Chinese Journal of Plant Ecology (植物生态学报) 2013/37:12 PP.1091-1100
Aims Little study has been conducted to quantify plant water sources for Myricaria squamosa, which is a domi-nant alpine riparian shrub in the Qinghai Lake basin and plays a key role in maintaining riverine wetland system. The objective of this study was to quantify water sources for M. squamosa growing under different hydrological conditions. Methods We collected the water samples from the xylem of M. squamosa, groundwater, river, and soils in the Qinghai Lake basin from June through September, and analyzed the seasonal variation of hydrogen stable isotope ratio (δD) in the xylem and potential water sources using stable hydrogen isotope tracer method. We then com-pared the differences in water sources for M. squamosa growing under two contrasting hydrological conditions. Important findings Myricaria squamosa plants growing on the river bank mainly used groundwater and water from the river stream in June and July, with groundwater contributing up to 89% of water use in June and 55% in July and river stream contributing up to 86% in June and 65% in July, respectively; whilst in August, they used water mainly from the 0–20 cm soil layer; the water source in September was identifiable. In contrast, Myricaria squamosa plants growing approximately about 100 m away from the river bank mainly accessed the groundwater and river water in June (91% and 70%, respectively), and used water from the 0–60 cm soil layer during the rainy months July, August and September. Results suggest that M. squamosa plants on the river bank use mainly groundwater and river water; soil water was more important for those far away from the river bank. These are resulted from the re-sponses of this shrub species to specific water conditions when growing under contrasting water regimes.