气候变化对太行山土壤水分及植被的影响

在太行山低山区将自然植被移入蒸渗仪,观察当降水分别为常年平均降水量的80%、90%、100%、110%和120%等5种处理条件下,植被生产力和土壤的不同反映。研究发现:受验植被对降水反映敏感,降水每增加10%,植被生产力增加15%左右,预示未来全球变化导致的降水变化会对太行山低山区植被产生影响。同时在利用野外实验结果对WAVES模型进行验证的基础上,模拟了不同温度和降水变化情景下,土壤水分的可能变化趋势。结果表明:增温和减少降水对土壤水分负作用明显,尽管降水增加可改善土壤的水分供应状况,但降水增加10%对土壤水分的正面影响,大体被3 oC的增温抵消。由于模型模拟中采用的是与目前没有改变降水条件的实验相同的植被(LAI),而植被生长在太行山这一半湿润、半干旱地区又受土壤水分控制,因而估计未来气候变化情景下的植被变化与土壤水分的变化趋势相似。

Impacts of Temperature and Precipitation Changes on Soil Moisture of Taihang Mountains

By transplanting original plants/soil system into lysimeters and treating those lysimeters with five precipitation treatments: 80%, 90%, 100%, 110% and 120% of the average annual precipitation, plant productivity and soil moisture were observed. Field experiment in Yuansi county, Hebei, showed that precipitation change was a very sensitive factor influencing both the productivity and soil moisture. Precipitation increase resulted in the increase of productivity. When precipitation increased by 10%, productivity increased by about 15%. The experiment also showed that higher precipitation generally resulted in higher soil moisture, which should be the reason for productivity increase in high precipitation treatments, though good plant growth, in some treatments, might also feed back on the soil moisture change. In order to see the possible effect of both temperature and precipitation changes on soil moisture, without changing plant growth pattern, WAVES model is calibrated, validated and used for the simulation of response of soil moisture to climatic change. The simulation shows that temperature associated with precipitation decrease or no precipitation change will definitely result in the decrease of soil moisture, indicating a great possibility of plant productivity decrease. Though precipitation increase would benefit the soil moisture, however, it is showed that 10% precipitation increase will not bring any benefit to soil moisture if temperature rises by 4 o C. Precipitation rise by 10% will possibly create only a slightly favorable soil moisture condition if temperature rises by 2 o C. It is thus suggested that the positive effect of 10% precipitation increase on soil moisture will possibly be offset by roughly a temperature rise of 3 o C . As soil moisture is the key factor influencing plant productivity, plant productivity will possibly follow the same trend. However, since the effect of CO 2 concentration rise on plant transpiration and plant growth is not considered in the model simulation, there are still quite a lot of uncertainties remaining. The results need to be testified by future studies.