Objective This study aims to systematically review the history of soil erosion mapping at the national and global scales prior to the widespread application of remote sensing and GIS， clarify its scientific achievements and historical contributions， explore its practical implications for contemporary digital soil erosion mapping， and promote further advancement in this field. Methods Classic maps and related literature from the mid-1920s to the late 1990s， both in China and worldwide， were systematically collected and analyzed. By examining the historical development trajectory and technical methods employed， this study assesses their scientific achievements and historical value， providing key insights for modern digital soil erosion mapping. Results Soil erosion mapping at national， major geographical unit， and global scales was systematically conducted during this period. Representative outputs include soil erosion maps of the United States， the former Soviet Union， and China， soil erosion maps of severely eroded regions such as the Loess Plateau， and the global soil erosion map. These maps were primarily compiled based on the degree of damage observed in soil profiles or used river sediment transport rate as a proxy indicator to evaluate erosion intensity， and spatial representation of soil erosion was achieved through manual cartographic methods. Conclusions The nearly 80 years of regional soil erosion mapping worldwide have achieved systematic foundational outcomes. Theoretically， it established soil erosion classification systems and an ontological framework， provided historical baseline data， and formed classic paradigms. Practically， it promoted soil and water conservation legislation and the establishment of soil conservation institutions in multiple countries， laying the foundation for global monitoring networks. Its scientific concepts and legacy data provide four insights for contemporary digital mapping， including focusing on erosion-specific themes， integrating classical cartographic theories， deeply utilizing historical data， and constructing a new paradigm of soil erosion mapping in the digital era.

Objective This study explores the spatiotemporal dynamics of vegetation net ecosystem productivity （NEP） and identifies its key driving factors in typical karst regions， providing a theoretical basis for the scientific understanding of carbon cycling mechanisms and the formulation of differentiated carbon neutrality strategies. Methods Vegetation NEP in Guizhou Province from 2000 to 2020 was quantitatively assessed based on an improved Carnegie-Ames-Stanford Approach （CASA） model and an empirical equation for soil microbial respiration. Theil-Sen Median trend analysis， Mann-Kendall significance test， Hurst index， and optimal parameters-based geographical detector were applied to systematically analyze the spatiotemporal variation trends， characteristics， and key driving factors of vegetation NEP in Guizhou. Results 1） During the study period， NEP across Guizhou increased significantly， indicating a continuous enhancement of carbon sequestration capacity. Spatially， NEP decreased from the south-central and southwestern regions to the northern and eastern regions. Vegetation NEP in karst regions ［278.20 g/（m²·a）（based on C）］ was significantly lower than that in non-karst regions ［326.83 g/（m²·a）（based on C）］， suggesting that differences in geological background were the core reason for divergence in carbon sequestration potential. 2） Across the province， changes in NEP mainly remained stable （50.31%） or showed an increasing trend （46.98%）. Increasing trends were concentrated in the western and northeastern regions， while decreasing trends were distributed in the central and eastern regions. Mean Hurst index was 0.48， and areas with Hurst index below 0.5 accounted for 61.59%. 3） Lithology （q=0.41）， as the core natural background factor， directly determined basic habitat conditions such as soil development， water retention， and nutrient conservation， while sunshine duration （q=0.35） was the key meteorological factor. Together， they established the inherent carbon sequestration potential of the region. The interactive effects of multiple factors were stronger than those of single factors. Notably， the interaction between sunshine duration and land use had explanatory power of 50%， representing the key driving factor regulating spatiotemporal patterns of carbon sequestration. Conclusion These findings provide scientific data support and decision-making reference for ecological conservation and restoration， carbon sequestration function enhancement， and sustainable development in ecologically fragile karst regions.

