几个主要地面因子对草原群落蒸发蒸腾的影响

EFFECTS OF SEVERAL GROUND FACTORON EVAPOTRANSPIRATION FROMTHE STEPPE COMMUNITIES

在中国科学院内蒙古草原生态系统定位研究站，采用“土柱称重法”，观测了几个主要地面因子对草原群落蒸发蒸腾的影响。主要研究结果如下：１．土壤因子的影响：（１）在通常情况下，草原群落蒸发、蒸腾及蒸散均随土壤水分增加而增大。当土壤水分过多时，群落蒸腾由于植物受涝而降低。（２）在低土壤含水量条件下，群落蒸发随土壤粘粒含量增加呈线性降低；在高土壤含水量条件下，群落蒸发随土壤粘粒含量增加而升高。（３）不同土壤含水量的群落蒸发，均随土壤紧实度增大而升高。并先后达最高值。土壤含水量意低，蒸发达最高值愈滞后。２．放牧同素的影响：群落蒸腾与牧压呈线性负相关；群落蒸发与牧压呈线性正相关。群落生物置随牧压增大而降低是导致群落蒸发和蒸腾与牧压呈正、负相关的主要原因。３．退化群落及其恢复群落的蒸发蒸腾。群落退化导致群落蒸发升高，蒸腾降低；相应的群落恢复导致群落蒸发降低，蒸腾升高。在一定程度上，群落退化及其恢复演替虽然能明显改变群落Ｔ／Ｅ值１），但却不会引起群落蒸散值的明显变化。

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.