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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]

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]

[Objective] The aims of this study are to investigate the effects of plateau sage grouse burrows on the infiltration performance of alpine meadow soils and its related factors and to reveal its potential role on water cycling and soil hydrological functions in alpine meadow ecosystems. [Methods] Soil infiltration rates were measured by the single-loop method in different parts of alpine meadow plateau pika burrows, including the entrance (PE) and the burrow pathway (PB), and the control was an undisturbed alpine meadow (AM) with no distribution of plateau pika burrows. [Results] (1) Compared with the native alpine meadow, the total porosity and capillary porosity of surface soil at the plateau pika cave entrance were significantly reduced by 4.69% and 16.27%, respectively, while the non-capillary porosity was significantly increased by 22.47%, and the mean weight diameters of aggregates at the entrance and burrow were significantly decreased by 20.09% and 9.45%, respectively. The soil organic matter content decreased significantly, and soil organic matter content of each part followed the order: native alpine meadow burrow> entrance (p<0.05). (2) Compared with native alpine meadow, the initial infiltration rate of the cave entrance and burrow increased by 377.63% and 189.47%, respectively, and the stable infiltration rate increased by 314.29% and 220.00% (p<0.05). (3) Plateau pika caves promoted the soil infiltration performance mainly through the destruction of mattic layer roots, and root biomass was the dominant factor affecting initial and stable infiltration rates, with the standardized total effects of 0.717 and 0,539, respectively. To some extent. pika caves were conducive to the water conservation of alpine meadow ecosystem. [Conclusion] Sage-grouse burrows favor water circulation in alpine meadow ecosystems to a certain extent, but also damage the original soil structure of alpine meadows and exacerbate the risk of alpine meadow degradation. [ABSTRACT FROM AUTHOR]

Unreasonable grassland use has degraded the alpine meadow on the Qinghai‐Tibetan Plateau in the past half a century, and approximately 32.1% of the degraded meadows degenerated to bare grassland. Artificial grassland reconstruction is a widespread measure for rebuilding the grassland ecosystems of these bare grasslands. However, does the soil microbe community structure improve with the aboveground vegetation restoration? Which microflora are more sensitive to environmental changes are not unclear. Thus, we analyzed four artificial grasslands established for different years on extreme‐degraded (ED) grasslands of the alpine meadows. These artificial grasslands were rationally utilized by grazing Tibetan sheep and Yak from December to April and were completely grazing‐prohibited in other seasons. In 2017, four plots of approximately 2400 m2 for each artificial restoration grassland (3, 6, 9, and 12 years) were selected as treatments with non‐degraded (ND) and ED meadows as controls. The potential predictors and regulators for soil microbial community structures and functions in the alpine meadows were evaluated. The results showed that artificial restoration did not affect soil microbe community compositions but dramatically changed the community constructions. The bacterial community structure was more sensitive to artificial interference than fungal. Actinobacteria, Acidobacteria, and Mortierellomycota could be used as indicators of environmental changes. Compared with ED grassland, the soil microbial biomass carbon increased significantly by 29.5% and 33.7% in 6 and 9 years grasslands, respectively. The species richness and below‐ground biomass of grassland vegetation play a decisive role in soil microbial community and functional structures, while the soil water content and organic carbon, and soil elemental balance play a regulating role. Moreover, the abundance of soil bacteria with ureolysis and nitrogen fixation functions decreased significantly in grassland degradation, and soil pH played a major regulatory role. In conclusion, the vegetation and soil of artificial grasslands were in good condition after 6 years of artificial restoration. However, all the indexes declined to different degrees after 12 years of establishment, and the grassland ecosystem faced the risk of secondary degradation. The mixed sowing of many plant species with developed root systems should be adopted when artificially restoring degenerated alpine grasslands. Simultaneously, soil organic material supplementation and the balanced application of nitrogen and phosphorus fertilizers are recommended. [ABSTRACT FROM AUTHOR]

Soil cracking induced by grassland degradation has become increasingly common in the Qinghai‐Tibetan Plateau in recent decades, and the intensification of soil cracking has implications for soil carbon (C) cycling. However, how patchy degradation affects soil aggregates and organic C and the underlying mechanisms remain unclear. In the present study, we investigated the changes in soil aggregates and organic C across various degradation stages in patchy alpine swamp meadows. The results showed a hump‐shaped trend in the proportion of macroaggregates, mean weight diameter (MWD), macroaggregate‐associated organic C (MAOC), and their contribution to soil organic carbon (SOC) throughout the degradation sequence. Conversely, the proportion of microaggregates initially decreased and then increased, with the contribution of microaggregate‐associated organic C (MIOC) to SOC increasing as degradation progressed. Regression and piecewise structural equation modeling (SEM) showed that soil texture played a decisive role in the change in MAOC and MIOC, and enzyme activity was the key factor leading to the difference between MAOC and MIOC. Enhanced enzyme activity accelerated the decomposition of MAOC while favoring the accumulation of MIOC. These findings are crucial for understanding the mechanisms influencing the physical protection of SOC by aggregates under patchy degradation. This emphasized soil cracking as a turning point in aggregate and organic C changes and a trigger for severe degradation in alpine swamp meadows, warranting proactive measures to mitigate its onset and progression. [ABSTRACT FROM AUTHOR]

ABSTRACT Global warming is exhibiting a seasonal trend, while different seasons have different warming variations. However, the impact of seasonal warming on plants remains unclear. This study employed Open Top Chambers (OTCs) to simulate future seasonal warming scenarios in alpine meadow. The study examined plant community dynamics following long‐term seasonal warming. The transcriptional and physiological responses of two dominant species (Kobresia pygmaea and Stipa purpurea) were examined. Results suggest that seasonal warming effects are correlated with both the duration of warming and the season which warming occurs. A long annual warming duration, especially growing season warming, made plants confront various stresses. K. pygmaea adopted a stress‐avoidance strategy, showing a negative response, and leading to population decline or disappearance. This kind of dieback had also been observed in other Cyperaceae species. Meanwhile, due to positive responses, S. purpurea adopted a stress‐tolerance strategy and overcame the impact of warming, partially gained the dominance over Cyperaceae species. Overall vegetation coverage and plant community diversity decreased over the years. These results reveal the impact of seasonal warming to plants, explaining the reasons for changes in plant communities under seasonal warming and providing new insights for future plant conservation under seasonal warming. [ABSTRACT FROM AUTHOR]

Rhododendron capitatum community expansion is a major threat to alpine meadow. Allelopathy is an important mediator in managing relationships between plants in natural ecosystems. However, allelopathy and specific allelochemicals of R. capitatum have not been studied yet. In this study, the allelopathy of the foliage litter of R. capitatum was explored on Elymus nutans, Poa pratensis and Medicago ruthenica, and the chemical composition and their allelopathy were studied. The results showed that the aqueous extract of the foliage litter of R. capitatum had an allelopathy of "low concentration promotion and high concentration inhibition" on the germination of E. nutans, P. pratensis, and M. ruthenica. Organic acids, fatty acids, terpenes, phenols, and phenolic acid compounds were identified, with Zanamivir (77.81%), alpha-linolenic acid (18%), Kaurenoic acid (23.50%), 4-hydroxyphenylglycolic acid (21.54%), and Quinic acid (28.24%) having the highest relative content, and all five compounds showed significantly inhibitory effects on seed germination and seedling growth of E. nutans, P. pratensis, and M. ruthenica, which further suggests that the five compounds are the critical allelochemicals for negative allelopathy of R. capitatum. These results highlight the crucial role of inhibitory allelopathy produced by R. capitatum in the establishment and expansion of its populations. [ABSTRACT FROM AUTHOR]

