EFFECTS OF SEVERAL GROUND FACTORON EVAPOTRANSPIRATION FROMTHE STEPPE COMMUNITIES
几个主要地面因子对草原群落蒸发蒸腾的影响

Effects of several ground factors on evapotranspiration from the steppe communities were observed at Inner Mongolia Grassland Ecosystem Research Station of Academia Sinica. The results were as follows:1. Effects of the soil factors:(1)Under normal conditions,evaporation,transpiration and evapotranspiration from the community increased with increase in the soil moisture. When the soil was too wet,transpiration from the community decreased due to that the plants were damaged by waterlogging.(2)Under low soil moisture condition,evaporation from the community decreased with increase in soil clay content. Under high soil moisture condition,evaporation from the community increased with increase in soil clay content.(3)Evaporations from the community having different soil moisture were increasing with increase in the soil compaction,and reached their maximums successively.The drier the soil was,the later the maximum reached.2. Effects of the grazing factors:Transpiration from the community was negatively correlated with the grazing pressure,but evaporation from the community was positively correlated with the grazing pressure.Decrement of the community biomass with the grazing pressure was the key reason for the positive and negative correlation.3. Evapotranspiration from the deteriorative and its recovery communities:Increase in evaporation and decrease in transpiration were caused by deterioration of the community, otherwise, decrease in evaporation and increase in transpiration were caused by recovery of the community. To a certain extent,T/E value of the community could be greatly changed by deterioration or recovery of the community,but evapotranspiration from the community kept constant.