Zhengan Su

The cover image is based on the article Spatial Characteristics of Cultivated Land Quality, Driving Forces and Enhancement Policies on the Tibetan Plateau: A Case Study of Qushui County, Tibet, China by Tao Zhou et al., https://doi.org/10.1002/ldr.70016. image

Cultivated land quality (CLQ) is the inherent capacity of cultivated land to function in productive activities and depends on soil properties, management practices, and landscape patterns. The aim of this study was to evaluate the current status of CLQ and landscape patterns in Qushui County and assess the influence of landscape patterns on CLQ. Consequently, complementary policies are recommended to improve CLQ on the Tibetan Plateau. The results indicated that the soil in Qushui County was classified as sandy loam, with a bulk density, effective soil thickness, pH, cation exchangeable capacity, organic matter, total nitrogen, available phosphorus, and available potassium of 1.41 g cm⁻³, 63.03 cm, 7.58, 8.82 cmol kg⁻¹, 18.27 g kg⁻¹, 1.14 g kg⁻¹, 15.82 mg kg,⁻¹ and 85.53 mg kg⁻¹, respectively. Elevation and soil type were key factors influencing CLQ. Consequently, the optimum quality of cultivated land was observed at low elevations, with fluvo‐aquic soils and cold brown calcic soils. These effects were driven mainly by human activities, including irrigation, drainage measures, and protected forests on farmland. Landscape patterns, which are products of human activity, constitute another important factor affecting CLQ. The results confirmed that CLQ had significant positive spatial relationships with the largest patch index (LPI), mean patch area (AREA_MN) and aggregation index (AI), whereas it had significant negative spatial relationships with the mean shape index (SHAPE_MN) and fractal dimension index (FRAC_MN) (p ≤ 0.01). Additionally, the influences of the area–edge, shape, and aggregation indices on the CLQ were either independent or interactive, with interactions being dominant. These results confirm that CLQ depends on its area and regular shape. The government should guide farmers to optimize cultivated landscapes through systematic management, leading to an improvement in CLQ.

Cultivated land quality (CLQ) is the inherent capacity of cultivated land to function in productive activities and depends on soil properties, management practices and landscape patterns. The aim of this study was to evaluate the current status of CLQ and landscape patterns in the Qushui County and assess the influence of landscape patterns on CLQ. Consequently, complementary policies are recommended to improve CLQ on the Tibetan Plateau. The results indicated that the soil in Qushui County was classified as sandy loam, with a bulk density, effective soil thickness, pH, cation exchangeable capacity, organic matter, total nitrogen, available phosphorus and available potassium of 1.41 g cm ^-3 , 63.03 cm, 7.58, 8.82 cmol kg ^-1 , 18.27 g kg ^-1 , 1.14 g kg ^-1 , 15.82 mg kg ^-1 and 85.53 mg kg ^-1 , respectively. Elevation and soil type were key factors influencing CLQ. Consequently, the optimum quality of cultivated land was observed at low elevations, with fluvo-aquic soils and cold brown calcic soils. These effects were driven mainly by human activities, including irrigation, drainage measures and protected forests on farmland. Landscape patterns, which are products of human activity, constitute another important factor affecting CLQ. The results confirmed that CLQ had significant positive spatial relationships with the largest patch index (LPI), mean patch area (AREA_MN) and aggregation index (AI), whereas it had significant negative spatial relationships with the mean shape index (SHAPE_MN) and fractal dimension index (FRAC_MN) (P≤0.01). Additionally, the influences of the area–edge, shape and aggregation indices on the CLQ were either independent or interactive, with interactions being dominant. These results confirm that CLQ depends on its area and regular shape. The government should guide farmers to optimize cultivated landscapes through systematic management, leading to an improvement in CLQ.

The ecological restoration of mine dumps is challenging because of the loose soil structure, toxic heavy metal, and severe soil erosion at such sites. The impacts of native grass and polyacrylamide (PAM) on the soil sediment concentration, hydraulic properties, and heavy metals at mine dumps were investigated via scouring tests with a flow discharge of 90 L min⁻¹. In the initial stages of the tests, fluctuating decreasing trends in the soil sediment concentration, flow velocity, and flow Ni concentration were observed, while a fluctuating increasing trend was observed in the flow resistance f. After a period of adjustment, the steady‐state soil sediment concentrations, hydraulic properties, and Ni concentrations in the flow were attained. An increasing–decreasing trend for the V concentration and a decreasing–increasing trend for the Cu concentration in the flow were observed over time. In addition, Zn was not dissolved or transported by the overland flow. A significant correlation between the heavy metal concentration in the flow and soil sediment concentration was observed (p ≤ 0.01). Both native grass and PAM could effectively control soil loss and change hydraulic properties by increasing the surface roughness. The steady‐state flow velocity of B5 was 1.11–1.36 times higher than in the other treatments, while the steady‐state resistance f of B5 was 12.54–45.02% lower than in the other treatments. However, the native grass and PAM had different effects on the transport of heavy metals. The native grass could effectively reduce the mobility of V, while the PAM could reduce the mobility of Cu and V.

Loess‐roads (LR) still experience severe soil erosion due to concentrated flow during rainstorms in watersheds on the Chinese Loess Plateau, where soil erosion in sloping farmland, abandoned land, and grassland has been controlled. However, road erosion is commonly overlooked because unpaved roads represent a small part of the catchment area. In situ scouring‐erosion experiments were performed on LR surfaces in the Liuaogou watershed on the Loess Plateau. The erosion rate of the LR was 14.1–234.6 g m⁻² min⁻¹, which is 10.8–57.5‐times higher than that on an adjacent grassy hillslope. In most experiments, the LR erosion rate generally increased linearly with increasing concentrated flow and slope gradient (R² > .85; significance p < .05). Concentrated flow had a greater impact on road erosion than the road surface slope. Rill erosion occurred in our road plots, with rill area densities of 0.03–0.38 m² m⁻². The total amount of road erosion was significantly correlated linearly with the rill area density (R² = .61, p < .01), indicating that high rill density led to high total erosion on the LR. A road erosion equation based on concentrated flow and slope gradient was established and validated. The R², p, and NSE results were .91, <.01 and 0.93, respectively, implying that the fitted equation can be considered acceptable. Our findings can provide references for the prevention of road erosion and the establishment of road erosion models.