Abstract: Tamarix chinensis is one of dominant species and widely distributed in the Chenier Island of the Yellow River Delta. To detect the water use patterns of T. chinensis, we conducted a comparative study at two habitats, seaside and dune crest. Soil moisture, soil salinity and oxygen isotope compositions in the xylem water of T. chinensis were measured during two plant growth seasons. The IsoSource model was used to calculate the feasible contributions of potential water sources to T. chinensis xylem water. In July 2013 with high precipitation, 90.9% of the xylem water in T. chinensis at the seaside was from the 20-40 cm soil layer, while 51.2% of the xylem water at the dune crest was from the 60-100 cm soil layer. In July 2014 with low precipitation, 58.4% of the xylem water at the seaside was from the 20-60 cm soil layer and 67.0% of the water at the dune crest from shallow groundwater. In addition, T. chinensis at the dune crest took up deeper water source than at the seaside because of the difference of soil and groundwater salinity. Thus, the water sources of T. chinensis varied with habitats and precipitation. These results suggested that T. chinensis could adapt to variable habitats and precipitation by altering the water use patterns, which benefits its competition capability for water resources and the maintenance of ecosystem stability of the Chenier Island under stresses.

Key words: supply-side reform, scale efficiency, effective supply, eco-product