PHOTOSYNTHESIS AND WATER-USE EFFICIENCY DURING DEGRADATION OF A SEMIARID LOESS STEPPE

Tolerance of Festuca rupicola Heuff., Botriochloa ischaemum (L.) Keng. , and Salvia nemorosa L. to co-occurring drought high air temperature and high irradiance were investigated in stands representing different degree of degradation. Air and leaf temperatures were higher for the stands in the advanced degradation stage. The net photosynthetic sate was not significantly lower and WUE was depressed in the degraded stan ds as compared to the intact stands. Carbon, fixation type seems to ha ve outstanding importance in the outcome of degradation processes in s emiarid temperate grasslands.