As competition among cities increases, shrinkage is increasingly observed in contemporary urban development. However, the systematic, fine-scale ecological impact of shrinkage, particularly on vegetation dynamics, remain poorly characterized. This study identified shrinking and non-shrinking counties in China using nighttime-light data during 2001-2020, examined vegetation growth dynamics using net primary productivity (NPP) validated by normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) and leaf area index (LAI), and analyzed influencing mechanisms via XGBoost modelling and SHAP interpretation. We reported three findings: (1) 39.8% of 2891 counties shrank, most severely in Northeast China. (2) Most shrinking counties showed an amplified vegetation greening trend, with median NPP trend (3.43 g C m-2 yr-1) 11.7% higher than non-shrinking counties (3.07 g C m-2 yr-1). Shrinkage intensity exerted a hump-shaped relationship with NPP trend, peaking at moderate levels, indicating an optimal shrinkage intensity for greening. (3) Differentiated strategies are needed: moderately shrinking counties can amplify gains with passive rewilding; severely shrinking ones need enhanced fiscal transfers for erosion controls and afforestation; non-shrinking collided with an NPP ceiling at ∼20% land conversion, necessitating densification-resistant designs and strict urban-growth boundaries. These findings advance our understanding of social-ecological coupling mechanisms between shrinkage and vegetation dynamics, offer critical insights for developing context-differentiated ecological strategies and enhancing county-level development quality.

Although the global population continues to grow,the coming decades will witness the most rapid expansion of urban population in human history,primarily,driven by large-scale rural-to-urban migration.This migration alleviates human pressure significantly in rural areas,promotes the transformation of land use patterns and ecosystem restoration,and profoundly reshapes regional land spatial configurations.These changes directly or indirectly affect local ecological environments,thereby presenting both new opportunities and challenges for biodiversity.The southwestern region of China serves as a critical ecological security barrier for the country.It is not only a key area for global vegetation greening and plant diversity conservation,but also a typical region experiencing marked rural-urban migration and a pronounced decline in rural population.The ongoing and accelerating outflow of rural population in this region is profoundly reshaping local human-land relationships.Moreover,its distinctive karst landforms and ecological fragility make it highly sensitive to human disturbances.While large-scale rural population decline is reshaping the ecological environment,it also creates opportunities for ecosystem restoration.However,the response mechanisms of plant diversity to rural population decline and its threshold effects remain unclear,which hinders a deeper understanding of the coupling mechanisms in human-earth systems and constrains the scientific rigor and effectiveness of regional ecological conservation strategies. This study focuses on southwestern China as the research area.Based on vascular plant species richness data,the spatial pattern of plant diversity from 2000 to 2020 was reconstructed using a Random Forest model.The K-means algorithm was employed to identify urban-rural boundaries,revealing the spatiotemporal evolution characteristics of the rural population and examining the impact of rural population decline on plant diversity and its threshold effects.Using the human footprint index to characterize human pressure,the relationship between the release of human pressure induced by rural population decrease and the increase in biodiversity was analyzed.Through relative contribution rate decomposition,the driving contributions of climate change and human pressure were quantified.The study addresses the following key questions:(1)Spatiotemporal patterns of population decline in southwestern rural China;(2)Impacts of population decline on the spatial distribution of plant diversity and underlying mechanisms;(3)Threshold responses of plant diversity to changes in population density;(4)Relative contributions of climate change and human pressure to plant diversity changes. The results indicate that between 2000 and 2020,southwestern China experienced a rural population decrease of approximately 137 million,a 5.23％reduction in human pressure,and a significant 44.32％increase in plant diversity.Over 60％of the areas with rural population loss showed significant increases in plant diversity,with an average increase of approximately 0.73 species per 100 km2,across an area of 266,600 km2,Further analysis revealed a nonlinear relationship between rural population density and plant diversity:when population density fell below 336.68 persons·km-2,population decline exerted a suppressive effect on plant diversity;within the range of 336.68 to 956.73 persons·km-2,this suppressive effect gradually weakened;and when density exceeded 956.73 persons·km-2,population decline transitioned to a positive facilitative effect.Decomposition of driving factors showed that changes in rural human pressure contributed 38.64％to plant diversity changes,while climatic factors accounted for 61.36％,indicating that climate change remains the dominant factor influencing regional plant diversity. This study quantifies and reveals for the first time the nonlinear relationship and key thresholds between rural population decline and plant diversity in southwest China.It systematically elucidates the response mechanisms of plant diversity to population decline and human pressure,and clarifies the relative contributions of human activities and climate change.By analyzing the response patterns of plant diversity to rural population outmigration and identifying critical thresholds of population density effects,this research provides a scientific basis for understanding the mechanisms by which rural-urban migration influences biodiversity.The findings offer important insights for biodiversity conservation and regional sustainable development in southwest China.