Leaves are the largest and more sensitive vegetative organs exposed to external environmental conditions. In order to investigate the effects of habitat aridification on the leaf anatomical structure of wetland plants, Carex moorcroftii leaf plots were set up along the gradient of habitat aridification, and the response of leaf anatomical structure to habitat aridification was analyzed in this study. The results were as follows: (1) The epidermal cells, bulliform cells and air cavity area on the abaxial surface of leaf tip and leaf base, leaf thickness and mechanical tissue thickness at leaf base were significantly positively correlated with soil volumetric moisture content (R²=0.06-0.34, P<0.01); the paraxial cuticle thickness, cell area, number of vascular bundles in parts of leaf tip, leaf middle and leaf base, and diameter of vascular bundle in leaf middle were significantly negatively correlated with soil volumetric moisture content (R²=0.08-0.53, P<0.01) . (2) The anatomical structure of C. moorcroftii leaf had great plasticity (0.53-0.94) and variability (18%-63%), and bulliform cells, air cavities, and paraxial epidermal cells had the greatest plasticity and variability, and the plasticity index and the coefficient of variation of leaf base anatomical structure were significantly higher than that of leaf tip and leaf middle (P<0.05) . When the habitat was aridified, C. moorcroftii leaf adapt to the arid habitat by thickening the cuticle on the paraxial surface, increasing the epidermal cell area, decreasing the air cavity area, and differentiating middle cells, and mainly adopted protective and frugal strategies to adapt to the arid habitat. The results of this study are helpful to reveal the response strategies of C. moorcroftii leaf anatomical structure to arid habitat, and provide theoretical reference for protection and vegetation restoration of alpine meadow. [ABSTRACT FROM AUTHOR]

Lignin, an organic compound with a complex structure, is formed through the polymerization of structural units linked by carbon–carbon bonds and ether bonds. The question of whether lignin is labile or resistant to biological and chemical degradation in soil, particularly in alpine ecosystems, remains unresolved. To address this knowledge gap, we analyzed the relationship between phospholipid fatty acid biomarkers and the abundance of lignin components in grassland soils from North Tibet, China. Soil samples were collected from alpine grasslands, including alpine meadows and alpine steppes. The relative abundance of lignin in these alpine grassland soils before and after a 210-day incubation period was measured. Our results indicate that the relative abundance of lignin in the alpine grassland soils decreased during the incubation period. Significant relationships were found between the phospholipid fatty acid biomarkers of bacteria, fungi, Gram-positive bacteria, and Gram-negative bacteria and the relative abundance of lignin components. This research was conducted under laboratory conditions that are optimal for the development of microorganisms but significantly different from the conditions in Tibet. Furthermore, this study contributes to the understanding of soil organic matter degradation and the dynamics of microbial communities in alpine grassland soils in the context of future global warming. [ABSTRACT FROM AUTHOR]

As a key component of the ecosystem, soil seed banks (SSBs) play a vital role in the evolution and renewal of plant communities. Although the pattern and mechanisms of influence of SSBs along the altitudinal gradient have been reported, most studies have focused on forest, grassland and alpine meadow ecosystems. The pattern and factors of SSBs across the altitudinal gradient in sedge peatlands remain largely unknown. Through vegetation surveys and seed germination experiments, we studied the changes in aboveground vegetation and SSBs in sedge peatlands at altitudes ranging from 300 m to 1300 m in the Changbai Mountains, China, and discussed the direct and indirect effects of climatic factors, soil properties and aboveground vegetation on SSBs. The results showed that the richness and density of the SSBs of sedge peatlands decreased with the altitude. Similarly, aboveground vegetation richness and density declined with altitude. A Spearman correlation analysis showed that SSB richness and density were mainly correlated with mean annual temperature, soil total phosphorus and ammonia nitrogen and the plant composition and richness of aboveground vegetation. A structural equation model analysis showed that climatic factors and aboveground vegetation directly affected seed bank richness, while soil properties indirectly affected it by directly affecting aboveground vegetation. Climatic factors, soil properties and aboveground vegetation directly affected SSB density, and soil properties indirectly affected it by directly affecting aboveground vegetation. This finding enhances our understanding of the altitude patterns of the SSBs in sedge peatlands and the response to future climate and environmental changes. [ABSTRACT FROM AUTHOR]

Grassland caterpillars (Lepidoptera: Lymantriinae: Gynaephora) are the most damaging pests to alpine meadows in the Qinghai–Tibetan Plateau (QTP). Here, we conducted extensive sampling from 39 geographic populations covering almost the entire distribution of the eight QTP Gynaephora (Hübner) species to investigate phylogeographic patterns and speciation based on two mitochondrial genes (COI and ND5). A total of 40 haplotypes were detected in the 39 populations, with >70% of all haplotypes not shared between populations. The monophyletic QTP Gynaephora migrated from non‐QTP regions during the Pliocene, corresponding to the uplift of the QTP, suggesting a mode of transport into the QTP. Among the eight QTP Gynaephora species described by morphological characteristics, two species (G. alpherakii and G. menyuanensis) were recovered as monophyletic groups (Clades B and C), while the remaining six formed two monophyletic clades: Clade A (G. qinghaiensis, G. jiuzhiensis, and G. qumalaiensis) and Clade D (G. aureata, G. ruoergensis, and G. minora). These results suggested that the number of the QTP Gynaephora species may be overestimated and further studies based on both morphological and nuclear gene data are needed. Genetic differentiation and speciation of the QTP Gynaephora were likely driven by the QTP uplifts and associated climate fluctuations during the Pleistocene, indicated by divergence time estimation, suggesting that isolation and subsequent divergence was the dominant mode of speciation. The Sanjiangyuan region (i.e., Clade A, characterized by high genetic diversity) may have been a glacial refugium of the QTP Gynaephora, as supported by analyses of gene flow and biogeography. High levels of genetic diversity were found in QTP Gynaephora, without population expansion, which may explain the high‐altitude adaptation and outbreaks of grassland caterpillars in alpine meadows of the QTP. This study provides the largest phylogeographic analysis of QTP Gynaephora and improves our understanding of the diversity and speciation of QTP insects. [ABSTRACT FROM AUTHOR]

Nitrogen enrichment impacts ecosystems productivity by altering different hierarchical community processes, ranging from responses of individual species traits to species reordering and ultimately species turnover. Most previous studies have focussed on examining the responses of these processes separately, but little has been done to examine how hierarchical community responses are linked and contribute to the changes in productivity.To fill this knowledge gap, we conducted a 4‐year nitrogen addition field experiment to investigate the hierarchical community responses of above‐ground net primary productivity (ANPP) in an alpine meadow ecosystem.We found that the individual species response contributed more to ANPP changes under nitrogen addition, while species reordering and species turnover contributed little over the 4‐year experiment. In particular, plant height was a key trait to ultimately explain and bridge nitrogen addition effects on ANPP across different community levels. Nitrogen addition promoted plant height and growth of individual species, and reordered functional groups by increasing taller grasses and sedges and decreasing shorter forbs and legumes. Species turnover had a weak effect on ANPP changes due to low biomass of both lost and gained species. Finally, taller persistent plants promoted ANPP more with nitrogen addition.Synthesis. This study provides a new perspective on how ecosystem productivity responds to nitrogen enrichment in a hierarchical manner linked to plant height, which is helpful for elucidating complex community processes and establishing direct links between plant traits and ecosystem function. [ABSTRACT FROM AUTHOR]

Background and Aims Some plants germinate their seeds enclosed by a pericarp, whereas others lack the outer packaging. As a maternal tissue, the pericarp might impart seeds with different germination strategies. Plants in a community with different flowering times might separately disperse and germinate their seeds; therefore, flowering time can be considered as one manifestation of maternal effects on the offspring. The mass of the seed is another important factor influencing germination and represents the intrinsic resource of the seed that supports germination. Using seeds from a species-rich alpine meadow located in the Hengduan Mountains of China, a global biodiversity hotspot, we aimed to illustrate whether and how the type of seed (with or without a pericarp) modulates the interaction of flowering time and seed mass with germination. Methods Seeds were germinated in generally favourable conditions, and the speed of germination [estimated by mean germination time (MGT)] was calculated. We quantified the maternal conditions by separation of flowering time for 67 species in the meadow, of which 31 produced seeds with pericarps and 36 yielded seeds without pericarps. We also weighed 100 seeds of each species to assess their mass. Key Results The MGT varied between the two types of seeds. For seeds with pericarps, MGT was associated with flowering time but not with seed mass. Plants with earlier flowering times in the meadow exhibited more rapid seed germination. For seeds without a pericarp, the MGT depended on seed mass, with smaller seeds germinating more rapidly than larger seeds. Conclusions The distinct responses of germination to flowering time and seed mass observed in seeds with and without a pericarp suggest that germination strategies might be mother-reliant for seeds protected by pericarps but self-reliant for those without such protection. This new finding improves our understanding of seed germination by integrating ecologically mediated maternal conditions and inherent genetic properties. [ABSTRACT FROM AUTHOR]

