Abstract
Ecological restoration has increased vegetation cover and reduced soil erosion, but it has also resulted in decreased soil-moisture content (SMC) and increased soil desiccation, which has ultimately led to a weakening of the “soil reservoir” function and a decline in the growth of plantations. Thus, soil desiccation has been a serious threat to the sustainable utilization of soil water resources and vegetation rehabilitation. In this study, the soil moisture of a Robinia pseudoacacia forest as well as its corresponding soil desiccation to a depth of 500 cm were measured across three different precipitation zones (400–450, 500–550 and 550–600 mm) along a north–south transect on the Loess Plateau. The results showed that the soil-moisture environment and soil desiccation status generally improved with the increasing precipitation gradient, while soil-moisture over-consumption significantly declined (p < 0.05). However, due to the elder forest-stand age and severe growth recession, the soil desiccation of R. pseudoacacia in the northern part was less than that in central zones. As the forest-stand age increased, SMC of R. pseudoacacia increased firstly and then decreased, and both soil-moisture consumption and the average soil desiccation rate peaked in the RP-5a, showing no significant consistence with forest-stand age. Therefore, understanding the soil-moisture status of forestland may better provide scientific basis for native vegetation restoration and reconstruction in water-limited regions.
Highlights
Published: 16 February 2022Soil desiccation on the Loess Plateau is a unique phenomenon of soil hydrological deficit, which is formed by the joint action of various biotic and abiotic factors, such as vegetation, arid climate and aeolian soil
Soil desiccation may result in the significant reduction of deepsoil-moisture storage, as well as the formation of desiccated-soil layers located beneath the rainfall-infiltration layer, with lower soil-moisture content and relative persistence [1,2,3]
In view of the high soil-moisture over-consumption and the average annual soil-desiccation rate of R. pseudoacacia forests, the results further demonstrated the above conclusion that each sampling site exhibited different levels of soil desiccation, except for the RP-45a in Yangjuangou catchment which was of the optimal soil-moisture conditions
Summary
Soil desiccation on the Loess Plateau is a unique phenomenon of soil hydrological deficit, which is formed by the joint action of various biotic and abiotic factors, such as vegetation, arid climate and aeolian soil. Wang [1,2,15] carried out a detailed evaluation of soil desiccation and its controlling factors in various land-use types and climate zones on the Loess Plateau and showed that the spatial distribution of desiccated-soil layers was mainly determined by soil texture and precipitation along the northwest–southeast direction. Due to the large span of the Loess Plateau along the north–south direction, there is a knowledge gap in understanding the overall soil-moisture and soil-desiccation conditions with regards to the specific tree species, such as R. pseudoacacia plantations in different precipitation zones This is a practical requirement for soil-desiccation. 454.89and explored as well, so as to provide a scientific basis for vegetation restoration prone steppe reconstruction on the Loess1274
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