Abstract Carbonate weathering carbon‐sink (CWCS) is a critical yet inaccurately quantified component of terrestrial carbon sequestration. However, the mechanisms through which climate change and vegetation dynamics drive the spatial heterogeneity of CWCS remain unclear. We integrated multi‐source data to identify altitude thresholds and nonlinear response characteristics of CWCS driven by climatic and vegetation globally. Our findings show that global carbonate weathering sequestered 127.60 ± 7.70 Tg C yr−1 from 1950 to 2014, equivalent to 3.65% of global forest carbon sink. We identified a dichotomous pattern in CWCS at an altitude threshold of 3,000 m: rates decreased below but increased significantly above this elevation. This altitude threshold marks a fundamental shift in climate sensitivity and driving mechanisms, meaning that warming inhibits carbonate weathering in warm lowlands, while high‐altitude cold regions accelerate carbonate weathering through enhanced glacial snowmelt (percent contribution: 20.71%–38.96%) and vegetation–carbon dioxide feedback (NDVI threshold: 0.33–0.67). By 2100, global CWCS is projected to increase by 14.51%–24.90% compared to historical period (1950–2014). High‐altitude cold regions are projected to emerge as pivotal growth areas for CWCS in the future (2015–2100), contributing 45.02%–59.50% of newly added CWCS, despite accounting for only 28.41% of carbonate areas. Our results demonstrate that climate warming has transformed cold high‐altitude regions into indispensable engines for enhancing terrestrial carbon sink.

Breeding red-fleshed apples with enhanced health benefits is a primary objective of modern apple improvement, yet high acidity and small fruit size limit their commercial potential. Resolving trade-offs among flesh color, flavor, and appearance and dissecting their underlying genetic relationships remain major challenges. In this study, using the red-fleshed 'CSR6R6' (Malus sieversii) and the cultivated 'Royal Gala' (M. domestica) as parents, we developed an F1 population comprising 140 individuals and performed integrative large-scale multi-omics analyses, identifying 13,331,096 SNPs and 2,134 metabolites. Red flesh correlated positively with malic acid but negatively with fruit weight. A major QTL linked to red flesh was mapped, and six genes regulating anthocyanin and proanthocyanidin biosynthesis were functionally validated, including MdUGT89A2.1, MdUGT89A2.2, MdALMT4, MdALMT4-like, MdTT1, and MdLAR1. Notably, MdALMT4 and MdALMT4-like encode malate transporters that coordinate malate accumulation and anthocyanin biosynthesis, suggesting a genetic link between acidity and pigmentation. Integrative multi-omics analysis revealed a large-scale regulatory network, revealing gene-metabolite-phenotype interactions and accurately predicting pathways involving the anthocyanin regulator MdTT1 and the fruit shape gene MdMADS13. Leveraging this network, we identified opposing effects of red-flesh QTL haplotypes across traits, defining the genetic basis of phenotypic antagonism, and resolved 11 positive and 13 negative haplotypes affecting red flesh, malic acid, and fruit weight. Pseudo-backcrossing further demonstrated that aggregating positive haplotypes substantially mitigates trade-offs among flesh color, flavor, and appearance, enabling their concurrent improvement. These findings will advance omics-assisted apple breeding, offering potential strategies for genetic improvement of other perennial fruit trees.