Soil seedbanks are particularly important for the resiliency of species living in habitats threatened by climate change, such as alpine meadows. We investigated the germination rate and seedbank potential for the endemic species Dianthus pavonius, a carnation native to the Maritime Alps that is used as model system for disease in natural populations due to its frequent infections by a sterilizing anther-smut pathogen. We aimed to ascertain whether this species can create a persistent reserve of viable seeds in the soil which could impact coevolutionary dynamics. Over three years, we collected data from seeds sown in natural soil and analyzed their germination and viability. We found that D. pavonius seeds are not physiologically dormant and they are able to create a persistent soil seed bank that can store seeds in the soil for up to three years, but lower than the estimated plant lifespan. We conclude that while the seedbank may provide some demographic stability to the host population, its short duration is unlikely to strongly affect the host's ability to respond to selection from disease. Our findings have implications for the conservation of this alpine species and for understanding the evolutionary dynamics between the host and its pathogen. [ABSTRACT FROM AUTHOR]

Leaf functional traits (LFTs) have become a popular topic in ecological research in recent years. Here, we measured eight LFTs, namely leaf area (LA), specific leaf area (SLA), leaf thickness (LT), leaf dry matter content (LDMC), leaf carbon content (LCC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), and leaf potassium content (LKC), in six typical vegetation communities (sclerophyllous evergreen broad-leaved forests, temperate evergreen coniferous forests, cold-temperate evergreen coniferous forests, alpine deciduous broad-leaved shrubs, alpine meadows, and alpine scree sparse vegetation) in the Chayu River Basin, southeastern Qinghai-Tibet Plateau. Our aim was to explore their relationships with evolutionary history and environmental factors by combining the RLQ and the fourth-corner method, and the method of testing phylogenetic signal. The results showed that (i) there were significant differences in the eight LFTs among the six vegetation communities; (ii) the K values of the eight LFTs were less than 1; and (iii) except for LCC, all other LFTs were more sensitive to environmental changes. Among these traits, LA was the most affected by the environmental factors, followed by LNC. It showed that the LFTs in the study were minimally influenced by phylogenetic development but significantly by environmental changes. This study further verified the ecological adaptability of plants to changes in environmental factors and provides a scientific basis for predicting the distribution and diffusion direction of plants under global change conditions. [ABSTRACT FROM AUTHOR]

Purpose: Understanding spatial variations in soil nutrients and its drivers is essential for sustainable nutrient management and related environmental assessment in terrestrial ecosystems. Here, we investigated the distribution characteristics and controlling factors of soil total nitrogen (N) and N fractions along an altitude gradient in an alpine meadow of the Qinghai-Tibet Plateau. Materials and methods: Six experimental sites at altitudes 4400, 4500, 4650, 4800, 4950, and 5200 m were established on southern slope of Nyainqentanglha Mountain since 2005. Total N and N fractions were quantified and their relationships with climate, vegetation, and edaphic factors were analyzed by Pearson correlation, redundancy analysis, and structural equation modeling. Results and discussion: With increasing altitude, the contents of total N, alkali-hydrolyzable N, inorganic N fractions (ammonium N and nitrate N), and organic N fractions (acid-hydrolyzable and acid-insoluble organic N) gradually increased, reached their maximums at altitude 4800 or 4950 m, and then decreased. Soil organic carbon explained 90.5% of the variations in TN and N fractions, and soil moisture, pH, mineralogy, texture, and N hydrolyzing enzyme activity explained 8.80% of the variations in TN and N fractions. Mean annual temperature and precipitation exhibited direct and positive impact on soil organic carbon, which had positive effect on inorganic N fractions and plant aboveground biomass in sequence. Conclusions: Soil organic carbon is the most dominant factors driving the variations in TN and N fractions along the altitude gradient. Climate change can impact alpine grassland productivity by regulating soil inorganic N distribution. [ABSTRACT FROM AUTHOR]

Extreme drought and intensification of land use pose substantial threats to ecosystem stability. However, existing studies that assess ecosystem stability focus primarily on the stability of aboveground net primary productivity (ANPP), while the stability of belowground net primary productivity (BNPP) is often not considered. Here, we examined the response patterns and drivers of ANPP stability and BNPP stability in an alpine meadow to drought and clipping (simulating grazing and mowing) by the implementation of five levels of simulated precipitation (1/12, 1/4, 1/2, 3/4 and ambient precipitation) and clipping (unclipped vs. clipped) treatments over 7 years (2016–2022). The results showed that extreme drought decreased ANPP stability, while moderate drought increased BNPP stability and net primary productivity stability. The findings highlight the importance of jointly considering above‐ and belowground processes when evaluating ecosystem stability. Moreover, clipping did not have an impact on ANPP stability but reduced BNPP stability, and clipping differentially affected the stability of ANPP and BNPP in response to extreme drought. Furthermore, ANPP stability was largely determined by species temporal asynchrony rather than richness, whereas dominant species stability strongly contributed to the variation in BNPP stability of this alpine meadow faced with drought and clipping. Synthesis: In general, these results provide experimental evidence for the decoupling of the responses of above‐ and belowground productivity stability to extreme drought and clipping. Our findings indicate that aboveground responses should not be used as the sole indicator of the whole ecosystem consequences of extreme drought and disturbance factors such as grazing or mowing, emphasizing the need to evaluate ecosystem stability from a whole ecosystem perspective. [ABSTRACT FROM AUTHOR]

Introduction: Grazing management is essential to maintain the stability of grassland ecosystems. Methods: To determine the optimal rest-grazing period of alpine meadow, five rest-grazing periods were set based on soil thawing and plant re-greening in this study. The niche, interspecific relationships, and stability of plant communities at different rest-grazing periods were investigated. Results: Rest-grazing during soil thawing resulted in a small niche width and niche overlap of plants, overall positive interspecific associations, and a high stability of plant communities. Delayed rest-grazing time to plant re-greening resulted in a large niche width and niche overlap of plants, overall negative interspecific associations, and a low stability of plant communities. Discussion: Rest-grazing in alpine meadows should begin as soon as possible to promote healthy and sustainable utilization of grasslands. [ABSTRACT FROM AUTHOR]

Vegetation restoration is among the most effective measures for controlling runoff and soil erosion resulting from human activities. Nevertheless, few studies have been undertaken to analyze the effects of grassland restoration on maintaining local runoff, especially on alpine degraded hillsides where mixed-cultivation grasslands predominate. In this research, runoff plots were established to investigate the impact of three mixed-cultivation grasslands, each sowing two grass species per plot on a 20° slope: Deschampsia cespitosa and Elymus nutans (DE), Poa pratensis L. cv. Qinghai and Elymus nutans (PE), and Poa pratensis L. cv. Qinghai and Deschampsia cespitosa (PD). The activation and volume of surface runoff and the magnitude of soil loss on alpine degraded hillsides over 3 years (2019, 2020, and 2022) were assessed. A severely degraded meadow (SDM) plot was used as a control. The findings indicated that mixed-cultivation grasslands can effectively maintain runoff and reduce soil loss as planting age increases. Between 2019 and 2022, the values of the average runoff depth for DE, PE, PD, and SDM were 0.47, 0.55, 0.45, and 0.27 mm , respectively. Despite the increase in runoff, grassland restoration favored soil conservation: the net soil losses per unit area of SDM were 1.4, 1.3, and 1.9 times greater than those in DE, PE, and PD, respectively. The key factors affecting soil loss and runoff were rainfall amount, duration, and intensity (60 min intensity). We conclude that the results of this study can serve as scientific guides to formulate efficient policy decisions for planning the most effective vegetation restoration in severely degraded hillside alpine meadows. To improve the effectiveness of grassland restoration, we suggest that protective measures should be prioritized during the initial planting stage of cultivated grasslands. [ABSTRACT FROM AUTHOR]

