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Trait measures are affected by intra- and interspecific variability. Most studies aggregate species-level data to averages to analyze patterns of interspecific variation. Reliable per-species averages require data for many individuals per species, which leads to insurmountable measuring effort when studying species-rich assemblages. Here we argue that across a large number of species, patterns and relationships can be precisely recovered even if they are based on measures from a single individual per species. While these deviate to an unknown degree from the true per-species averages, randomly distributed errors will level out across many species. We used subsamples of body size data along elevational gradients for moths and small mammals (dozens to several hundred species per dataset), as well as simulated species assemblages, to illustrate this effect and explore some of its consequences. Single-individual measures correlated well with “true” (i.e., full data) averages. Furthermore, single-individual measures recovered the same conclusions on elevation-body size relationships as true data. Randomly removing individuals per species recovered true elevation-body size relationships very well, while randomly dropping species quickly led to high random variability in relationships across subsampling runs. Simulated species assemblages illustrated how the ratio of intraspecific to interspecific variability affects the correlation between singleton-based and true data. We conclude that trait measures based on single individuals are a viable alternative to multi-individual averages when analyzing assemblages of medium to high species richness. Reducing study effort by limiting the measurement of individuals per species, while retaining all species, is a much more reliable approach than restricting the number of species included in a study.

Aim: Mountains are often used to study how environmental factors influence biodiversity. However, we have limited understanding of the processes causing biodiversity variation in mountains and whether such processes vary across trophic levels and spatial scales. The aim of this study was to evaluate (i) whether community assembly processes varied along elevational gradients, (ii) whether there were differences in such variation between primary producers (vascular plants) and secondary consumers (spiders) and (iii) whether there were scale dependencies in any elevational variation in community assembly. Location: Fennoscandia, Northern Sweden. Taxon: Vascular plants, spiders. Methods: We used phenotypic and phylogenetic dispersion to quantify how elevation influenced community assembly of vascular plants and spiders and whether there were any scale dependencies in such influences. Our original data of plant and spider communities came from our own field surveys, phenotypic dispersion was calculated based on matrices of ecological traits, and phylogenetic dispersion was calculated from phylogenetic trees for each organism group. Trait matrices were based on a combination of literature values and our own measurements. The phylogeny for vascular plants was based on a published plant super‐tree, whereas the phylogeny for spiders was created by ourselves based on the DNA sequences at the mitochondrial cytochrome c oxidase subunit 1 (COI). Results: Plants were environmentally filtered throughout all elevations and scales, but the importance of convergent evolution increased with elevation. For spiders, the importance of environmental filtering as well as niche conservatism increased with elevation. For both groups, communities at smaller scales were more influenced by biotic regulation and niche conservatism than at larger scales. Main Conclusions: Our study highlights both taxonomic differences and scale dependencies in how elevation influences community assembly. We argue that these results can have broad ramifications for our understanding of how spatial variation in biodiversity is generated and maintained. This may have particular relevance for our ability to predict the ecological consequences of climate change. Our results further highlight that high elevation specialists may suffer increased risks of climate driven extinctions due to a combination of increased competition and increased fragmentation of suitable habitats. Particularly for spiders, which had high elevation specialists clustered along specific lineages, such extinctions could lead to significant loss of phylogenetic variation. [ABSTRACT FROM AUTHOR]

The Himalayan high-altitude eco-regions exhibit higher plant species diversity, and several environmental factors play a crucial role in shaping species distribution and diversity. The aim of the present study is to investigate the floristic composition, distribution of endemic, threatened and native taxa across the elevation zones and the effect of various environmental factors on species richness pattern along the elevation gradient in Pangi, a remote high-altitude region of Himalaya. We conducted extensive field surveys covering 31 localities and established elevational transects for assessing species distribution and the factors affecting thereof. Additionally, information on nativity, endemism, and IUCN red-list categories of threatened species were compiled from published and online resources. Data were analysed using regression model and Non-Metric Multi-Dimensional Scaling (NMDS). In the present study, we recorded a total of 771 plant species across the region. In regression model, the elevation and anthropogenic variables and their interaction showed significant negative effects on the species richness. Species richness was found to decrease with the increasing elevation, showing a humped shaped pattern, with maximum richness observed in the mid-elevations (2,400m to 3,300m above sea level). The pattern of distribution of native and non-native species along the elevation gradient showed opposite trends, and proportion of native species increased towards the higher elevations. Further, NMDS ordination suggests that zone-I (2,100–2,500m asl) and zone-V (4,001–4,500m asl) had highest differences in species composition, while zone-I, zone-II (2,501–3,000m asl), and zone-III (3,001–3,500m asl) showed higher affinity with respect to their species composition. Thus, the present study revealed that remote and hitherto un-explored Pangi eco-region is rich in floristic diversity and provides pertinent information on the species distribution and composition, and various underlying factors influencing the richness patterns, which is necessary for framing suitable conservation strategies, management plans and futuristic population studies. [ABSTRACT FROM AUTHOR]

