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The alpine grasslands of the Kashmir Himalayas serve as a lifeline for the region's pastoral communities, providing the primary source of forage for their livestock. These high-altitude rangelands are not only crucial for the livelihood of these communities but also play a significant role in maintaining the ecological balance of the area. However, sustainable pastoralism in these fragile ecosystem hinges on a thorough understanding of forage availability and livestock carrying capacity. This study assesses the forage dynamics and livestock carrying capacity of these high-altitude grasslands. Through comprehensive biomass sampling across 23 strategically selected sites, we calculated an average dry matter above ground biomass yield of 5.10 metric tons per hectare, resulting in a total dry biomass weight of approximately 820,489.22 metric tons (820,489,220 kg), over the entire grassland area of 160,974 ha. Using a daily forage intake of 1.3 kg per Sheep Unit (SU) over 50 grazing days, time period which corresponds to the renewal period for new grass growth, the average carrying capacity of the rangelands was determined to be 39.08 Animal Units (AU) per hectare and the total carrying capacity was estimated as 62,78,556 SU. The current stocking rate of 4,661,800 SU utilizes about 74.21% of this Carrying capacity, leaving a surplus of 25.77% or 1,616,756 Animal Sheep Units. However, localized overgrazing in areas such as Thajwas and Mohand Marg highlights the need for targeted management practices to prevent rangeland degradation. This data is critical as it provides a baseline for understanding the potential of these rangelands to support livestock. This study underscores the importance of sustainable livestock management to optimize carrying capacity while maintaining the ecological balance of the grasslands. Engaging local pastoral communities in these efforts is essential for the effective and sustainable management of the alpine grasslands in the Kashmir Himalayas. [ABSTRACT FROM AUTHOR]

The fractional cover of native grass species (NGS) and noxious weeds (NW) provides a more comprehensive understanding of grassland health in the alpine grasslands. However, coverage extraction of NGS and NW from satellite hyperspectral imagery can be challenging due to the small spectral and spatial feature difference, insufficient training samples, and the lack of effective fractional cover extraction methods. In this research, firstly, a feature optimization method is proposed to optimize the difference feature between NGS and NW. Secondly, a spectral–spatial constrained re-clustering training sample extension method (SSCTSE) is proposed to increase the number of training samples. Thirdly, a composite three-kernel SVM method (CTK-SVM) is developed to produce fractional cover maps of NGS and NW. The experimental results show that (1) the feature optimization method is effective in preserving the spectral and spatial difference features while eliminating invalid features; (2) the SSCTSE algorithm is capable of significantly increasing the number of training samples; (3) the fractional cover maps of NGS and NW are produced with the CTK-SVM method with overall accuracies of approximately 65%, and the RMSEs of NGS and NW are approximately 16% and 11%, respectively. The results provide a foundation for the fractional cover extraction of different grass species in alpine grasslands based on satellite hyperspectral imagery. [ABSTRACT FROM AUTHOR]

The alpine grasslands of the Qiangtang Plateau face significant ecological risks due to extensive human activities, particularly in areas along lakeshores and riverbanks, where overgrazing has caused severe degradation and salinization of the grasslands. Conducting fieldwork in such environments presents significant challenges for long‐term community‐scale landscape ecological research. In this study, the habitat characteristics of dominant plant communities in the alpine basin of Zhari Namco were quantified from three perspectives: topography, hydrology, and fractional vegetation cover. Using Aster GDEM and Landsat imagery, five grassland types were mapped for 2001–2021. Based on the spatial variables of area, shape, and distance, 13 landscape indices were selected to observe spatiotemporal changes. The results revealed several key findings: (1) The patch structure of the zonal vegetation Stipa purpurea steppe has undergone a pattern of dispersion‐aggregation‐dispersion in the past 20 years, yet the core habitat area remains unchanged by more than 52%, indicating fundamental stability in the southern Qiangtang alpine grassland; (2) Using the minimally grazed Kobresia pygmaea meadow as a reference, other communities exhibit stability similar to or approaching it, but with significant differences in aggregation level. The gradual expansion of grazing and economic activities has been a driving factor; and (3) Water conservation projects have diversified the use of water resources in river and lakeside habitats. Stipa purpurea + Carex moorcroftii steppe and Carex swamp meadow exhibit optimal carrying capacity, making them the only areas with relatively high sustainability. The study underscores that the current ecological benefits are a result of effective management. However, without proper management, the region could trend towards landscape fragmentation, becoming the most vulnerable zone in the watershed. Therefore, it is essential to strengthen retrospective analysis of grazing intensity and trend analysis of habitat changes to provide a scientific basis for local economic development and grazing management. [ABSTRACT FROM AUTHOR]

Carbon use efficiency (CUE) is essential for understanding how climate change impacts carbon fixation by vegetation across diverse ecosystems globally. However, the effects of anthropogenic efforts, such as ecosystem restoration of degraded grasslands via livestock grazing exclusion with fences on the spatiotemporal variation in CUE under ongoing climate change remain poorly evaluated and understood. In this study, we calculated CUE values for fenced and adjacent grazed alpine grasslands in Tibet, China. We considered soil properties, topographical features, and climate conditions as potential predictors to explain the spatial patterns and temporal dynamics of CUE across these grasslands. Our results showed that the annual mean CUE of fenced vs. grazed grasslands were similar with values of 0.6961 and 0.6956 across the whole plateau. However, the annual CUE of fenced grasslands increased at a faster rate (6.89 × 10−5 per year) compared to grazed grasslands (0.23 × 10−5 per year) from 2006 to 2019. CUE also exhibited substantial variation across alpine grassland communities, with the highest values observed in alpine steppe meadows under both fenced and grazed management. Precipitation was identified as the most influential factor controlling the spatial pattern of CUE and showed a significant negative correlation with CUE. Moreover, the presence of fences was found to reduce the sensitivity of CUE to in response to varying precipitation. The effectiveness of fences in enhancing CUE primarily depends on local environmental conditions. Our study sheds light on the interplays between ecological restoration efforts and climate change in shaping the CUE dynamics of alpine grasslands on the Tibetan Plateau and emphasizes the importance of local environmental contexts when programming and implementing restoration projects.

The alpine grasslands of the Kashmir Himalayas serve as a lifeline for the region’s pastoral communities, providing the primary source of forage for their livestock. These high-altitude rangelands are not only crucial for the livelihood of these communities but also play a significant role in maintaining the ecological balance of the area. However, sustainable pastoralism in these fragile ecosystem hinges on a thorough understanding of forage availability and livestock carrying capacity. This study assesses the forage dynamics and livestock carrying capacity of these high-altitude grasslands. Through comprehensive biomass sampling across 23 strategically selected sites, we calculated an average dry matter above ground biomass yield of 5.10 metric tons per hectare, resulting in a total dry biomass weight of approximately 820,489.22 metric tons (820,489,220 kg), over the entire grassland area of 160,974 ha. Using a daily forage intake of 1.3 kg per Sheep Unit (SU) over 50 grazing days, time period which corresponds to the renewal period for new grass growth, the average carrying capacity of the rangelands was determined to be 39.08 Animal Units (AU) per hectare and the total carrying capacity was estimated as 62,78,556 SU. The current stocking rate of 4,661,800 SU utilizes about 74.21% of this Carrying capacity, leaving a surplus of 25.77% or 1,616,756 Animal Sheep Units. However, localized overgrazing in areas such as Thajwas and Mohand Marg highlights the need for targeted management practices to prevent rangeland degradation. This data is critical as it provides a baseline for understanding the potential of these rangelands to support livestock. This study underscores the importance of sustainable livestock management to optimize carrying capacity while maintaining the ecological balance of the grasslands. Engaging local pastoral communities in these efforts is essential for the effective and sustainable management of the alpine grasslands in the Kashmir Himalayas.