The alpine meadows of the Qinghai–Tibet Plateau have significant potential for storing soil carbon, which is important to global carbon sequestration. Grazing is a major threat to its potential for carbon sequestration. However, grazing poses a major threat to this potential by speeding up the breakdown of organic matter in the soil and releasing carbon, which may further lead to positive carbon-climate change feedback and threaten ecological security. Therefore, in order to accurately explore the driving mechanism and regulatory factors of soil organic matter decomposition in grazing alpine meadows on the Qinghai–Tibet Plateau, we took the grazing sample plots of typical alpine meadows as the research object and set up grazing intensities of different life cycles, aiming to explore the relationship and main regulatory factors of grazing on soil organic matter decomposition and soil microorganisms. The results show the following: (1) soil microorganisms, especially Acidobacteria and Acidobacteria, drove the decomposition of organic matter in the soil, thereby accelerating the release of soil carbon, which was not conducive to soil carbon sequestration in grassland; (2) the grazing triggering effect formed a positive feedback with soil microbial carbon release, accelerating the decomposition of organic matter and soil carbon loss; and (3) the grazing ban and light grazing were more conducive to slowing down soil organic matter decomposition and increasing soil carbon sequestration. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of environmental disturbances on the stoichiometry characteristics of plants in degraded alpine meadows. To achieve this, a mowing experiment was conducted on an alpine meadow with three degradation levels [light degradation (LD), moderate degradation (MD), and severe degradation (SD)] in Shangri-La from 2018 to 2020. Subsequently, differences in plant carbon (C) content, nitrogen (N) content, phosphorous (P) content, C: N P ratio, and N-P power function relationship among different mowing durations (0, 1, 2 a, respectively) were analysed. The results were as follows: (1) Except for the P content of Cyperaceae, plant C, N and P contents of the entire plant community, Gramineae and forbs did not vary among degradation levels (P > 0.05) during the mowing experiment. Plant C, N and P contents tended increase and then decrease with increasing mowing years, i.e., these indices were the highest after 1 a of mowing (P < 0.05) . (2) At the plant community and functional group levels, there was no significant difference in plant C: N ratio and C: P ratio among degradation levels (P > 0.05) . From LD to SD, the N P ratio of the plant community, Cyperaceae and forbs tended to decrease slightly first and then increased (P < 0.05), while the N P ratio of Gramineae did not change significantly (P > 0.05) (3) The N: P ratio and C P ratio showed a parabolic trend, while the C: N ratio showed an inverse trend with the increasing of mowing duration. Before mowing (i.e., mowing 0a), the C: P ratio and N P ratio of Cyperaceae were higher than those of forbs (P < 0.05) but did not vary from those of the plant community and Gramineae (P > 0.05) . After mowing (i.e., mowing 1 a or 2 a), the C: P ratio and N P ratio of Cyperaceae were higher than those of the whole plant community, Gramineae, and forbs (P < 0.05) At each mowing duration, the C N ratio of plants did not vary among plant communities and functional groups (P > 0.05) . (4) Mowing caused a stronger N-P power function relationship and a stable power exponent bot both at the plant community and functional group levels. And the N-P power exponent of Cyperaceae was less than 0.1, while those of the plant community, Gramineae and forbs remained stable at 0.19- 0.22. In conclusion, this study found that plant stoichiometry remained stable across degradation levels but changed significantly with the prolongation of the mowing duration, which implies that different degraded alpine meadows in Northwest Yunnan may share common response mechanisms to mowing disturbance. [ABSTRACT FROM AUTHOR]

Glomalin-related soil protein (GRSP) is an important component of soil organic carbon (SOC), which can promote long-term SOC sequestration. However, GRSP distribution characteristics and its contribution to the SOC pool among different grassland types remain poorly understood. Therefore, six grassland types (alpine meadow, mountain meadow, temperate meadow steppe, temperate steppe, temperate desert steppe, and temperate desert) were chosen to evaluate the contribution of GRSP to the SOC pool and the factors that influence GRSP accumulation in the Irtysh River Basin in China. The results revealed that GRSP (EE-GRSP, T-GRSP) accumulated more in the 0–10 cm soil layer than in the 10–20 cm soil layer (p < 0.05). GRSP content was higher in alpine grasslands (15.69 mg·g−1) than in desert grasslands (5.45 mg·g−1). However, their contribution to the SOC pool exhibited an opposite trend, whereas GRSP-C/SOC even accounted for 11.88% in the desert grasslands. The redundancy analysis (RDA) showed that SOC was the top important positive regulator for GRSP accumulation both in the two layers (explanatory rate > 80%). Besides the SOC factor, the two soil layers had different factors in regulating GRSP accumulation. Changes in GRSP content in the 0–10 cm soil layer were more strongly associated with mean annual temperature (MAT), sand content, soil water content (SWC), and silt content. In contrast, in the 10–20 cm soil layer, GRSP content was more influenced by SWC, electrical conductivity (EC), and pH (p < 0.05). Additionally, the main factor in the GRSP content variation was the interaction between climate and soil in the two soil layers (explanatory rate > 80%). Our findings underscore the critical role of GRSP in facilitating SOC sequestration within desert grasslands and elucidate the primary factors driving GRSP distribution across varying soil depths. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to elucidate the response of soil and water loss resulting from slag dumping engineering disturbances during railway construction, and to unveil the impact of slag accumulation and vegetation restoration on soil and water loss at a slope scale in the ecologically fragile mountain meadow region of eastern Xizang. [Methods] Four slope types such as undisturbed, mildly disturbed, severely disturbed, and disturbed then covered with soil restoration were selected. The in-situ runoff plots were established. The process of sediment production and loss on slope was monitored by artificially simulated rainfall experiment. [Results] (1) The quantity of spattering on the slope increased with the intensity of disturbance, with the amount on the downhill side being approximately 1.14 to 2.67 times greater than that on the uphill side. (2) The initial flow generation time for the lightly disturbed slope, heavily disturbed slope, and covered slope reduced from 53.8% to 66.7%, 34.6% to 46.7%, and 86.7% to 92.9%, respectively. (3) The flow production rates for the undisturbed slope, lightly disturbed slope, heavily disturbed slope, and covered slope ranged from 44 to 86 ml/(min m²), 104 to 147 ml/(min.m²), 200 to 373 ml/(minm²), and 46 to 95 ml/(minm²), respectively. The sediment production rates ranged from 0.026 to 0.055 g/(min m²), 0.05 to 0.098 g/(min m²), 1.034 to 2.189 g/(min m²), and 0.047 to 0.077 g/(min m²), respectively. [Conclusion] The soil and water conservation capacity of the restored slope has been significantly improved in comparison to the lightly disturbed and heavily disturbed slopes. However, there still exists a disparity between the undisturbed slope and the covered slope. Therefore, additional vegetation or engineering measures need to be implemented to restore the disturbed slope effectively. [ABSTRACT FROM AUTHOR]

Plant community stability and diversity play crucial roles in maintaining the stable performance of grassland ecosystem functions. In this study, we selected 55 representative grassland community sample plots in the Habahe Forest region of the Altai Mountains, Xinjiang. We examined the number of species, the number of individuals, and the cover of each species in the sample plots. Additionally, we determined the aboveground biomass of grassland communities, the stability of M. Godron communities, and plant diversity (using the Margalef index, Simpson index, Shannon–Wiener index, and Alatalo evenness index) in the sample plots. We analyzed community stability, plant diversity, and the correlation between community stability, plant diversity, and environmental factors (such as longitude, latitude, altitude, slope, humus thickness, soil thickness, air temperature, precipitation, and soil moisture). The results show that the plant coverage and height of different grassland types in the Habahe Forest area decrease from mountain meadow to desert steppe. The aboveground biomass and species diversity of meadows are significantly higher than those of steppes. The stability of different grassland types is as follows: montane steppe > montane meadow steppe > mountain meadow > desert steppe. The species richness of the four grassland types is positively correlated with community stability, while evenness is negatively correlated with community stability. Dominance in montane steppe and montane meadow steppe is significantly positively correlated with community stability, whereas diversity in desert steppe and montane steppe is significantly negatively correlated with community stability. Precipitation and soil moisture are the main factors affecting species diversity and stability in the Habahe Forest area. Soil nutrients and slope can also impact community stability by affecting species diversity. In summary, the ecological management of grasslands in the Habahe Forest area should consider climate, soil, and terrain factors, and different management measures should be selected to adapt to different grassland types. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation 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.)

