Severe drought strongly reduces water use and its recovery ability of mature Mongolian Scots pine (Pinus sylvestris var. mongolica Litv.) in a semi-arid sandy environment of northern China

分类： 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间： 2019-12-06 合作期刊: 《干旱区科学》

DANG Hongzhong ZHANG Lizhen YANG Wenbin FENG Jinchao HAN Hui CHEN Yiben

摘要： Trees growing in a semi-arid sandy environment are often exposed to drought conditions due to seasonal variations in precipitation, low soil water retention and deep groundwater level. However, adaptability and plasticity of individuals to the changing drought conditions greatly vary among tree species. In this study, we estimated water use (Ts) of Mongolian Scots pine (MSP; Pinus sylvestris var. mongolica Litv.) based on sap flux density measurements over four successive years (2013–2016) that exhibited significant fluctuations in precipitation in a semi-arid sandy environment of northern China. The results showed that fluctuations in daily Ts synchronously varied with dry-wet cycles of soil moisture over the study period. The daily ratio of water use to reference evapotranspiration (Ts/ET0) on sunny days in each year showed a negative linear relationship with the severity of drought in the upper soil layer (0–1 m; P<0.01). The decrease in Ts induced by erratic drought during the growing season recovered due to precipitation. However, this recovery ability failed under prolonged and severe droughts. The Ts/ET0 ratio significantly declined with the progressive reduction in the groundwater level (gw) over the study period (P<0.01). We concluded that the upper soil layer contributed the most to the Ts of MSP during the growing season. The severity and duration of droughts in this layer greatly reduced Ts. Nevertheless, gw determined whether the Ts could completely recover after the alleviation of long-term soil drought. These results provide practical information for optimizing MSP management to stop ongoing degradation in the semi-arid sandy environments.

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