Soil water migration under three tree species in response to water stress and extreme rainstorms

In arid and semi-arid areas, plant growth and survival are directly related to the soil water content. The soil water content is an important parameter for monitoring land degradation. A better understanding of how forests use soil water is crucial for the quantification how the terrestrial hydrologic cycle adapts to forestry practices and regional climate anomalies in these areas. This study investigated the variation of the water balance under different precipitation patterns (including soil water redistribution patterns under water stress and extreme rainstorms) under three common tree species in a mountainous area of Beijing were investigated. The results showed that soil water storage in the 80-150 cm layer played an important role for the ability of Platycladus orientalis (L.) Franco and Quercus variabilis Blume to survive drought during a dry season. Compared to P. orientalis and Q. variabilis, the duration of water stress was shortest for Pinus tabulaeformis Carr. (15 months). P. tabulaeformis had a higher ability to utilize top soil water but showed a less balanced use of soil water in each soil layer. It also had the strongest ability to replenish groundwater through deep seepage. P. tabulaeformis may resist drought by transferring water to deeper soil horizons, where it is less susceptible to evaporation and where moisture can be temporarily stored. P. orientalis and Q. variabilis are more dependent on soil water storage in response to water stress conditions.