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Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation 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.)

Global climate change poses a severe threat to mountain biodiversity. Phenotypic plasticity and local adaptation are two common strategies for alpine plant to cope with such change. They may facilitate organismal adaptation to contrasting environments, depending on the influences of the environment or genotype or their interacted effects. In this study, we use an endemic alpine plant (Rorippa elata) in the Hengduan mountains (HDM) to unravel its phenotypic basis of adaptation strategy and evaluate the relative contributions of environment and genotype to its phenotype. We transplanted 37 genotypes of R. elata into two common gardens across low and high elevations (2800 vs. 3800 m) during 2021–2022. Nine fitness-related traits were measured, including flowering probability and glucosinolates (GS) content. We estimated the environmental or genotypic contributions to the phenotype and identified the main environmental components. Our results revealed that both environment and genotype-by-environment interactions contributed to the phenotypes of R. elata. Latitudinal heterogeneity was identified as a key factor that explained 24% of the total phenotypic variation. In particular, genotypes of the northern HDM showed significantly higher plasticity in flowering probability than those of the southern HDM. Furthermore, within the southern HDM, GS content indicated local adaptation to herbivory stresses for R. elata genotypes along elevations. In conclusion, our results suggest that R. elata may have adapted to the alpine environment through species-level plasticity or regional-level local adaptation. These processes were shaped by either complex topography or interactions between genotype and mountain environments. Our study provides empirical evidence on the adaptation of alpine plants. [ABSTRACT FROM AUTHOR]

The mountains of Southwest China comprise a significant large mountain range and biodiversity hotspot imperiled by global climate change. The high species diversity in this mountain system has long been attributed to a complex set of factors, and recent large‐scale macroevolutionary investigations have placed a broad timeline on plant diversification that stretches from 10 million years ago (Mya) to the present. Despite our increasing understanding of the temporal mode of speciation, finer‐scale population‐level investigations are lacking to better refine these temporal trends and illuminate the abiotic and biotic influences of cryptic speciation. This is largely due to the dearth of organismal sampling among closely related species and populations, spanning the incredible size and topological heterogeneity of this region. Our study dives into these evolutionary dynamics of speciation using genomic and eco‐morphological data of Stellera chamaejasme L. We identified four previously unrecognized cryptic species having indistinct morphological traits and large metapopulation of evolving lineages, suggesting a more recent diversification (~2.67–0.90 Mya), largely influenced by Pleistocene glaciation and biotic factors. These factors likely influenced allopatric speciation and advocated cyclical warming–cooling episodes along elevational gradients during the Pleistocene. The study refines the evolutionary timeline to be much younger than previously implicated and raises the concern that projected future warming may influence the alpine species diversity, necessitating increased conservation efforts. [ABSTRACT FROM AUTHOR]

The distributions of forest, ice and snow in the Hengduan Mountains of China have undergone significant changes due to ongoing climatic warming. To better understand the spatiotemporal pattern of temperature changes in the Hengduan Mountains, we used tree-ring cores collected from multiple individuals of Larix speciosa Cheng et Law at five sites to develop a regional chronology and to establish the relationship between tree-ring radial growth and warm-season (May–September) mean temperature. The regional chronology accounts for 46.1% of the observed variance in the warm season and was used to reconstruct regional temperature levels back to 1420. Four cool intervals (1490–1570, 1590–1660, 1700–1790, and 1800–1880) indicate that the Western Hengduan Mountains experienced the Little Ice Age, and the changes were synchronous with cooling on the Tibetan Plateau and in the Northern Hemisphere, demonstrating a well-defined Little Ice Age signal in the South Asian monsoon region. Air–sea interactions and solar activity affected the variability of the warm-season mean temperature variations on interannual or interdecadal scales. Our temperature reconstruction improves the understanding of multi-centennial climate change in the Western Hengduan Mountains and has implications for advancing high-resolution paleoclimate science in the region. [ABSTRACT FROM AUTHOR]

To help address the underrepresentation of arthropods and Asian biodiversity from climate‐change assessments, we carried out year‐long, weekly sampling campaigns with Malaise traps at different elevations and latitudes in Gaoligongshan National Park in southwestern China. From these 623 samples, we barcoded 10,524 beetles and compared scenarios of climate‐change‐induced biodiversity loss, by designating seasonal, elevational, and latitudinal subsets of beetles as communities that plausibly could go extinct as a group, which we call "loss sets". The availability of a published mitochondrial‐genome‐based phylogeny of the Coleoptera allowed us to compare the loss of species diversity with and without accounting for phylogenetic relatedness. We hypothesised that phylogenetic relatedness would mitigate extinction, since the extinction of any loss set would result in the disappearance of all its species but only part of its evolutionary history, which is still extant in the remaining loss sets. We found different patterns of community clustering by season and latitude, depending on whether phylogenetic information was incorporated. However, accounting for phylogeny only slightly mitigated the amount of biodiversity loss under climate change scenarios, against our expectations: there is no phylogenetic "escape clause" for biodiversity conservation. We achieve the same results whether phylogenetic information was derived from the mitogenome phylogeny or from a de novo barcode‐gene tree. We encourage interested researchers to use this data set to study lineage‐specific community assembly patterns in conjunction with life‐history traits and environmental covariates. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment 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.)

