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Grassland which covers 40% of terrestrial land is an important ecosystem having a multitude of functions, which has suffered various degrees of degradation with the interaction between global climate change and unreasonable human utilization (e.g., grazing and reclamation). Improved understanding of soil and microbial community diversity during meadow steppe degradation is crucial for predicting degradation mechanisms and restoration strategies. Here, we used Illumina sequencing technology to investigate the patterns of soil microbial community structure and the driving factors of its change across different degradation degrees of meadow steppe [i.e., non-degraded grasslands (NDG), lightly degraded grasslands (LDG), moderately degraded grasslands (MDG), and severely degraded grasslands (SDG)] south of the Greater Khingan Mountains. Our results showed a significant variation in soil properties, enzyme activity, and soil metal elements across the degraded meadows. Soil available phosphorus (AP), urease (UE), and cellulase (CL) in soils increased with the intensity of grassland degradation. Grassland degradation significantly decreased soil bacterial and fungal richness. In addition, grassland degradation significantly increased the relative abundance of Firmicutes (from 1.65% to 5.38%) and Myxococcota (from 2.13% to 3.13%). Degradation considerably increased the relative abundance of Ascomycota (from 66.54% to 75.05%), but decreased Basidiomycota (from 18.33% to 9.92%). The relative abundance of nitrogen fixation and cellulolysis decreased significantly due to grassland degradation. For fungal functional guilds, the relative abundance of pathotrophs increased while saprotrophs decreased significantly with increasing severity of degradation. Total nitrogen (TP), AP, available potassium (AK), manganese (Mn), lead (Pb), UE, sucrase (SC), and alcalase protease (ALPT) were the main drivers of soil bacterial community composition, while TP, AP, AK, Pb, UE, and SC were the main drivers of soil fungal community composition in the degraded grassland. Our findings demonstrated that severe grassland degradation has an enormous effect on soil microbial communities and soil physicochemical dynamics. These findings improve our theoretical understanding of the interactions between soil microbial populations and soil environmental variables in degraded grassland. [ABSTRACT FROM AUTHOR]

Net primary production (NPP) serves as a critical proxy for monitoring changes in the global capacity for vegetation carbon sequestration. The assessment of the factors (i.e., human activities and climate changes) influencing NPP is of great value for the study of terrestrial systems. To investigate the influence of factors on grassland NPP, the ecologically vulnerable Qinghai–Tibet Plateau region was considered an appropriate study area for the period from 2000 to 2020. We innovated the use of the RICI index to quantitatively represent human activities and analyzed the effects of RICI and climatic factors on grassland NPP using the geographical detector. In addition, the future NPP was predicted through the integration of two modeling approaches: The Patch-Generating Land Use Simulation (PLUS) model and the Carnegie–Ames–Stanford Approach (CASA) model. The assessment revealed that the expanded grassland contributed 7.55 × 104 Gg C (Gg = 109 g) to the total NPP, whereas the deterioration of grassland resulted in a decline of 1.06 × 105 Gg C. The climatic factor was identified as the dominant factor in grassland restoration, representing 70.85% of the total NPP, as well as the dominant factor in grassland degradation, representing 92.54% of the total NPP. By subdividing the climate change and human activity factors into sub-factors and detecting them with a geographical detector, the results show that climate change and anthropogenic factors have significant ability to explain geographic variation in NPP to a considerable extent, and the effect on NPP is greater when the factors interact. The q-values of the Relative Impact Contribution Index (RICI) and the RICI of the land use change NPP are consistently greater than 0.6, with the RICI of the human management practices NPP and the evapotranspiration remaining at approximately 0.5. The analysis of the interaction between climate and human activity factors reveals an average impact of greater than 0.8. By 2030, the NPP of the natural development scenario, economic development scenario (ED), and ecological protection scenario (EP) show a decreasing trend due to climate change, the dominant factor, causing them to decrease. Human activities play a role in the improvement. The EP indicates a positive expansion in the growth rate of forests, water, and wetlands, while the ED reveals rapid urbanization. It is notable that this is accompanied by a temporary suspension of urban greening. [ABSTRACT FROM AUTHOR]

While it is established that dominant plant species of alpine meadows showed differential preference for N forms (ammonia, nitrate, and amino acids) under various degradation stages, the perseverance of the N-uptake preference and its affecting factors remains unknown. This is an important consideration because it determines efficacy of nutrient additions for restoration of degraded alpine meadows. An indoor pot experiment was conducted to investigate the plasticity and determinants of different plant species' N-uptake preference using 15N-labeled inorganic N (15NH4+ and 15NO3−) and one of dual-labeled (13C-15N) amino acid (glycine). In the experiment, dominant species of alpine meadow from specific degradation status were planted in soils of alpine meadows with three different degradation status. Most species preferred to uptake nitrate in all soils, except the Kobresia humilis, Carex moorcroftii, and Aster flaccidus planted in the soil of severely degraded alpine meadow (SD-soil) that take up more ammonia. The relative abundance of different available N forms directly affects the N-uptake preferences of all species. The partial correlations between percentage uptake and availability of various N forms were different with the zero-order correlations when either soil moisture or pH was controlled. Differences in soil moisture and pH among the three alpine meadows affects the N uptake preference of the nine species through their impacts on the relative abundance of different available N forms. In conclusion, the differences in soil moisture and pH among soils of alpine meadows under different degradation statuses influence the relative abundance of various available N forms, thereby affecting the plant N uptake. [ABSTRACT FROM AUTHOR]

Grassland degradation poses a significant challenge to achieving the Sustainable Development Goals (SDGs) on the Qinghai–Tibetan Plateau (QTP). Effective monitoring of grassland degradation is essential for ecological restoration. Hyperspectral technology offers efficient and accurate identification of degradation. However, the influence of observation time, data analysis methods and classification techniques on the accuracy of identifying alpine grasslands remains unclear. In this study, the spectral reflectance of degraded alpine meadow, alpine meadow, alpine shrub and Tibetan barley was measured from May to September 2023 using a ground spectrometer in the northeastern QTP. First-order derivatives (FDR) and continuum removal were applied to the spectra, and characteristic parameters and vegetation indices were calculated. Support vector machine (SVM), random forest (RF), artificial neural network (ANN) and decision tree (DT) were then used to compare the classification accuracy between different months, transformation methods and characteristic parameters. The results showed that the spectral reflectance peaked in July, with significant differences in the near infrared (NIR) bands between alpine meadow and degraded alpine meadow. Alpine shrub and Tibetan barley showed greater differences in reflectance compared to other vegetation types, especially in the NIR bands. Data transformations improved reflectance and absorption characteristics in the NIR and visible bands. Indices such as DVI, RVI and NDGI effectively differentiated vegetation types. Optimal accuracy for the identification of degraded alpine meadow in July was achieved using FDR transformations and ANN or SVM for classification. This study provides methodological insights for monitoring grassland degradation on the QTP. [ABSTRACT FROM AUTHOR]

Understanding the plant–soil feedbacks (PSFs) of dominant species of alpine meadow under different degradation status could provide insights into sustainable restoration. The direction, strength, and influencing factors of dominant species' PSFs in nondegraded (Intact), moderately degraded (MD), and severely degraded (SD) alpine meadows were examined in a two-phase PSFs experiment. Species of Intact exhibited neutral conspecific PSFs, whereas those of MD and SD exhibited negative conspecific PSFs. The species of MD demonstrated neutral heterospecific PSFs to those of Intact, whereas that of SD negatively feedbacked to those of Intact and MD. The NO3−-N and NH4+-N of soil conditioned by the species of Intact were 66% and 58% higher than the control (mixture soil conditioned by all species); but they were 37% and 32% lower in soil conditioned by the dominant species of SD. The relative abundance of soil fungal pathotrophs was 57% and 74% higher in soil conditioned by the dominant species of MD and SD than in Intact soil. The conspecific and heterospecific PSFs of all species positively correlated with the plant conditioning and degradation induced changes of difference in NO3−-N and NH4+-N and negatively correlated with the difference in relative abundance of pathotrophs. Soil microorganisms and nutrients explained most of the variation in conspecific (43%) and heterospecific PSFs (60%). Our results indicated that the N addition would facilitate the sustainable restoration of degraded alpine meadows because the addition of available N could drive the heterospecific PSFs toward more positive. [ABSTRACT FROM AUTHOR]