Despite playing a fundamental role in plant population dynamics, the considerable variability and control of belowground bud banks in grasslands currently remain unknown globally. Here, we explored the size and driver of belowground bud bank both in alpine (Qinghai-Tibet Plateau: QTP) and temperate (Inner Mongolia Plateau: IMP) grasslands across China, using a dataset comprising 209 observations at 171 sites compiled from laboratory and published data. We found that temperate grassland had higher density (912 no./m2) dominated by tiller buds (72.26 %) than alpine grasslands (768 no./m2) dominated by rhizome buds (51.56 %). Moreover, belowground bud of alpine grassland exhibited longitudinal, latitudinal and altitudinal patterns, more diverse than those of longitudinal and latitudinal pattern in temperate grassland. Furthermore, climate, particularly the precipitation, is the factor controlling belowground bud in alpine grassland, while soil nutrient predominantly controls those in temperate grassland. Our study advances understanding of the variability and its climate and soil regulation on belowground buds in grasslands, sheds new light on differing management respectively for alpine and temperate grasslands in the context of climate change.

Quantifying the elevation dependency of radiation partitioning in high‐altitude mountains is crucial for projecting regional energy balance while remains highly uncertain. We compared the surface radiation partitioning parameters across a meadow (3,200 m), shrub (3,400 m), and forb (3,600 m) along a southern slope of the Qilian Mountains. At a daily scale, the downward shortwave radiation (Rs) fluctuated minimally among the grassland types probably induced by similar site orientations. The greatest downward and upward longwave radiation (Ld and Lu) happened at the lowest meadow while the largest net shortwave (Sn) and longwave (Ln) radiation occurred at the deciduous shrub. The net all‐wave radiation (Rn) of the meadow and shrub was similar and exceeded that of the forb by ∼20%. The differences in Rn between the sites were jointly explained by those of upward shortwave radiation (Ru) and Lu, more than by Rs and Ld, suggesting the importance of surface attributes. The monthly normalized effective terrestrial radiation (λ, the ratio of Ln to Rs) varied insignificantly among the sites and averaged 0.25 ± 0.05, which was comparable to the global mean value (0.26). The smallest surface albedo (α, the ratio of Ru to Rs) and largest radiation efficiency (η, the ratio of Rn to Rs) were 0.13 ± 0.02 and 0.64 ± 0.09, respectively, both at the shrub. Grassland type dominated the spatial variations of monthly α and η. These findings highlighted the importance of grassland types to explain the spatiotemporal variations of radiation partitioning parameters in high‐altitude alpine grasslands. Plain Language Summary: An accurate understanding of the radiation budget and partitioning of high‐altitude mountainous regions played a pivotal role in projecting the global climate system. This is especially true in the Qinghai‐Tibetan Plateau, the so‐called "roof of the world", where there is a large scarcity of high‐quality field observations from different vegetation types. We compared the four‐component radiation measurements of alpine grasslands along an altitudinal gradient (a meadow at 3,200 m, a shrub at 3,400 m, and a forb at 3,600 m) of a southern slope of the Qilian Mountains. We found that the incoming shortwave radiation changed little across the three sites. However, the lowest meadow had the largest incoming and outgoing longwave radiation. The net all‐wave radiation of the meadow and shrub exceeded that of the highest forb. The shrub had the lowest annual surface albedo and the biggest annual radiation efficiency. The annual normalized effective terrestrial radiation fluctuated minimally across the three sites and was comparable to the global mean value. Grassland type was the most important variable responsible for the variations of surface albedo and radiation efficiency. Our findings underscored the importance of taking surface attributes into account when projecting radiation budget and partitioning in high‐altitude alpine grasslands. Key Points: The differences in net all‐wave radiation were jointly explained by the differences in upward shortwave and longwave radiationThe normalized effective terrestrial radiation was conservative among these grasslands and comparable to the global mean valueGrassland type, more than environmental variables explained the spatiotemporal variations of surface albedo and radiation efficiency [ABSTRACT FROM AUTHOR]

Abstract The alpine grasslands of the Qiangtang Plateau face significant ecological risks due to extensive human activities, particularly in areas along lakeshores and riverbanks, where overgrazing has caused severe degradation and salinization of the grasslands. Conducting fieldwork in such environments presents significant challenges for long‐term community‐scale landscape ecological research. In this study, the habitat characteristics of dominant plant communities in the alpine basin of Zhari Namco were quantified from three perspectives: topography, hydrology, and fractional vegetation cover. Using Aster GDEM and Landsat imagery, five grassland types were mapped for 2001–2021. Based on the spatial variables of area, shape, and distance, 13 landscape indices were selected to observe spatiotemporal changes. The results revealed several key findings: (1) The patch structure of the zonal vegetation Stipa purpurea steppe has undergone a pattern of dispersion‐aggregation‐dispersion in the past 20 years, yet the core habitat area remains unchanged by more than 52%, indicating fundamental stability in the southern Qiangtang alpine grassland; (2) Using the minimally grazed Kobresia pygmaea meadow as a reference, other communities exhibit stability similar to or approaching it, but with significant differences in aggregation level. The gradual expansion of grazing and economic activities has been a driving factor; and (3) Water conservation projects have diversified the use of water resources in river and lakeside habitats. Stipa purpurea + Carex moorcroftii steppe and Carex swamp meadow exhibit optimal carrying capacity, making them the only areas with relatively high sustainability. The study underscores that the current ecological benefits are a result of effective management. However, without proper management, the region could trend towards landscape fragmentation, becoming the most vulnerable zone in the watershed. Therefore, it is essential to strengthen retrospective analysis of grazing intensity and trend analysis of habitat changes to provide a scientific basis for local economic development and grazing management.

Study region: The source region of the Yangtze River in the Qinghai-Tibet Plateau, China. Study focus: In the context of global warming, conducting a comprehensive study on the hydrothermal processes and their influencing factors in the permafrost active layer of the Tibetan Plateau is crucial for gaining a better understanding of the ecohydrological processes in alpine grasslands. In this study, we analyzed differences in soil temperature and humidity change patterns in the active layer of four alpine grassland types in the Totuohe Basin of the Yangtze River source area. We aimed to discuss the influence of vegetation, soil, and other factors on the hydrothermal mechanism of the active layer. The main research results are as follows: (1) Significant differences in the active layer's hydrothermal regime, with higher vegetation cover correlating to lower thaw indices and better moisture conditions. (2) Vegetation and water content strongly influence thermal conditions and active layer thickness. In high-cover alpine meadows, ground surface temperature is lower with a 200 cm active layer, while swamp meadows have a shallowest layer at 160 cm. (3) Deeper active layer moisture is influenced by freezing and thawing, while shallower layers are affected by warm-season precipitation and soil texture. (4) Negative heat fluxes in the topsoil of alpine swamp and high-cover meadows indicate substantial heat release, likely contributing to permafrost preservation due to high active layer water content. New hydrological insights for the region: (1) Vegetation cover significantly influences the thermal and moisture conditions of the active layer, with higher vegetation associated with lower thaw indices and better moisture conditions.(2) Soil moisture distribution within the active layer is controlled by both freeze-thaw cycles and warm-season precipitation, indicating complex interactions between seasonal processes and soil properties.

The fractional cover of native grass species (NGS) and noxious weeds (NW) provides a more comprehensive understanding of grassland health in the alpine grasslands. However, coverage extraction of NGS and NW from satellite hyperspectral imagery can be challenging due to the small spectral and spatial feature difference, insufficient training samples, and the lack of effective fractional cover extraction methods. In this research, firstly, a feature optimization method is proposed to optimize the difference feature between NGS and NW. Secondly, a spectral–spatial constrained re-clustering training sample extension method (SSCTSE) is proposed to increase the number of training samples. Thirdly, a composite three-kernel SVM method (CTK-SVM) is developed to produce fractional cover maps of NGS and NW. The experimental results show that (1) the feature optimization method is effective in preserving the spectral and spatial difference features while eliminating invalid features; (2) the SSCTSE algorithm is capable of significantly increasing the number of training samples; (3) the fractional cover maps of NGS and NW are produced with the CTK-SVM method with overall accuracies of approximately 65%, and the RMSEs of NGS and NW are approximately 16% and 11%, respectively. The results provide a foundation for the fractional cover extraction of different grass species in alpine grasslands based on satellite hyperspectral imagery.