In partial migrant systems, where residents and migrants coexist within a population, residents are commonly predicted to gain a reproductive advantage over migrants through priority access to high‐quality territories and an earlier breeding start. Annual variation in reproductive benefits has been suggested to be important for the coexistence of both strategies in a population, as differences in wintering conditions experienced by the two strategies may result in a periodic reproductive advantage for migrants. However, the importance of spatial environmental variation for reproductive output in partially migrant populations remains largely unexplored. We investigated variation in the reproductive output of migrants and residents in a population of Swiss red kites (Milvus milvus) both temporally, across and within years, and spatially, along an elevational gradient. We gathered 4 years of reproductive data combined with 183 GPS‐derived full annual cycles from individuals breeding in the Swiss Alpine foothills. At low, but not high, elevations, residents produced more fledglings than migrants. We also found evidence for annual variation in the reproductive advantage of the two strategies. Furthermore, while reproductive output did decline with a later breeding start, there was no difference in the start of breeding between the two migration strategies. The results of this study suggest that differences in reproductive output between migrants and residents in partial migrant populations can vary both due to the use of spatially distinct overwintering grounds and because the strategies are differently affected by spatial variables in the breeding area, such as elevation. The study emphasizes that spatial and temporal variation in reproductive benefits must be considered when predicting how migratory species will respond to future environmental change. [ABSTRACT FROM AUTHOR]

We lack many quantitative data on the current distributions of several bear species, and hypotheses about the mechanisms underlying those distributions. We raise this point by discussing visual detections of Andean bears (Tremarctos ornatus) in sampling from 14 September 2016 to 24 August 2017 in the Haramba Queros Wachiperi Ecological Reserve Conservation Concession in southeastern Peru, at 811–920 m above sea level, lower in elevation than >90% of known locations for this species on the eastern slope of the Peruvian Andes. Resumo No tenemos muchos datos cuantitativos sobre las distribuciones actuales de varias especies de osos, ni hipótesis sobre los mecanismos detrás de esas distribuciones. Ilustramos esto discutiendo unos registros visuales del oso andino (Tremarctos ornatus) durante foto trampeo del 14 septiembre 2016 al 24 agosto 2017 dentro de la Concesión para la Conservación Reserva Ecológica Haramba Queros Wachiperi, de elevaciones de 820–920 msnm, más bajos que 90% de los lugares conocidos para la especie en las laderas orientales de los Andes peruanos. [ABSTRACT FROM AUTHOR]

Quantitative classification and ordination are instrumental in improving our understanding of plant community patterns and facilitating effective conservation efforts in national mountain ecosystems worldwide. However, there has been a lack of relevant research focused on arid and semi-arid mountain ecosystems. This study aims to address this gap by investigating the Ningxia Helan Mountain National Nature Reserve (located in Northwest China). We conducted a comprehensive study on the patterns of plant communities and their association with environmental factors across a broad elevation range from 1200 m a.s.l. to 2600 m a.s.l. Our findings revealed the presence of 121 angiosperm species across 41 families, with vegetation classified into six distinct groups through two-way indicator species analysis (TWINSPAN) along the elevational gradient. Notably, the communities of Ulmus, Prunus, and Stipa in the middle elevation range exhibited the highest Shannon–Wiener (SW) and Simpson (SN) diversity indices, and these indices followed a single-peak pattern with increasing elevation. Canonical correspondence analysis (CCA) further revealed six distinct yet interrelated plant communities, revealing elevation (ELE) and the biological aridity index (BK) as the most influential environmental factors influencing plant communities' distribution. This understanding is critically important for biodiversity conservation and the management of ecosystems in arid and semi-arid mountain ecosystems. [ABSTRACT FROM AUTHOR]