Abstract Background With the profound changes in the global climate, the issue of grassland degradation is becoming increasingly prominent. Grassland degradation poses a severe threat to the carbon cycle and carbon storage within grassland ecosystems. Additionally, it will adversely affect the sustainability of food production. The grassland ecosystem in the northwest region of Liaoning Province, China, is particularly vulnerable due to factors such as erosion from the northern Horqin Sandy Land, persistent arid climate, and issues related to overgrazing and mismanagement of grassland. The degradation issue is especially pronounced in this ecological environment. However, previous research on the carbon density of degraded grasslands in Northeast China has predominantly focused on Inner Mongolia, neglecting the impact on the grasslands in the northwest of Liaoning Province. Therefore, this experiment aims to assess the influence of grassland degradation intensity on the vegetation and soil carbon density in the northwest of Liaoning Province. The objective is to investigate the changes in grassland vegetation and soil carbon density resulting from different degrees of grassland degradation. Methodology This study focuses on the carbon density of grasslands at different degrees of degradation in the northwest of Liaoning Province, exploring the variations in vegetation and soil carbon density under different levels of degradation. This experiment employed field sampling techniques to establish 100 × 100 m plots in grasslands exhibiting varying degrees of degradation. Six replications of 100 × 100 m plots per degradation intensity were sampled. Vegetation and soil samples were collected for analysis of carbon density. Results The results indicate that in the context of grassland degradation, there is a significant reduction in vegetation carbon density. Furthermore, it was found that root carbon density is the primary contributor to vegetation carbon density. In comparison to mildly degraded grasslands, moderately and severely degraded grasslands experience a reduction in vegetation carbon density by 25.6% and 52.6%, respectively. However, with regard to the impact of grassland degradation on soil carbon density, it was observed that while grassland degradation leads to a slight decrease in soil carbon density, there is no significant change in soil carbon density in the short term under the influence of grassland degradation. Conclusions Therefore, grassland degradation has exerted a negative impact on aboveground vegetation carbon density, reducing the carbon storage of above-ground vegetation in grasslands. However, there was no significant effect on grassland soil carbon density.

As a vital component of the terrestrial ecosystem, grassland accounts for one-third of the global vegetation system. Grassland degradation has been exacerbated due to extreme overgrazing in China's Inner Mongolia Autonomous Region (IMAR). While conservation was carried out via the Ecological Subsidy and Award Program (ESAP) to mitigate grassland degradation, little is known about its effectiveness in improving the biophysical conditions of grassland. This paper integrates the conceptual frameworks of total socio-environmental systems (TSESs) to assess how ecological systems respond to the ESAP, investigate the spatial heterogeneity of the ESAP, and explore the meddling effects of socio-environmental interactions on the ESAP. We integrated ecological, climate, and socioeconomic data and developed several hierarchical linear mixed models (HLMMs) to investigate how these factors interact with the ESAP in the IMAR. Our findings prove that the above-ground biomass between 2011 and 2015 responds significantly to variations in socioeconomic conditions and ecological communities. Available land resources, hospital and medical facilities, and net farmer and herdsman income are the most critical factors positively related to grassland productivity. Primary industries like mining, total consumer retail value, farming, forestry, animal husbandry, fishery productions, and GDP are the most damaging factors affecting biomass. Our study recommends a regionally or locally tailored ecological recovery policy, instead of a generalized one, in future efforts to conserve grassland. [ABSTRACT FROM AUTHOR]

After two decades of implementing top-down grassland restoration projects focused on reducing livestock numbers and pastoralist populations, the Chinese government's well-funded efforts have not significantly reversed grassland degradation. This study reviews the institutional changes in grassland management over the past forty years, highlighting the Livestock and Grassland Double Contract Household Responsibility System of the early 1980s and the Grassland Ecological Reward and Compensation Policy introduced in 2011. It demonstrates how these institutional transformations have shaped pastoralists' evolving understanding of grassland value and reveals that commodifying grassland's economic and ecological value has led to the capitalization of nature, disembedding husbandry from grassland production, and undermining the effectiveness of conservation projects. This article also showcases the development of grassland ecology research in China, noting its increasing detachment from a holistic understanding of ecosystems and the interdisciplinary needs of management practices. The disjunction between grassland ecology research and practical management has resulted in a lack of techniques aligned with local ecological and socioeconomic contexts. This article champions active engagement with and protection of pastoralist communities to reintegrate grasslands' true economic and ecological value into management practices, thereby effectively restoring degraded grasslands and achieving sustainable management. [ABSTRACT FROM AUTHOR]

Background: With the profound changes in the global climate, the issue of grassland degradation is becoming increasingly prominent. Grassland degradation poses a severe threat to the carbon cycle and carbon storage within grassland ecosystems. Additionally, it will adversely affect the sustainability of food production. The grassland ecosystem in the northwest region of Liaoning Province, China, is particularly vulnerable due to factors such as erosion from the northern Horqin Sandy Land, persistent arid climate, and issues related to overgrazing and mismanagement of grassland. The degradation issue is especially pronounced in this ecological environment. However, previous research on the carbon density of degraded grasslands in Northeast China has predominantly focused on Inner Mongolia, neglecting the impact on the grasslands in the northwest of Liaoning Province. Therefore, this experiment aims to assess the influence of grassland degradation intensity on the vegetation and soil carbon density in the northwest of Liaoning Province. The objective is to investigate the changes in grassland vegetation and soil carbon density resulting from different degrees of grassland degradation. Methodology: This study focuses on the carbon density of grasslands at different degrees of degradation in the northwest of Liaoning Province, exploring the variations in vegetation and soil carbon density under different levels of degradation. This experiment employed field sampling techniques to establish 100 × 100 m plots in grasslands exhibiting varying degrees of degradation. Six replications of 100 × 100 m plots per degradation intensity were sampled. Vegetation and soil samples were collected for analysis of carbon density. Results: The results indicate that in the context of grassland degradation, there is a significant reduction in vegetation carbon density. Furthermore, it was found that root carbon density is the primary contributor to vegetation carbon density. In comparison to mildly degraded grasslands, moderately and severely degraded grasslands experience a reduction in vegetation carbon density by 25.6% and 52.6%, respectively. However, with regard to the impact of grassland degradation on soil carbon density, it was observed that while grassland degradation leads to a slight decrease in soil carbon density, there is no significant change in soil carbon density in the short term under the influence of grassland degradation. Conclusions: Therefore, grassland degradation has exerted a negative impact on aboveground vegetation carbon density, reducing the carbon storage of above-ground vegetation in grasslands. However, there was no significant effect on grassland soil carbon density. [ABSTRACT FROM AUTHOR]

On the basis of careful analysis of the status quo, problems and experience of grassland ecological protection and restoration in Inner Mongolia, this study selected representative pilot areas to carry out pilot ecological restoration projects in the warm steppe of Inner Mongolia. Through the ecological benefit assessment of the ecological restoration project, it objectively reflected the achievements of the implementation of the ecological restoration project in the warm steppe of Inner Mongolia Autonomous Region and the contribution to the local economic development. The results showed that after the implementation of ecological restoration measures for 3 years, the two restoration measures (fence+replanting+management, land leveling+replanting+fertilization+sand barrier) had obvious ecological benefits. The ecological restoration projects combining fencing, reseeding and management and protection had more obvious ecological benefits. The accuracy of remote sensing monitoring model fluctuated greatly, so it was still necessary to explore the technical means to improve the monitoring accuracy. [ABSTRACT FROM AUTHOR]

Ecosystem regime shifts refer to the drastically changes of an ecosystem from one state to another after suffering disturbances that exceed the thresholds. Although land desertification and grassland degradation, which are common in the cold and arid regions, are gradual processes, sudden changes can also occur when the duration or intensity of disturbances exceed the thresholds. Therefore, the study of ecosystem regime shifts is of great significance to the management of ecosystems in cold and arid regions. In this review, we summarized the evolution of ecosystem regime shift theory and early warning signals, and analyzed the problems of land desertification and grassland degradation in cold and arid regions, as well as potential responses of ecosystems to different stresses. We further put forward research frameworks for the evolution and mutation characteristics of the rain-fed artificial sand fixation system and alpine meadows. The future research needed to be strengthened in identifying the key drivers of ecosystem regime shifts at different stages, determining the corresponding thresholds, emphasizing the mechanism of water-limited mutation induced by extreme climatic events and its early warning, and promoting the application of regime shift research to ecosystem management in arid and arid regions. [ABSTRACT FROM AUTHOR]