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office 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.)

The construction of mountain tunnels can lead to groundwater loss and severely impact plant growth. In order to study the limited discharge of groundwater in mountain tunnels for the normal growth of typical herbaceous plants, a tunnel in the alpine meadow area of Qinghai Province was taken as the research objective. Based on transplant experiments, numerical simulations, and the empirical calculation of tunnel discharge limits, the minimum water level required for the normal growth of herbaceous plants, groundwater changes, and grouting parameters during tunnel construction, as well as limited discharge values of groundwater based on the normal growth requirements of plants, were studied. The results indicate that when the groundwater level declined by 0.6–0.8 m, herbaceous plants were able to normally grow. Generally, tunnel excavation lowered the groundwater level so that the normal growth of herbaceous plants was significantly affected. The reasonable grouting parameters were obtained by numerical simulation. They were able to ensure that the groundwater level decline was less than 0.8 m and ultimately recovered to over 90% of the pre-construction level. The herbaceous plants in Qinghai's alpine grasslands were able to normally grow when the groundwater discharge limit was 0.2~4.0 m3/(m·d). This research offers guidance and support for managing groundwater discharge during tunnel construction in ecologically fragile areas, such as the Three Rivers Source in Qinghai. [ABSTRACT FROM AUTHOR]

Mountain meadows are an essential part of the alpine–subalpine ecosystem; they provide ecosystem services like pollination and are home to diverse plant communities. Changes in climate affect meadow ecology on multiple levels, for example, by altering growing season dynamics. Tracking the effects of climate change on meadow diversity through the impacts on individual species and overall growing season dynamics is critical to conservation efforts. Here, we explore how to combine crowd‐sourced camera images with machine learning to quantify flowering species richness across a range of elevations in alpine meadows located in Mt. Rainier National Park, Washington, USA. We employed three machine‐learning techniques (Mask R‐CNN, RetinaNet and YOLOv5) to detect wildflower species in images taken during two flowering seasons. We demonstrate that deep learning techniques can detect multiple species, providing information on flowering richness in photographed meadows. The results indicate higher richness just above the tree line for most of the species, which is comparable with patterns found using field studies. We found that the two‐stage detector Mask R‐CNN was more accurate than single‐stage detectors like RetinaNet and YOLO, with the Mask R‐CNN network performing best overall with mean average precision (mAP) of 0.67 followed by RetinaNet (0.5) and YOLO (0.4). We found that across the methods using anchor box variations in multiples of 16 led to enhanced accuracy. We also show that detection is possible even when pictures are interspersed with complex backgrounds and are not in focus. We found differential detection rates depending on species abundance, with additional challenges related to similarity in flower characteristics, labeling errors and occlusion issues. Despite these potential biases and limitations in capturing flowering abundance and location‐specific quantification, accuracy was notable considering the complexity of flower types and picture angles in this dataset. We, therefore, expect that this approach can be used to address many ecological questions that benefit from automated flower detection, including studies of flowering phenology and floral resources, and that this approach can, therefore, complement a wide range of ecological approaches (e.g., field observations, experiments, community science, etc.). In all, our study suggests that ecological metrics like floral richness can be efficiently monitored by combining machine learning with easily accessible publicly curated datasets (e.g., Flickr, iNaturalist). [ABSTRACT FROM AUTHOR]

Introduction: Arbuscular mycorrhizal fungi (AMF) are pivotal in plant resource acquisition, mediating plant interactions, and influencing soil carbon dynamics. However, their biogeographical distribution in Tibetan alpine grasslands remains understudied. Methods: In this research, we examined the distribution pattern of AMF communities and their key determinants along a 2000-km transect across the Tibetan plateau, encompassing 7 alpine meadows and 8 alpine steppes. Results: Our findings indicate that AMF community diversity and composition exhibit similarities between alpine meadows and alpine steppes, primarily influenced by latitude and evapotranspiration. At the genus level, Glomus predominated in both alpine meadow (36.49%±2.67%) and alpine steppe (41.87%±2.36%) soils, followed by Paraglomus (27.14%±3.69%, 32.34%±3.28%). Furthermore, a significant decay relationship of AMF community was observed over geographical distance. Null model analyses revealed that random processes predominantly (>50%) drove the assembly of AMF communities. Discussion: In summary, our study elucidates the spatial distribution pattern of AMF in Tibetan plateau grasslands and underscores the significant influence of geographical and climatic factors on AMF community dynamics. [ABSTRACT FROM AUTHOR]

Overgrazing and climate change are the main causes of grassland degradation, and grazing exclusion is one of the most common measures for restoring degraded grasslands worldwide. Soil fungi can respond rapidly to environmental stresses, but the response of different grassland types to grazing control has not been uniformly determined. Three grassland types (temperate desert, temperate steppe grassland, and mountain meadow) that were closed for grazing exclusion for 9 years were used to study the effects of grazing exclusion on soil nutrients as well as fungal community structure in the three grassland types. The results showed that (1) in the 0-5cm soil layer, grazing exclusion significantly affected the soil water content of the three grassland types (P < 0.05), and the pH, total phosphorous (TP), and nitrogen-to-phosphorous ratio (N/P) changed significantly in all three grassland types (P < 0.05). Significant changes in soil nutrients in the 5-10cm soil layer after grazing exclusion occurred in the mountain meadow grasslands (P < 0.05), but not in the temperate desert and temperate steppe grasslands. (2) For the different grassland types, Archaeorhizomycetes was most abundant in the montane meadows, and Dothideomycetes was most abundant in the temperate desert grasslands and was significantly more abundant than in the remaining two grassland types (P < 0.05). Grazing exclusion led to insignificant changes in the dominant soil fungal phyla and a diversity, but significant changes in the b diversity of soil fungi (P < 0.05). (3) Grazing exclusion areas have higher mean clustering coefficients and modularity classes than grazing areas. In particular, the highest modularity class is found in temperate steppe grassland grazing exclusion areas. (4) We also found that pH is the main driving factor affecting soil fungal community structure, that plant coverage is a key environmental factor affecting soil community composition, and that grazing exclusion indirectly affects soil fungal communities by affecting soil nutrients. The above results suggest that grazing exclusion may regulate microbial ecological processes by changing the soil fungal b diversity in the three grassland types. Grazing exclusion is not conducive to the recovery of soil nutrients in areas with mountain grassland but improves the stability of soil fungi in temperate steppe grassland. Therefore, the type of degraded grassland should be considered when formulating suitable restoration programmes when grazing exclusion measures are implemented. The results of this study provide new insights into the response of soil fungal communities to grazing exclusion, providing a theoretical basis for themanagement of degraded grassland restoration. [ABSTRACT FROM AUTHOR]

