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The topographies of soil erosion and deposition are critical factors that significantly influence soil quality, subsequently impacting the erodibility of soils in karst regions. However, the investigation into the effects of erosion and deposition topographies on soil erodibility across different stages of vegetation succession in karst trough valleys is still at a preliminary stage. Therefore, three distinct topographic features (dip slopes, anti-dip slopes, and valley depressions) were selected at erosion (dip/anti-dip slope) and deposition sites (valley) to investigate the spatial heterogeneity of soil physicochemical properties, infiltration capacity, aggregate stability, and erodibility in karst trough valleys. Additionally, five different stages of vegetation succession in karst forests were considered: Abandoned land stage (ALS), Herb stage (HS), Herb-Shrub stage (HES), Shrub stage (SHS), and Forest stage (FS). Additionally, the relationships among these factors were analyzed to identify the key driving factors influencing soil erodibility. The results revealed that soil physicochemical properties and soil aggregate stability at the deposition site were significantly superior to those at the erosion site. The FS resulted in the best soil physicochemical properties, whereas the HS resulted in the highest soil aggregate stability within the deposition site. However, the soil infiltration capacity at the erosion site was significantly greater than that at the deposition sites. The ALS had the strongest soil infiltration capacity at both the erosion and deposition sites. The soil erodibility at erosion sites (0.064) was significantly greater than that at deposition sites (0.051), with the highest soil erodibility observed on anti-dip slopes during the HES at erosion sites (0.142). The structural equation model reveals that erosion and deposition topographies, vegetation succession, soil physicochemical properties, soil aggregates, and soil infiltration characteristics collectively account for 88% of the variation in soil erodibility under different conditions. Specifically, both direct and indirect influences on soil erodibility are most significantly exerted by soil aggregate stability and vegetation succession. This study provides scientific evidence to support the management of soil erosion and ecological restoration in karst trough valleys while offering technical assistance for regional ecological improvement and poverty alleviation. [ABSTRACT FROM AUTHOR]

Shallow karst fissures are the main hydrological paths, underground loss channels, and one of the most critical root habitats in fragile karst rocky desertification areas. Revegetation may alter the type of vegetation cover in fissures, resulting in changes to soil properties and erosion reduction. In this study, we evaluate the influence of revegetation on the soil erosion reduction of fissure‐soil–plant systems (FSPS) for three vegetation types (herbs, shrubs, and trees) in FSPS and use bare FSPS without vegetation as a control in a karst rocky desertification area. The results show that the soil physicochemical properties of FSFS degraded first and then improved after abandonment, resulting in the order of soil erosion reduction of FSPS with vegetation succession being: shrub < herb < bare < tree. Vegetation restoration can significantly improve the soil erosion resistance of the 10–20 cm soil layer in the fissure zone, making it stronger than that in the non‐fissure zone, thus reducing the risk of underground leakage on the slope. The results obtained in this study deepen our knowledge of the impact of vegetation restoration type on soil erosion reduction and has significant implications for guiding vegetation restoration and preventing underground leakage in karst areas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Long-term localization monitoring experiment under natural rainfall. • Outcrop bedrock pattern effect the characteristics of solute migration. • Soil-rock interface is the main pathway for transporting source into the groundwater system. The severe non-point pollution threatens to karst aquifers, which supply freshwater resources for approximately 25 % of the global population. The unique natural landscape of diverse rock outcroppings on karst slopes significantly influences hydrological processes and alters the solute transport characteristics. However, there is still insufficient understanding of the impact of bedrock outcroppings on solute transport. This study aimed to investigate the spatial patterns of dissolved nitrogen and phosphorus transport in karst slopes, considering the effects of bedrock morphology, bedrock patterns, and rainfall type. The findings indicated that sub-surface runoff production was associated with higher concentrations of dissolved total nitrogen (TN) (7.72 mg·L-1–30.88 mg·L-1) and that the soil–bedrock interface became the primary pathway for TN migration, particularly during moderate rainfall (10–25 mm·d-1), achieving efficiencies of 51.54 % to 91.92 % depending on bedrock distribution patterns. Conversely, surface runoff had 1.05–2.61 times more dissolved phosphorus (TP) concentration than sub-surface runoff, soil-rock runoff, and underground pore fissure runoff, with surface pathway losses being the main TP loss channel. The TN and TP positively correlation with rainfall, with correlation coefficients exceeding 0.85 across different bedrock pattern treatments. Power function analysis revealed exponents of 3.58 and 3.34 for TN and TP loss fluxes, indicating higher vulnerability of dissolved TN to runoff losses. Moreover, surface dissolved TN and TP losses were greater in the bedrock morphologies 1:2 aspect ratio than 1:1 aspect ratio and were aggregated distribution > uniform distribution > centered distribution in various bedrock distribution patterns. The findings suggest that minimizing the scattered distribution of bedrock on karst slopes has potential for decreasing influxes of dissolved substances into underground aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Surface soil water shortages are among the primary factors limiting revegetation in most degraded regions with shallow soil, especially in karst areas. Finding water sources for plants is an urgent task to ensure maximum vegetation restoration in these areas. We combined soil water content monitoring and isotope tracing to reveal the principal water source supply systems for plants in karst areas. The results showed that the content and storage of water in the shallow fissure soil system (SFSS) of the epikarst zone were consistently higher and more temporally stable than that of the surface soil. Thus, epikarsts with dissolution voids and fissures are important, stable aquifers that provide water to plants. Moreover, the IsoSource results showed that the SFSS was the primary water source for three monitored tree species (Cupressus torulosa D. Don, Pyracantha fortuneana [Maxim.] Li and Rosa cymosa Tratt.), especially C. torulosa and P. fortuneana. The water‐uptake patterns of C. torulosa and P. fortuneana changed from dominant SFSS and surface soil water sources during the rainy period to the dominant SFSS and transfer zone (TZ) of vadose zone water sources during the dry period. In contrast, Rhynchospora cymosa uses water from SFSS and TZ water sources only during drought. These results suggest that the SFSS is key to eliminating vegetation restoration limitations due to surface drought in karst areas. It is proposed that deeply rooted plants with dimorphic root systems are optimal for sustainable vegetation restoration in karst areas. [ABSTRACT FROM AUTHOR]