Global change is accelerating the chemical weathering of silicate rocks and the associated phosphorus release. However, the effects of phosphorus release on the global patterns of plant phosphorus limitation remain unclear. Here, we show that approximately 47% of the exposed areas in global silicate rocks are subject to phosphorus limitation of vegetation growth, as estimated using the ratio of leaf nitrogen to phosphorus resorption efficiency. Phosphorus-limited areas are projected to expand markedly with global warming, and the proportion may reach 54 - 59% according to two model scenarios (the shared socioeconomic pathways SSP2-4.5 and SSP5-8.5). Nevertheless, phosphorus release from accelerated chemical weathering of silicate rocks mitigates this limitation, with a relative contribution of approximately 15.5%. This work highlights the implications of accelerated chemical weathering of silicate rocks and its resulting phosphorus release for the global patterns of phosphorus limitation, providing a scientific foundation for phosphorus management strategies.

The magnitude and distribution of organic carbon (OC) transport from the terrestrial surface to the oceans is not well understood on a global scale. This hinders our understanding of terrestrial and marine carbon cycles. In this study, we determined the characteristics of OC flux. Our results showed that approximately 420 Tg C/yr of OC are transported from the terrestrial surface to the oceans, including 220 Tg C/yr of particulate organic carbon (POC) and 200 Tg C/yr of dissolved organic carbon (DOC). Asia, with only 32.46

Large-scale rural depopulation has altered the rural environment and reshaped the distribution pattern of species. However, the impact of rural depopulation on biodiversity is unclear. Based on plant species richness data, we used random forest model (RFM) and generalized additive model (GAM) to explore the impact of rural depopulation on plant diversity. The results showed that a 1.82 % decrease in human pressure in rural depopulation areas in China promoted vegetation restoration and increased plant diversity. Plant diversity in rural decreased by 2.25 % on average, while it increased by 3.75 % in rural areas that experienced depopulation. Plant diversity was 1.48 times greater in the severely depopulated rural areas than in the slightly depopulated areas. When the total population reaches around 1.33 billion, the plant diversity affected by population changes will reach a threshold. This research helps understand the potential positive impacts of rural depopulation on environmental restoration and plant diversity increase.

Identifying priority protected areas based on biodiversity and ecosystem services is crucial for ecological planning and sustainable development.Guizhou is an important ecological barrier in the upper reaches of the Yangtze River and the Pearl River,with a complex ecosystem and rich biodiversity.However,most studies delineated protected areas based on a single target of biodiversity or ecosystem services,often neglecting the combination of the two.Therefore,taking Guizhou Province as an example,this article determines priority protected areas based on dual objectives by combining biodiversity and three different ecosystem services.The results show that the priority protected areas for biodiversity are in the southwest of Guizhou Province,and the priority protected areas for ecosystem services are in the eastern region;The overlap of priority protected areas between the two is mainly concentrated in the central part of Tongren,Qiannan,and Qiandongnan,with a spatial overlap area of 10.88％;The priority protection area for biodiversity is relatively large(49.7％),while the protection area for ecosystem services is relatively small(19.5％).In the Qiandongnan,Qiannan,and Bijie regions,new protected areas can be built and existing protected areas can be expanded in the future.The establishment of protected areas should consider the combination of biodiversity and ecosystem services,and the results can provide reference for the development and utilization of natural resources,sustainable development,and the expansion of protected areas.

Emerging evidence suggests that female education levels play a role in ecological restoration by indirectly attenuating human stress through fertility and migration. However, this relationship is difficult to quantify and has not yet been investigated in China. Here, a comprehensive analytical framework for national multi-source data is constructed, multiple types of data are integrated to quantify the associations, and regression analyses and geodetector model are applied to explore the mechanisms influencing the changes in female education levels and ecological environments. The results showed that the population density in the areas with decreasing and increasing vegetation cover increased by an average of 31 and 1 person/km2, respectively, i.e., there is a high degree of overlap between the degraded vegetation areas and the areas with high population density distribution. The Average years of schooling for female increased from 6.34 years in 1996 to 9.47 years in 2021, with an average annual growth rate of 0.12/yr, which was 1.33 times and 1.2 times that of male and the national average, respectively, and it is expected that around 2035, the education level of female will be the same as that of male, or surpass male. The fertility rate declines by 0.37 for every year of female schooling; for every 1 % of schooling. These findings have initially elucidated the key role of female educational advancement in alleviating human-land conflicts, promoting ecological restoration and educational development, and providing effective references for relevant policies.