The alpine meadow of the Qinghai–Tibetan Plateau is an essential terrestrial ecosystem that provides a livelihood for approximately 9.8 million local inhabitants and serves as a habitat for millions of livestock. Changing facets of the global environment, such as increased nitrogen deposition, have not only affected the abundance and quality of forgeable plants but have also increased the prevalence and severity of plant diseases caused by pathogens. However, whether or not and to what extent these pathogens affect the rangeland quality of the alpine meadow remains unclear. We conducted a factorial experiment with the exclusion of fungal and oomycete pathogens to investigate the impact of various pathogens on rangeland quality in an alpine meadow in the Qinghai–Tibetan Plateau. We measured forage production for each plant species, forage quality (including measurements of organic matter, crude protein, phosphorus, total phenolics, neutral detergent fiber (NDF), metabolizable energy, and digestibility) for 11 abundant species, and community composition. We found that fungal pathogen exclusion and the combination of fungal and oomycete pathogen exclusion primarily affected nutrient production by altering forage production rather than changing community composition or forage quality. Exclusion of both fungal and oomycete pathogens led to a significant increase in community forage production, although no significant effect was observed for individual exclusion of fungal or oomycete pathogens. Excluding either fungal pathogens alone or simultaneous exclusion of both fungal and oomycete pathogens significantly increased the metabolizable energy content of the community. In contrast, oomycete pathogen exclusion significantly decreased the forage metabolizable energy content of the community. The exclusion of both fungal and oomycete pathogens also considerably increased the yield of organic matter, total phenolics, NDF, digestible dry matter, and metabolizable energy. However, the direction and magnitude of the effect of fungal and oomycete pathogen exclusion varied widely across the different species studied. These results suggest that the interaction of fungal and oomycete pathogens constitutes an essential limiting factor in rangeland quality that has not been previously recognized. Greater attention should be placed on overall forage production rather than forage quality in the context of grassland pathogen control strategies. Furthermore, metabolizable energy content may serve as an effective indicator for predicting the impact of pathogenic activity on forage quality. [ABSTRACT FROM AUTHOR]

Purpose: Livestock dung deposition significantly impacts the greenhouse gas emissions, soil nutrient dynamics, soil microbial biomass, and enzyme activities of grasslands. As a typical process of microbial community coalescence, dung deposition may also affect grassland ecosystems by changing soil microbiomes. However, its effects on alpine grassland soil microbial abundance, diversity, and community profiles remain largely unexplored. Therefore, this study aimed at evaluating the influences of dung deposition-mediated community coalescence on alpine grassland soil microbiomes. Methods: Soils were collected from 40 pairs of yak dung-covered patches and their adjacent grasslands along a transect on the Tibetan Plateau. Quantitative PCR and amplicon high-throughput sequencing were employed to determine the abundance, diversity, and community composition of soil microbes. Results: Dung deposition-mediated community coalescence significantly altered multiple soil properties and the composition of soil microbial communities. Specifically, the relative abundance of diazotrophs, photoautotrophs, nitrifiers, pathogens, and lichens significantly decreased due to dung-soil microbial community coalescence, while the proportions of methanogens, denitrifiers, saprotrophs, cellulolytic microbes, and chemoheterotrophs showed opposite change trends. Soil microbial community structures were closely correlated with multiple soil and plant properties (e.g., nutrient contents and plant aboveground biomass) in both control and dung-covered soils. Additionally, dung deposition-mediated community coalescence dramatically decreased the complexity of soil microbial co-occurrence patterns but exerted negligible effects on network stability. Conclusions: These findings suggest that yak dung deposition has the potential to increase greenhouse gas emissions, but it can also improve soil nutrient contents and decrease plant disease risks. This study highlights the dual effects of dung deposition on grassland ecosystems and provides critical information for guiding alpine grassland management. [ABSTRACT FROM AUTHOR]

Copyright of Flora Montibérica is the property of Flora Montiberica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: The study of soil erodibility is an important step in understanding the mechanism of soil erosion, and is crucial to the sustainable development of grassland ecosystems. However, few studies have investigated the potential effects of different degradation levels and restoration ages on soil erodibility on the Qinghai−Tibetan Plateau where many alpine grasslands suffering from severe degradation have been restored for different years. Materials and methods: In order to quantify the impact of alpine grassland degradation and restoration on soil erodibility, we selected different degradation levels (non-degraded, lightly degraded, moderately degraded, and heavily degraded) and restored ages (3, 8, 13, and 19 years) on the Qinghai-Tibet Plateau. Soil sampling was carried out at different depths, and the microaggregate fractal dimension (Dv), multifractal theory (Dm) and erodibility factor (K) were measured and calculated to quantify the soil changes in erodibility. Results and discussion: With the degree of degradation increased, the K value in the surface soil changed little, but the Dv value increased significantly. On the grassland recovery sequence, the K value showed a trend of increasing first and then decreasing, and the K factor and Dm of 19-y restored grasslands was reverted to the same level as that of the non-degraded site. Furthermore, the K value and Dv value increased with the increase in soil depth. Our result also shows that root biomass, microorganisms, and soil physicochemical properties including SOC, TN, TP, PSD, and MSD were all significantly correlated with K value. Conclusions: Our research proves that restoration of alpine grassland on the Qinghai-Tibet Plateau helps reduce soil erodibility, and reveals that plant roots, soil physical and chemical properties, and microorganisms play an important role in reducing soil erodibility, further deepening the influence on soil erodibility. This understanding can provide a certain theoretical basis for the sustainable development of grassland ecosystems. [ABSTRACT FROM AUTHOR]

Solar-induced chlorophyll fluorescence (SIF) is strongly physiologically associated with vegetation photosynthesis, and has been broadly employed to monitor gross primary productivity (GPP). However, for some understudied ecosystems, such as the alpine grasslands of the Tibetan Plateau (TP), it is highly uncertain about how SIF performs in tracking GPP. Here, by collecting eddy covariance-derived GPP and climatic data at four grassland sites in the TP, the performances of remotely sensed SIF products (CSIF and GOSIF) in estimating GPP at different time scales (8-day, monthly and growing season) were evaluated and compared against reflectance-based greenness vegetation indices (GVIs) and photochemical reflectance indices (PRIs). Moreover, the SIF-GPP relationship was further examined under different water conditions. The results showed that SIF performed best in tracking GPP variations at all temporal scales compared with GVIs and PRIs. With temporal aggregation, the SIF-GPP relationship was markedly enhanced. We further found that both determination coefficient (R2) values and slopes of the SIF-GPP relationship tended to be lower with decreasing soil water content or increasing vapor pressure deficit. This indicates SIF and GPP will be decoupled with aggravating water stress and their relationship is not universal under different water conditions. Morever, integrating soil water content with SIF improved GPP estimation, underscoring the vital role of water availability in influencing the SIF-GPP relationship. This study can boost our understanding on the variant SIF-GPP relationship and suggests that the regulation effect of water availability need be considered to improve the SIF-derived GPP estimation.

Soil greenhouse gas (GHG) emissions play an important role in regional climate feedback on the Qinghai-Tibetan Plateau (QTP). Previous studies have focused on soil GHGs based on observations within a limited space on the QTP, however, the regional GHG emissions remain unclear. Analyzing soil samples from 25 sites along a 2,700 km transect across QTP, we showed significantly higher soil CO2 and N2O emission rates in alpine meadows than other upland grassland types, but similar soil CH4 uptake rates across all grassland types. The spatial variations of total soil GHG balance were dominated by CO2 emission. We found that CO2 emission was primarily constrained by high soil pH, low soil moisture and nutrient availability, and fungal abundance, N2O emission was inhibited by high soil pH, while CH4 uptake was dominated by methanotrophic abundance. Furthermore, we estimated a current regional total soil GHG balance of 144.4 Tg CO2-eq yr−1 for surface soil across Tibetan alpine grasslands, which increased by 17.6%, 24.8%, and 38.9% under warming scenarios of 1.5℃, 2℃ and 3℃, respectively. Our results provide a baseline for regional soil GHG emissions responding to climate warming on the QTP.