Roads are an increasingly prevalent form of human activity that drives the decrease in plant community functions and threatens global biodiversity. However, few studies have focused on the changes in the function and diversity of alpine meadows caused by road infrastructure in the Tibetan Plateau. In this study, the changes in species diversity, functional diversity, and community stability were examined at different distances from the Qinghai-Tibet highway. The results showed that the road intensified the degradation of vegetation, which significantly altered species diversity and community structure. This effect gradually decreased from near to far from the highway. Plant community cover and species diversity were highest at intermediate distances (50-100 m) from the roadway; species diversity and stability were lowest in the grassland most disturbed by the road (0 m), and species diversity and functional diversity tended to stabilize farther away from the road (250 m). Our findings indicate that changes in species diversity are synchronized with changes in functional diversity, which largely determines the outcome of degraded grassland community diversity and stability. Our results provide a reference point for restoring degraded alpine areas and mitigating the ecological impacts of roads. [ABSTRACT FROM AUTHOR]

Background: Rickettsia and related diseases have been identified as significant global public health threats. This study involved comprehensive field and systematic investigations of various rickettsial organisms in Yunnan Province. Methods: Between May 18, 2011 and November 23, 2020, field investigations were conducted across 42 counties in Yunnan Province, China, encompassing small mammals, livestock, and ticks. Preliminary screenings for Rickettsiales involved amplifying the 16S rRNA genes, along with additional genus- or species-specific genes, which were subsequently confirmed through sequencing results. Sequence comparisons were carried out using the Basic Local Alignment Search Tool (BLAST). Phylogenetic relationships were analyzed using the default parameters in the Molecular Evolutionary Genetics Analysis (MEGA) program. The chi-squared test was used to assess the diversities and component ratios of rickettsial agents across various parameters. Results: A total of 7964 samples were collected from small mammals, livestock, and ticks through Yunnan Province and submitted for screening for rickettsial organisms. Sixteen rickettsial species from the genera Rickettsia, Anaplasma, Ehrlichia, Neoehrlichia, and Wolbachia were detected, with an overall prevalence of 14.72%. Among these, 11 species were identified as pathogens or potential pathogens to humans and livestock. Specifically, 10 rickettsial organisms were widely found in 42.11% (24 out of 57) of small mammal species. High prevalence was observed in Dremomys samples at 5.60%, in samples from regions with latitudes above 4000 m or alpine meadows, and in those obtained from Yuanmou County. Anaplasma phagocytophilum and Candidatus Neoehrlichia mikurensis were broadly infecting multiple genera of animal hosts. In contrast, the small mammal genera Neodon, Dremomys, Ochotona, Anourosorex, and Mus were carrying individually specific rickettsial agents, indicating host tropism. There were 13 rickettsial species detected in 57.14% (8 out of 14) of tick species, with the highest prevalence (37.07%) observed in the genus Rhipicephalus. Eight rickettsial species were identified in 2375 livestock samples. Notably, six new Rickettsiales variants/strains were discovered, and Candidatus Rickettsia longicornii was unambiguously identified. Conclusions: This large-scale survey provided further insight into the high genetic diversity and overall prevalence of emerging Rickettsiales within endemic hotspots in Yunnan Province. The potential threats posed by these emerging tick-borne Rickettsiales to public health warrant attention, underscoring the need for effective strategies to guide the prevention and control of emerging zoonotic diseases in China. [ABSTRACT FROM AUTHOR]

Herbivore-avoided plant patches are one of the initial characteristics of natural grassland degradation. These vegetation patches can intensify the spatial heterogeneity of soil nutrients within these grasslands. However, the effects of non-edible plant patches patches on the spatial heterogeneity of microorganisms have not been sufficiently studied in alpine meadows of the Qinghai-Tibetan Plateau, especially patches formed by herbaceous plants. To answer this question, soil nutrients, plant assembly, and microbial communities were measured inside, around, and outside of Artemisia smithii patches. These were 0 m (within the patch), 0-1 m (one meter from the edge of the patch), 1-2 m (two meters from the edge of the patch), 2-3 m (three meters from the edge of the patch), and >30 m (non-patch grassland more than thirty meters from the edge of the patch). Our results showed that A. smithii patches accumulated more aboveground biomass (AGB) within the patches (0 m), and formed fertile islands with the soil around the patches. Additionally, A. smithii patches increased soil bacterial diversity within (0 m) and around (0-1 m) the patches by primarily enriching copiotrophic bacteria (Actinobacteria), while the diversity of fungal communities increased mainly in the 0-1 m area but not within the patches. Bacterial community diversity was driven by pH, urease, nitrate nitrogen (NO3 -- N), and microbial biomass carbon (MBC). The contents of soil water (SWC), soil organic matter (SOM), urease, NO3--N, and MBC were the main factors influencing the diversity of the fungal community. This study elucidates the vegetation, nutrients, and microbial heterogeneity and their interrelationships, which are observed in fertile islands of herbivore-avoided plant patches in alpine meadows, and provides further insights into the spatial pattern of nutrients in patchy degraded grasslands. [ABSTRACT FROM AUTHOR]

Aims: Climate warming at high altitudes occurs at an above‐average rate. Due to short geographical distances, warm‐adapted species might establish rapidly in mountain communities, while cold‐adapted specialists are likely to locally disappear, sometimes after a lag phase. Here, we investigate changes not only of the community composition of species‐rich mountain meadows, but also resulting alterations of their functional identity and diversity. Thereby, we hypothesize that transplantation to a warmer lowland environment leads to a shift towards a more acquisitive resource‐use strategy, caused by the immigration of lowland species. Temporarily this leads to an increase in functional diversity through the lagged extinction of high‐altitude species with conservative resource‐use strategies. Location: European Alps, Germany. Methods: Using a space‐for‐time substitution, we conducted a community transplant experiment at a high‐ and low‐elevation common garden site, where we compared the development of highland communities transplanted to the warmer low‐elevation site and control plant communities locally replanted at both sites over a period of 4 years after transplantation. In situ, we collected functional leaf morphological and biochemical traits based on which we calculated community weighted mean traits as well as community functional richness and functional divergence. Results: Species richness of the communities transplanted to the low‐elevation site increased over time, resulting from more species invasions than disappearances. This led to increasing similarity between transplanted highland communities and local lowland communities, and to greater functional richness and divergence 4 years after transplantation, although mean community traits did not diverge yet. Conclusions: Although the exposure to warmer temperatures did not immediately lead to the extinction of typical mountain meadow species, substantial community changes are expected through immigration of warm‐adapted species. Resulting changes in the functional characteristics of mountain communities are likely to modify competition regimes within these communities, which might accelerate the local extinction of mountain specialists. [ABSTRACT FROM AUTHOR]

Walnut trees on the Tibetan Plateau have sustainable and nutritious characteristics. They grow naturally without the use of any chemical fertilizers and pesticides. Therefore, the soil fertility of walnut orchards is a key factor influencing walnut yield and quality. This experiment measured and analyzed the basic soil nutrient content, microbial biomass carbon (MBC), nitrogen (MBN), phosphorus (MBP), and leaf nutrient indicators in five types of representative walnut orchard soil parent materials in Gyaca County to clarify the fertility characteristics of different soil types and their correlations with walnut nutrients, providing a basis for the sustainable development of the plateau walnut industry. The results showed that there were significant differences in soil organic matter (SOM), total nitrogen (TN), available nutrient contents, and microbial activity among soil types with different parent materials. The comprehensive representation of available nutrient levels in the soils is as follows: gray-cinnamon soil and calcareous alluvial soil > mountain meadow soil > plateau prairie soil and brush prairie soil. The average MBC, MBN, and MBP contents in the five soils were 368.8 mg/kg, 28.4 mg/kg, and 23.6 mg/kg, respectively, and the content in the topsoil (0–20 cm) was higher than that of the subsoil (20–40 cm). The total nitrogen (PN), total phosphorus (PP), and total potassium (PK) contents in walnut leaves were found to be closely related to the soil physicochemical properties and microbial activity, among which five indicators, including soil TN, available nitrogen (AN), SOM, MBC, and slowly available potassium (SAK), had the greatest impact on leaf nutrient levels. These findings are valuable for the future management and development of walnut orchards. Therefore, for different soil parent materials and soil types, improving the soil fertility and actively applying nitrogen-rich organic fertilizers should be prioritized to improve the yield and quality of Tibetan Plateau walnuts. [ABSTRACT FROM AUTHOR]

