Effects of Land Use Change on Soil Carbon Storage and Water Consumption in an Oasis-Desert Ecotone

Abstract

Land use and ecosystem services need to be assessed simultaneously to better understand the relevant factors in sustainable land management. This paper analyzed land use changes in the middle reach of the arid Heihe River Basin in northwest China over the last two decades and their impacts on water resources and soil organic carbon (SOC) storage. The results indicated that from 1986 to 2007: (1) cropland and human settlements expanded by 45.0 and 17.6 %, respectively, at the expense of 70.1, 35.7, and 4.1 % shrinkage on woodland, grassland, and semi-shrubby desert; (2) irrigation water use was dominant and increased (with fluctuations) at an average rate of 8.2 %, while basic human water consumption increased monotonically over a longer period from 1981 to 2011 at a rate of 58 %; and (3) cropland expansion or continuous cultivation led to a significant reduction of SOC, while the land use transition from grassland to semishrubby desert and the progressive succession of natural ecosystems such as semi-shrubby desert and grassland, in contrast, can bring about significant carbon sequestration benefits. The increased water consumption and decreased SOC pool associated with some observed land use changes may induce and aggravate potential ecological risks for both local and downstream ecosystems, including water resource shortages, soil quality declines, and degeneration of natural vegetation. Therefore, it is necessary to balance socioeconomic wellbeing and ecosystem services in land use planning and management for the sustainability of socio-ecological systems across spatiotemporal scales, especially in resource-poor arid environments.

Relationship between soil water content and soil particle size on typical slopes of the Loess Plateau during a drought year

“…Precipitation is the only source of soil water that can be used by plants in this area (Jiao et al, 2006;Ning et al, 2013;Yan et al, 2015;Yu et al, 2015b). Due to the close relationship between plant growth and soil water content (Wang et al 2012), studies of soil water under typical vegetation types in this region have changed from focusing on water content to water movement and hydraulic characteristics (Lü et al, 2014a;Shao et al, 2006). Soil available water is the water that can be directly used by plants and is therefore a more useful indicator than volumetric water content, particularly in the context of vegetation growth (Fang et al, 2016;Gao et al, 2015;Wang et al, 2013).…”

Multi-scale variability of soil carbon and nitrogen in the middle reaches of the Heihe River basin, northwestern China

“…Mean annual air temperature is approximately 7.6°C, with the lowest and highest air temperature of −27°C in January and 39°C in August, respectively. Mean annual precipitation is approximately 120 mm in Ganzhou and Linze (Lü et al, 2014) and 79 mm in Gaotai (Li et al, 2009). Precipitation is erratic and shows strong seasonal variation, with approximately 60% occurring from July to September and only 3% falling during winter (from December to February).…”

“…Irrigation is applied 7 times, summing up to 9660 m 3 ha −1 in Linze and Ganzhou (Lü et al, 2014). In Gaotai, maize is irrigated 4-5 times, totaling 11,250 m 3 ha −1 throughout the growing season (Li et al, 2009).…”

“…Lü et al (2014) indicated that cropland expansion or continuous cultivation significantly reduced SOC content, whereas progressive succession of the natural ecosystem led to SOC sequestration from 1986 to 2007. The above studies have provided insight into the variability of soil C and TN in the middle reaches of the Heihe River basin.…”

Effect of Land Use Change on Soil Carbon Storage over the Last 40 Years in the Shi Yang River Basin, China

“…In China, the impact of land use change on carbon cycling brought on by land management policies has become increasingly apparent in recent years [17][18][19]. For example, Lü et al [20] investigated soil carbon storage and water consumption in an oasis-desert ecotone facing land use change. Zhao et al [21] researched the impact of shifts in land use on SC in an agro-pastoral ecotone of Inner Mongolia.…”