Understanding the evolutionary and ecological processes driving population differentiation and speciation can provide critical insights into the formation of biodiversity. Here, we examine the link between population genetic processes and biogeographic history underlying the generation of diversity in the Hengduan Mountains (HM), a region harboring a rich and dynamic flora. We used restriction site-associated DNA sequencing to generate 1,907 singlenucleotide polymorphisms (SNPs) and four-kb of plastid sequence in species of the Gentiana hexaphylla complex (Gentianaceae). We performed genetic clustering with spatial and non-spatial models, phylogenetic reconstructions, and ancestral range estimation, with the aim of addressing the processes influencing diversification of G. hexaphylla in the HM. We find the G. hexaphylla complex is characterized by geographic genetic structure with clusters corresponding to the South, North and the central HM. Phylogenetic reconstruction and pairwise FST analyses showed deep differentiation between Southern and Northern populations in the HM. The population in Mount Taibai exhibited the highest genetic similarity to the North HM. Ancestral range estimation indicated that the G. hexaphylla complex originated in the central HM and then diverged in the Pliocene and the Early Pleistocene, before dispersing widely, resulting in the current distinct lineages. Overall, we found deep genomic differentiation in the G. hexaphylla complex corresponds to geographic barriers to dispersal in the HM and highlights a critical role of the uplift of the Daxue Mountains and subsequent climatic fluctuations underlying diversification. The colonization of G. hexaphylla in the Mount Taibai region suggests directional dispersal between the alpine flora of the Qinling Mountains and the HM. [ABSTRACT FROM AUTHOR]

Endemic vertebrates are a crucial component of biodiversity, yet face disproportionally high extinction risk as climate and land-use changes drive habitat loss. Large protected areas are therefore deemed necessary to mitigate biodiversity loss. In 2021, China’s Giant Panda National Park (GPNP, 27,134 km2) was established in one of the global endemism hotspots. In this study we ask the question whether this large national park is able to conserve the many threatened endemic vertebrates occurring in the region in the face of climate and land-use changes, in order to assess the long-term effectiveness of the GPNP. We used species distribution modeling techniques to project the distributions of 40 threatened terrestrial (and freshwater) endemic vertebrates under land-use and climate change scenarios SSP2–4.5, SSP3–7.0 and SSP5–8.5 in 2081–2100, and assessed the extent to which their distributions are covered by the GPNP, now and in the future. We found that by 2081–2100, two thirds of the threatened endemic vertebrates are predicted to lose part (15–79%, N = 4) of or (nearly) their entire (80–100% loss, N = 23) range under all three climate and land-use change scenarios. Consequently, fewer species are predicted to occur in the GPNP than at present. Our findings confirm the high vulnerability of threatened endemic species to climate and land-use changes, despite protected areas. Habitat loss due to climate and land-use changes elevate extinction risk of species in endemism hotspots across the globe. Urgent, widespread and intensified mitigation measures and adaptation measures are required at a landscape scale for effective conservation efforts in the future.

The Fraction of Absorbed Photosynthetically Active Radiation (FPAR) is an important indicator of the primary productivity of vegetation. FPAR is often used to estimate the assimilation of carbon dioxide in vegetation. Based on MOD15A2H/FPAR data product, the temporal and spatial variation characteristics and variation trend of FPAR in different vegetation types in 2001 to 2018 were analyzed in the Hengduan Mountains. The response of FPAR to climate change was investigated by using Pearson correlation analytical method and partial least squares regression analysis. Results showed that the FPAR in Hengduan Mountains presented an increasing trend with time. Spatially, it was high in the south and low in the north, and it also showed obvious vertical zonality by elevation gradient. The vegetation FPAR was found to be positively correlated with air temperature and sunshine duration but negatively correlated with precipitation. Partial least squares regression analysis showed that the influence of sunshine duration on vegetation FPAR in Hengduan Mountains was stronger than that of air temperature and precipitation. [ABSTRACT FROM AUTHOR]

Assessing the impacts of climate change on geographic distribution by identifying how biological response relates to environmental conditions is important for addressing the adverse effects of climate change. Using the maximum entropy algorithm and spatial analysis module of ArcGIS, we construct a habitat prediction model for the geographic distribution of alpine vegetation in the Hengduan Mountains of southwestern China. We use the model to identify how alpine vegetation has responded to climatic changes during the period 1980–2018, and to predict responses to possible temperature and precipitation changes in the future. The results indicate that the geographic distribution of alpine vegetation in the Hengduan Mountains is most sensitive to annual mean minimum temperature variation. The most suitable habitat for alpine vegetation under climate change is in northernmost Sichuan, in the Hengduan–Himalayan mountain area, at elevations from 4500 to 5000 masl. The current area of alpine vegetation in the Hengduan Mountains accounts for 8.20% of their total area. As the annual mean temperature increases, the area suitable for alpine vegetation increases by 0.32–1.27%, regardless of changes in precipitation. When the temperature increases by 1–2°C, the area unsuitable for alpine vegetation decreases by 1.64–2.97%. These results indicate that a temperature increase influences the geographic distribution pattern of alpine vegetation in the Hengduan Mountains. The most notable effect was under the 2°C increase scenario. The predictions suggest that under future climate change, the geographic distribution of alpine vegetation will continue to shift toward middle and higher elevations. To protect endemic alpine vegetation, the best habitats should be protected from interference and destruction by human activities.