The ongoing intensification of the hydrological cycle due to global climate change alters intra-annual precipitation variability. Changes in precipitation patterns lead to disparities in soil moisture; however, the responses of soil extracellular enzyme activities (EEAs) and microbial metabolism limitations to them is unclear. This study conducted an in situ field experiment in the alpine grasslands of the Kunlun Mountains to simulate the same amount of precipitation but change the distribution time of precipitation within the plant growing season. We examined the effects of variability in intra-annual precipitation patterns on the stoichiometry of topsoil (0–5 and 5–20 cm) properties, microbial biomass, and EEAs. Results showed that altered precipitation patterns significantly increased soil moisture’s disparity index (D) by 57 %–89 %. The activity of nitrogen-acquiring enzymes (L-leucine aminopeptidase) was increased by 20.82–32.08 % (P

Earthquakes are environmental disturbances affecting ecosystem functioning, health, and biodiversity, but their potential impacts on plant--soil interface are still poorly understood. In this study, grassland habitats in areas near and away from the seismo-fault in Madou, a region typical of alpine conditions on the Qinghai-- Tibetan Plateau, were randomly selected. The impacts of earthquake on soil properties and plant nutrient content in the short term were emphasized, and their potential relationships with community diversity and productivity were examined. According to the findings of the study, the Maduo earthquake led to a decrease in soil nutrient content in alpine grassland ecosystems, especially soil TC, TN, TP, TCa, AP, AK, NH4 +-N, and SOC, and inhibited the absorption of N, Ca, and Mg nutrients by plants. In addition, the diversity and productivity of communities were affected by both direct and indirect earthquake pathways. The negative impacts of seismic fracture on soil structure had the most significant direct impact on plant community diversity. Earthquakes also indirectly reduced community productivity by reducing the soil N content and inhibiting the absorption of plant nutrients. Our findings suggested that earthquakes could potentially decrease the stability of the alpine grassland ecosystem on the QTP by affecting nutrient availability at the plant--soil interface. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Ecology is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Grazing exclusion (GE) and rest grazing (RG) are important management systems for the restoration of degraded grassland ecosystems. In order to evaluate the effects and mechanisms of different grazing management systems on the scale dependency of species diversity, plant community indices and soil variables were determined in 32 plots in the Qilian Mountains in Gansu Province. The results show that diversity effects and their regulating mechanisms had space-scale dependence under different grazing management systems. The species richness and species diversity indices of RG grassland were significantly higher than those of GE at the regional scale. Species richness for RG and GE plots was 128 and 98, respectively, and the Shannon–Wiener and Simpson indices for RG and GE plots were 2.26 and 2.16, and 0.85 and 0.83, respectively. Additionally, three grazing management systems had a significant effect on species richness in mountain meadows, but different management systems had significantly different effects on species diversity indices in mountain meadows and temperate steppes. Meanwhile, soil variables only influenced species diversity at the regional scale. Most of the plant and soil variables at each scale had positive effects on species diversity. However, a negative correlation was seen between biodiversity and species coverage, mean plant height, soil porosity (SP) and bulk density (BD) under the two contrasting grazing management systems. In conclusion, choosing RG at the regional scale and selecting grazing management systems according to different grassland types at the local scale can help to restore degraded grassland vegetation. [ABSTRACT FROM AUTHOR]

Abstract Nitrogen (N), phosphorus (P), and potassium (K) contents are crucial quality indicators for forage in alpine natural grasslands and are closely related to plant growth and reproduction. One of the greatest challenges for the sustainable utilization of grassland resources and the development of high-quality animal husbandry is to efficiently and accurately obtain information about the distribution and dynamic changes in N, P, and K contents in alpine grasslands. A new generation of multispectral sensors, the Sentinel-2 multispectral instrument (MSI) and Tiangong-2 moderate-resolution wide-wavelength imager (MWI), is equipped with several spectral bands suitable for specific applications, showing great potential for mapping forage nutrients at the regional scale. This study aims to achieve high-accuracy spatial mapping of the N, P, and K contents in alpine grasslands at the regional scale on the eastern Qinghai-Tibet Plateau. The Sentinel-2 MSI and Tiangong-2 MWI data, coupled with multiple feature selection algorithms and machine learning models, are applied to develop forage N, P, and K estimation models from data collected at 92 sample sites ranging from the vigorous growth stage to the senescent stage. The results show that the spectral bands of both the Sentinel-2 MSI and Tiangong-2 MWI have an excellent performance in estimating the forage N, P, and K contents (the R2 values are 0.68–0.76, 0.54–0.73, and 0.74–0.82 for forage N, P, and K estimations, respectively). Moreover, the model integrating the spectral bands of these two sensors explains 78%, 74%, and 84% of the variations in the forage N, P, and K contents, respectively. These results indicate that the estimation ability of forage nutrients can be further improved by integrating Tiangong-2 MWI and Sentinel-2 MSI data. In conclusion, integration of the spectral bands of multiple sensors is a promising approach to map the forage N, P, and K contents in alpine grasslands with high accuracy at the regional scale. This study offers valuable information for growth monitoring and real-time determination of forage quality in alpine grasslands.

Alpine grasslands are the dominant vegetation of the Tibetan Plateau (TP) and are essential to understanding the mechanism of change in water use efficiency (WUE) in high-cold ecosystems in a changing environment. However, it is still unclear how the WUE of different alpine grasslands respond to changes in precipitation. Therefore, we investigated the variations in growing season WUE and its drivers among different grassland types, including alpine meadow of permafrost (PAM), alpine meadow of seasonal frost (SAM), alpine steppe of permafrost (PAS), and alpine steppe of seasonal frost (SAS), in different precipitation years. The mean growing season WUE was significantly higher for alpine meadow and seasonal frost regions and lower for alpine steppe and permafrost regions. WUE increased significantly in the alpine meadow (PAM and SAM) but decreased (PAS) or varied little (SAS) in the alpine steppe during the period of 1982–2014. Compared to normal years, WUE in the PAS region increased by 22% and 10% in severe and mild dry years, respectively, and decreased by approximately 10% in wet years. For the alpine meadow, WUE decreased more in severe dry years than in mild dry years and increased slightly in wet years. In different precipitation years, WUE for all grassland types was mainly controlled by the vegetation factor. Results suggest that the WUE in alpine grasslands, especially in the PAS region, may decline if the “dry gets wet, wet gets dry” happen over the TP in the future.

In grassland ecosystems, the occurrence and transmission of foliar fungal diseases are largely dependent on grazing by large herbivores. However, whether herbivores that have different body sizes differentially impact foliar fungal diseases remains largely unexplored. Thus, we conducted an 8-year grazing experiment in an alpine grassland on the Qinghai–Tibet Plateau in China and tested how different types of livestock (sheep (Ovis aries), yak (Bos grunniens), or both)) affected foliar fungal diseases at the levels of both plant population and community. At the population level, grazing by a single species (yak or sheep) or mixed species (sheep and yak) significantly decreased the severity of eight leaf spot diseases. Similarly, at the community level, both single species (yak or sheep) and mixed grazing by both sheep and yak significantly decreased the community pathogen load. However, we did not find a significant difference in the community pathogen load among different types of livestock. These results suggest that grazing by large herbivores, independently of livestock type, consistently decreased the prevalence of foliar fungal diseases at both the plant population and community levels. We suggest that moderate grazing by sheep or yak is effective to control the occurrence of foliar fungal diseases in alpine grasslands. This study advances our knowledge of the interface between disease ecology, large herbivores, and grassland science. [ABSTRACT FROM AUTHOR]

The Carpathian region harbors a wide range of threatened species, making it an area of exceptional conservation value. In the Alpine belt, grasslands cover the entire region and this study aims to describe the communities in the Bucegi Massif of the Romanian Carpathians and highlight their importance for conservation. The Braun–Blanquet approach was used to record floristic data from 47 phytosociological surveys, identifying a total of 235 plant species from 40 different families, including 30 threatened species. Canonical correspondence analysis was used to analyze the data, revealing that the distribution of vegetation is mainly influenced by elevation, slope and vegetation cover. Dominant grass species in these communities include Nardus stricta, Festuca violacea, Kobresia myosuroides, Festuca amethystina, Festuca airoides, Sesleria rigida, Festuca versicolor and Festuca carpatica. The alpine and boreal siliceous grasslands of the Carpathian Mountains, identified by Natura 2000 codes 6150, 6130 and 6170, host a wide range of plant species of significant conservation value. The higher altitude grasslands, especially, have outstanding plant species richness. We argue that although the habitats have been grazed, significant parts of the area are still in good ecological condition, having many typical natural features. [ABSTRACT FROM AUTHOR]