Premise: Agriculture expansion, livestock, and global change have transformed biological communities and altered, through aerosols and direct deposition, N:P balance in soils of inter‐Andean valleys, potentially affecting flowering phenology of many species and thereby flowering synchrony and plant reproduction. Methods: We evaluated the influence of variation in temperature and moisture along the local elevational gradient and treatments with the addition of N and P and grazing on flowering synchrony and reproduction of Croton, a dominant shrub of the inter‐Andean dry scrub. Along the elevational gradient (300 m difference between the lowest and highest site), we set up plots with and without grazing nested with four nutrient treatments: control and addition of N or P alone or combined N + P. We recorded the number of female and male flowers in bloom monthly from September 2017 to August 2019 to calculate flowering synchrony. We assessed fruiting, seed mass, and pre‐dispersal seed predation. Results: Higher growing‐season soil temperatures, which were negatively associated with local elevation and higher nitrogen availability promoted flowering synchrony of Croton, particularly among larger plants. Greater flowering synchrony, high soil temperatures, and addition of N + P resulted in production of more fruits of Croton, but also intensified pre‐dispersal seed predation. Conclusions: Temperature, availability of moisture throughout the elevational gradient, and nutrient manipulation affected flowering synchrony, which subsequently affected production of fruits in Croton. These results emphasize the critical role of current anthropogenic changes in climate and nutrient availability on flowering synchrony and reproduction of Croton, a dominant plant of the inter‐Andean scrub. [ABSTRACT FROM AUTHOR]

The Himalayas are undergoing significant changes in temperature and moisture availability due to global climate change. Understanding how these changes affect tree growth is critical for conserving and managing this biodiverse region. To investigate the growth-limiting climatic factors, we collected tree-ring data from Abies pindrow old-growth mountain forests across 3190 to 3700 m a.s.l. in the inner valleys of the Garhwal Himalayas. This area faces significant temperature increases, reduced summer monsoon activity, and decreased winter precipitation. We found that over the past century, tree growth suffered from warm and dry springs and benefited from cool and moist springs, particularly at lower elevations (< 3400 m a.s.l.). Conversely, summer climate dynamics had minimal impact on radial growth. The sensitivity of Abies growth to spring climate can be attributed to the inner valleys' continental climate, marked by spring water deficit. Additionally, higher elevation trees (> 3400 m a.s.l.) showed positive correlations with dormant period temperatures in prior October and January, with the positive effect of October warmth strengthening over time. A dynamic analysis of the impact of spring (March–May) temperature, precipitation and Standardized Precipitation-Evapotranspiration Index revealed a recent unification (the 1980–2010s) of the climate–growth relationship across elevations. Specifically, the low-elevation trees have become less sensitive to warm springs, while the high-elevation trees have only recently become sensitive to warm and dry springs. The varying growth responses along the elevation gradient highlight the necessity of site-dependent differentiation when assessing the impacts of global climate change on species performance and geographic range shifts. [ABSTRACT FROM AUTHOR]

Litter decomposition in mountainous forest ecosystems is an essential process that affects carbon and nutrient cycling. However, the contribution of litter decomposition to terrestrial ecosystems is difficult to estimate accurately because of the limited comparability of different studies and limited data on local microclimatic and non‐climatic factors. Here, we designed a coordinated experiment within subtropical and tropical forests across ten mountains to evaluate variation in litter decomposition rates and stabilization. We tested whether elevations, soil microclimate, soil physiochemistry, tree species diversity, and microhabitat affect decomposition rates and stabilization by using the Tea bag index as a standardized protocol. We found that the associations of decomposition rates and stabilization with elevation and each environmental factor varied between mountains. Elevation significantly affected decomposition rates and stabilization in the western mountains, where soil microclimate also played a dominant role due to relatively cold environments. Across all mountains, decomposition rates decreased while stabilization increased with increasing elevation. In terms of microclimate, decomposition rates increased with increasing soil temperature and temperature variation during the growing season, whereas stabilization decreased with increasing soil temperature and moisture variation. In terms of non‐climatic factors, decomposition rates increased with increasing tree species diversity, whereas stabilization decreased with soil pH and slope. Our findings enhance the general understanding of how different factors control forest litter decomposition, highlighting the dominant role of soil microclimate in controlling carbon and nutrient cycling in cold environments and high elevations. [ABSTRACT FROM AUTHOR]