Alpine grassland ecosystems are the most important ecosystem type, exhibiting a high sensitivity to anthropogenic nitrogen (N) and phosphorus (P) inputs into terrestrial ecosystems and significantly affecting the carbon (C) cycle within these ecosystems. However, the effects of N and P additions on soil C stability and the processes of organic C transformation remain unclear. This study measured the soil enzyme activities and oxidizable C fractions over a 9-year period following N and P additions to an alpine meadow in the Qinghai–Tibet Plateau. It included four treatments: control (CK), N addition, P addition, and combined N and P addition (NP), utilizing statistical methods such as analysis of variance (ANOVA), correlation analysis, and redundancy analysis. The findings indicated that NP addition significantly increased the non-labile soil oxidizable C fraction in the topsoil layer. Redundancy and correlation analyses revealed strong associations between the vegetation characteristics, C-cycling enzyme activities, soil-oxidized C fractions, and SOC stability index. These results underscore the role of NP addition in enhancing SOC accumulation and stability in grassland ecosystems, with the soil vegetation properties and C source enzyme activities serving as key regulators of the SOC stability. This study offers valuable insights into predicting the SOC dynamics amid rising N and P availability, thereby elucidating the effect of nutrient addition on soil C-cycling mechanisms. [ABSTRACT FROM AUTHOR]

Background and aims: Dominant plants shape belowground communities, which in turn influences ecosystem functioning. Similarly, herbivores affect belowground communities through physical disturbance and redistribution of organic inputs, but also through their interactions with plants themselves. However, we know little about how grazing moderates the effects of dominant plants on belowground organisms. Methods: We established a three-year shrub removal experiment in a grazed and an ungrazed alpine meadow on the Qinghai-Tibet plateau to assess how grazing moderates the effects of a dominant plant, Dasiphora fruticosa, on nematode communities. We used piecewise structural equation modelling to assess how grazing moderates the direct effects of dominant plants and, indirect effects via changes in edaphic variables and microbial pathways. Results: We found that 1) grazing significantly decreased nematode diversity mainly due to a reduction in omnivores; 2) there was a significant grazing by shrub interaction effect on nematode diversity, whereby shrub had a positive direct effect on nematode diversity only in the grazed meadow; 3) in the ungrazed alpine meadow, microbial diversity was a strong predictor of nematode, while in the grazed meadow, grazing suppressed the microbial pathways of shrub presence. Conclusion: The study shows that grazing decreases the diversity of soil communities and suppresses the interactions among soil biota, while shrub presence plays a vital role in alleviating the negative effects of grazing on understory communities. Therefore, the findings further highlight herbivory in inducing facilitation of dominant shrubs on understory community stabilization and ecosystem functioning in alpine meadows of the Qinghai-Tibetan plateau. [ABSTRACT FROM AUTHOR]

Background and aims: Long-term nitrogen (N) and phosphorus (P) fertilization could immensely alter plant-soil-microbial properties, thereby impacting the priming effect (PE). However, previous studies mostly simulated PE responses to fertilization by adding nutrient in the laboratory, which could not represent PE changes under long-term fertilization-induced ecosystem alteration. Our aim is to clarify the PE alteration in soils with long-term fertilization history in an alpine meadow. Methods: Soil samples (0–10 cm) were collected from a 9-year field fertilization experiment (including four treatments: control, + N with urea, + P with triple superphosphate, + NP with both fertilizers), and incubated for 30 days with 13C-labeled glucose amendment (2% SOC). Plant-soil-microbial properties were measured before/after incubation. Results: Glucose addition induced a positive PE in all soils with a range from 0.56 to 1.37 mg C g−1 soil. N fertilization did not affect PE intensity due to the microbial adaptation and fast utilization of the added glucose for metabolic needs. P fertilization caused P accumulation in soils, and decreased available N and pH. Such changes inhibited microbes, and glucose activated microbial activities, causing higher PE intensity. Conclusion: Long-term N fertilization did not significantly affect PE, while P fertilization stimulated PE intensity. Overall, we highlight that P fertilization may induce higher risk of CO2 release, which deserves more attention when applying P fertilizers in this alpine meadow. [ABSTRACT FROM AUTHOR]

Parasitism is known to affect the behavior of host species to enhance parasite dispersal and transmission. However, host behavioral responses to parasitism unrelated to parasite dispersal and transmission have been much less studied. The objective of this study was to determine whether grasshopper hosts infected and uninfected with a parasitic fly (Blaesoxipha sp.) differ in terms of the nutrient content of the diet they consume. We investigated the dietary preferences of two grasshopper species (i.e. Asulconotus chinghaiensis and Chorthippus fallax) in terms of the C/N composition of plant species consumed, and determined whether this affected the egg production of unparasitized and parasitized grasshoppers by flies in a Tibetan alpine meadow. The composition of plants consumed differed significantly between the unparasitized and parasitized grasshoppers. Specifically, the abundance of N‐rich legumes was lower and that of high C/N grasses was higher in the diet of the parasitized compared to the unparasitized grasshoppers. Diet N content was higher and C/N was lower in the diet of unparasitized grasshoppers, and parasitized females produced fewer eggs than their unparasitized conspecifics. Future enquiries are needed to understand the specific mechanisms underlying these dietary differences. The effects of parasites on the fitness–associated behavior of hosts should be studied more broadly to better understand parasite evolution and adaptation. [ABSTRACT FROM AUTHOR]

[Objective] To explore the dynamic changes of vegetation-soil system biomass and soil nutrients in alpine meadows in the Sanjiangyuan area is favorable for the adaptive management of grassland and the related work of grassland ecological restoration. [Method] Vegetation biomass (aboveground biomass and root biomass), vegetation (aboveground and root system) and soil (0-15 and 15-30 cm) contents of total nitrogen, ammonium nitrogen, nitrate nitrogen, quick-acting nitrogen, organic carbon, total phosphorus and total potassium of alpine meadows were consistently observed from 2020 to 2022 during the months of July, August and September in the moderately degraded alpine meadows as the research objects. The dynamics of vegetation biomass, vegetation nutrients and soil nutrients were compared between months using One-way ANOVA. [Result] There was a significant incremental trend (P<0.05, the same as below) in vegetation biomass between months (except for 2021), with an overall maximum in September, with maximum values of 74.58 and 72.80 g/m² for aboveground bio-mass and 39.82 and 57.32 g/m² for root biomass, respectively. Significant inter-monthly dynamics existed between vegetation (aboveground and root system) and soil (0-15 and 15-30 cm) nutrient contents, as evidenced by the maximum values in August. Vegetation biomass was significantly correlated with total nitrogen content of vegetation aboveground and root system, and positively (P<0.05) correlated with total nitrogen content of soil in the 0-15 and 15-30 cm layers. [Conclusion] Nutrients of alpine meadow vegetation (aboveground and root system) and soil (0-15 and 15-30 cm soil layers) reach the peak in August. The results of the study can provide a reference for scholars in the field of alpine meadow nutrient management to crystallize scientific issues. [ABSTRACT FROM AUTHOR]

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A community functional structure may respond to environmental changes such as nitrogen (N) enrichment by altering intraspecific and interspecific trait variations. However, the relative contributions of both components in determining the community response to N enrichment are unclear. In this study, we measured the plant height (H), leaf area (LA), leaf dry matter content (LDMC), and specific leaf area (SLA) based on a nine-year N addition gradient experiment in an alpine meadow on the Tibetan Plateau. We examined the intraspecific and interspecific variations within and among the communities, the responses of traits in terms of community weighted mean (CWM) and non-weighted mean (CM) to N addition, and the effects of these trait variations on aboveground net primary productivity (ANPP). Our results show that N addition increased the interspecific variation in H while decreasing that of LA within the community, whereas it had no significant effects on the intraspecific variations in the four traits within the community. In contrast, N addition significantly increased the intraspecific variation in H and decreased that of LA among the communities. Moreover, the contribution of intraspecific variation was greater than that of the interspecific variation in terms of CWM for all traits, while the opposite contribution was observed in terms of CM, suggesting that the dominant species would have greater resilience while subdominant species would become less resistant to N addition. Further, intraspecific variations of LA and LDMC within the community played an important role in explaining community productivity. Our results highlight the importance of both intraspecific and interspecific variations in mediating functional trait responses to N enrichment, and intraspecific variation within the communities has important implications for community functioning that should be considered to better understand and predict the responses of the alpine grasslands to N enrichment. [ABSTRACT FROM AUTHOR]