• Extreme rainfall triggers rill erosion in karst slopes. • Flow shear force dominates the rill formation and development. • Rill density is the preferred indicator for characterizing soil erosion of surface. Driven by climate change and increased human activities, the frequency and intensity of extreme rainfall events are increasing, leading to increased risk of water erosion on slopes in karst rocky desertification (KRD) areas. However, the driving factors (rainfall intensity, slope gradient, and the degree of underground fissure pore), characteristics, and dynamic mechanisms of rill erosion on KRD slopes under extreme rainfall have received limited attention. A rainfall simulation experiment was performed to investigate the driving factors of rill erosion on KRD slopes under extreme rainfall events. The experiments were conducted using an erosion flume (4 m long, 1.5 m wide and 0.35 m deep) with five rainfall intensities (50, 105, 115, 125 and 145 mm·h−1), three-level slope gradients (5°, 15° and 25°), and three typical degrees of underground pore fissure (1 %, 3 % and 5 %). The results showed that extreme rainfall significantly stimulated the formation and development of rill erosion on KRD slopes. In particular, rainfall intensity and slope gradient significantly affected rill erosion (p < 0.05), whereas the degree of underground pore fissure did not have any distinct effect. Increasing rainfall intensity intensified rill erosion by significantly (p < 0.05) promoting the rill density, total rill surface area, and longest of rill length. With increasing slope gradient, the rill density, rill distribution density, and average rill depth significantly increased (p < 0.05). Moreover, extreme rainfall events exacerbated surface soil erosion by enhancing the hydrodynamic characteristics of slope runoff. Rill erosion was most sensitive to the shear stress of runoff, and rill density was found to be the most suitable rill index for describing surface soil erosion on the slope under extreme rainfall. The findings provide valuable insights into the characteristics and mechanisms of soil erosion in karst regions under future climate warming. [ABSTRACT FROM AUTHOR]

Plantations play a vital role in the global nutrient cycle because they have large stocks of soil macronutrients. However, the impacts of plantations on soil macronutrient stocks combined with stand age and soil physicochemical properties have not been well quantified. We compared soil macronutrient stocks at soil depths of 0−20 and 20−40 cm across a 7-, 14-, 25-, and 30-year chronosequence of Masson pine (Pinus massoniana Lamb.) plantations. The results showed that the nitrogen (N), phosphorus (P), and potassium (K) stocks first increased and then decreased with stand age. The highest N and P stocks were observed in the 14-year-old plantation, and the 25-year-old plantation displayed the highest K stock. The C, N, and P stocks declined with increasing soil depth across all sites, whereas the reverse trend was found in the K stock. Carbon stocks were highest for all plantations, followed by the K, N, and P stocks. Plantation soils exhibited a higher C:P ratio and a lower P:K ratio at various soil depths. The dominant controlling factors for the soil macronutrient stocks varied significantly at different stand ages and soil depths according to statistical analysis. For the total soil system, the C stock was affected by the available nutrients, organic matter, and stoichiometry; the available nutrients and organic matter were the determinant factors of the N and P stocks. Aggregate stability could be the primary parameter affecting the K stock. Organic matter explained most of the variation in soil macronutrient stocks, followed by the P:K ratio and available K. Collectively, our results suggest that the response of soil macronutrient stocks to stand age and soil depth will be dependent on different soil physicochemical properties, and P and K may be important limiting factors in Masson pine plantation ecosystems. [ABSTRACT FROM AUTHOR]