Grassland which covers 40% of terrestrial land is an important ecosystem having a multitude of functions, which has suffered various degrees of degradation with the interaction between global climate change and unreasonable human utilization (e.g., grazing and reclamation). Improved understanding of soil and microbial community diversity during meadow steppe degradation is crucial for predicting degradation mechanisms and restoration strategies. Here, we used Illumina sequencing technology to investigate the patterns of soil microbial community structure and the driving factors of its change across different degradation degrees of meadow steppe [i.e., non-degraded grasslands (NDG), lightly degraded grasslands (LDG), moderately degraded grasslands (MDG), and severely degraded grasslands (SDG)] south of the Greater Khingan Mountains. Our results showed a significant variation in soil properties, enzyme activity, and soil metal elements across the degraded meadows. Soil available phosphorus (AP), urease (UE), and cellulase (CL) in soils increased with the intensity of grassland degradation. Grassland degradation significantly decreased soil bacterial and fungal richness. In addition, grassland degradation significantly increased the relative abundance of Firmicutes (from 1.65% to 5.38%) and Myxococcota (from 2.13% to 3.13%). Degradation considerably increased the relative abundance of Ascomycota (from 66.54% to 75.05%), but decreased Basidiomycota (from 18.33% to 9.92%). The relative abundance of nitrogen fixation and cellulolysis decreased significantly due to grassland degradation. For fungal functional guilds, the relative abundance of pathotrophs increased while saprotrophs decreased significantly with increasing severity of degradation. Total nitrogen (TP), AP, available potassium (AK), manganese (Mn), lead (Pb), UE, sucrase (SC), and alcalase protease (ALPT) were the main drivers of soil bacterial community composition, while TP, AP, AK, Pb, UE, and SC were the main drivers of soil fungal community composition in the degraded grassland. Our findings demonstrated that severe grassland degradation has an enormous effect on soil microbial communities and soil physicochemical dynamics. These findings improve our theoretical understanding of the interactions between soil microbial populations and soil environmental variables in degraded grassland.

Worldwide grasslands are experiencing degradation due to overgrazing and the effects of climate change, and warming-induced changes in degraded grasslands could accelerate degradation. As one of the direct manipulating factors of grassland degradation, soil water is governed by climatological and anthropogenic processes. Evapotranspiration (ET) plays a key role in regulating soil water content in these processes, but the underlying mechanisms remain unclear. In this study, a two-year field experiment was conducted in different degraded grasslands. The calibrated Hydrus-1D model was applied to identified the dynamic of ET and soil water in 2022 and 2023 under normal condition and warming (+1.5 °C) scenarios. ET decreased slightly with grassland degradation, mainly due to the reduction of transpiration (T). T/ET decreased as well, 57.87 %∼69.06 %, 51.71 %∼65.60 %, 31.76 %∼49.44 % and 15.54 %∼22.61 % in undegraded control (CK), light degraded (LD), moderately degraded (MD) and heavy degraded (HD) grasslands, respectively, during growing seasons. With the aggravation of grassland degradation, the influence of warming on ET was gradually enhanced. Soil water content (SWC) responded differently to degraded degrees. Additionally, warming showed more significant effects on SWC in LD and MD grasslands than in HD grassland. Furthermore, ET contribution to regulating SWC response to degradation and warming in LD and MD grasslands at 30–100 cm soil depth. Compared to other meteorological factors, vapor pressure deficit (VPD) exhibited significantly stronger correlation with T, and this correlation weakened gradually with grassland degradation, indicating a diminished regulatory role of vegetation in response to environmental moisture changes. Grassland T/ET during the growing season could serve as a potential parameter for predicting vegetation productivity. In dry conditions, irrigation at critical growth stages in the field can be implemented to achieve optimal results in enhancing water use efficiency and degraded grassland restoration. These findings not only can improve our understanding of the hydrological processes and water budget during grassland degradation, but also provide valuable guidelines for the management of water resources and the restoration of ecological environment.

Grassland degradation levels determine plant eco‐physiological properties, and thus influences ecosystem function. However, how land degradation affects the relationship between plant biomass and eco‐physiological properties of native and artificially restored grasslands is insufficiently understood. Here, we evaluated aboveground biomass (AGB), plant photosynthetic capacity, as well as soil texture, in a series of native grasslands (non‐degraded, slightly degraded, moderately degraded, heavily degraded, and extremely degraded) and artificially restored grasslands with different growth times (5, 9, 11, 14 and 17 years) within the alpine grassland ecosystem of the Qinghai–Tibet Plateau during the plant growing season. Results showed that, in native grasslands, land degradation significantly decreased the nitrogen (N) concentration and AGB of grasses but did not impact the phosphorus (P) concentration. In actively restored grasslands, the AGB, photosynthetic rate (Pn), N and P of grasses decreased significantly after 9 years or longer of replanting time. Furthermore, the AGB of grasses in actively restored grasslands showed stronger association with eco‐physiological properties than in native grasslands. In native grasslands, degradation affected AGB directly, but also indirectly through Pn. In actively restored grasslands, degradation affected AGB directly, but also indirectly through Pn, N and P. Our findings suggest that the mechanisms by which grass species respond to degradation differ between native and actively restored grasslands. Also, compared to native grasslands, the eco‐physiological properties of grasses are more sensitive to changing environmental conditions in actively restored grasslands. More importantly, the differing response mechanisms are likely to alter the plant community dynamics and future ecosystem stability. [ABSTRACT FROM AUTHOR]

The grassland area is nearly 400 million hm 2 in China, accounting for more than 40% of the land area. Grassland plays an important role in animal husbandry and environmental protection. Although China has taken many measures to curb grassland degradation, grassland degradation is still widely spreading due to overgrazing, abuse of arable land, climate change and other factors. In this paper, the present situation of grassland degradation in China was analyzed in detail. At the same time, the grassland degradation mechanism, the grassland ecosystem function, the grassland degradation diagnosis methods, the grassland restoration and improvement, the utilization of geospatial technology and the grassland management methods were discussed in depth. What’s more, the roots of grassland degradation, the characteristics of grassland degradation, and the control strategies of grassland degradation were analyzed deeply based on the basic situation of grassland degradation in China. The research results not only provide theoretical support for the restoration of grassland ecosystem, but also guide the improvement and restoration of degraded grassland and promote the sustainable development of the grassland ecological animal husbandry in China. [ABSTRACT FROM AUTHOR]

Grassland degradation is challenging the health of grassland ecosystems globally and causing biodiversity decline. Previous studies have demonstrated the impact of grassland degradation on the abundance and behavior of small mammals. Little is known about how it affects the genetic structure of gregarious mammals in the wild. This study explores the effects of grassland degradation on the genetic structure of a small burrowing mammal, plateau pika (Ochotona curzoniae). We used nine microsatellite loci to analyze the genetic diversity and genetic differentiation between colonies and genetic relatedness between individuals within the colony. We found that pikas in severely degraded grasslands had a significantly higher genetic diversity within colonies, a higher level of gene flow between colonies, and a lower genetic differentiation between colonies compared to pikas in less degraded grasslands. Individuals within colonies had a significantly lower genetic relatedness in severely degraded grasslands than in less degraded grasslands. This study has provided potential evidence of a significant impact of grassland degradation on the genetic structure of pikas, which has caused a breakdown of their kin‐selected colony structure. [ABSTRACT FROM AUTHOR]

Shrub encroaching on grasslands threatens grassland ecosystems and negatively affects human land use and livelihood. However, existing research on this subject is limited, having focused on small areas, thus hindering a comprehensive understanding of the diverse patterns of large-scale shrub invasions into grasslands. In recent decades, a significant encroachment of shrubs into Xilin Gol grassland has been observed in China, resulting in considerable damage to the grasslands. Therefore, this study aimed to investigate the rapid expansion of shrub-encroached grassland (SEG) from 1990 to 2020 in the Xilin Gol League, Inner Mongolia Autonomous Region, China, using long-term Landsat images. The spatial distribution characteristics of the new SEG areas were analyzed. The main factors driving the shrub encroachment in the study area were identified using a geographic detector. Our results revealed a continuous expansion of SEG in the study area over the past three decades, marked by an increase of 48.76 × 103 km2 and an average annual gain rate of 9.41 %. The increased SEG was primarily owing to grassland transition. The sprawl of the SEG was the most prominent in the western and northern regions of the study area, extending to gentle slopes of approximately 5° and low-middle elevations between 600–1300 m above mean sea level. Shrub encroachment was primarily influenced by surface temperature, wind speed, and relative humidity, with elevation, slope, and precipitation exerting relatively weaker influences. Rather than being driven by a singular factor, the expansion was a result of the combined influence of various factors. This study provides a valuable case study for understanding shrub invasion dynamics in arid and semi-arid regions globally.