Long‐lived tree species are genetically differentiated and locally adapted with respect to fitness‐related traits, but the genetic basis of local adaptation remains largely unresolved. Recent advances in population genetics and landscape genomic analyses enable identification of putative adaptive loci and specific selective pressures acting on local adaptation. Here, we sampled 60 evergreen oak (Quercus aquifolioides) populations throughout the species' range and pool‐sequenced 587 individuals at drought‐stress candidate genes. We analyzed patterns of genetic diversity and differentiation for 381 single nucleotide polymorphisms (SNPs) from 65 candidate genes and eight microsatellites. Outlier loci were identified by genetic differentiation analysis and genome–environment associations. The response pattern of genetic variation to environmental gradient was assessed by linear isolation‐by‐distance/environment tests, redundancy analysis, and nonlinear methods. SNPs and microsatellites revealed two genetic lineages: Tibet and Hengduan Mountains–Western Sichuan Plateau (HDM‐WSP), with reduced genetic diversity in Tibet lineage. More outlier loci were detected in HDM‐WSP lineage than Tibet lineage. Among these, three SNPs in two genes responded to dry season precipitation in the HDM‐WSP lineage but not in Tibet. By contrast, genetic variation in the Tibet lineage was related to geographic distance instead of the environment. Furthermore, risk of nonadaptedness (RONA) analyses suggested HDM‐WSP lineage will have a better capacity to adapt in the predicted future climate compared with the Tibet lineage. We detected genetic imprints consistent with natural selection and molecular adaptation to drought on the Qinghai–Tibet Plateau (QTP) over a range of long‐lived and widely distributed oak species in a changing environment. Our results suggest that different within‐species adaptation processes occur in species occurring in heterogeneous environments. [ABSTRACT FROM AUTHOR]

Assessing the impacts of climate change on geographic distribution by identifying how biological response relates to environmental conditions is important for addressing the adverse effects of climate change. Using the maximum entropy algorithm and spatial analysis module of ArcGIS, we construct a habitat prediction model for the geographic distribution of alpine vegetation in the Hengduan Mountains of southwestern China. We use the model to identify how alpine vegetation has responded to climatic changes during the period 1980–2018, and to predict responses to possible temperature and precipitation changes in the future. The results indicate that the geographic distribution of alpine vegetation in the Hengduan Mountains is most sensitive to annual mean minimum temperature variation. The most suitable habitat for alpine vegetation under climate change is in northernmost Sichuan, in the Hengduan–Himalayan mountain area, at elevations from 4500 to 5000 masl. The current area of alpine vegetation in the Hengduan Mountains accounts for 8.20% of their total area. As the annual mean temperature increases, the area suitable for alpine vegetation increases by 0.32–1.27%, regardless of changes in precipitation. When the temperature increases by 1–2°C, the area unsuitable for alpine vegetation decreases by 1.64–2.97%. These results indicate that a temperature increase influences the geographic distribution pattern of alpine vegetation in the Hengduan Mountains. The most notable effect was under the 2°C increase scenario. The predictions suggest that under future climate change, the geographic distribution of alpine vegetation will continue to shift toward middle and higher elevations. To protect endemic alpine vegetation, the best habitats should be protected from interference and destruction by human activities. [ABSTRACT FROM AUTHOR]

Improved understanding of climate-growth relationships of multiple species is fundamental to understanding and predicting the response of forest growth to future climate change. Forests are mainly composed of conifers in Northwestern Yunnan Plateau, but variations of growth response to climate conditions among the species are not well understood. To detect the growth response of multiple species to climate change, we developed residual chronologies of four major conifers, i.e., George’s fir (Abies georgei Orr), Likiang spruce (Picea likiangensis (Franch.) E.Pritz.), Gaoshan pine (Pinus densata Mast.) and Chinese larch (Larix potaninii Batalin) at the upper distributional limits in Shika Snow Mountain. Using the dendroclimatology method, we analyzed correlations between the residual chronologies and climate variables. The results showed that conifer radial growth was influenced by both temperature and precipitation in Shika Snow Mountain. Previous November temperature, previous July temperature, and current May precipitation were the common climatic factors that had consistent influences on radial growth of the four species. Temperature in the previous post-growing season (September–October) and moisture conditions in the current growing season (June–August) were the common climatic factors that had divergent impacts on the radial growth of the four species. Based on the predictions of climate models and our understanding of the growth response of four species to climate variables, we may understand the growth response to climate change at the species level. It is difficult to predict future forest growth in the study area, since future climate change might cause both increases and decreases for the four species and indirect effects of climate change on forests should be considered. [ABSTRACT FROM AUTHOR]

