Because of seasonal drought and flooding in corresponding dry and rainy season of Xishuangbanna, riparian vegetation usually suffers an extreme range of water stresses (water inundation and drought). However, water use patterns of riparian plants under such environmental condition have not yet been explored. Moreover, the contribution of river to supply the water for riparian vegetation is also unclear. 

Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) used isotopic data of hydrogen (δD) and oxygen (δ¹⁸O) to explore the spatial and seasonal variation in water use pattern of riparian vegetation. 

They also used the MixSIAR model (Bayesian mixing model) to determine the contribution of different water sources of riparian plants.  

The study has been published online in Ecohydrology.  

They surveyed riparian vegetation at two characteristically different locations: the floodplain sites flooded several times during the rainy season every year, and the terrace sites which is seldom flooded.

An apparent seasonal variation in water use patterns was shown for most species between the dry and rainy seasons but little spatial variations between terrace and floodplain sites.  

Moreover, the variation in water use pattern was also observed between species having different plant functional type.  

They further found that the shallow and medium soil layers were the predominant source of water for the majority of plants across the year. While water of deep soil layers was an important source for the deep-rooted trees and mainly during the dry season.  

Similarly, the river was an important source of water for some trees that have deep and extensive root system, and for some plants which use it as a medium to complete their life cycle (e.g. seed dispersal).  

"Our study results may be useful for the long-term monitoring and management of riparian zone, particularly under tropical conditions", said Prof. LIU Wenjie, principal investigator of the study.