Question: Foraging‐tunnel disturbances created by herbivorous mammals can influence the above‐ground plant biomass of grassland communities. The plateau zokor (Eospalax baileyi) was considered a focal animal for investigating the effect of foraging‐tunnel disturbances created by herbivorous mammals on the above‐ground biomass and species richness of graminoids and forbs. Here, we ask how foraging‐tunnel disturbances created by plateau zokors influences above‐ground plant biomass and species richness of graminoids and forbs in alpine grasslands. Location: The study was conducted at three sites of alpine grasslands in the Qinghai‐Tibetan Plateau, China. Methods: In this study, all vascular plants were divided into graminoids and forbs, and 30 paired quadrats were randomly selected from each site. In total, 90 tunnel quadrats and 90 non‐tunnel quadrats were surveyed and sampled. Results: This study showed that foraging‐tunnel disturbances decreased the plant species richness of the grassland community and forbs by 16.5% and 17.7% respectively, whereas the response of graminoid species richness to foraging‐tunnel disturbance was different among the three sites, in which foraging‐tunnel disturbance decreased the graminoid species richness at Maqu and Xiahe sites and had no impact on the graminoid species richness at Tianzhu site. Regarding forbs, some legumes identified in the non‐tunnel quadrats were not observed in the tunnel quadrats. The foraging‐tunnel disturbances resulted in an above‐ground plant biomass decrease of 21.9% in the grassland community, 27.3% in forbs, and 17.2% in graminoids respectively. The percentage of graminoids in the above‐ground plant biomass increased from 50.4% in non‐tunnel quadrats to 55.5% in tunnel quadrats, a relative increase of 10.1% from the initial percentage. Conclusions: These results indicate that the foraging‐tunnel disturbances seemed to improve the forage availability for livestock in tunnel quadrats due to a higher relative proportion of graminoids in the grassland plant community, despite a decrease in graminoid biomass. However, the tunnels not only decreased the above‐ground plant biomass and species richness of forbs, but also might have a negative impact on soil nitrogen input because of the absence of some legumes. The findings of this study suggest that reseeding some legumes is an effective approach to maintaining plant diversity and soil fertility, which can compensate for the negative effect of foraging‐tunnel disturbance on alpine grasslands. [ABSTRACT FROM AUTHOR]

Introduction: The Three-River Source Nature Reserve is located in the core area of the Qinghai-Tibetan Plateau, with the alpine swamp, meadow and steppe as the main ecosystem types. However, the microbial communities in these alpine ecosystems, and their carbon and nitrogen degrading metabolic networks and limiting factors remain unclear. Methods: We sequenced the diversity of bacteria and fungi in alpine swamps, meadows, steppes, and their degraded and artificially restored ecosystems and analyzed soil environmental conditions Results: The results indicated that moisture content had a greater influence on soil microbial community structure compared to degradation and restoration. Proteobacteria dominated in high moisture alpine swamps and alpine meadows, while Actinobacteria dominated in low moisture alpine steppes and artificial grasslands. A metabolic network analysis of carbon and nitrogen degradation and transformation using metagenomic sequencing revealed that plateau microorganisms lacked comprehensive and efficient enzyme systems to degrade organic carbon, nitrogen, and other biological macromolecules, so that the shortterm degradation of alpine vegetation had no effect on the basic composition of soil microbial community. Correlation analysis found that nitrogen fixation was strong in meadows with high moisture content, and their key nitrogen-fixing enzymes were significantly related to Sphingomonas. Denitrification metabolism was enhanced in water-deficient habitats, and the key enzyme, nitrous oxide reductase, was significantly related to Phycicoccus and accelerated the loss of nitrogen. Furthermore, Bacillus contained a large number of amylases (GH13 and GH15) and proteases (S8, S11, S26, and M24) which may promote the efficient degradation of organic carbon and nitrogen in artificially restored grasslands. Discussion: This study illustrated the irrecoverability of meadow degradation and offered fundamental information for altering microbial communities to restore alpine ecosystems. [ABSTRACT FROM AUTHOR]

Nitrogen (N), phosphorus (P), and potassium (K) contents are crucial quality indicators for forage in alpine natural grasslands and are closely related to plant growth and reproduction. One of the greatest challenges for the sustainable utilization of grassland resources and the development of high-quality animal husbandry is to efficiently and accurately obtain information about the distribution and dynamic changes in N, P, and K contents in alpine grasslands. A new generation of multispectral sensors, the Sentinel-2 multispectral instrument (MSI) and Tiangong-2 moderate-resolution wide-wavelength imager (MWI), is equipped with several spectral bands suitable for specific applications, showing great potential for mapping forage nutrients at the regional scale. This study aims to achieve high-accuracy spatial mapping of the N, P, and K contents in alpine grasslands at the regional scale on the eastern Qinghai-Tibet Plateau. The Sentinel-2 MSI and Tiangong-2 MWI data, coupled with multiple feature selection algorithms and machine learning models, are applied to develop forage N, P, and K estimation models from data collected at 92 sample sites ranging from the vigorous growth stage to the senescent stage. The results show that the spectral bands of both the Sentinel-2 MSI and Tiangong-2 MWI have an excellent performance in estimating the forage N, P, and K contents (the R2 values are 0.68–0.76, 0.54–0.73, and 0.74–0.82 for forage N, P, and K estimations, respectively). Moreover, the model integrating the spectral bands of these two sensors explains 78%, 74%, and 84% of the variations in the forage N, P, and K contents, respectively. These results indicate that the estimation ability of forage nutrients can be further improved by integrating Tiangong-2 MWI and Sentinel-2 MSI data. In conclusion, integration of the spectral bands of multiple sensors is a promising approach to map the forage N, P, and K contents in alpine grasslands with high accuracy at the regional scale. This study offers valuable information for growth monitoring and real-time determination of forage quality in alpine grasslands. [ABSTRACT FROM AUTHOR]

With an average elevation of more than 4500 m, northern Tibet, known as the "roof of the world roof", serves as the main body of the Qinghai-Tibetan Plateau's ecological security barrier. However, the alpine grassland ecosystem in northern Tibet has suffered considerable alterations as a result of both climate change and overgrazing, and there is a degradation trend in some regions. In 2009, one ecological engineering, the Protection and Construction Project of Ecological Security Barrier in Tibet (hereafter referred to as the "Project") was implemented to preserve the alpine ecosystem and restore service functions in the plateau. Water conservation is one of the most important service functions in alpine grassland ecosystem in northern Tibet, where is one part of the Asian Water Tower. To clarify the specific ecological benefits of the Project, this paper utilized the InVEST model to evaluate the variation trend of the water conservation function of alpine grasslands in northern Tibet before and after the implementation of the Project from 2000 to 2020, and contribution rate of climate change and the Project was also quantified. Results showed that: (1) Although the water conservation capacity of different grassland types in northern Tibet were varied, their water conservation function all altered dramatically after implementation of the Project. Specifically, the water yield has increased by 10.07%, and the water source supply service has increased by 8.86%. Among these grasslands, the alpine meadow had the highest increasing rate, water conservation capacity increased from –1.84 mm yr–1 to 2.24 mm yr–1 Followed by the alpine desert steppe and the alpine steppe, the rate of water conservation function were decreased significantly due to the Project. (2) Although climate is still the primary factor affecting the water conservation function of alpine grasslands in northern Tibet, the Project has effectively promoted the local water conservation function, with contribution rates of 13.99%, 8.75%, and 3.71% in the alpine meadow, alpine steppe and alpine desert steppe regions respectively. [ABSTRACT FROM AUTHOR]

