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Due to the coupled or interconnected relationships among frequent climate extremes, unique geological conditions, discontinuous soil distribution, rugged geomorphology, and highly heterogeneous landscapes in different karst watersheds, few studies were conducted to decouple the relative magnitudes of the climate, lithology, soil, topography, and landscape on soil erosion in karst regions. The objective of this study was to quantify the relative importance of these influencing factors on runoff and sediment yield (SY) in 40 typical karst watersheds in southwest China. To address this issue, the Pearson correlation and random forest were first to select the dominant factors influencing runoff and SY. Subsequently, the partial least squares‐structural equation model (PLS‐SEM) was used to decouple the complex relationships among runoff, SY and their potential influencing factors. Results showed that climate, lithology, soil, topography and landscape could explain 79% of the runoff variation, and only climate factors have significant impact on runoff for heterogeneous karst watersheds (P < 0.01, path coefficient (β) = 0.589). The explanation of five factors to SY variability is 59%, and the landscape has the greatest impact on SY (P < 0.01, β = −0.458). Different from runoff, climatic factors have no significant influence on SY. By elucidating a complex coupled relationship framework, this study can provide a scientific basis for the formulation of soil and water loss program, and the optimization of land resources and ecological environment sustainable development in karst watersheds. Plain Language Summary: The variations of runoff and sediment yield (SY) among heterogeneous watersheds are expected to be influenced by climate, lithology, soil, topography and landscape, which are generally interconnected and coupled. Therefore, it is important to decouple the complex relationship between runoff, SY and their potential influencing factors, especially in karst areas where ecologically fragile regions experience severe soil erosion. The results show that only climate factors play a significant influence on runoff. Unlike runoff, all factors have significant effects on SY except climate factors. Interestingly, landscape factors have the greatest influence on SY. Our findings are conducive to better understanding the hydrological and sediment transport characteristics of karst watersheds, and provide scientific basis for soil erosion control and sustainable development of ecological environment. Key Points: We decoupled the effects of climate, lithology, soil, topography and landscape on runoff and sediment yield (SY)Climate and landscape exerted the largest influence on runoff and SY, respectivelyLithology, soil, topography, and landscape significantly affected SY rather than runoff variability [ABSTRACT FROM AUTHOR]

Earth's critical zone, which spans from the top of the vegetation canopy to bottom of the aquifer, provides a systematic framework for integrated studies of air, biota, soil, rocks, and water. However, the complex structure and interactive processes make many challenges to research this zone. Recently, the booming of hydrology, which interacts with other disciplines in the form of subdisciplines such as hydropedology, hydrogeology, and ecohydrology, has greatly promoted the development of critical zone research. Therefore, this study focuses on the role of water playing in the Earth's critical zone:water shapes the three-dimensional network of critical zone structure; water cycle coupled with biogeochemical process maintains the critical zone function and service; and the hydrology-extended model helps to simulate the critical zone evolution. Overall, this study proposes a conceptual framework that integrates the above three topics, and try to reveal the fundamental issues to be addressed for further advancing Earth's critical zone science. [ABSTRACT FROM AUTHOR]

Spatial distribution of soil moisture (SM) is a prerequisite for research and management of agriculture and ecology. However, it is still a challenge to retrieve SM data in highly heterogeneous landscapes. By investigating environmental factors (soil, vegetation and topography) and comparing different remote sensing sources (Landsat-8, Radarsat-2, ASTER Global Digital Elevation Model (DEM) V002 (ASTGTM2), unmanned aerial vehicle (UAV)) for karst mountainous catchments of southwest China, this study identified key controlling factors on the spatial distribution of SM and built a remote sensing model for SM estimation in highly heterogeneous landscapes. Results showed that vegetation type (35.7%), aspect (7.7%), height index (4.2%), soil bulk density (3.3%), soil total nitrogen (3.1%), aspect interact with vegetation type (3.4%) and soil total phosphorous (1.3%) totally explained 58.8% of the SM variability. The correlations between SM and topographic derivatives varied with DEM resolutions (1 - 50 m), and generally reached their highest values at 7 m for height index, slope gradient, and aspect, 16 m for flow accumulation and topographic wetness index, and 43 m for curvature. Partial least-squares regression analysis showed that optical and infrared bands from Landsat-8 and topographic derivatives from UAV photogrammetry DEM were more strongly correlated with SM than other datasets. An empirical model (SM = 9.27 * (10) ^ (-2) HI - 1.82 * (10) ^ (-5) B5 + 0.519) with only height index and B5 band from Landsat-8 as inputs is proposed, as it shows acceptable performance (R2 = 0.36; RMSE = 0.076). The results of this study provide useful information for SM remote sensing in karst mountainous area and similar heterogeneous landscapes. [ABSTRACT FROM AUTHOR]

