Influences of Phragmites australis density and groundwater level on soil water in semiarid wetland, North China: Which is more influential?

Understanding soil water dynamics and their influencing factors is an important basis for formulating efficient water-use strategies aimed at alleviating water stress, especially in areas with water shortages. In this research, six plots with different densities were designed to systematically analyze the influences of Phragmites australis density and groundwater level on soil water in a semiarid wetland. (1) The Phragmites australis density had a negative influence on the soil water in the 0-40 cm profile and from April to August. (2) The Phragmites australis density had a positive effect on the annual variation degree of the soil water storage. The water replenishment could be implemented in April and June for low and high Phragmites australis densities, respectively. (3) The groundwater level had a significant influence on the soil water content of the 0-50 cm layer, and the change was positively correlated with the Phragmites australis density. The influence of groundwater level on soil water was more influential than that of Phragmites australis density. (4) The suitable average groundwater depth for the 0%, 20%, 40%, 60%, 80% and 100% densities were 76 cm, 63 cm, 50 cm, 37 cm, 23 cm and 10 cm, respectively. The suitable average densities of Phragmites australis for the groundwater depth of 35 cm, 40 cm, 45 cm and 50 cm were 62%, 55%, 47% and 40%, respectively. This research can provide a theoretical support for the management of Phragmites australis density and groundwater level in the Baiyangdian wetland. (c) 2021 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.