Species living in high mountain areas are currently threatened by climate change and human land use changes. High‐elevation birds frequently inhabit island‐like suitable patches around mountain peaks, and in such conditions the capability to exchange individuals among patches is crucial to maintain gene flow. However, we lack information regarding the dispersal ability of most of these species and the possible influence of landscape features on dispersal. In this study, we used population genomics and landscape resistance modelling to investigate dispersal in a high‐elevation specialist migratory bird, the water pipit Anthus spinoletta. We aimed to assess the levels of gene flow in this species within a wide area of the European Alps, and to assess the effects of environmental characteristics on gene flow, by testing the isolation by distance (IBD) hypothesis against the isolation by resistance (IBR) hypothesis. We found clear support for IBR, indicating that water pipits preferentially disperse across suitable breeding habitat (i.e., high‐elevation grassland). IBR was stronger in the part of the study area with less extended suitable habitat. Landscape resistance was slightly better described by habitat suitability models than landscape connectivity models. Despite the observed IBR, gene flow within the study area was high, probably also because of the still wide and relatively continuous breeding range. The forecasted reduction of range of this species may lead to stronger effects of IBR on gene flow. Other high‐elevation specialist birds may show similar IBR patterns, but with possibly stronger effects on gene flow because of their more reduced and patchy habitats. [ABSTRACT FROM AUTHOR]

Global changes are recognized as one of the main drivers of biodiversity changes over time, especially in mountain ecosystems. A key approach to detect and investigate the effect of climate and land use change on these ecosystems is represented by vegetation surveys. In this study, based on the resurvey of historical vegetation data, we assessed temporal beta-diversity patterns within and between subalpine and alpine vegetation types in the Dolomiti Bellunesi National Park. Resurvey was focussed on plots sampled in four main vegetation types: 1 and 2) Mesophytic and xerophytic grasslands on neutral or base-rich soils respectively dominated by Sesleria caerulea and Carex sempervirens and by Sesleria caerulea and Helictotrichon parlatorei; 3) Acidophytic grasslands dominated by Nardus stricta; 4) Snowbeds with dominance of dwarf willows (Salix herbacea or S. retusa) or Luzula alpinopilosa. Our results revealed a pattern of floristic homogenization in grasslands and snowbeds indicating a decreasing heterogeneity, both within and between different vegetation types that can be associated with different components of global change. The highest temporal beta diversity and floristic homogenization were detected in snowbeds. In general, the magnitude of temporal changes differ between communities, thus claiming for conservation activities that are tailored to each vegetation type. [ABSTRACT FROM AUTHOR]

There is a debate about unmatched results between manipulative warming using constant warming rates every year (CW) and long-term observations warming affect temperature sensitivity of flowering phenology. This may be because long-term observations represent the actual yearly increase in temperature (i.e. a yearly stepwise warming rate per year, SW) which would differ from CW and their effects would be regulated by precipitation alteration. We conducted a warming experiment with CW (temperature increase by +1 °C and sustained this elevated temperature for the duration of the study) and SW (temperature increase by + 0.25 °C progressively each year) with precipitation addition in an alpine grassland for four years. Our results showed that neither warming rate affected community flowering phenology. However, precipitation addition advanced onsets of flowering for early-spring flowering (ESF) and mid-summer flowering (MSF) groups, and advanced the end date of flowering for ESF but delayed it for the MSF group. Therefore, flowering duration remained stable for the ESF group and prolonged for the MSF group, and further prolonging the flowering duration of the community. There were no interactions between warming rates and precipitation addition on the community's flowering phenology. A severe drought in a year significantly decreased the maximal number of community flowers in the following year. Therefore, a change in precipitation has a greater effect than warming on the community flowering phenology in the semi-arid alpine grassland. [ABSTRACT FROM AUTHOR]

Introduction: Soil microbial communities are key to functional processes in terrestrial ecosystems, and they serve as an important indicator of grasslands status. However, the responses of soil microbial communities and functional potential to drought stress in semiarid alpine grasslands remain unclear. Methods: Here, a field experiment was conducted under ambient precipitation as a control, -20% and -40% of precipitation to explore the responses of soil microbial diversity, community composition, and predicted functional potential to drought stress in a semiarid alpine grassland located in the northwest of China. Moreover, 16S rRNA gene and ITS sequencing were used to detect bacterial and fungal communities, and the PICRUST and FUNGuild databases were used to predict bacterial and fungal functional groups. Results: Results showed drought stress substantially changes the community diversity of bacteria and fungi, among which the bacteria community is more sensitive to drought stress than fungi, indicating that the diversity or structure of soil bacteria community could serve as an indicator of alpine grasslands status. However, the fungal community still has difficulty maintaining resistance under excessive drought stress. Our paper also highlighted that soil moisture content, plant diversity (Shannon Wiener, Pieiou, and Simpson), and soil organic matter are the main drivers affecting soil bacterial and fungal community composition and predicted functional potential. Notably, the soil microbial functional potential could be predictable through taxonomic community profiles. Conclusions: Our research provides insight for exploring the mechanisms of microbial community composition and functional response to climate change (longer drought) in a semiarid alpine grassland. [ABSTRACT FROM AUTHOR]

Long-term active restoration is often employed to restore degraded grasslands. The establishment of a viable soil seed bank is the key to successful restoration, as it enhances the resilience of vegetation. However, little is known of how the soil seed bank affects vegetation resilience following long-term active restoration of degraded grasslands. We determined seed abundance and species composition of the soil seed bank and soil properties and vegetation resilience of intact, degraded, and long-term (>10 years) actively restored grasslands on the Tibetan plateau (3900–4200 m a.s.l.). The plant-soil-seed bank quality index and structural equation modelling (SEM) were used to assess the effect of the soil seed bank on vegetation resilience. After long-term (>10 years) active restoration of degraded grasslands by sowing seeds of native plant species, the densities of transient and persistent seeds increased by 5%, but seed richness (number of species) decreased by 25% when compared with degraded grasslands. This occurred largely as a result of an increase in grass but decrease in forb seeds. Persistent seeds of grasses play an important role in the productivity of restored grasslands, while the density of persistent seeds serves as an indicator of the resilience of vegetation. A combination of the plant community and soil properties determined seed density. Here, we show for the first time that long-term active restoration enhances vegetation resilience of grasslands by altering the soil seed bank. A high seed density of sown Gramineae and a low seed density of forbs in the soil seed bank is a key to the successful active restoration of degraded grasslands. [ABSTRACT FROM AUTHOR]

Introduction: In grassland ecosystems dominated by asexual plants, the maintenance, renewal, and resistance of plant populations to disturbance are more dependent on the belowground bud bank (BBB). However, the response of the BBB to environmental factors in the alpine grassland of the Qinghai-Tibet Plateau (QTP) is still unknown. Methods: Therefore, a transect survey was conducted to measure the size and scale of BBB and 21 factors in the alpine grassland of the QTP. In addition, the critical driving factors of BBB were screened by boost regression tree analysis, and a structural equation model (SEM) was employed to express the path coefficients of the key factors on the BBB size. Results: The results showed that BBB size had no significant geographical pattern in the QTP, and the BBB size was mainly accounted for by soil leucine aminopeptidase (LAP, 17.32%), followed by Margalef and Shannon -Wiener indices of plants (12.63% and 9.24%, respectively), and precipitation (9.23%). SEM further indicated significant positive effects of plant diversity (scored at 0.296) and precipitation (scored at 0.180) on BBB size, and a significant negative effect of LAP (scored at 0.280) on BBB size. Discussion: Generally, the findings allow for better understanding of the regulated mechanisms of BBB size and the importance of the role of bud bank in the restoration of the grassland ecosystem. [ABSTRACT FROM AUTHOR]

Grazing exclusion (GE) and rest grazing (RG) are important management systems for the restoration of degraded grassland ecosystems. In order to evaluate the effects and mechanisms of different grazing management systems on the scale dependency of species diversity, plant community indices and soil variables were determined in 32 plots in the Qilian Mountains in Gansu Province. The results show that diversity effects and their regulating mechanisms had space-scale dependence under different grazing management systems. The species richness and species diversity indices of RG grassland were significantly higher than those of GE at the regional scale. Species richness for RG and GE plots was 128 and 98, respectively, and the Shannon–Wiener and Simpson indices for RG and GE plots were 2.26 and 2.16, and 0.85 and 0.83, respectively. Additionally, three grazing management systems had a significant effect on species richness in mountain meadows, but different management systems had significantly different effects on species diversity indices in mountain meadows and temperate steppes. Meanwhile, soil variables only influenced species diversity at the regional scale. Most of the plant and soil variables at each scale had positive effects on species diversity. However, a negative correlation was seen between biodiversity and species coverage, mean plant height, soil porosity (SP) and bulk density (BD) under the two contrasting grazing management systems. In conclusion, choosing RG at the regional scale and selecting grazing management systems according to different grassland types at the local scale can help to restore degraded grassland vegetation.

