Spatial pattern and temporal trend of land degradation in the Heihe River Basin of China using local net primary production scaling

Abstract

Biophysical processes and people's livelihoods largely depend on ecosystem productivity; thus, land degradation is harmful for local sustainable development. Most previous assessments of land degradation used a comprehensive index system or trend analysis without localized benchmarks; thus, they were not fully objective. Here, we assessed the land degradation in the Heihe River Basin (HRB), China using the local net primary production (NPP) scaling (LNS) method. We improved the method by dividing land capability classes (LCC) using remote sensing data, and determining the reference NPP for each LCC to represent the productivity under optimal environmental conditions. To assess the extent, severity and trend of land degradation, we obtained LNS percent values which was defined as the ratio of present NPP to reference NPP. We categorized our identified land degradation hotspots, determined their causes and proposed potential strategies for land conservation. Our results showed that nearly one quarter of the area was degraded land, mainly located in the upper stream. The average NPP was 35.75% lower than the reference NPP, with a reduction amount of 0.82 GgC yr −1 . Only the lower stream showed a significant decreasing trend in LNS percent values. The areas with a positive trend in LNS percent values were primarily observed in the middle stream croplands. We found the degradation condition deteriorated first and recovered later in the HRB. Land use change contributed more than climate change to the local NPP of the degraded areas. Our research provides a more general framework for assessing land productivity reduction induced by anthropogenic and natural processes in the drylands. K E Y W O R D Sdrylands, land capability classes, land degradation, local net primary production scaling, NPP, the Heihe River Basin

Is land degradation worsening in Northern China? Quantitative evidence and enlightenment from satellites

“…(2) Extract NPP Land degradation describes a temporary or permanent decline in land productivity (Li, Meng, et al, 2020). Vegetation productivity can act as an index reflecting land degradation or rehabilitation (Kang et al, 2020).…”

“…Previous studies assessed land degradation using remote-sensing indices of vegetation, such as FVC (Han et al, 2021), NDVI (Li, Yang, & Zhang, 2021), NPP (Li, Meng, et al, 2020) and NDVI+NPP (Kang et al, 2021). Land degradation is a comprehensive degradation process caused by various factors (Pr av alie et al, 2021).…”

Impact of deeper groundwater depth on vegetation and soil in semi-arid region of eastern China

“…Numerous studies of the effects of soil properties on plant growth have demonstrated that revegetation is threatened by the spatial heterogeneity of soil salinization, indicating that soil conditions have a significant impact on plant growth ( Hao et al., 2010 ; Huang et al., 2019 ; Han et al., 2020 ; Wang et al., 2021a ). The distribution variability of soil properties is likely to be a critical driving force in forming vegetation distribution patterns and adaptation strategies ( Li et al., 2020 ; Zhang et al., 2020b ; Wang et al., 2021b ). Recent research found that soil nitrogen, soil phosphorus, and soil potassium concentrations in arid regions decreased significantly with increased groundwater depth, aggravating erosion ( Zhang et al., 2018 ; Huang et al., 2019 ; Wang et al., 2021b ).…”

Response of Land Use and Net Primary Productivity to Coal Mining: A Case Study of Huainan City and Its Mining Areas

“…Land-use and land-cover change (LUCC) is the most direct manifestation of the interaction between coal mining and the natural environment [14]. The ecosystem's type, structure, and function will change with the LUCC, affecting the mining area's carbon-sequestration capacity [15,16]. Therefore, the study of how the temporal and spatial responses of land-use structures and NPP are driven by coal mining helps to reveal the processes of coal mining that affect the ecosystem, and is of great significance to balancing the relationship between resource mining and the environment.…”