Since the Industrial Revolution, significant changes in global land-use patterns have occurred, which have disrupted terrestrial carbon emissions. However, the disturbance processes, change trends, and distribution patterns are not clear. Therefore, the changes in terrestrial carbon emissions (Eluc) caused by land-use change (LUC) since 1850 were analyzed in this study. The results showed that, owing to the sharp decrease in forestland (-13.39 %; 84.26 × 105 km2) and significant increases in built-up land (+1360.4 %; 7.21 × 105 km2), cropland (+175.8 %; 130.88 × 105 km2), and grassland (+162.6 %; 239.73 × 105 km2), the global Eluc increased from 0.42 Pg C in 1850 to 11.05 Pg C in 2018, with an average annual increase of approximately 3.42 Pg C yr-1, while the average annual carbon emissions after the 21st century reached 9.65 Pg C yr-1. Among them, direct Eluc increased by approximately 0.80 Pg C yr-1 and indirect Eluc increased by 2.62 Pg C yr-1. In addition, from 1850 to 2018, global Eluc was approximately 578.26 Pg C, with North America, Europe, and Asia being the largest regional sources. Our results highlight the changing trend and distribution pattern of global terrestrial carbon emissions under the influence of LUC since the Industrial Revolution and provide a scientific basis for regional and sectoral formulation of low-carbon emission-reduction policies and planning of low-carbon land-use patterns.

The karst geological carbon sink, formed through the chemical weathering of carbonate rocks, is an important part of the global terrestrial carbon sink. It has substantial potential and plays a crucial role in the global carbon cycle and regional carbon neutrality efforts. The fifth (AR5) and sixth (AR6) assessment reports of the Intergovernmental Panel on Climate Change (IPCC) have clearly affirmed the existence of geological carbon sinks associated with the chemical weathering of carbonate rocks, stating that carbon capture and geological storage are key mitigation schemes. However, numerous studies have shown that exogenous acids are widely involved during the chemical weathering of rocks, adding complexity to the carbon sequestration process and its driving mechanisms. This increases the uncertainty in assessing the carbon sequestration potential. Therefore, a key task is to accurately estimate the geological carbon sinks generated by the chemical weathering of carbonate rocks to resolve the problem of the global carbon sink loss, balancing the carbon budget, and achieving carbon neutrality. In this review, we examine assessments of the carbonate rocks chemical weathering carbon sink influenced by exogenous acids, focusing on the principles, frameworks and methodologies of carbon sink estimation. We also highlight recent advancements, key influencing factors, and underlying driving mechanisms. Looking ahead, we highlight key challenges in enhancing the accuracy and precision of carbonate rocks chemical weathering carbon sink assessments under the influence of exogenous acids. Addressing these issues will support more informed policy decisions on pathways to global carbon neutrality.