Monitoring the variability of snow cover is necessary and meaningful because snow cover is closely connected with climate and ecological change. In this work, 500 m resolution MODIS daily snow cover products from 2000 to 2014 were adopted to analyze the status in Hengduan Mountains. In order to solve the spatial discontinuity caused by clouds in the products, we propose an adaptive spatio-temporal weighted method (ASTWM), which is based on the initial result of a Terra and Aqua combination. This novel method simultaneously considers the temporal and spatial correlations of the snow cover. The simulated experiments indicate that ASTWM removes clouds completely, with a robust overall accuracy (OA) of above 93% under different cloud fractions. The spatio-temporal variability of snow cover in the Hengduan Mountains was investigated with two indices: snow cover days (SCD) and snow fraction. The results reveal that the annual SCD gradually increases and the coefficient of variation (CV) decreases with elevation. The pixel-wise trends of SCD first rise and then drop in most areas. Moreover, intense intra-annual variability of the snow fraction occurs from October to March, during which time there is abundant snow cover. The inter-annual variability, which mainly occurs in high elevation areas, shows an increasing trend before 2004/2005 and a decreasing trend after 2004/2005. In addition, the snow fraction responds to the two climate factors of air temperature and precipitation. For the intra-annual variability, when the air temperature and precipitation decrease, the snow cover increases. Besides, precipitation plays a more important role in the inter-annual variability of snow cover than temperature. [ABSTRACT FROM AUTHOR]

Explaining how plants from eastern Asia migrated to other Northern Hemisphere regions is still challenging. The genus Sorbus sensu stricto (including c . 88 species) is considered as a good example to illuminate this scenario, due to the wide distribution in the temperate zone and high diversity in the Himalayas and Hengduan Mountains. Based on four nuclear markers ( LEAFY -2, GBSSI -1, SBEI and WD ) and one chloroplast marker ( rps16 - trnK ), we reconstructed the phylogenetic relationship of Sorbus using 54 taxa (60% of the genus representing all subgenera, sections, or series and geographical areas in the previous classifications), and estimated divergence time and historical biogeography of the genus. Phylogenetic analyses supported that the subgenera Sorbus and Albo - carmesinae , as defined by traditional morphological characters (such as fruit color), are suitable. However, five clades defined by phylogenetic analysis of the genus are not consistent with traditionally defined sections or series. Molecular dating and biogeographic reconstruction showed that the age of the most recent common ancestor was estimated at 41 mya (95% HPD: 49–35 mya) in eastern Asia. Four dispersal events are assumed to explain the wide distribution of Sorbus in the temperate zone and diversification in the edges of Qinghai-Tibet Plateau (QTP). Species dispersed from eastern Asia to the Tianshan Mountains, North America and Europe during the Oligocene and Miocene period. We found that polyploidization occurred multiple times in the subgenus Albo - carmesinae , in the Tianshan Mountains, Himalayas, and H-D Mountains. Finally, we suggest that apomixis, polyploidization, and hybridization may have combined with the multistage uplifting of Himalayas and H-D Mountains (and the subsequent increases in geologic, ecological and climatic heterogeneity) to drive the striking species diversity of Sorbus in this region. [ABSTRACT FROM AUTHOR]

Aim To identify hotspots of endemic and non-endemic avian diversity in the mountains of south-west China and delineate biodiversity corridors that connect the faunas of northern and southern Asia. To understand how biodiversity and endemism in this region has been maintained through palaeoclimate change. Location The mountains of south-west China, spanning an elevational gradient > 7000 m. Methods We used the distributional data of 752 breeding birds to investigate current patterns of diversity across elevational and geographical space. We simulated species richness under palaeoclimate models of global temperature change, assessing changes in species richness. Results Contemporary species richness of non-endemic birds peaked at 800-1800 m elevation, while endemic richness peaked at 2000-3000 m. Richness of non-endemic birds was highest in the southern Hengduan Mountains and Yungui Plateau, while endemic richness peaked further north, extending into the mountains along the western edge of the Sichuan Basin. Under global warming models, species richness remained high throughout the Hengduan Mountains region. Under global cooling models, the Sichuan Basin showed increased richness. Conclusions Endemism peaked in the mountains along the western edge of the Sichuan Basin, highlighting the importance of this region in promoting and maintaining diversity. This region has likely functioned as a biodiversity corridor, bridging the Palaearctic and Oriental biotas to the north and south. Climate simulations suggest that the mountains of south-west China can accommodate upslope range shifts in response to warming, but low elevation specialists may have experienced increased extinction probabilities during cold periods in the recent past, which may in part explain the current mid-elevation diversity peak. During glacial periods the Sichuan Basin likely served as a warm refugium for montane birds. Steep environmental heterogeneity has been a key to maintaining high diversity and endemism in the region during palaeoclimate change. These same features will likely shape the effects of future climate change on biodiversity in the region. [ABSTRACT FROM AUTHOR]