Net primary production (NPP) serves as a critical proxy for monitoring changes in the global capacity for vegetation carbon sequestration. The assessment of the factors (i.e., human activities and climate changes) influencing NPP is of great value for the study of terrestrial systems. To investigate the influence of factors on grassland NPP, the ecologically vulnerable Qinghai–Tibet Plateau region was considered an appropriate study area for the period from 2000 to 2020. We innovated the use of the RICI index to quantitatively represent human activities and analyzed the effects of RICI and climatic factors on grassland NPP using the geographical detector. In addition, the future NPP was predicted through the integration of two modeling approaches: The Patch-Generating Land Use Simulation (PLUS) model and the Carnegie–Ames–Stanford Approach (CASA) model. The assessment revealed that the expanded grassland contributed 7.55 × 104 Gg C (Gg = 109 g) to the total NPP, whereas the deterioration of grassland resulted in a decline of 1.06 × 105 Gg C. The climatic factor was identified as the dominant factor in grassland restoration, representing 70.85% of the total NPP, as well as the dominant factor in grassland degradation, representing 92.54% of the total NPP. By subdividing the climate change and human activity factors into sub-factors and detecting them with a geographical detector, the results show that climate change and anthropogenic factors have significant ability to explain geographic variation in NPP to a considerable extent, and the effect on NPP is greater when the factors interact. The q-values of the Relative Impact Contribution Index (RICI) and the RICI of the land use change NPP are consistently greater than 0.6, with the RICI of the human management practices NPP and the evapotranspiration remaining at approximately 0.5. The analysis of the interaction between climate and human activity factors reveals an average impact of greater than 0.8. By 2030, the NPP of the natural development scenario, economic development scenario (ED), and ecological protection scenario (EP) show a decreasing trend due to climate change, the dominant factor, causing them to decrease. Human activities play a role in the improvement. The EP indicates a positive expansion in the growth rate of forests, water, and wetlands, while the ED reveals rapid urbanization. It is notable that this is accompanied by a temporary suspension of urban greening.

Grassland degradation poses a significant challenge to achieving the Sustainable Development Goals (SDGs) on the Qinghai–Tibetan Plateau (QTP). Effective monitoring of grassland degradation is essential for ecological restoration. Hyperspectral technology offers efficient and accurate identification of degradation. However, the influence of observation time, data analysis methods and classification techniques on the accuracy of identifying alpine grasslands remains unclear. In this study, the spectral reflectance of degraded alpine meadow, alpine meadow, alpine shrub and Tibetan barley was measured from May to September 2023 using a ground spectrometer in the northeastern QTP. First-order derivatives (FDR) and continuum removal were applied to the spectra, and characteristic parameters and vegetation indices were calculated. Support vector machine (SVM), random forest (RF), artificial neural network (ANN) and decision tree (DT) were then used to compare the classification accuracy between different months, transformation methods and characteristic parameters. The results showed that the spectral reflectance peaked in July, with significant differences in the near infrared (NIR) bands between alpine meadow and degraded alpine meadow. Alpine shrub and Tibetan barley showed greater differences in reflectance compared to other vegetation types, especially in the NIR bands. Data transformations improved reflectance and absorption characteristics in the NIR and visible bands. Indices such as DVI, RVI and NDGI effectively differentiated vegetation types. Optimal accuracy for the identification of degraded alpine meadow in July was achieved using FDR transformations and ANN or SVM for classification. This study provides methodological insights for monitoring grassland degradation on the QTP.

Purpose: Grassland ecosystems in ecologically fragile areas have experienced severe degradation due to global climate change and intensified human activities. However, responses of grassland ecosystems to degradation in different ecologically fragile areas remain unclear. Methods: We applied a meta-analysis approach to examine data about vegetation biomass, soil physicochemical properties, and soil microorganisms across different degradation stages in two ecologically fragile areas: Tibetan Plateau (QTP) and Northern Agro-pastoral Ecotone (NAPE). Results: Grassland degradation leads to reduction in vegetation biomass, and loss of soil carbon (C), nitrogen (N), and phosphorus (P). However, the response of soil potassium (K) to degradation isn't significant in NAPE. Physicochemical properties of soil on QTP exhibit a higher sensitivity to grassland degradation than those in NAPE. Model analysis results suggest mean annual precipitation (MAP), ecosystem type, and soil depth are primary factors contributing to differences in soil physicochemical properties between QTP and NAPE. Within different ecologically fragile areas, changes in enzyme activities are more pronounced, with general decline in soil sucrase (SR) activity, greater sensitivity of urease (URE) to degradation on QTP, and higher sensitivity of polyphenol oxidase (PPO) in NAPE. Further analysis reveals that the main influencing factors of enzyme activity are different in the QTP and the NAPE. Conclusions: In summary, grassland degradation is a result of the coordinated degradation of vegetation, soil, and microorganisms, displaying variations across different ecologically vulnerable regions and degradation stages. An in-depth investigation of these differences and their driving factors can facilitate the accurate assessment of grassland degradation and formulation of restoration strategies tailored to different regions. [ABSTRACT FROM AUTHOR]

Globally, grassland degradation is an acute ecological problem. In alpine grassland on the Tibetan Plateau, increased densities of various small mammals in degraded grassland are assumed to intensify the degradation process and these mammals are subject to lethal control. However, whether the negative impact of small mammals is solely a result of population size or also a result of activity and behavior has not been tested. In this study, we use plateau pika as a model to compare population size, core area of colony, and the number of burrow entrances and latrines between lightly and severely degraded grassland. We test whether the alleged contribution of pika to grassland degradation is a result of increased population size or increased burrowing activities of individuals in response to lower food abundance. We found that grassland degradation resulted in lower plant species richness, plant height, and biomass. Furthermore, the overall population size of pika was not significantly affected by location in lightly and severely degraded grassland. However, pika core areas in severely grassland degradation were significantly larger and had significantly higher densities of burrows and latrines. Our study provides convincing evidence that habitat‐induced changes in the behavior of small, burrowing mammals, such as pika, can exacerbate grassland degradation. This finding has significant implications for managing small mammals and restoring degraded grassland ecosystems. [ABSTRACT FROM AUTHOR]

Although nitrogen (N) enrichment is known to threaten the temporal stability of aboveground net primary productivity, it remains unclear how it alters that of belowground microbial abundance and whether its impact can be regulated by grassland degradation. Using data from N enrichment experiments at temperate grasslands with no, moderate, severe, and extreme degradation degrees, we quantified the temporal stability of soil microbial abundance (hereafter 'microbial community stability') using the ratio of the mean quantitative PCR to its standard deviation over 4 years. Both bacterial and fungal community stability sharply decreased when N input exceeded 30 g N m−2 year−1 in non‐degraded grasslands, whereas a reduction in this threshold occurred in degraded grasslands. Microbial species diversity, species asynchrony, and species associations jointly altered microbial community stability. Interestingly, the linkages between plant and microbial community stability were strengthened in degraded grasslands, suggesting that plants and soil microbes might depend on each other to keep stable communities in harsh environments. Our findings highlighted the importance of grassland degradation in regulating the responses of microbial community stability to N enrichment and provided experimental evidence for understanding the relationships between plant and microbial community stability. [ABSTRACT FROM AUTHOR]

Introduction: Forage culture is a common way to restore degraded grasslands and soil functions, in which the reconstruction of the soil microbial community and its relationship with extracellular enzyme activity (EEAs) can characterize the recovery effects of degraded grasslands. However, the impacts of forage culture on the interaction between soil microbes and EEAs and whether the recovery effect of soil functions depends on the varying degradation statuses remain unclear. Methods: We conducted a plantation of a dominant grass, Leymus chinensis, in the soil collected from severe, moderate, light, and non-degradation statuses in the Songnen grassland in northeastern China. We measured soil microbial diversity and soil EEAs, and predicted microbial functional groups using FUNGuild. Results: The results showed that L. chinensis culture promoted soil bacterial alpha diversity and soil EEAs only in the moderate degradation status, indicating a dramatic dependence of the recovery effects of the grass culture on degradation status of the grassland. After planting L. chinensis for 10weeks, a decreasing trend in the chemoheterotrophy and nitrate-reduction microbial functional groups was found. In contrast, the abundance of the nitrogen (N)-fixing microbial functional group tended to increase. The positive correlation between soil EEAs and the nitratereduction and N-fixing microbial functional groups was enhanced by planting L. chinensis, indicating that grass culture could promote soil N cycle functions. Conclusion: We illuminate that grass culture may promote the restoration of soil functions, especially soil N cycling in degraded grasslands, and the recovery effect may depend on the grassland degradation status. We emphasized that selection of the plant species for restoration of grasslands needs to consider the restoration effects of microbial functional groups and soil functions. [ABSTRACT FROM AUTHOR]