Objective This study aims to investigate the effects of different vegetation restoration models on runoff and sediment reduction in dry-hot valleys and to analyze their underlying mechanisms， thereby providing a scientific basis for functional vegetation restoration for soil and water conservation in these areas. Methods Taking the Yuanmou dry-hot valley in Yunnan Province as the study area， an in-situ monitoring experiment was conducted from 2019 to 2022. Bare land was used as the control， and vegetation restoration models including cultivated land， shrub-grassland， tree-shrub-grassland， naturally restored land 1 and naturally restored land 2 were established. The runoff and sediment reduction benefits under different vegetation restoration models were compared， and the influence mechanisms of rainfall， soil， and vegetation factors on soil loss and runoff under different models were explored. Results Compared with bare land， runoff decreased by 64.25%， 89.08%， 91.81%， 87.20% and 84.79%， and soil loss decreased by 92.16%， 99.45%， 99.92%， 99.37% and 97.26% in cultivated land， shrub-grassland， tree-shrub-grassland， naturally restored land 1， and naturally restored land 2， respectively. The effectiveness of runoff and sediment reduction followed the order： tree-shrub-grassland > shrub-grassland > naturally restored land 1 > naturally restored land 2 > cultivated land > bare land. Rainfall erosivity was the major driving factor of runoff， with a total effect ranging from 21.90% to 70.73%， while runoff was the primary driving factor of soil loss， with a total effect ranging from 26.94% to 97.81%. In bare land and intensively disturbed cultivated land， the water and sediment processes were mainly dominated by rainfall factors （rainfall erosivity）. In contrast， under restoration models such as shrub-grassland and tree-shrub-grassland， the system shifted to being dominated by "surface hydrological processes"， where vegetation and soil factors fundamentally reduced the occurrence of runoff and soil loss by curbing runoff volume. Conclusion The tree-shrub-grass model combining Bombax ceiba， Bauhinia purpurea， Heteropogon contortus， and Bothriochloa pertusa was the most effective in reducing runoff and sediment. This model achieves significant soil and water conservation benefits by jointly regulating soil and vegetation factors to suppress the generation of runoff and soil loss.

Objective This study aims to investigate the regulatory effects of electric field treatment （ET） on soil microecology in rocky desertification areas under different climatic conditions. Methods Using severely rocky desertified soil as the research subject， a laboratory simulation of the rocky desertification soil habitat along with drought and rainfall processes was conducted. The effects of a continuously operating 20 V electric field treatment on soil physicochemical properties and the structure and functions of bacterial communities were investigated. Results Compared with the control （CK）， the electric field treatment significantly increased the contents of soil organic carbon， alkaline hydrolyzable nitrogen， and available potassium during both the dry and rainy seasons， and inhibited the loss of available phosphorus during the dry season. However， the electric field treatment significantly decreased soil water content and pH. Under the electric field treatment， the richness and diversity indices of the soil bacterial communities were significantly reduced in both the dry and rainy seasons. The community structure composition at the genus level differed significantly between the dry and rainy seasons， while the composition at the phylum level remained unchanged. During the dry season， the electric field significantly enriched Proteobacteria， Sphingomonas， Flavisolibacter， and Chthoniobacter. During the rainy season， it significantly enriched Actinobacte-riota， Cyanobacteria， Bradyrhizobium， Mesorhizobium， Dyella， Burkholderia-Caballeronia-Paraburkholderia， Catenulispora， Amycolatopsis， Mucilaginibacter， and Edaphobacter. During the rainy season， electric field treatment significantly increased the relative abundance of functions such as photosynthesis （chloroplast） and nitrogen fixation in the soil bacterial community. Redundancy analysis （RDA） indicated that soil alkaline hydrolyzable nitrogen， available phosphorus， and water content were the main environmental factors driving the evolution of the bacterial community. Conclusion Electric field treatment can optimize bacterial community structure and enhance its ecological functions by regulating key soil factors， thereby promoting nutrient cycling and system restoration in rocky desertified soil and providing a theoretical basis for ecological management in rocky desertification areas.