Dendrochronological methods have been used to reconstruct insect outbreaks, yet the application has been scarce in the high Asia. We compiled tree-ring data from 4 host (Larix potaninii) and 4 non-host (Abies and Picea) sites in the central Hengduan Mountains, southwestern China. We assessed site-specific growth-climate responses and applied two methods to detecting larch insect defoliation events during the past 250 years. Compared with the non-host chronologies, larch trees (host) showed periodic reduction in radial growth, which may be associated with outbreaks of a larch defoliator. Synchronously, growth reductions was found for three low-elevation sites, such as during 1783–1790, 1846–1850, 1860–1865, 1873–1878, 1900–1909, 1939–1945, 1965–1970 and 1981–1986. However, these periods of outbreaks differ from those of a high-elevation site. With spectral analyses, we found 11–13 years frequency domains for three low-elevation larch chronologies, while 7–9 year peaks presented one high-elevation site. Contrastively, no significant frequency domains within the same periodicity were found in ring-width chronologies of co-occurring non-host species. We provide tree-ring evidence that larch trees growing in the central Hengduan Mountains have been infected by insect defoliators repeatedly. We suggest that appropriate approaches should be applied to correct insect-defoliation signals when using larch tree-ring data as a climatic proxy. [ABSTRACT FROM AUTHOR]

[Display omitted] • The evolutionary history of Pleione was investigated using single-copy gene single nucleotide polymorphisms and chloroplast genome datasets. The data revealed that Pleione can be divided into five clades. • Ancestral area reconstruction suggested that Pleione likely originated from the HDM. The uplifting of the HDM drove rapid diversification by creating conditions favoring rapid speciation. This coincided with two periods of strengthening of the Asian monsoon climate, which caused the first rapid diversification of Pleione from 8.87 to 7.83 Mya, and a second rapid diversification started at around 4.05 Mya to Pleistocene. • In addition to revealing the evolutionary relationship of Pleione with orogeny and climate changes, the findings provide insights into the speciation and diversification mechanisms of plants in the East Asian flora. Pleione is an orchid endemically distributed in high mountain areas across the Hengduan Mountains (HDM), Himalayas, Southeast Asia and South of China. The unique flower shapes, rich colors and immense medicinal importance of Pleione are valuable ornamental and economic resources. However, the phylogenetic relationships and evolutionary history of the genus have not yet been comprehensively resolved. Here, the evolutionary history of Pleione was investigated using single-copy gene single nucleotide polymorphisms and chloroplast genome datasets. The data revealed that Pleione could be divided into five clades. Discordance in topology between the two phylogenetic trees and network and D -statistic analyses indicated the occurrence of reticulate evolution in the genus. The evolution could be attributed to introgression and incomplete lineage sorting. Ancestral area reconstruction suggested that Pleione was originated from the HDM. Uplifting of the HDM drove rapid diversification by creating conditions favoring rapid speciation. This coincided with two periods of consolidation of the Asian monsoon climate, which caused the first rapid diversification of Pleione from 8.87 to 7.83 Mya, and a second rapid diversification started at around 4.05 Mya to Pleistocene. The interaction between Pleione and climate changes, especially the monsoons, led to the current distribution pattern and shaped the dormancy characteristic of the different clades. In addition to revealing the evolutionary relationship of Pleione with orogeny and climate changes, the findings of this study provide insights into the speciation and diversification mechanisms of plants in the East Asian flora. [ABSTRACT FROM AUTHOR]

Aim: To assess the validity of four hypothesized drivers (Quaternary climate, niche conservatism, contemporary climate, spatial configuration) of small mammal beta diversity in the Qinghai-Tibetan Plateau (QTP) and the Hengduan Mountains (HDM). Location: QTP and HDM of China. Methods: We partitioned the beta diversity of small mammals in QTP and HDM into the spatial turnover and nestedness components at the regional (longitudinal/latitudinal zones) and grid (1° 1°) scales. Regional beta diversity was evaluated by calculating the multiple-site dissimilarities and the distance- dissimilarity relationships. We examined the relative effects of geographical distance, environmental difference, habitat diversity, geographical isolation and Quaternary climate stability on the beta diversity patterns. Results: The overall beta diversity in all longitudinal/latitudinal zones of both regions was primarily driven by spatial turnover, longitudinal nestedness patterns were almost non-existent in QTP. Turnover was stronger in the latitudinal direction of QTP and in the longitudinal direction of HDM, which corresponded to the general topography of each region. At the grid scale, higher turnover was primarily concentrated in mountainous areas. Turnover was highly correlated with geographical distance and environmental difference in both regions, and geographical isolation was another strong predictor of turnover in HDM. Habitat diversity independently explained most of the variation in nestedness of HDM. Main conclusions: Spatial turnover is the primary cause of the small mammal beta diversity in QTP and HDM. Three non-exclusive mechanisms including the historic effect of past glaciation, contemporary climate and spatial configuration of the landscape might act in combination to shape the beta diversity patterns in QTP and HDM, particularly the directional patterns. Our results challenge the prevailing view that the current distribution of QTP fauna is primarily explained by westward post-glacial recolonization, and support the alternative idea that QTP retained considerable refugia and even centres of origin during the Quaternary glaciations. [ABSTRACT FROM AUTHOR]

