干旱区对降水变化响应的研究进展

水分是干旱区的主要限制因子之一,降水是干旱区最重要的水分来源。根据气候变化研究的预测,未来我国干旱区的降水格局会改变,包括降水量、降水频率和降水强度等。降水变化会影响干旱区的土壤变化,植被变化,土地荒漠化和水文变化等方面。我国极端干旱区和干旱区的降水有总体增加趋势,而部分半干旱区和亚湿润干旱区的降水则出现减少趋势。降水的增加能够促进生物土壤结皮的发育,改善土壤水分状况,促进植物生长,提高植被盖度,促使荒漠植被向草原植被方向发展,有利于土地荒漠化的逆转;另外,降水增加会增加河流的径流量和湖泊水量,促进洪水的发生,降水减少则具有相反的效应。这些研究有助于人们预测干旱区在未来降水格局改变之后可能发生的变化,对于天然植被保育以及荒漠化防治等实践工作等具有重要的理论指导意义。未来的研究需要加强实验,如增雨、升温、模拟氮沉降和CO₂浓度增加等对干旱区的土壤、植被、荒漠化和水文等方面的影响,才能获得更有说服力的结果。

Progress in the Study on Response of Arid Zones to Precipitation Change

The pattern of precipitation, including precipitation amount, frequency and intensity, may change in the future according to the prediction of climate change. In arid zones, the soil dynamics, plant growth and vegetation change, desertification and hydrology might be affected by precipitation change. In general, the precipitation in extreme arid zone and arid zone showed an increase tendency whereas the precipitation in some area in semi-arid zone and sub-humid arid zone showed a decrease tendency. The increase of precipitation could enhance the growth of biological soil crust, improve soil water status, promote plant growth, increase vegetation coverage, facilitate the change from desert vegetation to grassland vegetation, and it is benefit to the reversion of land desertification. In addition, the increase of precipitation could also increase the river runoff, lake storage and promote the occurrence of flood, while the decrease of precipitation has the adverse effect. These studies will benefit the prediction of the possible response of ecosystem processes to the potential change of precipitation pattern in arid zones in the future, and it is important to the conservation of natural vegetation and the control of desertification. More field experiments and studies should be conducted in the future, including the effect of increased precipitation or temperature, nitrogen deposition and CO₂ on soil, vegetation, desertification and hydrology of arid zones, so as the more persuasive results could be obtained from these experiments and studies.