In the study of global change, one of the key issues is the global and regional carbon cycle, and estimating the carbon sink magnitude and determining the spatiotemporal pattern of carbon sources have attracted considerable attention from the academic community and are of great scientific significance. The Chinese karst region, which has considerable potential for carbon sequestration, is the principal area for carbon sequestration in China and even in the world. Changes in temperature and precipitation caused by global warming not only affect the hydrological processes in the karst region but also profoundly impact its carbon sink capacity. Nevertheless, no studies have as yet revealed the magnitude and spatial pattern of carbon sinks in the Chinese karst region, as well as the mechanism of the impact of climate change (CC) and human activities (HA) on the region. Therefore, to elucidate the spatial and temporal patterns of carbon sinks in Chinese karst ecosystems and reveal their responses to CC and HA, this paper employed data on climate, lithology, and ion concentration, in combination with a random forest model, a maximal potential dissolution model, and partial derivative analysis. According to the results: (1) during 2000-2020, the average annual flux of the ecosystem organic carbon sinks (NEP) and the total amount were 148.04 t C km(-2) a(-1) and 374.54 Tg C a(-1), respectively, while NEP showed a steady growth trend with an average annual growth rate of 2.35 t C km(-2) a(-1). (2) The average annual flux of carbonate rock weathering carbon sinks (CCSs) and the total amount were 5.32 t C km(-2) a(-1) and 13.45 Tg C a(-1), respectively, while the average annual growth rate of the CCSs was 0.04 t C km(-2) a(-1). (3) The average annual flux of the ecosystem carbon sink was123.49 t C km(-2) a(-1) and the total amount was 319.24 Tg C a(-1). (4) The carbon sink of the Chinese karst ecosystem exhibited an increasing trend, with an increase rate of 2.16 t C km(-2) a(-1), while precipitation (P), temperature (T) and solar radiation (SR) respectively contributed 15.91%, 13.12%, and 17.85% to changes in the ecosystem carbon sink. The contribution of CC to changes in the ecosystem carbon sink was 46.88%, and the contribution of HA was 53.12%. (5) In the karst region, the total increase in the area of the ecosystem carbon sink was 184.73x10(4) km(2), while the decrease in the area was68.27x10(4) km(2). Furthermore, areas of growth in the carbon sinks were considerably larger than areas of decline. As the main factor influencing changes in the ecosystem carbon sink, HA was largely concentrated in the southern karst area, with a principal area of 64.66x10(4) km(2). This study will facilitate the realization of China's "dual carbon" goal, thereby providing an important reference for diagnosing the country's global carbon neutrality capacity. By integrating long time series of multisource data and advanced modeling analysis, this study systematically quantified the dynamic changes in ecosystem carbon sinks in China's karst region with respect to scale, spatial distribution, and driving mechanism. Not only do these results provide a scientific basis for realizing China's "double carbon" goal, but they also serve as an important reference for the formulation and implementation of global carbon-neutral strategies. To provide more in-depth scientific support for global climate governance in the future, the quantitative assessment of the balance between regional carbon sinks and carbon emissions can be further strengthened to explore the long-term stability of the carbon sink function and the risk of extreme climate events.

The rhizosphere microbiome, as the second genome of plant immunity, forms a critical ecological barrier in plant-pathogen interactions. However, its functional mechanism in resisting the replanting disease pathogenic Fusarium proliferatum MR5 in apples has not been systematically elucidated. This study employed an integrated multi-omics approach to investigate the rhizosphere mechanisms of resistant (CG935) and sensitive (M9T337) apple rootstocks, aiming to uncover the metabolic and microbial interactions underlying apple replant disease resistance. Multiple omics joint analysis found that the infection of Fusarium proliferatum MR5 triggered the activation of a specific lysine biosynthesis pathway in resistant rootstocks, and the expression levels of key rate limiting enzymes aspartate kinase and dihydrodipicolinate synthase were significantly upregulated by 2.79 6.81 times compared to M9T337. Along with the metabolic reprogramming process, the efflux of lysine from the rhizosphere increased, and Bacillus with broad-spectrum antibacterial activity were specifically recruited, increasing its relative abundance by 40.73

Street view images are often used to assess the impact of the built environment on urban vitality from an eye-level perspective. However, the influence of analyzing scale on the accuracy of assessment results is often ignored. To find the appropriate scale, we need to quantify the scale effect of street view images and urban vitality. Therefore, in this study, Shenzhen is selected as the study area. Urban vitality is characterized by Weibo check-in records. VGG19 is employed to learn the features of street view images and performs regression analysis of the image features and Weibo check-in records in different sizes of grids (100 m, 150 m, …, 1000 m). Finally, we fit the scale effect of their correlation via a function. We find that as the scale increases, the correlation between street view images and urban vitality tends to increase and then decrease, which is consistent with the distribution law of a Gaussian function. This study provides a basis for selecting appropriate scales of the correlation between street view images and urban vitality.