• Tree diversity and traits are important for epiphytic bryophytes-phorophytes network. • Ecological interactions of epiphytic bryophytes and phorophytes were explored. • Biodiversity conservation of epiphytic bryophytes and phorophytes are consistent. The Qinghai-Tibet Plateau (QTP), the highest and largest plateau in the world, plays a vital role in maintaining the balance of the global ecosystem and China's ecological barriers. The QTP ecosystems are facing serious challenges under the scenario of global climate change. Epiphytic plant diversity is one of the most significant contributors to forest diversity. Epiphytic bryophytes play an important role in forest ecosystem functioning. However, previous studies of epiphytic bryophyte diversity have rarely considered both phorophyte diversity and their ecological networks, factors that are crucial for revealing the ecological processes of community assembly and the mechanisms of biodiversity maintenance and ecosystem stability. We investigated the diversity of epiphytic bryophytes and their host trees in 18 forest sites in the southeastern QTP and analyzed the characteristics of their ecological network. A total of 57 epiphytic bryophyte species in 35 genera and 24 families and 72 individuals of host trees belonging to 14 genera and 10 families were recorded. Epiphytic bryophyte species on Picea , Abies , and Sorbus accounted for 77% of all species. The ecological network structure of epiphytic bryophytes-phorophytes exhibited low connectance and nestedness and a low degree of specialization. The cover of epiphytic bryophytes was significant positively correlated with host tree size (diameter at breast height) and not significantly correlated with bark roughness. Both tree size and bark roughness were weakly positively correlated with epiphytic bryophyte richness. The study results showed that increasing tree diversity is essential for the maintenance of the epiphytic bryophyte diversity in forests of the QTP. Biodiversity conservation of epiphytic bryophytes is consistent with conservation of their host trees. [ABSTRACT FROM AUTHOR]

Aim To understand the causes of historical and current elevational richness patterns of Leiothrichinae babblers, a diverse and mostly endemic group of birds. Location A 5000-m elevational gradient in the Hengduan Mountains, China. Methods By means of a dated phylogenetic tree and reconstructed ancestral states, we estimated elevation-specific diversification rate, applied a new method to estimate colonization frequency and age and, for the first time, modelled historical species richness patterns that take account of temporal patterns of palaeotemperature. As explanations for current richness patterns, we assessed area, geometric constraints, temperature, precipitation, seasonality and productivity. Results The current elevational pattern of species richness is a hump-shaped curve with a peak at about 1000-2500 m. The reconstructed palaeopatterns of species richness suggest that babblers, as a clade, first occupied the Hengduan Mountains at low to mid-elevations, although the method of ancestral state reconstruction cannot conclusively reject origins outside the current elevational distribution of the group. Diversification rates varied little along the elevational gradient, and thus cannot explain the richness pattern, but historical colonization frequency and colonization age were highly correlated with present-day species richness. Seasonality and productivity had greater power than area and geometric constraints in explaining the present-day richness pattern of babblers along the elevational gradient. Conclusions Historical and modern factors have both played important roles in shaping species richness patterns. Reconstructed historical richness patterns suggest that babblers first diversified in the Hengduan Mountains at low to mid elevations, but richness patterns almost certainly shifted substantially under changing climates of the past 10 Myr. The current richness patterns of babblers are associated with seasonality and productivity, but they are also a product of historical evolutionary and ecological dynamics. The methods we introduce for assessing historical colonization rates and past patterns of richness offer promise for understanding other elevational richness gradients. [ABSTRACT FROM AUTHOR]

Our understanding of geographic patterns of species diversity and the underlying mechanisms is increasing rapidly, whereas the temporal variation in these patterns remains poorly understood. We examined the seasonal species richness and species turnover patterns of non-volant small mammals along three subtropical elevational gradients in southwest China. Small mammal diversity was surveyed in two seasons (early wet season and late wet season) using a standardized sampling protocol. The comparison of species richness patterns between two seasons indicated a temporal component in magnitude and shape, with species richness at high elevations clearly increased during the late wet season. Species richness demonstrated weak correlations with modelled temperature and precipitation. The elevational pattern of species turnover measured by Chao- Sørenson similarity index also changed seasonally, even though the temporal pattern varied with scale. Species turnover between neighboring elevations at high elevations was slower in the late wet season. Meanwhile, there was an acceleration of species turnover along the whole range of the gradient. The seasonal change in species diversity patterns may be due to population-level increases in abundance and elevational migration, whereas seasonal variation in factors other than temperature and precipitation may play a greater role in driving seasonal diversity patterns. Our study strongly supports the seasonality in elevational patterns of small mammal diversity in subtropical montane forests. Thus it is recommended that subsequent field surveys consider temporal sampling replicate for elevational diversity studies. [ABSTRACT FROM AUTHOR]