Introduction: Grassland degradation has seriously affected the ecological environment and human livelihood. To abate these, implementing effective management strategies to restore and improve the service functions and productivity of degraded grasslands is crucial. Methods: To evaluate the influences of restoration measures combined with different grazing intensities on short-term (1 year) grassland restoration, the changes in soil physicochemical properties, as well as plant traits under restoration measures of different grazing intensities, reseeding, and fertilization, were analyzed. Results: Soil organic carbon (SOC) increased to varying degrees, whereas available nutrients decreased under all combined restoration measures. Reseeding, alone and in combination with fertilization, substantially increased SOC, improved grassland vegetation status, and enhanced grassland productivity. The aboveground biomass of Gramineae and the total aboveground biomass increased under the combined restoration measures of transferring livestock out of the pasture 45 days in advance, reseeding, and fertilization (T4). Redundancy analysis revealed a strong correlation between grassland vegetation characteristics, SOC, and available potassium. Considering soil and vegetation factors, the short-term results suggested that the combination measures in T4had the most marked positive impact on grassland restoration. Discussion: These findings offer valuable theoretical insights for the ecological restoration of degraded grasslands in alpine regions. [ABSTRACT FROM AUTHOR]

This study focuses on the dynamic changes of pika and rabbit populations in Sanjiangyuan National Park and its impact on grassland degradation. The Sanjiangyuan region, as an important part of the Qinghai-Tibet Plateau, has a unique ecosystem and rich biodiversity. As a key species in the area, the pika's activities play an important role in loosening the grassland soil and retaining moisture. However, due to the dual impact of climate change and human activities, the excessive growth of the pika population has led to the severe degradation of the grassland ecosystem and the formation of “black soil beaches”, which not only destroys the natural recovery ability of the grassland but also affects the livelihood of local herders had a negative impact. In the context of global sustainable development, this study proposes a series of scientific and reasonable management measures, including the implementation of dynamic rotational grazing, returning grazing to grassland, forage planting, and green prevention and control of pikas, etc., to achieve the goal of realizing cattle, sheep, and pasture and ecological coordination among pikas. At the same time, the study emphasizes the in-depth understanding of the role of pikas in the ecosystem and their relationship with grassland degradation through scientific research, providing a scientific basis for formulating effective ecological protection and restoration strategies. In addition, the study also puts forward suggestions for establishing a sound legal and regulatory system, strengthening protected area management institutions, and promoting public participation, publicity, and education. These measures aim to ensure that ecological protection work in Sanjiangyuan National Park is effectively implemented and to promote the sustainable development of local communities. The case of Sanjiangyuan National Park has important reference significance at the global level, demonstrating how to achieve a balance between economic development and environmental protection through ecological protection and restoration work. This has a guiding role for other regions around the world facing similar ecological problems and will help promote the implementation of the global sustainable development agenda. In short, the ecological protection and management of Sanjiangyuan National Park requires the joint efforts of the government, scientific research institutions, local communities, and the international community to achieve long-term ecological security and sustainable development. [ABSTRACT FROM AUTHOR]

After two decades of implementing top-down grassland restoration projects focused on reducing livestock numbers and pastoralist populations, the Chinese government’s well-funded efforts have not significantly reversed grassland degradation. This study reviews the institutional changes in grassland management over the past forty years, highlighting the Livestock and Grassland Double Contract Household Responsibility System of the early 1980s and the Grassland Ecological Reward and Compensation Policy introduced in 2011. It demonstrates how these institutional transformations have shaped pastoralists’ evolving understanding of grassland value and reveals that commodifying grassland’s economic and ecological value has led to the capitalization of nature, disembedding husbandry from grassland production, and undermining the effectiveness of conservation projects. This article also showcases the development of grassland ecology research in China, noting its increasing detachment from a holistic understanding of ecosystems and the interdisciplinary needs of management practices. The disjunction between grassland ecology research and practical management has resulted in a lack of techniques aligned with local ecological and socioeconomic contexts. This article champions active engagement with and protection of pastoralist communities to reintegrate grasslands’ true economic and ecological value into management practices, thereby effectively restoring degraded grasslands and achieving sustainable management.

Within the Tibetan Plateau (TP), grassland degradation is of great concern, and there is a need to better understand the spatial variability and landscape patterns in grassland degradation across the TP. This study explores potential patterns in grassland degradation, estimated using Landsat-derived normalized difference vegetation index (NDVI) growing season change products generated by a prior study. Shuttle Radar Topography Mission (SRTM) digital terrain model (DTM)-derived geomorphons, topographic slope and the topographic position index (TPI) were used to explore grassland degradation and assess whether changes in growing season NDVI are associated with specific grasslands or landforms. An increase in NDVI within the TP was observed especially during the 1990 to 2018 and 2000 to 2018 time periods. Higher growing season median NDVI change values were found for the Southeast Tibet Shrublands and Meadows (SETSM) and TP Alpine Shrublands and Meadows (TPASM) grasslands in comparison to the other grassland types analysed, suggesting a more pronounced greening trend in the eastern portion of the plateau in comparison to the western portion. Small differences in NDVI change were observed for different geomorphon-based landforms, while topographic slope and TPI showed only modest correlations with NDVI change for all time periods and grassland types. More localized patterns of grassland degradation were masked by the widespread greening trends. Further analysis of only pixels that experienced a decreasing NDVI magnitude of less than or equal to −0.1 also generally suggested more change in the SETSM and TPASM. While this study generally supports the use of geomorphons as an analysis and aggregating unit for studying change patterns at the hillslope scale, more research is required to fully grasp the dynamics of landscape change at the hillslope scale in the TP. [ABSTRACT FROM AUTHOR]

Soil enzyme activity and its stoichiometry are excellent representatives of soil microorganisms' response to changing conditions, and act as a good indicator of microbial energy and nutrient demands. However, how soil enzyme activity and microbial nutrient limitation will be modified by grassland degradation is not well understood, especially in the saline‐alkaline meadow. Here, we presented how soil enzyme activity and microbial nutrient limitation shifted along a well‐characterized gradient of salinized degraded grasslands (non‐degraded, moderately degraded, and severely degraded). Our results showed soil enzyme activity was the highest in moderately degraded grasslands, which was mainly regulated by soil bacterial diversity. Soil microbial community metabolism in alkali‐saline meadow grasslands was limited by both carbon and phosphorus. Microbial carbon limitation showed a hump‐shaped pattern along the grassland degradation gradient, while microbial phosphorus limitation showed a gradually decreasing trend. Soil bacterial diversity is a key regulator of soil microbial carbon limitation, but the structure of the soil bacterial and plant community determines microbial phosphorus limitation. Taken together, our findings, taken together, provide evidence that soil bacteria are direct drivers of soil enzyme activity and microbial nutrient limitation along a grassland degradation gradient with salinization and suggest that these changes are regulated by soil salinity. [ABSTRACT FROM AUTHOR]

Central Asia is one of the most sensitive regions to climate changes in the world and the grassland degradation of this region has attracted considerable concern. Quantifying the driving force of grassland degradation is important for understanding the effects of climate variation and human activities on grassland. In this study, net primary productivity (NPP) was selected as an indicator to quantitatively evaluate the relative role of climate variation and human activities in Central Asia from 2000 to 2020. This study used the global NPP product MOD17A3 as actual NPP and estimated the potential NPP using the Thornthwaite memorial model. The potential NPP and the difference between the potential NPP and actual NPP were used to represent the influence of climate variation and human activities. The grassland degradation or restoration can be demonstrated by the slope of actual NPP (SA). A positive slope value (SA) suggested that restoration occurs, whereas a negative slope value suggested that degradation occurred. The results showed that 23.08% of the total grassland area experienced grassland degradation, whereas 2.51% of the whole grassland underwent grassland restoration. Furthermore, 53.8% of the degraded grassland areas were influenced by climate variation, and 14.5% were caused by human activities. By contrast, the relative roles of climate variation and human activities in grassland restoration were 25% and 47.9%, respectively. The NPP variation also could be calculated by assessing the effects of these factors and the results showed that 55.7% of the NPP decrease was caused by climate variation, whereas 9.6% was a result of human activities. On the contrary, climate variation and human activities resulted in 19.8% and 37.3% of grassland restoration, respectively. Therefore, climate variation was the dominant factor of grassland degradation, and human activities were the main driver of grassland restoration in Central Asia. [ABSTRACT FROM AUTHOR]

