models (GFDL and CGCM3.1) provide future predictions under the SRES-A1B IPCC scenario, which is a moderate global warming scenario. According to the GFDL model, both the Australian and Kalahari basin dunes will apparently remain stable towards the end of the 21st century because the DP will stay small, while the rate of precipitation is expected to remain much above the minimal threshold necessary for the vegetative growth that leads to dune stabilization. The CGCM model predicts insignificant changes in DPs and shows that the precipitation rate is above 500 mm/year for almost the entire Kalahari basin. The central-northern part of Australia is predicted to have larger DPs and greater precipitation than the southern part. Since the predicted changes in DP and precipitation are generally not drastic, both the Australian desert and Kalahari basin dunes are not likely to become active. Still, the Australian dunes are more likely to remobilize than the Kalahari ones due to some decrease in precipitation and an increase in wind power.