Alpine grassland ecosystem supports high diversity of terrestrial flora and fauna species. Despite the ecological importance and economic potential of this unique ecosystem type, it experiences increasing anthropogenic disturbances such as trampling, which impose negative impact on the health and integrity of alpine grasslands. Previous studies of trampling impact on alpine vegetation mainly focus on changes in vegetation cover and taxonomic diversity after trampling disturbance, but rarely test community-level responses of alpine vegetation to trampling from a functional trait perspective. Through the lens of vegetation functional traits, the present study evaluates the impacts of simulated trampling on typical alpine grasslands in Shangri-la, China. The results showed that although increased trampling intensity did not always lead to changes in functional diversity across all three experimental sites, characteristics of community-weighted mean trait values had consistently changed toward plant species with shorter height, reduced leaf area and lower leaf dry matter content, and such strong shifts in functional attributes may further affect ecosystem goods and services provided by alpine grasslands. Therefore, a functional trait approach can help us better understand the mechanisms that drive trait changes, function shifts and vegetation stability following anthropogenic disturbances.

The stability of grassland is pivotal in maintaining the grassland functioning and services. However, the knowledge about the consequences of grazing on stability of grassland productivity is limited. Based on a 3-year manipulated experiment with two grazing regimes (i.e., continuous grazing and rotational grazing) along four levels of grazing-intensity (0, 4, 6, and 8 sheep per hectare) on the Qinghai-Tibetan Plateau, we researched the responses of temporal stability of plant community and functional groups of alpine grasslands to different grazing management regimes. We found that grazing regimes, intensity and their interaction affected the temporal stability of aboveground net primary productivity of alpine grassland (ANPP), and intermediate rotational grazing significantly reduced the temporal stability of ANPP, whereas increased the stability of productivity of functional group of forbs. The response species to continuous grazing and rotational grazing are different, for grasses and forbs respectively. Rotational grazing and intermediate continuous grazing increased the diversity of response species. Structural equation modeling further revealed that functional groups asynchrony stabilized the productivity of the alpine grassland ecosystem under grazing in the Qinghai-Tibetan Plateau. These results showed that the rotational grazing and intermediate continuous grazing can maintain the productivity stability, and highlighted importance of regulating the relationships among functional groups for promoting the stability of alpine grassland under grazing management.

IntroductionIn grassland ecosystems dominated by asexual plants, the maintenance, renewal, and resistance of plant populations to disturbance are more dependent on the belowground bud bank (BBB). However, the response of the BBB to environmental factors in the alpine grassland of the Qinghai-Tibet Plateau (QTP) is still unknown.MethodsTherefore, a transect survey was conducted to measure the size and scale of BBB and 21 factors in the alpine grassland of the QTP. In addition, the critical driving factors of BBB were screened by boost regression tree analysis, and a structural equation model (SEM) was employed to express the path coefficients of the key factors on the BBB size.ResultsThe results showed that BBB size had no significant geographical pattern in the QTP, and the BBB size was mainly accounted for by soil leucine aminopeptidase (LAP, 17.32%), followed by Margalef and Shannon -Wiener indices of plants (12.63% and 9.24%, respectively), and precipitation (9.23%). SEM further indicated significant positive effects of plant diversity (scored at 0.296) and precipitation (scored at 0.180) on BBB size, and a significant negative effect of LAP (scored at 0.280) on BBB size.DiscussionGenerally, the findings allow for better understanding of the regulated mechanisms of BBB size and the importance of the role of bud bank in the restoration of the grassland ecosystem.

Grazing exclusion by fencing is the principal option to restore degraded grassland, but its effects on recovery and succession of vegetation are not clear, especially in high mountain areas. In this study, we aimed to fill this gap by assessing the effect of seven‐year grazing exclusion on vegetation and soil seed bank along an altitudinal gradient in northern Tibet, China. Species richness, Shannon‐Wiener index and Simpson's diversity index of vegetation and soil seed bank, seed density, and the Sørensen index all displayed a mid‐domain (hump‐shaped) pattern with increasing altitude, except for the Shannon‐Wiener and Pielou indices of soil seed bank in fenced grasslands. These results demonstrated that the impact of grazing exclusion on the patterns of vegetation and soil seed bank change with altitude but are not synchronous. Grazing exclusion increased vegetation coverage but decreased soil seed bank density, and species diversity of vegetation and soil seed bank. The Sørensen index (0.03–0.2) and non‐metric multidimensional scaling (NMDS) analysis indicated that the species composition differed between vegetation and soil seed bank, but no difference was found between fenced and grazed grasslands. The low similarity suggests that the soil seed bank contributes little to vegetation recovery in alpine grassland. Seven‐year grazing exclusion had no effect on either vegetation succession or species composition of soil seed bank in alpine grassland. Overall, our findings suggest reconsidering the use of long‐term grazing exclusion to restore degraded grassland at high altitudes (above 4400 m above sea level) on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Pasture biomass and quality are dependent on herbivore grazing and precipitation, but the responses of vegetation to the interactive effects of climate and grazing regimes remain unclear. We conducted an eight-year sheep grazing experiment with 4 stocking rates (0, 3.5, 5.5, and 7.5 sheep/ha) in an alpine meadow of the northeastern Tibetan Plateau. The above-ground net primary productivity (ANPP) and forage nutritional value (FNV) of four dominant species (Poa annua, Kobresia humilis, Astragalus adsurgens and Potentilla fruticosa) were measured during a wet year (360 mm rainfall) and a drought year (216 mm rainfall). The FNV was used as indicator of forage quality and was calculated from the crude protein (CP) content, in vitro true dry matter digestibility (IVTD), metabolic energy (ME) yield, and neutral detergent fiber (NDF) content of the plant. The stocking rate explained a minimum of 76% of the variations of ANPP, and the precipitation sub-additive effect for ANPP ranged from 5% to 12%. The interaction of sheep stocking rate and precipitation affected ANPP of the 4 species, except for P. fruticosa. The FNV of the pasture increased with increasing grazing pressure, but ANPP and forage nutritional yield (FNY) decreased. In calculating FNY, the increase in FNV did not compensate for the decrease in ANPP. In non-grazed plots, the CP yield declined sharply (18%-55%) in response to drought, but there was no effect on ME yield. The interaction between stocking rate and precipitation affected forage quality of the 4 plant species differently. The grassland ANPP and FNY could be maintained at a grazing intensity of 3.5 sheep/ha in wet and dry years. Our results highlight that stocking density affects pasture ANPP and FNV, and is contingent on rainfall. [ABSTRACT FROM AUTHOR]

Plant and microbial diversity are key to determine ecosystem functioning. Despite the well‐known role of local‐scale α diversity in affecting vegetation biomass, the effects of community heterogeneity (β diversity) of plants and soil microbes on above‐ and belowground biomass (AGB and BGB) across contrasting environments still remain unclear. Here, we conducted a dryness‐gradient transect survey over 3000 km across grasslands on the Tibetan Plateau. We found that plant β diversity was more dominant than α diversity in maintaining higher levels of AGB, while soil fungal β diversity was the key driver in enhancing BGB. However, these positive effects of plant and microbial β diversity on AGB and BGB were strongly weakened by increasing climatic dryness, mainly because higher soil available phosphorus caused by increasing dryness reduced both plant and soil fungal β diversities. Overall, these new findings highlight the critical role of above‐ and belowground β diversity in sustaining grassland biomass, raising our awareness to the ecological risks of large‐scale biotic homogenization under future climate change. [ABSTRACT FROM AUTHOR]