1.Atmospheric nitrogen (N) deposition poses serious threats to plant and soil microbial communities in natural grasslands, which can have consequences on ecosystem functioning. However, the effects of atmospheric N deposition can be modulated by grassland degradation, defined here as soil erosion, soil nutrient decline and loss of plant diversity, which has become a global threat to the functioning of these ecosystems. It remains poorly understood whether the responses of plant and soil microbial communities to N deposition vary with grassland degradation.2.We conducted a 9‐year multilevel (0, 10, 20, 30, 40, 50 g N m−2 year−1) N enrichment experiment at four sites in Inner Mongolia, China. We evaluated grassland degradation using a compound index (grassland degradation index) and classified grassland sites into four categories: non‐degraded, moderately, severely and extremely degraded grasslands. One site was selected for each category, and then three replicates were set up within each site. N was added in the form of urea.3.We first observed that the response of soil bacterial diversity to N addition was stronger in degraded grasslands than in non‐degraded grasslands, whereas the response of soil fungal diversity was not affected by degradation. Meanwhile, N enrichment had a weaker impact on plant diversity in degraded grasslands compared to non‐degraded grasslands. The controlling factors that affected the responses of soil microbial diversity and community composition to N addition were inconsistent among grasslands with different degradation status. Soil pH was the main driver in non‐degraded grasslands, and plant community composition became an important driver in degraded grasslands.4.Synthesis. Our findings highlighted that grassland degradation affected the response of bacterial and plant communities to N deposition and provided new information for the management and conservation of biodiversity in degraded grasslands. [ABSTRACT FROM AUTHOR]

As an essential ecological barrier in the north of China, the grassland degradation situation in the Xilin Gol League of Inner Mongolia has remained severe in recent years. Based on data spanning from 2010 to 2022, this study utilizes a set of ten indicators, encompassing altitude, temperature, precipitation, wind speed, FVC, LAI, FRAR, NPP, ET, and above-ground biomass, to construct a Bayesian model for assessing ecological risks associated with vegetation change in the Xilin Gol League. In the case of the most crucial parameter, above-ground biomass, we integrate spectral bands, vegetation indices, and ground-truth data, employing the Random Forest algorithm to estimate the above-ground biomass in the Xilin Gol League. The study further applies the Mann-Kendall trend test and Sen's slope estimation to analyze changes in this parameter and employs it as an indicator for assessing grassland degradation. The results showed that (1) Overall, the risk level decreases gradually from the west to the east and aligns with the grassland types of the Xilin Gol League. (2) In terms of spatial and temporal distribution, medium and high-risk areas are primarily located in the western region of the Xilin Gol League, showing a distinct westward shift from 2010 to 2022. (3) Areas with higher grassland degradation risk are characterized by lower altitudes, higher temperatures, less precipitation, lower vegetation coverage, and reduced potential evapotranspiration. (4) Under the pressures of both climate warming and vegetation change, there has been a significant shift in grassland degradation risk levels in the Xilin Gol League. The application of the Bayesian model effectively reveals intricate causal relationships among various variables, such as climate, terrain, and vegetation dynamics. This study could provide guidance for the prevention and control of grassland degradation in the Xilin Gol League.

Pastures provide different ecosystem services, such as carbon dioxide fixation, are indicators of climate change and prevent soil erosion. However, anthropogenic activities degrade and decrease soil diversity. Therefore, the objective was to evaluate pasture degradation using vegetation indices. For this purpose, the floristic composition was evaluated by means of linear transects (50 m) to determine the percentage of area covered by forages and weeds; the Normalized Vegetation Index (NDVI) and the Pasture Vegetation Cover (PVC) assessment methodology were used to determine pasture degradation, and the chemical properties of the soils were characterized. The degradation map showed that the range ''S4-Strongly degraded (CVP,

We analyzed the primary livelihood risks faced by livestock-herding households across six counties and three grassland types in Inner Mongolia. The major livelihood risks were natural, market, financial, and policy. These risks are influenced by changes in stocking rate (SR), which are critical for controlling livestock numbers and averting risks associated with overgrazing in natural grasslands. We propose a correction method for SR based on hay purchase from a survey of 450 herders. We compared the distribution of households’ SR after the correction and used a multiple linear regression model to empirically test the effect of livelihood risks on SR. The empirical model passed robustness test and the regression results of variables were robust. SR declined across grassland types after hay purchases. The SR of the meadow steppe was reduced by 35%, typical steppe by 23%, and desert steppe by 32%. Various factors affected changes in SR, including ecological subsidies to household income, timely access to market information, and annual livestock losses. We discuss implications of our findings for policy, market transactions, livestock insurance, social security, and formal credit systems in pastoral areas.

Central Asia hosts one of the largest continuous grassland areas on our planet, that is of vital importance for food security, biodiversity and carbon sequestration. However, this region is also subjected to some of the most intense land degradation processes, related to large scale land use change and climate change.To combat land degradation and pursue sustainable land management the concept of land degradation neutrality (LDN) has been proposed. LDN assessments are recommended to be based on global data in regions that lack sufficient regional data such as Central Asia. However, it remains unclear how the selection of datasets influences the estimated extent of land degradation. We followed the LDN framework and first calculated changes to three LDN indicators: land productivity, land cover, and Soil Organic Carbon (SOC). We then evaluated the impact of using different regional and global land cover data on the extent of land degradation in the region. Finally, we calculated a regionally specific integrated indicator on soil quality that we used to assess the “like-for-like” principle which enables counterbalancing losses and gains.Our results indicate that particularly the selection of land cover data has a significant impact on the overall assessment of degradation state. The extent of land between 2000 and 2019 varies considerably depending on the data and ranges between 15 and 34 % of the whole Central Asian region. Our findings reveal that the area of degraded land on high quality soils is twice as high as the area of high quality soils where the land condition has improved (12 % versus 6 %). In areas with low soil quality, 13 % was subject to degradation, and 10 % improved.Whilst the degradation extent varies according to the selected land cover datasets, our results demonstrates that Central Asia is undergoing land degradation affecting high quality soils. Sensitivity analysis of multiple datasets can reduce the risk of misjudgement in degradation extent assessments, especially in regions with mosaic ecosystems, such as grasslands.

Grassland degradation (within-state change) and desertification (state conversion from grasslands to deserts) are different states in the complex dynamic process of grassland deterioration. However, the dynamics and associated drivers of the two states have been rarely examined separately, which is critical for early warning and conservation policy making. Here, the grassland degradation and desertification in Central Asia (CA) were studied due to their evident vulnerability to climate extremes and human activities. We performed a two-step approach to identify the critical state zones first (i.e., grasslands, deserts, and the desertification zones) and then assess the vegetation dynamics within each zone. Finally, we quantified the roles of CO2 fertilization effect, climate change, climate variability, land use (LU), and anthropogenic climate change (ACC) on the vegetation dynamics in different state zones. The results showed that the areas of grasslands and sparse vegetation regions (including deserts and desertification zones) were stable from 2000 to 2020, but the trends of vegetation greenness were divergent with a reduction in grasslands and an increase in sparse vegetation regions. Furthermore, climate change and climate variability were the main driving force affecting grassland degradation in CA. Yet the vegetation greening in the desertification and desert zones was mainly driven by the rising CO2 and LU. Moreover, ACC degraded 20.63% of grasslands and sparsely vegetated lands in CA on the baseline of 2000. The results highlighted the risks of grassland degradation in CA. This study proposed a methodology to examine grassland degradation and desertification in detail and quantify the associated driving factors (especially ACC) at the pixel scale, which provided some insights on developing region-precise strategies for grassland conservation in CA and other drylands.

