Abstract:

The present study in transpiration intensity of plants in alpine Kobresia humilis meadows was carried out at Haibei Research Station of Alpine Meadow Ecosystem during the growing season from May to September in 1986.The transpiration intensity of Kobresia humilis and plants of nine other species, the daily courses of transpiration intensity of Elymus nutans and plants of two other species as well as the evapotranspiration intensity of different ground covers in Kobresia humilis meadows were measured by method of cobalt paper. At the same time,meteorological data ewer also recorded.The study results are as follows:

1. The transpiration intensity of Kobresia humilis and plants of nine other species and their phenological phases, were lower during the early growth period and higher during the growth-development period. In general, the transpiration intensity of plants in alpine meadows is higher due to the special habitat conditions on the Qinghai-Xizang plateau.

2. The daily transpiration courses of Elymus nutans and plants of other species showed one peak curve at noon or afternoon, due to the longer time opening of the stoma to which is also one of the reasons of the higher transpiration intensity. But on the other hand, the transpiration coefficient is higher and the transpiration ratio is lower of the plants in Kobresia humilis meadows.

3. The evapotranspiration of different ground covers showed that evapotranspiration with ground cover is higher than that without ground cover (bare land).