This paper presents a 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau using tree-ring records. Tree-ring samples were collected from the Hengduan Mountains in the southeastern part of the Qinghai-Tibet Plateau, China. A nearly 500-year chronology was developed using tree-ring width records. Correlation analysis shows moisture is the main factor limiting tree growth in this region. Ring-widths were significantly positively correlated with the Palmer Drought Severity Index (PDSI) and precipitation in many months. The highest correlation coefficient was found between the annual growth of trees and precipitation from the previous September to the current June (0.738). Based on this relationship, we reconstructed the precipitation history from 1509 to 2006. The reconstruction explains 54.4% ( R=53.5%, N=49, F=56.12) of the actual precipitation variation during the calibration period (1958-2006). During the reliable period of the reconstruction (1549-2006), some low-frequency climate signals are included, indicating this region has been getting wetter in the last 20 years. The reconstruction documents six apparently dry and five pluvial periods and the 17th century dry period lasted longer than any other. When compared with other recent studies, this study and these earlier reconstructions show a similar trend in the variation of drought and pluvial. Further spatial correlation analysis confirms that the reconstructed precipitation adequately represents the rainfall history of the entire Hengduan Mountain area. The Multi-taper method, a type of spectral analysis, reveals that precipitation in this area had significant ( P<0.01) spectral peaks at 3-5 a, 60 a and 79-85 a. [ABSTRACT FROM AUTHOR]

Abstract: Improved understanding of tree-growth responses to climate is needed to model and predict forest ecosystem responses to current and future climatic variability. We applied dendroclimatological techniques to assess the effects of inter-annual climate variations on radial growth of high-elevation conifers in the central Hengduan Mountains, southwestern China. Eight tree-ring width chronologies of the major tree genera Abies and Picea that are aligned along an elevation gradient from 3200 to 4200m a.s.l. were developed. Correlation and principal component analyses for the eight chronologies identified three groups of sites, representing different patterns of growth–climate relationships. Correlation and redundancy analyses with regional climate data revealed that radial growth of fir growing at high-elevation sites is enhanced by normal or warm summer temperatures (June and July) during the current growing season. In addition, radial growth of trees growing from high to middle elevations is sensitive to low temperatures during winter season. At low-elevation sites, trees display low sensitivity to temperature variation. However spring moisture availability becomes crucial for radial growth regardless of tree species. High- to middle-elevation conifers in the central Hengduan Mountains may benefit from the current climate warming, especially from rising winter temperatures. [Copyright &y& Elsevier]

[Display omitted] • Investigate the spatiotemporal dynamics of the timberline over the past 3 decades. • The overall average elevation of the alpine timberline increased by about 55 m. • There was a clear tendency for the alpine timberline to accelerate upward. • The timberline on shaded slopes is about 160 m higher than on sunward slopes. • Temperature is the main climate driving factor in alpine timberline rise. The spatiotemporal change in the alpine timberline, an ecosystem ecotone, is an ideal indicator for use in climate change research. In order to gain a quantitative understanding of the response of the alpine timberline to climate change, the Hengduan Mountains region of China was selected as a study area and a series of 136 Landsat images covering this area that were acquired in 1985, 1995, 2005 and 2015 were collected. First, the alpine timberline was retrieved and the spatiotemporal dynamics of the timberline were explored. The effect of topography on the location of the alpine timberline was also analyzed. The results indicate that the average elevation of the timberline increased by about 55 (±8.54) m from 3992.58 m in 1985 to 4047.60 m in 2015; however, there was obvious spatial heterogeneity in these changes. On the whole, the average elevation of the timberline on shaded slopes (northern, northeastern, and northwestern slopes) were found to be about 160 m higher than on sunward slopes (southern, southeastern, and southwestern slopes). It was also found that, over the period 1985–2015, there has been an obvious acceleration in the upward tendency of the alpine timberline. Finally, the climate variables that are driving this timberline shift were identified and evaluated using the partial least squares (PLS) regression method. The results indicate that the average annual temperature (TEM_Year), total precipitation during the growing season (PRE_Grow), and growing season temperature (TEM_Grow) were the significant positive factors driving the rise in the timberline elevation; the total annual precipitation (PRE_Year) was found to have an unexpected negative influence. Besides, other climatic factors (e.g., strong winds) and non-climate variables (e.g., human influence and soil properties) should be also included in future related studies to enhance the understanding of the link between forest vegetation and climate change under extreme conditions. [ABSTRACT FROM AUTHOR]