The Tibetan Plateau (TP), a vital region for terrestrial ecosystem services and biodiversity, is facing severe grassland degradation influenced by multiple factors. However, it remains unclear how several influential factors interactively influence grassland degradation. Here, we used five land cover products and six vegetation indexes to quantify grassland degradation on the TP. We then applied structural equation modeling (SEM) to quantitatively assess multiple factors and interactions affecting grassland degradation. We found that grassland degradation on the TP was mainly concentrated in the central and southern regions which were under high pressure from human activities, with the area of 325,430 km2, accounting for about 12.63% of the total grassland area on the TP during 2000–2020. The factors such as overgrazing, climate change, and human activities have contributed to the grassland degradation on the TP. Moreover, we found that there is a complex and interrelated relationship between these factors and that addressing one factor alone is unlikely to solve the problem of grassland degradation. Human activities significantly (p

Since the 1970s, certain areas within the Three-Rivers Headwater Region (TRHR) of China have faced severe land degradation due to the combined effects of climate change and human activities, leading to restricted ecological service functions and hindering the achievement of sustainable development goals (SDGs). Land degradation in the TRHR has received widespread attention. However, the current research mainly focuses on single-dimensional degradation and lacks a comprehensive evaluation of patterns and structures, as well as above-ground and underground assessments. To address this gap, this study employed the SDG indicator 15.3.1 framework, comprehensively considering fragmentation and habitat quality index based on land cover changes, grassland degradation index, and soil water erosion index. These indexes represent the three land degradation pathways of landscape degradation, vegetation degradation, and soil erosion. This study assessed land degradation patterns in the TRHR from 2000 to 2020. Results show that approximately 44.67% of the TRHR experienced land degradation during this period, mainly in meadow-dominated regions. Additionally, 5.64% of the regions experienced the superimposition of two or more land degradation pathways, with the frequent coexistence of soil erosion and grassland degradation, accounting for 4.1% of the affected areas. Landscape degradation affected approximately 2.39% of the regions, characterized by increased grassland fragmentation or habitat quality degradation. In terms of grassland degradation, 22.26% of the regions showed medium degradation, while 7.21% and 5.63% experienced moderate and severe degradation, respectively. Moreover, approximately 13.36% of the region faced a worsening situation of soil erosion. Approximately 55.34% of the study area underwent land improvement, with significant enhancements mainly concentrated in the western and eastern regions. The regrowth of grassland in the western region and the enhancement and homogenization of grassland productivity in the eastern region played pivotal roles in promoting land improvement. This study provides critical insights into the land degradation pattern in the TRHR over the past 20 years, offering valuable references for formulating and implementing measures to protect and construct the ecological security barrier of the plateau. [ABSTRACT FROM AUTHOR]

Accurate and timely estimation of grass yield is crucial for understanding the ecological conditions of grasslands in the Mongolian Plateau (MP). In this study, a new artificial neural network (ANN) model was selected for grassland yield inversion after comparison with multiple linear regression, K-nearest neighbor, and random forest models. The ANN performed better than the other machine learning models. Simultaneously, we conducted an analysis to examine the spatial and temporal characteristics and trends of grass yield in the MP from 2000 to 2020. Grassland productivity decreased from north to south. Additionally, 92.64% of the grasslands exhibited an increasing trend, whereas 7.35% exhibited a decreasing trend. Grassland degradation areas were primarily located in Inner Mongolia and the central Gobi region of Mongolia. Grassland productivity was positively correlated with land surface temperature and precipitation, although the latter was less sensitive than the former in certain areas. These findings indicate that ANN model-based grass yield estimation is an effective method for grassland productivity evaluation in the MP and can be used in a larger area, such as the Eurasian Steppe. [ABSTRACT FROM AUTHOR]

Alpine shrub meadows hold significant importance as grassland ecosystems on the Qinghai‐Tibetan Plateau (QTP). They provide a range of vital ecosystem services (ESs) and are commonly utilized as summer pastures by herders, resulting in short grazing periods and high grazing intensities. Unfortunately, these practices have led to varying degrees of degradation, thereby affecting the sustainable provision of ESs. However, the current knowledge regarding changes in ESs and their characteristics under the influence of degradation, particularly the differences between alpine shrub and alpine meadow ecosystems, is insufficient. To address this gap, this study aimed to investigate and analyse changes in four ESs within alpine shrub meadows across different levels of degradation, as well as explore their relationships. The research was conducted in a summer pasture located in the northeastern QTP. The findings revealed a substantial reduction of 85.9% in forage supply due to degradation in alpine shrub meadows. Moreover, regulating services experienced a decline followed by an increase in instances of heavy degradation. Trade‐offs were observed between provisioning and regulating services, while synergistic relationships were identified among different regulating services. Degradation exacerbated imbalances between provisioning and regulating services, whereas light degradation allowed for a better equilibrium between the two. Comparatively, alpine meadows exhibited higher levels of forage supply and carbon storage services, whereas alpine shrub ecosystems displayed greater nutrient supply and water retention services. It was observed that changes in ESs and relationship patterns within alpine shrub meadows were significantly influenced by the presence of alpine meadows. Consequently, safeguarding the structural integrity of alpine meadows and addressing conflicts over ESs is essential to ensure coordination and sustainability of ESs within alpine shrub meadows. The outcomes of this study provide valuable insights for ecosystem management and ecological restoration initiatives in alpine shrub meadows on the QTP. [ABSTRACT FROM AUTHOR]

Grassland is one of the largest terrestrial biomes, providing critical ecosystem services such as food production, biodiversity conservation, and climate change mitigation. Global climate change and land-use intensification have been causing grassland degradation and desertification worldwide. As one of the primary medium for ecosystem energy flow and biogeochemical cycling, grassland carbon (C) cycling is the most fundamental process for maintaining ecosystem services. In this review, we first summarize recent advances in our understanding of the mechanisms underpinning spatial and temporal patterns of the grassland C cycle, discuss the importance of grasslands in regulating inter- and intra-annual variations in global C fluxes, and explore the previously unappreciated complexity in abiotic processes controlling the grassland C balance, including soil inorganic C accumulation, photochemical and thermal degradation, and wind erosion. We also discuss how climate and land-use changes could alter the grassland C balance by modifying the water budget, nutrient cycling and additional plant and soil processes. Further, we examine why and how increasing aridity and improper land use may induce significant losses in grassland C stocks. Finally, we identify several priorities for future grassland C research, including improving understanding of abiotic processes in the grassland C cycle, strengthening monitoring of grassland C dynamics by integrating ground inventory, flux monitoring, and modern remote sensing techniques, and selecting appropriate plant species combinations with suitable traits and strong resistance to climate fluctuations, which would help design sustainable grassland restoration strategies in a changing climate.

Human‐mediated environmental change transforms ecosystems worldwide. Understanding the detailed impact of these unprecedented changes on biodiversity and ecosystem functioning, however, is challenging. Meadow ecosystems on the Tibetan Plateau transform as a result of climate change and anthropogenic disturbances. Evaluating the consequences of these meadow transformations on above‐ and below‐ground community structure, ecological network and ecosystem functioning is critical for predicting the impact on biodiversity and developing mitigation strategies.Here, we used a natural experiment across replicated sites to assess the responses of ecological networks of soil microbial communities and plant‐pollinator communities to meadow transformations and investigate the impacts of these changes on ecosystem multifunctionality.As a result of swampy meadow desiccation, species richness and ecological network complexity at multiple trophic levels increased, pollination networks became more robust while soil microbial networks became more vulnerable to species loss. Pollination function appeared to benefit from increased diversity in resources and the formation of dry soil, but important below‐ground functions decreased. When alpine meadows degraded further because of extensive grazing pressure, above‐ground diversity and network complexity tended to decline. Soil microbial richness and composition remained unchanged but associations among soil microbes homogenized, and ecosystem productivity and pollination function decreased.Our study provides empirical evidence that human‐mediated meadow transformations influence above‐ and below‐ground ecological networks and ecosystem functioning simultaneously. The findings highlight that ecosystem transformations can have contrasting effects on above‐ and below‐ground diversity and ecological networks, as well as ecosystem functions. Such contrasting responses call for targeted and nuanced management strategies to conserve biodiversity and ecosystem functioning in the Tibetan Plateau. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

One of the challenges of managing grasslands sustainably is the conflict between the different ecosystem services they provide. This is especially evident in the Qinghai-Tibetan Plateau (QTP) region, where fragile alpine ecosystems make balancing the needs of grassland conservation and development difficult. However, our current understanding of the relationships and drivers of ecosystem services in degraded alpine shrub meadows on the QTP is insufficient. To address this, we studied forage provisioning and water retention services in a degraded alpine shrub meadow in the northeastern QTP. We analyzed the changes and relationships between these services at different levels of degradation and identified those factors that influenced ecosystem service relationships. The results showed that the forage supply service and the water retention service of the alpine shrub meadow increased and decreased by 23.6% and 27.07%, respectively, due to degradation. The trade-offs between these two services varied depending on the degree of degradation, with light and moderate degradation showing a preference for water retention service, and heavy and extreme degradation showing a preference for forage supply. Water retention was constrained by forage supply and both services showed an exponential function form of decay. The physical and chemical properties of the soil in the alpine shrub meadow remained relatively stable during the degradation process, with only soil organic carbon (SOC), total potassium (TK), and total nitrogen (TN) decreasing significantly. SOC may have indirectly influenced the relationship between the two services by affecting water retention. This study provides insights into alpine shrub meadow management and conservation on the QTP. [ABSTRACT FROM AUTHOR]