The cultivation of apples in replanted orchards is essential given limitations in land resources. However, the presence of Fusarium and phenolic acids in the replanted soil harms the soil environment, which impedes the sustainable development of the apple industry. In this study, earthworm was used as the fermentation precursor protein to optimize the fermentation conditions, and the inhibition mechanism of the fermentation product on Fusarium and its potential to repair the apple replant soil environment were explored. Laboratory experiments showed that the optimum initial pH, temperature and time of earthworm fermentation were 7, 37 °C and 10 d, respectively. The inhibition rates of earthworm fermentation products against F. oxysporum, F. solani, F. proliferatum, and F. moniliforme were 79.8%, 75.1%, 78.7% and 79.2%, respectively. The inhibition rates of spore germination on F. oxysporum, F. solani, F. proliferatum, and F. moniliforme were 83.8%, 87.3%, 83.2% and 84.8%, respectively. In the field, use 300 mL of earthworm fermentation products for each planting pits before planting. The experimental results showed that, compared with the control, the content of soil pathogenic Fusarium and phenolic acid in Wantou (W3) were decreased by 75.1% and 59.8%, respectively, after treatment with earthworm fermentation products in 2019. Soil urease, phosphatase, sucrase and catalase activities increased by 383.2%, 78.2%, 130.3% and 43.5%, respectively. The fruit weight, anthocyanin content, soluble sugar, sugar-acid ratio, total ester ratio, total ester concentration and yield increased by 80.7%, 60.6%, 25.6%, 50.3%, 19.7%, 262.4% and 193.5%, respectively, while titratable acid content decreased by 16.9%. In conclusion, earthworm fermentation products can be used as a sustainable amendment to control apple replant disease.

Global climate change has significantly altered the patterns of Annual Snow Cover(ASC),including glaciers,which in turn,have reshaped regional hydrological processes.These changes pro-foundly impact the weathering rates of continental rocks and their associated carbon sink potential,particularly for silicate(Eq.(1))and carbonate(Eq.(2))rocks under natural conditions[1-3].Low Temperature(Tem)in regions with ASC typically limit the rates of chemical weathering and the occurrence of weathering prod-ucts.

Seismic peak ground acceleration (PGA) is a key indicator to characterize the strength of seismic effects, which affects the rate of chemical weathering of carbonate rocks and the ability to capture CO2. However, the response mechanism and process of Carbonate rock weathering Carbon Sink (CCS) to PGA are not clear. To this end, this paper clarifies the spatial and temporal patterns of CCS in China and reveals their response to PGA based on PGA, climate, lithology and other datas, combined with methods such as the random forest model and maximal potential dissolution model. The results showed that the CCS Flux(CCSF) was 5.32 t C km-2 yr-1 and the Full CCS (FCCS) was 1346 x 104 t C yr-1, which was influenced by PGA, with the flux being the largest at 0.05 g PGA (5.38 t C km-2 yr-1), mainly in the south-western part of the country where hydrothermal conditions are favourable. Meanwhile, the response of CCS to PGA was affected by latitude and altitude divergence. CCS at the same latitude showed a fluctuating downward trend with the enhancement of PGA. Two trends of CCS and PGA at the same altitude appeared, one was that CCS increased with the enhancement of PGA when the altitude was less than 2500 m as well as 4500-6500 m, and the other was that CCS decreased with the enhancement of PGA when the altitude was 2500-4500 m. At the same PGA, CCS decreased with increasing latitude and elevation, respectively. This may be due to the fact that higher altitude and latitude are associated with lower temperatures, which affects the rate of chemical weathering of carbonate rocks, and hence CCS. The aim of this paper is to understand the response relationship between CCS and PGA, which helps to reveal how geologic activities affect the carbon cycle. The results of the study bridge the gap between tectonic geology and CCS systematic research to a certain extent, and promote the integration of the disciplines. This is of great significance for assessing the potential impact of natural disasters such as earthquakes on carbon sinks.

The ecological vulnerability in the southwestern karst region is significant, and the protection of biodiversity (BD) and ecosystem services (ES) is of great significance for coordinating ecological protection and sustainable development. However, most studies focus on single targets of BD or ES, while neglecting to identify protected areas by merging them. Therefore, this article quantifies the spatial distribution of BD and ES from 2000 to 2019 using the revised universal soil loss equation model, constructs a biodiversity index, and other methods. The ordered weighted average method and superposition analysis method are further used to determine the southwest karst priority ecological protection area based on dual objectives. The results indicate that setting up priority protection areas in karst areas with better hydrothermal conditions can better protect ES and BD. The priority protected area accounts for 34.76 % of the total karst area in Southwest China, with a relatively small biodiversity protection area (15.59 %) and a relatively large ecosystem service protection area (19.17 %). Nature reserves account for 28.72 % of the BD priority conservation area and 30.89% of the ES priority conservation area. However, in the adjacent areas of Yunnan, Guizhou, and Guangxi provinces, as well as in the central regions of Guizhou, Guangxi, and Hunan, compared with the designated nature reserves in China, the existing protected areas do not provide high protection for the ecosystem services in these areas. Taking into account the dual goals of protecting BD and ES in the protected area, the results can provide reference for the development and utilization of natural resources, sustainable development, and the expansion of the protected area.