Vegetation restoration was implemented to control soil erosion in the karst regions of southwest China. It is essential to assess the soil function and quality scientifically during this process and to adopt suitable management practices for this area. However, few studies have been conducted to comprehensively evaluate the effect of vegetation restoration on soil quality in this severely eroded karst area. By taking 302 soil samples from 11 vegetation types, this study investigated the influence of different types of vegetation restoration on soil quality using an integrated soil quality index (SQI) and a generalized linear model (GLM). Vegetation types had a significant effects on soil properties and thus on soil quality. SQI was developed by using TN, TP, TK, AP, and clay content; TN had highest weighting values (0.58), which indicated that it contributed the most to final SQI. The highest and lowest SQI values was observed for primary forest and cropland, respectively. Overall, vegetation restoration (e.g., natural restoration, artificial forests and artificial grassland) improved soil quality significantly. A GLM model explained 73.20% of the total variation in SQI, and vegetation type explained the largest proportion (46.39%) of the variation, which implies that the vegetation restoration practices can greatly enhance the soil quality in karst landscapes of southwest China. The results of this study may be used to improve implication of ecological restoration and management in degraded regions. [ABSTRACT FROM AUTHOR]

Karst landscape, covers more than 10% of the global land surface and plays an important role in supporting ecosystems and human society, may be strongly influenced by climate change. Vegetation available water (VAW) is a key variable impacting the sensitivity of ecosystems to a changing environment. However, VAW in karst region is difficult to determine and remains uncertain. This study improved a dynamic Budyko-type water balance model, by introducing a nonlinear equation linking climate, vegetation and Budyko-type water balance. This model was calibrated using evolutionary algorithm based on monthly runoff. Comparison results in the Pearl, Yangtze and 12 karst catchments in south China, suggested high effectiveness of this improved model in simulating monthly runoff and evapotranspiration. Furthermore, in the 12 karst catchments, the max VAW was negatively correlated to the portion of karst landscape of the catchment (POK, r=-0.63,α=0.027) and the elasticity of evapotranspiration to precipitation (r=-0.60,α=0.04). These implied that karst catchments with higher POK had lower VAW, making the ecosystems rely more on precipitation. [ABSTRACT FROM AUTHOR]

Background: Necroptosis is a programmed necrotic cell death, in which dying cells rupture and release intracellular components that trigger a proinflammatory response. The current study aimed at probing the circular RNA (circRNA)-mediated regulatory mechanisms in necroptosis in premature ovarian failure (POF)., Methods: CircRNA sequencing analysis was conducted in ovarian tissues of control and POF rats and transcriptome microarrays were acquired from the GSE33423 dataset. Differential expression analysis of circRNAs and mRNAs was executed between the POF and control data. Both a necroptosis-based circRNA-microRNA (miRNA)-mRNA network and a protein-protein interaction (PPI) network were established. Then, the functional annotation and immunological traits were analyzed., Results: Totally, 1266 upregulated and 1283 downregulated circRNAs as well as 1101 upregulated and 1168 downregulated mRNAs were determined in the POF rats versus the controls. The differentially expressed mRNAs predominantly correlated with necroptosis. The circRNA-miRNA-mRNA networks of downregulated necroptosis genes (comprising rno&#95;circRNA&#95;004995-rno-miR-148b-5p-H2afy2, rno&#95;circRNA&#95;016998-rno-miR-29a-5p-Hmgb1, and rno&#95;circRNA&#95;017593-rno-miR-29a-5p-Hmgb1) and upregulated necroptosis genes (comprising rno&#95;circRNA&#95;015900-rno-miR-935-Stat1, rno&#95;circRNA&#95;007946-rno-miR-328a-3p-Stat5a, rno&#95;circRNA&#95;007947-rno-miR-328a-3p-Stat5a, rno&#95;circRNA&#95;005064-rno-miR-18a-5p-Stat1, rno&#95;circRNA&#95;005064-rno-miR-18a-5p-Stat5a, rno&#95;circRNA&#95;005115-rno-miR-22-3p-Stat1, rno&#95;circRNA&#95;009028-rno-miR-342-5p-Stat1, rno&#95;circRNA&#95;011240-rno-miR-1224-Stat5a, rno&#95;circRNA&#95;016078-rno-miR-711-Stat5a) were built. POF-specific necroptosis genes ( STAT1, STAT5A, PLA2G4A, HMG1L1, HMGB1, AGER, EGFR, HDAC7, IFNA1, IL10RB, IL27RA, PYGL, SOCS1, TRADD, CXCL10, DDX5, EZH2, FADS2, FER, H2AFY2, HIST1H2AF, IFI44L, IL27, IRGM, MX1, NFKB2, PAFAH2, PEMT, PGM2L1, PGR , PHKA2 , and PLB1 ) were selected since they displayed notable associations with most immune cells, immune checkpoints, chemokines, human leukocyte antigen (HLA) molecules, and immune receptors., Conclusions: Altogether, we proposed the presence of widespread regulatory mechanisms of circRNAs in necroptosis and demonstrated that altered circRNA biogenesis might contribute to POF by affecting necroptosis., Competing Interests: The authors declare no conflict of interest., (© 2023 The Author(s). Published by IMR Press.)