Background: Systematic studies on the biodiversity of bryophytes along elevational gradients have been conductuted within the native vegetation of the Azores, using the MOVECLIM framework. The primary objective of this study was to inventory the bryophytes present within preserved areas of native vegetation in Terceira Island (Azores). From 25 to 28 September 2012, an inventory of the bryoflora was carried out along an elevational gradient, starting near Serreta lighthouse (38.76658 Latitude; -27.37539 Longitude; 40 m a.s.l.) and culminating on the top of Santa Bárbara Mountain (38.73064 Latitude; -27.32164 Longitude; 1000 m a.s.l.). The study followed the adapted MOVECLIM standardised protocol, as follows: i) six sites were selected along an elevational transect, each site spaced at 200 m elevation intervals; ii) within each site, two 10 m x 10 m plots were established in close proximity from each other (10-15 m); iii) within these plots, three 2 m x 2 m quadrats were randomly selected and sampled for bryophytes. The following substrates were surveyed in each quadrat: rock, soil, humus, organic matter, tree bark at three different heights and leaves/fronds. For each available and bryophyte-colonised substrate, three replicate microplots of 10 cm x 5 cm were collected, resulting in a maximum of 24 microplots per quadrat. New information: Nearly three-quarters of the maximum expected number of microplots (636 out of 864; eventID) were found across the six sites on Terceira Island, resulting in a total of 3677 records (occurrenceID). A high proportion of the specimens could be identified to the species rank (n = 3661; 99.6%), representing 38 families, 60 genera and 92 species, including 58 species of liverworts (Marchantiophyta) and 34 species of mosses (Bryophyta). The inventory included several endemic species: two liverwort species endemic to the Azores, five species endemic to Macaronesia (three mosses and two liverworts) and 11 European endemic species (three mosses and eight liverworts). The elevations with the highest species richness, the highest number of endemic species and the highest number of conservation concern species, spanned between 600 and 1000 m a.s.l. above sea level, coinciding with the best preserved forest vegetation. Overall, tree-dwelling and ground-dwelling substrates showed similar levels of bryophyte occupation (75% vs. 72%). However, the 636 events were unevenly distributed across substrates: leaves and rocks had the fewest replicates (n = 54; 50.0%), while humus and the lowest tree height had the highest values (n = 106; 98.1% and n = 98; 90.7%, respectively). The study contributed to expanding knowledge about the diversity and distribution of the Azorean Bryoflora, both on a local and a regional scale. [ABSTRACT FROM AUTHOR]

How do species' distributions respond to their environments? This question was at the heart of the Clements-Gleason controversy, ecology's most famous debate. Do species respond to the environment in concerted ways, leading to distinct and cohesive assemblages (the Clementsian paradigm), or do species respond to the environment independently (the Gleasonian paradigm)? Using plant occurrences along the elevation gradient of Pikes Peak (Colorado) as a lens through which to gain insight into Clements's perspectives on the debate, we formally test for community patterns along this gradient using a modern framework unavailable at the time of Clements and Gleason. The Pikes Peak region was Clements's study area for more than 40 years, where he established a research lab and distributed sites along the elevational gradient. His investigations of plant distributions on this mountain likely influenced his views on communities. We found mixed support for the paradigms, with neither the Gleasonian paradigm nor the Clementsian paradigm fully supported. While distributions along the gradient showed evidence of clustering of species range edges, considered to be consistent with the Clementsian paradigm, the pattern was weak, and neither range edges nor species turnover peaked at ecotone elevations, as expected under the Clementsian paradigm. Our results illuminate the Clements-Gleason debate by allowing us to probe issues that complicate conclusively testing the paradigms, such as deciding on how we quantify environmental gradients and determining the appropriate scales for community patterns and processes that might generate them. Revisiting the debate also revealed that Clements's and Gleason's views had more in common than we realize. The debate may be less neatly resolved than we assume from mythos, and it continues to have relevance to basic and applied ecology today, as its legacy has shaped our (still tenuous) notion of ecological communities and the trajectory of our field. [ABSTRACT FROM AUTHOR]