• Radial growth of Abies delavayi in southwest China is mainly limited by high temperatures and low moisture availability. • Tree growth rate of A. delavayi has been declining since the 1950s, accompanied with a remarkable increase of iWUE. • Xylem stable carbon (δ13C) and oxygen (δ18O) isotopic composition shifted to higher values from cold to warm years. • Growth declines of A. delavayi were driven by increasing drought stress and stomatal closure under a warming climate. Long-term tree growth trends and physiological responses to environmental changes, i.e., climate warming, and the rise of atmospheric [CO 2 ] (C a), need to be investigated across diverse forest ecosystems. We detected long-term trends in tree growth and δ13C derived intrinsic water use efficiency (iWUE) of Abies delavayi in the Cangshan Mountains, at its southern distribution edge in the Hengduan Mountains in southwestern China. We applied a dual-isotopic approach (δ13C, δ18O) to detect the shifts of tree physiological responses (photosynthetic, stomatal conductance) from colder to warmer conditions. Annual basal area increment (BAI) of A. delavayi in the Cangshan Mountains was decreasing since the 1950s, whilst the declining trend of tree growth was not obvious during the earlier period (1800–1951) after removing tree age- and size-related growth signals. Tree growth correlated negatively with temperatures and positively with relative humidity and self-calibrated Palmer drought severity index (scPDSI) during the early growing season (February to June), indicating a predominant growth limitation by moisture availability. Leaf inter-cellular [CO 2 ] (C i) derived from tree-ring δ13C of A. delavayi increased over time, with a rate slower than atmospheric C a rise, resulting in a decrease in the C i /C a ratio. Intrinsic water-use efficiency (iWUE) was increasing, especially after the 1950s. Dual-isotopic analyses revealed a reduction of stomatal conductance and stable or declined photosynthetic assimilation under warmer and drier environmental conditions. Recent growth decline of A. delavayi in the Cangshan Mountains was mainly related to the increase of warming-mediated drought stress and the resulting stomatal closure, while a positive effect of CO 2 fertilization was diminished under warming and drying environmental conditions. Our results serve as an early warning for tree growth and productivity of A. delavayi forests at the southern distribution limits under the ongoing warming climate. [ABSTRACT FROM AUTHOR]

The relationship between climate and forest is critical to understanding the influence of future climate change on terrestrial ecosystems. Research on trees at high elevations has uncovered the relationship in the Hengduan Mountains region, a critical biodiversity hotspot area in southwestern China. The relationship for the area at low elevations below 2800 m a.s.l. in the region remains unclear. In this study, we developed tree ring width chronologies of Pinus yunnanensis Franch. at five sites with elevations of 1170–1725 m in this area. Monthly precipitation, relative humidity, maximum/mean/minimum air temperature and the standardized precipitation evapotranspiration index (SPEI), a drought indicator with a multi-timescale, were used to investigate the radial growth-climate relationship. Results show that the growth of P. yunnanensis at different sites has a similar response pattern to climate variation. Relative humidity, precipitation, and air temperature in the dry season, especially in its last month (May), are critical to the radial growth of trees. Supplemental precipitation amounts and reduced mean or maximum air temperature can promote tree growth. The high correlations between chronologies and SPEI indicate that the radial growth of trees at the low elevations of the region is significantly limited by the moisture availability. Precipitation in the last month of the previous wet season determines the drought regime in the following dry seasons. In spite of some differences in the magnitudes of correlations in the low-elevation area of the Hengduan Mountains region, chronologies generally matched well with each other at different elevations, and the differences are not evident with the change in elevation. [ABSTRACT FROM AUTHOR]

Both radial growth and canopy dynamics of trees play a critical role in terrestrial carbon cycle. Yet, it is still not very clear about how climate variability influences radial growth and canopy dynamics. To help bridge the knowledge gap in this field, we combined Tree Ring Width Index (TRWI, radial growth) and Normalized Difference Vegetation Index (NDVI, canopy dynamic), to quantify how forests responded to climatic variability across altitudinal gradients in Hengdaun Mountain, China. We applied TRWI of Pinus yunnanensis at nine sample sites and NDVI from 2000 AD to 2016 to analyze how these two indicators respond to temperature and precipitation. The results showed that the radial growth of P. yunnanensis was mainly limited by precipitation at low altitudes (≤1700 m). But the limited factor transformed into temperature at high altitudes (≥2200 m). NDVI presented significantly positive correlation with temperature and negative correlation with precipitation at annual scale. Relationship between TRWI and NDVI showed significantly positive correlation in July but negative correlation during dry season, indicating that both indicators had consistent response to climate during growing season, while the response was heterogeneous in dry season. Our comprehensive study helps to elucidate the unique contributions of foliar and radial growth to terrestrial carbon cycling and to explore the difference of these two indicators response to climate change. • Trends of TRWI and NDVI at temporal and spatial scale are analyzed. • Precipitation is the key influencing factor for vegetation growth in low altitude. • Temperature is the key influencing factors for vegetation growth in high altitude. • NDVI has increased from 2000 to 2016, and is larger at high altitude than low altitude. • Significantly correlation between TRWI and NDVI existed in wet-season and low altitude. [ABSTRACT FROM AUTHOR]