Carbonate rock chemical weathering carbon sinks reduce the rate of increase of the atmospheric CO2 concentration and global warming. However, uncertainty still exists in the estimation results of carbonate rock chemical weathering carbon sink fluxes (CCSF), and the contributions of climate change and ecological restoration to the CCSF are not clear. To this end, we compiled published site data on ion concentrations in different watersheds in China and used a classical thermodynamic dissolution model to reassess the potential and spatial and temporal patterns of the CCSF in China from 1991 to 2020. We quantified the contributions of temperature (MAT), precipitation (MAP), evapotranspiration (ET), soil water (SM), and the normalized difference vegetation index (NDVI) to the CCSF. The results revealed that (1) China's CCSF was 22.76 t CO2 km-2 yr-1, which was higher than the global average (15.771CO2 km-2 yr-1). The total carbonate rock chemical weathering carbon sink (CCS) was 4772.67x104 t CO2, contributing 14.91% of the global CCS through a carbonate rock area of 252.98x104 km-2. (2) China's CCSF decreased gradually from southeast to northwest, with values of 33.14, 12.93, and 7.27 t CO2 km-2 yr-1 in the southern karst, Qinghai-Tibetan karst, and northern karst regions, respectively. (3) The overall CCSF in China exhibited an increasing trend from 1991 to 2020, with a rate of increase of 0.16 t CO2 km-2 yr-1. (4) The contributions of the MAP, MAT, ET, SM, and NDVI to the CCSF were 63.3%, 3.02%, 27.5%, 3.1%, and 3.05%, respectively. Among them, the increase in precipitation was the main contributor to the increase in the CCSF in China over the last 30 years, while the enhancement of ET offset part of the positive contribution of the increase in precipitation to the CCSF. In conclusion, the results of this study provide a systematic quantification of the magnitude, the patterns, and the influencing factors of CCS over a long time series in China. The results are of great significance and provide a reference for the diagnosis and gap analysis of the national and global carbon neutrality capacities.

The control of rocky desertification is the largest ecological restoration project in southwestern China, but its impact on the carbon sequestration capacity of karst ecosystems is not clear. Therefore, in this paper selects typical subtropical karst areas in Guangxi are selected as the research object, the carbon sequestration potential of the terrestrial ecosystems are quantified, including karst inorganic carbon sinks, and the response of the terrestrial ecosystem carbon sink to rocky desertification restorationis discussed. The results show that (1) the karst inorganic carbon sink flux (CCSF) is 42.75 t CO2/km2/yr, with a total CCS of 491.12 x 104 t CO2, accounting for only 2.5 % of the country's land area and contributing 7.6 % of the karst inorganic carbon sink. (2) The flux of the vegetation organic carbon sink is 380.44 t CO2/km2/yr, and the total amount is 4403.55 x 104 t CO2/yr., Overall, the spatial distribution exhibits a pattern of high in the northwest and low in the northeast. (3) With decreasing rocky desertification area, the magnitude of the terrestrial ecosystem carbon sink has exhibited a corresponding increasing trend. In particular, during 2010-2020, the rocky desertification area decreased by about 0.868 x 104 km2, and the terrestrial ecosystem carbon sink increased by 114.04 t CO2/km2/yr. This article provides a systematic spatial diagnosis of the carbon sequestration potential of terrestrial ecosystems, including karst inorganic carbon sinks, in the karst areas of Guangxi, and reveals their responses to the restoration of karst rocky desertification. This work has strong reference value and significance for the diagnosis and analysis of the carbon neutrality capacity at the national and global levels.