An ecohydrological perspective of reconstructed vegetation in the semi-arid region in drought seasons

Abstract

Desertification has long seriously threatened the ecological security of northern China, for which China has established the world's largest shelterbelt project. After 40 years of reconstruction of vegetation, the trend of desertification in northern China has been reversed. The shelterbelt forest project in northern China, however, at the same time, tells signs of degradation, and therefore its effectiveness has been questioned by scientists from various countries. In order to study the impact of the vegetation reconstruction process in the semi-arid area on the precipitation water redistribution process in this area, and how the reconstructed vegetation survives in dry season. This study selected the reconstruction Pinus sylvestris var. Mongolica (PSM) forest on Mu Us sandy land as the research object, and used new lysimeters, stem flow meters, miniature weather stations, etc. to monitor the deep soil water penetration, stem flux. The purpose of this current study is to find out how PSM forest changed the process of precipitation water redistribution in this area, and how PSM adjusts its own water storage capacity to adapt to the annual precipitation changes. In wet years such as 2017, DSR is only 0.4 mm, soil water storage is reduced by 16 mm, and evapotranspiration is 324.6 mm. In a wet year such as 2016, the DSR is 1.4 mm, the soil water storage is enlarged by 38.06 mm, and the evapotranspiration is 466.94 mm. The results showed that the water consumption of PSM in Mu Us area and the precipitation water replenishment in this area reached a balance but blocked precipitation to recharge deep soil water and groundwater. The rain-fed PSM stem can be used as a reservoir unit to supply water consumption and adjusting the evapotranspiration intensity to adapt to changes in annual precipitation. This research has advanced our understanding of the scale of reconstruction vegetation utilization of precipitation and the utilization mechanism of tree stem storage water in semi-arid areas.