The drought stress and rehydration influence on chlorophyll fluorescence characteristics of Barbula fallax Hedw. in areas of karst rocky desertification: Case study near Huaxi district, Guiyang City

Guiyang city is located in the central Guizhou Province, at an average elevation of 1 100 m, annual average temperature 15.2 ℃ and annual average rainfall of 1 178 mm. The soil in Guiyang is predominately calcareous (accounting for 85 %), whose parent rocks are mainly dolomitic limestone and calcium dolomite. Its forest coverage is 5 %-15 %, the vegetation coverage is 10 %-90 %, the bare rock is 30 %-90 %, the land reclamation is 10 %-70 %, and the average rocky desertification is 36.79 %. Huaxi district in Guiyang is taken as an example for ecological restoration and treatment research, which provides the basis for scientific selection of drought-resistant plants for cultivation in karst rocky desertificationareas. Chlorophyll-fluorescence was measured by a handy PAM-2100 fluorometer in moss Barbula fallax Hedw. when drought and rehydration affected chlorophyll content and fluorescence under increased drought stress, the total chlorophyll content first dropped , and then increased gradually. F0 and qN of three kinds of mosses increased while the Fm , Fv/Fm, Yield, ETR and qP decreased with drought stress. Fluorescence parameters after rehydration were restored to normal levels by mild to moderate stress, and severe stress is more difficult to return to the control level. 