Objective This study aims to investigate the co-developmental relationship between the overlying soil and the underlying strongly weathered bedrock layer， thereby providing fundamental data for the quantitative prediction of subsurface rock-soil structures in karst areas. Methods In the Mulian small watershed of Huanjiang， Guangxi， intelligent photogrammetry technology was employed， using a 3 m high standard leveling staff as a reference， to investigate 68 rock-soil profiles， each 5 m in width， across four different geomorphic positions： upper slope， middle slope， lower slope， and depression （17 profiles per position）. Through image characterization in AutoCAD and vectorization processing using ArcGIS-Fragstats， structural indicators of the rock-soil profiles were obtained and compared， including equivalent thickness （T）， number of patches （NP）， shape index （SHAPE）， perimeter-to-thickness ratio （PTR）， fractal dimension （FRAC）， and coefficient of variation of thickness （CV）. Results 1） The equivalent thickness of the soil layer and the strongly weathered bedrock layer increased non-uniformly from the upper slope to the depression. The soil thickness on the upper slope was less than 25 cm， while the thickness of the strongly weathered bedrock layer in the depression ranged from 110 cm to 250 cm. 2） The number of patches （NP>4） and the shape index （SHAPE） on the middle slope were significantly higher than those at other slope positions， exhibiting fragmented and interlocked rock-soil mosaic characteristics. The number of trees and shrubs and the maximum root depth were significantly positively correlated with the thickness of the soil and the strongly weathered bedrock layer （r=0.86， r=0.65）， and increasing woody vegetation effectively reduced the spatial variability of soil thickness. 3） A linear model indicated that the thickness of the strongly weathered bedrock layer was approximately 69% of the soil layer thickness. The complex characteristics of the concealed subsurface structure could be effectively predicted through easily measurable surface indicators， such as soil thickness （T） and woody stem density （Sd）. Conclusion Quantitative research at the rock-soil profile scale reveals differences in structural characteristics among various geomorphic positions， providing a scientific basis for precise zonal management of geomorphic positions in karst ecological restoration.

Objective This study aims to achieve efficient utilization and value transformation of the space under photovoltaic panels in rocky desertification areas， and to reveal the effects of different "medicinal herb-liana" utilization models on improving soil nutrients and enzyme activities， thereby selecting a model that can efficiently utilize the space under panels while having socioeconomic value. Methods Based on a near-natural indoor simulation test site， composite utilization models of Polygonum multiflorum with various lianas were established. Drawing from soil data in both dry and rainy seasons， one-way ANOVA， nonlinear regression， and redundancy analysis were employed to systematically analyze the temporal variation trends of total soil nutrients and available nutrients under different utilization models， thereby further clarifying the correlation characteristics between soil physicochemical properties and enzyme activity. Results 1） The model of P. multiflorum with Lonicera japonica exhibited a stable nutrient accumulation effect； the model of P. multiflorum with Puerarialobata showed strong seasonal fluctuations， with a net depletion of nutrient content throughout the year； the model of P. multi-florum with Wisteria showed an initial increase followed by a decrease in nutrients. In comparison， the control group exhibited continuous nutrient depletion. 2） The seasonal dynamics of available nutrients showed significant species specificity. The L. japonica model achieved accumulation of available phosphorus and potassium in both dry and rainy seasons. In addition， despite an explosive increase of 4.02 mg/kg in alkali-hydrolyzable nitrogen in the Wisteria model during the dry season， this increase was rapidly lost during the rainy season. 3） Organic carbon and available phosphorus served as key factors driving enzyme activity variation， with explanatory rates of 71.8% （dry season） and 83.5% （rainy season）， respectively. The L. japonica model alleviated carbon and phosphorus limitations through the accumulation of organic carbon， resulting in a steady increase in both soil nutrients and enzyme activity， whereas the Wisteria model presented a state of high enzyme activity but low nutrient content. Conclusion The "medicinal herb-liana" composite utilization model plays an important role in enhancing the stability of the soil biochemical system and nutrient cycling efficiency in the area under photovoltaic panels. The composite utilization model of P. multiflorum with L. japonica exhibits the best adaptation potential and ecological benefits. The research results can provide a theoretical basis and practical guidance for under-panel economic deve-lopment and sustainable soil ecological management of photovoltaic power stations in rocky desertification areas.