Abstract Background Leaf nitrogen (N) and phosphorus (P) resorption is a fundamental adaptation strategy for plant nutrient conservation. However, the relative roles that environmental factors and plant functional traits play in regulating N and P resorption remain largely unclear, and little is known about the underlying mechanism of plant functional traits affecting nutrient resorption. Here, we measured leaf N and P resorption and 13 plant functional traits of leaf, petiole, and twig for 101 representative broad-leaved tree species in our target subtropical transitional forests. We integrated these multiple functional traits into the plant economics spectrum (PES). We further explored whether and how elevation-related environmental factors and these functional traits collectively control leaf N and P resorption. Results We found that deciduous and evergreen trees exhibited highly diversified PES strategies, tending to be acquisitive and conservative, respectively. The effects of PES, rather than of environmental factors, dominated leaf N and P resorption patterns along the elevational gradient. Specifically, the photosynthesis and nutrient recourse utilization axis positively affected N and P resorption for both deciduous and evergreen trees, whereas the structural and functional investment axis positively affected leaf N and P resorption for evergreen species only. Specific leaf area and green leaf nutrient concentrations were the most influential traits driving leaf N and P resorption. Conclusions Our study simultaneously elucidated the relative contributions of environmental factors and plant functional traits to leaf N and P resorption by including more representative tree species than previous studies, expanding our understanding beyond the relatively well-studied tropical and temperate forests. We highlight that prioritizing the fundamental role of traits related to leaf resource capture and defense contributes to the monitoring and modeling of leaf nutrient resorption. Therefore, we need to integrate PES effects on leaf nutrient resorption into the current nutrient cycling model framework to better advance our general understanding of the consequences of shifting tree species composition for nutrient cycles across diverse forests.

Background: Leaf nitrogen (N) and phosphorus (P) resorption is a fundamental adaptation strategy for plant nutrient conservation. However, the relative roles that environmental factors and plant functional traits play in regulating N and P resorption remain largely unclear, and little is known about the underlying mechanism of plant functional traits affecting nutrient resorption. Here, we measured leaf N and P resorption and 13 plant functional traits of leaf, petiole, and twig for 101 representative broad-leaved tree species in our target subtropical transitional forests. We integrated these multiple functional traits into the plant economics spectrum (PES). We further explored whether and how elevation-related environmental factors and these functional traits collectively control leaf N and P resorption. Results: We found that deciduous and evergreen trees exhibited highly diversified PES strategies, tending to be acquisitive and conservative, respectively. The effects of PES, rather than of environmental factors, dominated leaf N and P resorption patterns along the elevational gradient. Specifically, the photosynthesis and nutrient recourse utilization axis positively affected N and P resorption for both deciduous and evergreen trees, whereas the structural and functional investment axis positively affected leaf N and P resorption for evergreen species only. Specific leaf area and green leaf nutrient concentrations were the most influential traits driving leaf N and P resorption. Conclusions: Our study simultaneously elucidated the relative contributions of environmental factors and plant functional traits to leaf N and P resorption by including more representative tree species than previous studies, expanding our understanding beyond the relatively well-studied tropical and temperate forests. We highlight that prioritizing the fundamental role of traits related to leaf resource capture and defense contributes to the monitoring and modeling of leaf nutrient resorption. Therefore, we need to integrate PES effects on leaf nutrient resorption into the current nutrient cycling model framework to better advance our general understanding of the consequences of shifting tree species composition for nutrient cycles across diverse forests. [ABSTRACT FROM AUTHOR]