In the context of "Carbon Emissions Peak" and "Carbon Neutrality", grazing exclusion (GE) has been applied widely to rehabilitate degraded grasslands and increase carbon sequestration. However, on the QingZang Plateau (QZP), the impacts of GE on the carbon dynamics of alpine grasslands are poorly understood, particularly at a regional scale. To fill this knowledge gap, we evaluated the responses of carbon sequestration to GE in different alpine grasslands across QZP by using meta-analysis. The effects of GE on ecosystem carbon fractions were dependent on GE duration, grassland types and climate factors. Specifically, our results indicated that GE had more obviously positive effects on carbon stock across the alpine meadow than the alpine steppe. However, when considering different GE duration, the longer duration of GE was more effective for increasing ecosystem carbon sequestration (R2 = 0.52, P<0.0001) in the alpine steppe. Our results further demonstrated that annual mean precipitation (AMP) and temperature (AMT) began to dominate ecosystem carbon sequestration after three years of GE duration across the alpine meadow; and AMP was an important climate factor limiting ecosystem carbon sequestration (R2 = 0.34, P<0.01) in the alpine steppe. In terms of plant carbon fraction, GE generated continuous positive effect (P<0.05) on aboveground biomass with the increased GE duration in the alpine meadow, while this positive effect disappeared after the 8th year of GE duration. And no positive effects were found on belowground biomass in the 11th year in alpine steppe. For soil organic carbon (SOC), there existed periodic fluctuations (increased and then decreased) on SOC in response to GE. For microbial biomass carbon, there were no obvious trends in response to GE duration. In general, we highlighted that the responses of different carbon fractions (plant-soil-microbe) to GE were non-uniform at spatial and temporal scales, thereby we should adopt different carbon management practices for sustainable development of different grasslands. [ABSTRACT FROM AUTHOR]

Alpine ecosystems are hotspots of biodiversity despite their cold climates. Here we investigate spatial patterns in the phylogenetic diversity (i.e. the degree of species relatedness) of European alpine floras and quantify the influence of climatic conditions since the late Pleistocene and historical climatic instability in shaping these patterns. We collected species‐pool data for 22 alpine regions in central and southern Europe and calculated phylogenetic diversity within and between regions using two metrics sensitive to terminal branching in the phylogeny. We regressed phylogenetic diversity against macroclimatic variables representing seasonal extremes between the Last Glacial Maximum (LGM; 21 000 years BP) and the present at 1000‐year intervals. We found the lowest phylogenetic diversity in the Carpathians and the central Alps, and the highest in the north‐eastern and southern Iberian Peninsula. Phylogenetic diversity decreased with temperature seasonality and low winter temperature. While the effect of temperature seasonality was relatively constant over time, the influence of winter temperature decreased after the LGM. We also found that phylogenetic diversity decreased with historical climatic instability. Between regions, phylogenetic diversity was mainly explained by current climatic distance rather than geographic distance, suggesting that alpine floras were primarily driven by species sorting along climatic gradients. Our results confirm the role of environmental filtering in shaping the current phylogenetic diversity of alpine floras, resulting in more closely related lineages in regions with relatively cold and unstable climates. We also highlight the importance of explicitly incorporating climatic variation through time to better understand the processes structuring the current biodiversity of alpine floras. [ABSTRACT FROM AUTHOR]

Soil water–salt variations at different spatiotemporal scales and their influencing factors are essential for regional vegetation restoration and management. However, the study of soil water–salt of the alpine area has not taken into account the effect of topography, especially in the long time series. This work investigated the spatiotemporal characteristics of water and salt in topsoil from 2000 to 2021, using regression analysis of on-site data and MODIS products. The heterogeneity and trends of soil water–salt in various topographic factors (elevation, slope, and aspect) were also explored by selecting the maximum area of each gradient factor as the constrained condition with the help of ArcGIS software. The results revealed that 1) the models applied to SWC (soil water content), EC (electrical conductivity), and pH utilizing vegetation indices were suitable for estimating the spatiotemporal variations of soil water–salt. 2) Soil water–salt exhibited local aggregation characteristics with an upward trend in SWC and a downward trend in EC and pH as a whole. 3) Mean annual SWC peaked at 3,400–3,800 m with increasing elevation and trended downward with increasing slope. The aspect of mean annual SWC was characterized by lower values in the southwest and south and higher values in the north, while the results for pH were reversed. The slope had a greater influence on EC than on SWC and pH. 4) The trend change of SWC, EC, and pH fluctuated at 2000–2,400 m and >4,600 m with a clear inflection point at 4°–8° and 20°–24°, respectively. In summary, the effects of topography responded to the distribution and trends of soil water–salt. The results have significant implications for implementing ecological improvements in regions with complicated topography and can serve as a reference for formulating future ecological policies.

In grassland ecosystems, the occurrence and transmission of foliar fungal diseases are largely dependent on grazing by large herbivores. However, whether herbivores that have different body sizes differentially impact foliar fungal diseases remains largely unexplored. Thus, we conducted an 8-year grazing experiment in an alpine grassland on the Qinghai–Tibet Plateau in China and tested how different types of livestock (sheep (Ovis aries), yak (Bos grunniens), or both)) affected foliar fungal diseases at the levels of both plant population and community. At the population level, grazing by a single species (yak or sheep) or mixed species (sheep and yak) significantly decreased the severity of eight leaf spot diseases. Similarly, at the community level, both single species (yak or sheep) and mixed grazing by both sheep and yak significantly decreased the community pathogen load. However, we did not find a significant difference in the community pathogen load among different types of livestock. These results suggest that grazing by large herbivores, independently of livestock type, consistently decreased the prevalence of foliar fungal diseases at both the plant population and community levels. We suggest that moderate grazing by sheep or yak is effective to control the occurrence of foliar fungal diseases in alpine grasslands. This study advances our knowledge of the interface between disease ecology, large herbivores, and grassland science.

One of the major uncertainties for projecting permafrost carbon (C)‐climate feedback is a poor representation of the non‐growing season carbon dioxide (CO2) emissions under a changing climate. Here, combining in situ field observations, regional synthesis and a random forest model, we assessed contemporary and future soil respired CO2 (i.e., soil respiration, Rs) across the Tibetan alpine permafrost region, which has received much less attention compared with the Arctic permafrost domain. We estimated the regional mean Rs of 229.8, 72.9 and 302.7 g C m−2 year−1 during growing season, non‐growing season and the entire year, respectively; corresponding to the contemporary losses of 296.9, 94.3 and 391.2 Tg C year−1 from this high‐altitude permafrost‐affected area. The non‐growing season Rs accounted for a quarter of the annual soil CO2 efflux. Different from the prevailing view that temperature is the most limiting factor for cold‐period CO2 release in Arctic permafrost ecosystems, precipitation determined the spatial pattern of non‐growing season Rs on the Tibetan Plateau. Using the key predictors, model extrapolation demonstrated additional losses of 38.8 and 74.5 Tg C from the non‐growing season for a moderate mitigation scenario and a business‐as‐usual emissions scenario, respectively. These results provide a baseline for non‐growing season CO2 emissions from high‐altitude permafrost areas and help for accurate projection of permafrost C‐climate feedback. [ABSTRACT FROM AUTHOR]

Ecosystem respiration (RE) plays a critical role in terrestrial carbon cycles, and quantification of RE is important for understanding the interaction between climate change and carbon dynamics. We used a multi-level attention network, Geoman, to identify the relative importance of environmental factors and to simulate spatiotemporal changes in RE in northern China's grasslands during 2001–2015, based on 18 flux sites and multi-source spatial data. Results indicate that Geoman performed well (R2 = 0.87, RMSE = 0.39 g C m−2 d−1, MAE = 0.28 g C m−2 d−1), and that grassland type and soil texture are the two most important environmental variables for RE estimation. RE in alpine grasslands showed a decreasing gradient from southeast to northwest, and that of temperate grasslands showed a decreasing gradient from northeast to southwest. This can be explained by the enhanced vegetation index (EVI), and soil factors including soil organic carbon density and soil texture. RE in northern China's grasslands showed a significant increase (1.81 g C m−2 yr−1) during 2001–2015. The increase rate of RE in alpine grassland (2.36 g C m−2 yr−1) was greater than that in temperate grassland (1.28 g C m−2 yr−1). Temperature and EVI contributed to the interannual change of RE in alpine grassland, and precipitation and EVI were the main contributors in temperate grassland. This study provides a key reference for the application of advanced deep learning models in carbon cycle simulation, to reduce uncertainties and improve understanding of the effects of biotic and climatic factors on spatiotemporal changes in RE. [ABSTRACT FROM AUTHOR]