Abstract
Neither single nor discontinuous hydrological observation data can truly reflect periodic changes in soil moisture under natural conditions or interrelationships between various water sources. Therefore, in this study, precipitation pulse characteristics and variations in the soil water content (SWC) and actual evapotranspiration (ETa) in relation to pulses are explored through a field multi-water continuous observation system set in desert steppe in Inner Mongolia, China. A comparison between precipitation events in the growing seasons of 2016 and 2017 shows that precipitation events that are greater than 10 mm are the main cause of dramatic interannual precipitation variations in this region. A single small precipitation event has a limited impact on SWC and provides no obvious increase in the SWC within the top 10 cm soil layer. The precipitation interval ratio (P/I) is suitable for comparing water stresses of different drying-wetting cycles, and correlations between soil layers are found to be closer in humid years than in dry years. In this study, three modes of interpulse ETa in the desert steppe are discussed: a stable ETa mode under a water-sufficient condition, an attenuation ETa mode, and a stable ETa mode under extreme drought conditions.
Highlights
Arid and semiarid ecosystems are some of the most sensitive and fragile ecosystems, and as such, they are severely affected by climate change and human activity [1,2,3]
Desert steppe is a significant type of arid and semiarid ecosystem [12,13,14], and it acts as an ecological barrier, as it is situated close to wind and sand sources [15,16]
The main objectives of this study are to: (1) recognize the features of precipitation events in different precipitation years; (2) discuss the dynamics of soil water content (SWC) and the correlation between the SWC in different soil layers under different precipitation situations; (3) investigate the reaction of shallow root vegetation ETa on precipitation pulse events and explore ETa modes during dry interpulse periods; and, (4) analyze the multi-water coupling process that is caused by precipitation pulses
Summary
Arid and semiarid ecosystems are some of the most sensitive and fragile ecosystems, and as such, they are severely affected by climate change and human activity [1,2,3]. Desert steppe is a significant type of arid and semiarid ecosystem [12,13,14], and it acts as an ecological barrier, as it is situated close to wind and sand sources [15,16]. Because it is a zone where grassland transitions to desert, it is extremely fragile in the context of climate change and human activity [17,18].
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