Objective To elucidate the characteristics of soil nutrients， microbial communities， and microbial necromass carbon， and their contributions to soil organic carbon in moss-dominated biocrusts of karst rocky desertification areas， and to identify the key environmental factors and microbial mechanisms underlying the formation of microbial necromass carbon. Methods The study was conducted in rocky desertification areas in Zhanyi District， Qujing City， Yunnan Province. Soil samples were collected from the moss-dominated biocrust layer （0-1 cm） and the sub-layer （1-5 cm） at sites representing non-degraded， lightly degraded， moderately degraded， and severely degraded conditions. Soil nutrients， microbial community structure， microbial biomass， and microbial necromass carbon were subsequently analyzed. Results The results showed that， in moss-covered soils， soil organic carbon， total nitrogen， microbial biomass carbon， and microbial biomass nitrogen generally increased with increasing rocky desertification severity， reaching their highest values at the severely degraded stage. Vertically， soil organic carbon， total nitrogen， total phosphorus， microbial biomass carbon， microbial biomass nitrogen， and microbial biomass phosphorus were 19.13%， 29.61%， 10.45%， 97.47%， 97.08%， and 36.21% higher in the biocrust layer than those in the sub-layer， respectively. Bacterial necromass carbon， fungal necromass carbon， and microbial necromass carbon increased with increasing rocky desertification severity， and were generally higher in the biocrust layer than in the sub-layer. The contribution of fungal necromass carbon to soil organic carbon was higher than that of bacterial necromass carbon， and the correlation between fungal necromass carbon and soil organic carbon was stronger than that between bacterial necromass carbon and soil organic carbon. Bacterial communities were more sensitive to soil depth， whereas fungal communities were more responsive to the severity of rocky desertification. Random forest analysis showed that the fungal Shannon index was significantly negatively correlated with fungal necromass carbon in the biocrust layer， while the bacterial Shannon index was significantly positively correlated with bacterial necromass carbon in the sub-layer. Mantel analysis showed that microbial necromass carbon in both soil layers was significantly correlated with soil nutrients and microbial biomass. Microbial necromass carbon in the biocrust layer was mainly associated with bacterial life-history strategies， whereas microbial necromass carbon in the sub-layer was mainly related to fungal life-history strategies. Conclusion Moss biocrusts can significantly enhance soil nutrient availability and microbial activities in karst rocky desertification areas， thereby promoting the accumulation of microbial necromass carbon and its contribution to soil organic carbon， with fungal necromass playing a more prominent role in enhancing the stabilization of soil organic carbon. The formation of microbial necromass carbon is jointly regulated by soil nutrients， microbial activities， community composition， and life-history strategies， and differs between the biocrust layer and the sub-layer.

Objective This study aims to investigate the evolution patterns of soil organic carbon （SOC） in abandoned farmland of karst areas and identify the transition threshold of carbon pool from quantitative expansion to structural stabilization. Methods A typical abandoned farmland of karst areas in Guizhou was selected as the research subject. A space-for-time substitution method was adopted to analyze the differences in SOC content and its fractions， including easily oxidizable organic carbon （EOC）， particulate organic carbon （POC）， light fraction organic carbon （LFOC）， and heavy fraction organic carbon （HFOC）， in the 0~20 cm soil layer across farmland （CK） and succession sequences （5， 10， and 15 a of abandonment）. The carbon pool management index （CPMI） and the HFOC/SOC ratio were used to evaluate carbon pool stability. Results 1） After 15 a of abandonment， SOC content in the 0~10 cm soil layer increased by 70.1% compared with CK， with accumulation mainly occurring in the first 10 a. 2） EOC and POC showed an inverted "U"-shaped pattern with increasing abandonment years and peaked at 10 a， increasing by 91.5% and 107.1%， respectively， in the 0~10 cm soil layer compared with CK. HFOC showed a highly significant continuous linear increase （R²>0.9）， with its contribution remaining at 88%~90%. 3） The 10 a of abandonment was the threshold for carbon pool functional transition from an activity-driven quantity increase stage to a stability-driven quality stabilization stage， at which CPMI peaked and then declined， while the stability ratio increased. 4） Carbon pool remodeling showed a vertical differentiation pattern with earlier transformation in the surface layer and a lagged response in deeper layers. The 0~10 cm soil layer exhibited significantly higher sensitivity to succession and faster stability improvement than the 10~20 cm soil layer. The first axis of redundancy analysis （RDA） explained 57.27% of the variations， and abandonment years were the dominant factor driving changes in carbon fractions. Conclusion 10 a is the key turning point for carbon pool functional remodeling in karst areas， and vegetation restoration promotes the transition from active accumulation to chemical stabilization. This finding emphasizes the importance of focusing on carbon pool transformation in surface soils and enhancing carbon sequestration capacity by utilizing strong mineral protection in calcium-rich habitats.

