Impacts of Temperature and Precipitation Changes on Soil Moisture of Taihang Mountains
气候变化对太行山土壤水分及植被的影响

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.