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Abstract Alpine shrub meadows hold significant importance as grassland ecosystems on the Qinghai‐Tibetan Plateau (QTP). They provide a range of vital ecosystem services (ESs) and are commonly utilized as summer pastures by herders, resulting in short grazing periods and high grazing intensities. Unfortunately, these practices have led to varying degrees of degradation, thereby affecting the sustainable provision of ESs. However, the current knowledge regarding changes in ESs and their characteristics under the influence of degradation, particularly the differences between alpine shrub and alpine meadow ecosystems, is insufficient. To address this gap, this study aimed to investigate and analyse changes in four ESs within alpine shrub meadows across different levels of degradation, as well as explore their relationships. The research was conducted in a summer pasture located in the northeastern QTP. The findings revealed a substantial reduction of 85.9% in forage supply due to degradation in alpine shrub meadows. Moreover, regulating services experienced a decline followed by an increase in instances of heavy degradation. Trade‐offs were observed between provisioning and regulating services, while synergistic relationships were identified among different regulating services. Degradation exacerbated imbalances between provisioning and regulating services, whereas light degradation allowed for a better equilibrium between the two. Comparatively, alpine meadows exhibited higher levels of forage supply and carbon storage services, whereas alpine shrub ecosystems displayed greater nutrient supply and water retention services. It was observed that changes in ESs and relationship patterns within alpine shrub meadows were significantly influenced by the presence of alpine meadows. Consequently, safeguarding the structural integrity of alpine meadows and addressing conflicts over ESs is essential to ensure coordination and sustainability of ESs within alpine shrub meadows. The outcomes of this study provide valuable insights for ecosystem management and ecological restoration initiatives in alpine shrub meadows on the QTP.

The alpine grasslands of the Qinghai–Tibet Plateau are one of the most famous grazing ecosystems in the world, providing a variety of ecosystem functions and services. The rate of grassland degradation has been slowed by the implementation of national grassland restoration projects, but the degradation of grasslands on the Qinghai–Tibet Plateau has not yet been fundamentally reversed, and some grasslands are still degraded to varying degrees. The main causes of grassland degradation on the Qinghai–Tibet Plateau are both human and natural factors. Human factors include overgrazing, over-cultivation, indiscriminate digging and mining, mineral resource development, infrastructure construction and use, and tourism development. Natural factors include climate change, wildlife destruction, pests, etc. Based on the principles of restoration ecology, a number of effective practices and integrated management responses for restoring degraded grasslands have been developed on the Qinghai–Tibet Plateau. The degraded grassland restoration practices include fencing, fertilization, sown grassland establishment, rodent control, and grazing management. Based on these practices, the comprehensive restoration of degraded grasslands and the establishment and sustainable management of sown grasslands in the alpine grasslands of the Qinghai–Tibet Plateau should be further strengthened, and research on the mechanisms of grassland degradation and restoration should be further developed. [ABSTRACT FROM AUTHOR]

Grassland degradation is a major ecological problem at present, leading to changes in the grassland environment and the soil microbial community. Here, based on full-length 16S rRNA gene sequencing, we highlight the importance of small-scale environmental changes on the Qinghai-Tibet Plateau grassland for the composition and assembly processes of abundant and rare bacterial taxa. The results showed that grassland vegetation coverage affected the taxonomic and phylogenetic composition of rare bacterial taxa more than abundant bacterial taxa. The taxonomic composition and phylogenetic composition of rare bacterial taxa were also affected by soil nutrients. The relative contribution of deterministic processes (variable selection and homogeneous selection) to rare bacterial taxa was higher than that of the abundant bacterial taxa. The competitive potential within rare bacterial taxa was lower than that of the competitive potential between rare and non-rare bacterial taxa or within non-rare bacterial taxa. The assembly of rare bacterial taxa was more susceptible to environmental changes caused by grassland degradation than the abundant bacterial taxa. Furthermore, the distribution of rare bacterial taxa in the different degraded grassland soil was more local than that of abundant bacterial taxa. Thus, rare bacterial taxa could be considered an ecological indicator of grassland degradation. These findings help to improve our understanding of the composition and assembly mechanism of the bacterial communities in degraded grassland and provide a basis for the establishment of the grassland degradation management strategy. [ABSTRACT FROM AUTHOR]

Grassland degradation is commonly thought to cause soil organic carbon (SOC) change, and the response of SOC stock to degradation is highly dependent on grassland type. However, the effects of grassland type on changes in SOC stocks with grassland degradation over broad geographic scales remain unclear. Here, we explored the probably different responses of SOC stocks to grassland degradation for alpine meadows and alpine steppes based on 58 peer‐reviewed publications regarding the Qinghai‐Tibetan Plateau. The results showed that SOC stock consistently decreased with increasing degradation levels in both alpine meadows and steppes, whereas the magnitudes of reduction of SOC stock in alpine meadows were significantly larger than those in alpine steppes (p < 0.05). The variations in SOC stock were significantly positively correlated with variations in aboveground biomass in the alpine steppes only (p < 0.05) but were significantly positively correlated with variations in belowground biomass in both alpine meadows and alpine steppes (p < 0.01). The relationships between change rates of SOC stock with initial SOC stock and mean annual precipitation were both significantly negative during the lightly and moderately degraded stages, while the negative relationship became nonsignificant for the heavily degraded stage (p > 0.05). These findings suggest that soil organic carbon stock responded more sensitively to degradation in alpine meadows with higher initial SOC stock and annual mean precipitation than in alpine steppes. Our study might have significant implications for future sustainable management practices for carbon sequestration of alpine grasslands on the Qinghai‐Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Soil microorganisms could obtain energy and nutrients during litter decomposition with the help of soil extracellular enzymes. The litter types were among the most critical factors that affect soil extracellular enzyme activities. However, how litter types modulate the soil extracellular enzyme activity with grassland gradation is unclear. Here, we conducted a 240-day experiment of two different types of litter decomposition on soil extracellular enzyme activity and stoichiometry in different degraded grasslands. We found that C-acquiring enzyme activity and the enzyme stoichiometry of C/N were higher in Chloris virgata litter than in Leymus chinensis litter at lightly degraded level and C-acquiring enzyme activity in C. virgata was 16.96% higher than in L. chinensis. P-acquiring enzyme activity had the same trend with litter types in moderately and highly degraded levels and it was 20.71% and 30.89% higher in C. virgata than that in L. chinensis, respectively. The change of the enzyme stoichiometry with litter types was only showed in the enzyme stoichiometry of C/N at lightly degraded level, suggesting that litter types only affected the microbial C limitation in lightly degraded grassland. Almost all soil extracellular enzyme activities and extracellular enzyme stoichiometry, except the enzyme stoichiometry of N/P, decreased with grassland degraded level increasing. All vector angles were less than 45° suggesting that soil microorganisms were limited by N rather than by P during the decomposition process. Enzyme vector analysis revealed that soil microbial communities were co-limited by C and N during litter decomposition. Moreover, based on Random Forest (explaining more than 80%), we found that soil total nitrogen, total carbon, total phosphorus, dissolved organic C, pH and EC were important factors affecting soil enzyme activities by degradation levels. Our results emphasized that degradation levels could modulate the influences of litter types on soil extracellular enzyme activity. Our study enhanced our understanding in resource requirements for microbial communities to litter resources in degraded grassland and helped us to provide new ideas for improving degraded grassland ecosystems. [ABSTRACT FROM AUTHOR]

The Kobresia meadow in the Tibetan plateau is the world's largest and most unique pastoral alpine ecosystem, forming dense and closed 'lawns'mainly dominated by Kobresia species. Soil cracking induced by overstocking is an important feature of degraded alpine Kobresia meadows: it cuts the closed, intact rangeland and alters microtopography. However, soil cracks in alpine grasslands of the Tibetan plateau have rarely been reported and the importance of cracking in relation to livestock overgrazing for the degradation and collapse of alpine rangelands has not been taken seriously. In this Perspectives article, we explain the mechanisms of soil crack formation in Kobresia meadows under overgrazing; the ways in which the soil cracks affect the dynamics of hydrological processes and trigger the erosion of Kobresia turfs; and finally the effects on plant community composition and distribution. We outline the importance of recognizing soil cracks as visual indicators and early warning signs of degradation in order to recover alpine Kobresia meadows by reducing stocking rate. The purpose of this article is to emphasize that researchers and managers of alpine rangelands should pay more attention to crack phenomena in an effort to promote sustainable practices and restoration in Kobresia meadow-livestock systems. [ABSTRACT FROM AUTHOR]