Large amounts of soil organic carbon (SOC) have accumulated over thousands of years in the northern permafrost regions. However, the SOC accumulation rates and the effects of topography, vegetation, and soil properties on SOC storage remain poorly constrained, leading to large uncertainties in the estimation of SOC storage and its response to warming. Here, we examined SOC stocks, densities, and accumulation rates using field sampling and radiometric dating in areas with different topographic parameters on the northern Qinghai–Tibet Plateau. Results show that SOC density and stock increases with elevation on south‐facing slopes but decreases with elevation on north‐facing slopes. The carbon accumulation rates in the upper 6 m soil are highest (16.32 g C m−2 year−1) in the north‐facing alpine wet meadow and lowest (1.07 g C m−2 year−1) in the south‐facing alpine steppe. Elevation‐, slope‐, and slope aspect‐induced variations in soil properties and vegetation type are the main factors controlling the spatial SOC distribution. These results imply that the topography strongly affects the spatial heterogeneity of SOC in mountainous permafrost regions. Overall, our findings highlight that topographic factors should be further integrated into carbon models of carbon responses to climate change in permafrost‐affected soils. [ABSTRACT FROM AUTHOR]

There is strong heterogeneity and gradient in various environmental variables in different terrains, resulting in a microclimate zone that deviates from the regional climate, and its impact on ecosystem function is very complex. Based on long-term moderate-resolution imaging spectroradiometer (MODIS) datasets, terrain and vegetation data of Chinese Loess Plateau, we estimate the ecosystem climate sensitivity under different terrain conditions. Our results show that, the ecosystem precipitation sensitivity is significantly higher than the temperature sensitivity in the Loess Plateau. The regional net primary productivity (NPP) shows a significant positive correlation with the precipitation more than 47.41% areas in the Loess Plateau, while with the temperature accounts for 2.06%. The precipitation sensitivity is the highest in flat territory with an average altitude around 2200 meters. Water deficit restricts the growth of plants in the temperate meadow at the middle altitude more seriously than in alpine meadow and deciduous broadleaf at high and low altitudes. With the increase of altitude and terrain position index, the precipitation sensitivity has an obvious linear trend of increasing first and then decreasing. This result can provide an important reference for us to delimit key environmental protection areas in the Loess Plateau and predict climate sensitivity. [ABSTRACT FROM AUTHOR]

The accurate identification of different restoration stages of degraded alpine meadow patches is essential to effectively curb the deterioration trend of 'Heitutan' (areas of severely degraded alpine meadows in western China). In this study, hyperspectral imaging (HSI) and machine learning techniques were used to develop a method for accurately distinguishing the different restoration stages of alpine meadow patches. First, hyperspectral images representing the four restoration stages of degraded alpine meadow patches were collected, and spectral reflectance, vegetation indexes (VIs), color features (CFs), and texture features (TFs) were extracted. Secondly, valid features were selected by competitive adaptive reweighted sampling (CARS), ReliefF, recursive feature elimination (RFE), and F-test algorithms. Finally, four machine learning models, including the support vector machine (SVM), k-nearest neighbor (KNN), random forest (RF), and extreme gradient boosting (XGBoost), were constructed. The results demonstrated that the SVM model based on the optimal wavelengths (OWs) and prominent VIs achieved the best value of accuracy (0.9320), precision (0.9369), recall (0.9308), and F1 score (0.9299). In addition, the models that combine multiple sets of preferred features showed a significant performance improvement over the models that relied only on a single set of preferred features. Overall, the method combined with HSI and machine learning technology showed excellent reliability and effectiveness in identifying the restoration stages of meadow patches, and provided an effective reference for the formulation of grassland degradation management measures. [ABSTRACT FROM AUTHOR]

Permafrost regions contain approximately half of the carbon stored in land ecosystems and have warmed at least twice as much as any other biome. This warming has influenced vegetation activity, leading to changes in plant composition, physiology, and biomass storage in aboveground and belowground components, ultimately impacting ecosystem carbon balance. Yet, little is known about the causes and magnitude of long-term changes in the above- to belowground biomass ratio of plants (n). Here, we analyzed n values using 3,013 plots and 26,337 species-specific measurements across eight sites on the Tibetan Plateau from 1995 to 2021. Our analysis revealed distinct temporal trends in n for three vegetation types: a 17% increase in alpine wetlands, and a decrease of 26% and 48% in alpine meadows and alpine steppes, respectively. These trends were primarily driven by temperature-induced growth preferences rather than shifts in plant species composition. Our findings indicate that in wetter ecosystems, climate warming promotes aboveground plant growth, while in drier ecosystems, such as alpine meadows and alpine steppes, plants allocate more biomass belowground. Furthermore, we observed a threefold strengthening of the warming effect on n over the past 27 y. Soil moisture was found to modulate the sensitivity of n to soil temperature in alpine meadows and alpine steppes, but not in alpine wetlands. Our results contribute to a better understanding of the processes driving the response of biomass distribution to climate warming, which is crucial for predicting the future carbon trajectory of permafrost ecosystems and climate feedback. [ABSTRACT FROM AUTHOR]

Burrow‐dwelling animals such as the plateau pika (Ochotona curzoniae) often seek sturdy entrances for their burrows, which can reduce the need for frequent maintenance. The toughness of the ground surface is often reinforced by the interweaving of plant roots and often varies with the root characteristics. To better understand ground cover preferences when selecting burrow entrances by plateau pikas, we investigated the ratios of different ground covers at the rear of the entrances, as well as their coverage and underlying soil compaction in an undegraded alpine meadow on the Qinghai‐Xizang Plateau. The results indicated a clear preference hierarchy of sedges > forbs > grass > bare soil. This distribution was aligned with the soil compaction hierarchy of the topsoil layer beneath each cover type. The sedge coverage was significantly negatively correlated with burrow density, suggesting that plateau pikas opt for sturdy entrances with a natural inclination toward energy conservation. However, there is consensus that the population density of plateau pikas often reaches its maximum on almost nonvegetated "black soil beaches." We hypothesized that the survival benefits brought about by vegetation degradation would be higher than the maintenance costs of burrow entrances. [ABSTRACT FROM AUTHOR]

Accurate estimation of livestock carrying capacity (LCC) and implementation of an appropriate actual stocking rate (ASR) are key to the sustainable management of grazing adapted alpine grassland ecosystems. The reliable determination of aboveground biomass is fundamental to these determinations. Peak aboveground biomass (AGBP) captured from satellite data at the peak of the growing season (POS) is widely used as a proxy for annual aboveground biomass (AGBA) to estimate LCC of grasslands. Here, we demonstrate the limitations of this approach and highlight the ability of POS in the estimation of ASR. We develop and trail new approaches that incorporate remote sensing phenology timings of grassland response to grazing activity, considering relations between biomass growth and consumption dynamics, in an effort to support more accurate and reliable estimation of LCC and ASR. The results show that based on averaged values from large-scale studies of alpine grassland on the Qinghai-Tibet Plateau (QTP), differences between AGBP and AGBA underestimate LCC by about 31%. The findings from a smaller-scale study that incorporate phenology timings into the estimation of annual aboveground biomass reveal that summer pastures in Haibei alpine meadows were overgrazed by 11.5% during the study period from 2000 to 2005. The methods proposed can be extended to map grassland grazing pressure by predicting the LCC and tracking the ASR, thereby improving sustainable resource use in alpine grasslands. [ABSTRACT FROM AUTHOR]