Estimation of water consumption of riparian forest in the lower reaches of Tarim River, northwest China

Abstract

The aim of this study is to estimate the water consumption of a Populus euphratica forest. Findings provide a scientific basis for water allocation to the lower reaches of the Tarim River, in Northwest China. In this paper, several different methods were used to gather data. The heat-pulse technique was applied to determine the stem sap flow of P. euphratica sample trees from May to September of 2015. Then, the P. euphratica sapwood area estimation model was established based on the correlation between the sapwood area and the tree biometric parameters. Finally, the water consumption of P. euphratica (n = 3000) trees was calculated. The results showed that the estimated sapwood area of P. euphratica (n = 3000) was 677,000 cm2, and the total water consumed by these trees during the measurement period was 23,000,000 L. The P. euphratica sap flow varies due to changing environmental factors. The average daily sap flow velocities were 814.3, 1461.75, 1907.27, 1657.51 and 1173.65 mL h−1 from May to September, respectively. The average daily accumulated sap flow was 22.44, 34.76, 46.98, 40.59 and 32.90 L from May to September, respectively. Pearson correlation analysis showed that variation of sap flow was positively related to solar radiation (R s) (R 2 = 0.715), air temperature (T a) (R 2 = 0.744), soil temperature (T s) (R 2 = 0.806), wind speed (W s) (R 2 = 0.104). At the same time, sap flow was negatively related to air humidity (H) (R 2 = −0.305). Stepwise regression analysis showed that solar radiation, air temperature, soil temperature and air humidity are the main factors influencing the P. euphratica sap flow variation.