Seasonal variation of water sources for plants growing on continuous rock outcrops in limestone area of Southwest China

Aims Woody plants in karst regions often grow on the continuous rock outcrops.However,the source of water for these plants is unclear.This study aimed at investigating the seasonal variation of water sources for plants growing on continuous limestone outcrops in southwestern China.Methods Stable isotope techniques were used to access plant water uptake patterns for five different species in both wet and dry seasons.Then the IsoSource model was used to determine the probable contribution of each potential water source to total plant water uptake.Important findings In the wet season,an average of 80% of water for four of the five species came from rainwater received in the previous 15 days and stored in fissures in shallow layers.Water accessed by the other species came mostly from recent rainwater;however,the species simultaneously absorbed water from fissures in deep layers that had been recharged from previous precipitation.In the dry season,all five species utilized both recent and previous rainwater,and the two tree species and one large evergreen shrub species used more previous rainwater(50%).