Objective This study aims to explore the root morphological characteristics， mechanical properties， and their relationships in herbaceous plants at different growth stages. Methods Root samples of Setaria viridis （fibrous root system） and Medicago sativa （tap root system） grown on purple soil slope land for 60， 90， 120， and 150 days were collected for root morphology scanning， single-root tensile tests， and whole-plant pull-out tests. Results 1） As growth time increased， the tensile and pull-out strength of the aforementioned herbaceous plants increased initially and then decreased. At the same growth time， the tensile and pull-out strengths of the fibrous root system were 1.21-2.89 times and 5.34-6.01 times greater than those of the tap root system， respectively. 2） The tensile strength showed a power function relationship with root diameter， and the pull-out strength showed a power function relationship with the diameter at the pull-out position. As growth time increased， the absolute values of the exponents in the function equation of the tensile strength showed an increasing trend. For the pull-out strength， the fibrous root system showed an increasing trend， while the tap root system showed a decreasing trend. 3） Random forest analysis showed that with the increase of growth time， the main influencing factors of tensile and pull-out strength of the fibrous root system changed from multiple root morphological indicators to a single indicator （root diameter）， while the tap root system showed the opposite trend. Conclusion The research findings provide a theoretical basis for the efficient utilization and scientific evaluation of biological measures in soil and water loss control in purple soil regions.

Objective This study investigates the effects of drought stress on soil reinforcement performance of root systems in the water-level fluctuation zone of the Three Gorges Reservoir area， providing a theoretical basis for vegetation restoration， soil and water conservation， and ecological protection in this area. Methods Taking the root-soil composite of Cynodon dactylon as the research object， samples were collected from the field and subjected to adaptive maintenance. Drought conditions were simulated through controlled water supply in pot experiments. The experiment established treatments of different drought intensities （CK for control， moderate drought MD， and severe drought SD）， drought durations （0， 5， 10， 15， 30， and 60 days）， and root contents （0% for bare soil， 0.1%， 0.2%， and 0.3%）. Direct shear tests were conducted on the remolded samples to analyze the effects of drought intensity and drought duration on the shear resistance of the Cynodon dactylon root-soil composite. In addition， the microscopic mechanisms of the effects of drought stress on the soil reinforcement performance were revealed through microscopic tests of roots. Results 1） Samples under all conditions exhibited distinct strain-hardening failure characteristics， and drought stress and root incorporation had little effect on the variation patterns of stress-strain curves. 2） Short-term moderate drought improved the shear strength of the Cynodon dactylon root-soil composite， while long-term severe drought significantly reduced the shear strength （p<0.05）. Root incorporation significantly increased the soil shear strength， and the enhancement performance increased with the increase of root content. Compared with the bare soil treatment， the shear strength of the root-soil composite in CK， MD， and SD groups increased by 8.70%-51.52%， 4.35%-63.64%， and -13.04%-39.39%， respectively. 3） The response patterns of cohesion to drought stress and root incorporation were consistent with those of shear strength， while the internal friction angle remained relatively stable with slight fluctuations. Compared to bare soil treatments， the cohesion of the root-soil composite for CK， MD， and SD groups increased by 42.46%-63.99%， 15.08%-67.50%， and 15.08%-48.49%， respectively， while the internal friction angle increased by 1.55%-1.83%， -1.61%-1.68%， and -1.16%-1.43%， respectively. Conclusion Short-term moderate drought stress can improve the shear resistance of the Cynodon dactylon root-soil compositeto a certain extent， but excessive stress severely damages the root structure and reduces the shear strength of the root-soil composite.