Temperature variation is one of the best‐known and studied factor constraining life history along the altitudinal gradients.Ectotherms such as insects are sensitive to temperature across all life stages, resulting in a wide range of adaptations in populations and species living at different elevations. In butterflies, the egg stage is particularly sensitive to temperature variation as eggs cannot move and deploy behavioural responses to overheating.Using a gradient polymerase chain reaction thermocycler to finely control temperature treatments, we tested for differences in egg heat tolerance between five closely related Coenonympha (Nymphalidae: Satyrinae) species living at different elevations.We found strong differences in egg heat tolerance ranges between lowland species (C. arcania (Linnaeus) and C. pamphilus (Linnaeus)) and two high elevation alpine species (C. gardetta (Prunner) and C. cephalidarwiniana Verity). Surprisingly, the third alpine species (C. darwiniana Staudinger) showed a heat tolerance range closer to that of the lowland species than that of alpine species.The sensitivity of eggs to overheating matched the temperature regimes recorded in the microhabitats utilised for oviposition and may explain the oviposition site selection of females observed in the wild.The narrower egg heat tolerance of some of alpine species may partly explain the position of their lower elevational limit but also raises concern about the fate of these species in the face of current climate change.Our results highlight the need to study all life stages, as well as microclimate choice for oviposition, to understand species distribution and the threats to their persistence. [ABSTRACT FROM AUTHOR]

Questions: Analysing how multiple facets of biodiversity vary across space and time can help to predict the vulnerability of mountaintop floras to future environmental changes. Here we addressed the following questions: (a) Are elevational patterns of mountaintop plant diversity consistent across taxonomy, function and phylogeny? (b) How have the taxonomic, functional and phylogenetic dimensions of mountaintop plant communities changed over the past two decades? (c) Is the magnitude of these temporal trends dependent on elevation? Location: Dovrefjell, central Norway. Methods: The floristic composition of four mountaintops, spread across an elevational gradient from the tree line to the uppermost margins of vascular plant life, was surveyed every 7 years between 2001 and 2022. Six metrics of taxonomic, functional and phylogenetic richness and differentiation were calculated for each mountaintop and survey. Using these data, we assessed how richness and differentiation metrics varied over space (across the elevational gradient) and over time (between surveys). Results: All diversity metrics decreased towards higher elevations, except phylogenetic differentiation which increased significantly by 7% per 100 m elevational gain. Taxonomic richness remained virtually stable between 2001 and 2022, whereas phylogenetic richness increased by 7.5% per decade. Functional richness also increased, but mainly on the lowest mountaintop, by 17% per decade. No significant temporal trends in taxonomic, functional and phylogenetic differentiation were detected. Conclusions: Our findings underpin rearrangements in the functional and phylogenetic structure of mountain plant communities over the past two decades that cannot be predicted from trends in taxonomic richness alone. This highlights the necessity to look beyond species richness and consider multiple facets of biodiversity when studying environmental change impacts on mountain biodiversity and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Much of the world's biodiversity lies in heterogeneous mountain areas with their diverse environments. As an example, Iranian montane ranges are highly diverse, particularly in the Irano-Turanian phytogeographical region. Understanding plant diversity patterns with increasing elevation is of high significance, not least for conservation planning. We studied the pattern of species richness, Shannon diversity, endemic richness, endemics ratio, and richness of life forms along a 3900 m elevational transect in Mount Palvar, overlooking the Lut Desert in Southeast Iran. We also analyzed the effect of environmental variables on species turnover along the vertical gradient. A total of 120 vegetation plots (10 m × 10 m) were sampled along the elevational transect containing species and environmental data. To discover plant diversity pattern along the elevational gradient, generalized additive model (GAM) was used. Non-metric multidimensional scaling (NMDS) was applied for illustrating the correlation between species composition and environmental variables. We found hump-shaped pattern for species richness, Shannon diversity, endemic richness, and species richness of different life forms, but a monotonic increasing pattern for ratio of endemic species from low to high elevations. Our study confirms the humped pattern of species richness peaking at intermediate elevations along a complete elevational gradient in a semi-arid mountain. The monotonic increase of endemics ratio with elevation in our area as a case study is consistent with global increase of endemism with elevation. According to our results, temperature and precipitation are two important climatic variables that drive elevational plant diversity, particularly in seasonally dry areas. Our study suggests that effective conservation and management are needed for this low latitude mountain area along with calling for long-term monitoring for species redistribution. [ABSTRACT FROM AUTHOR]

Studying key leaf functional traits is crucial for understanding plant resource utilization strategies and growth. To explore the patterns and driving factors of key leaf functional traits in forests along elevational gradients under global change, we collected survey data from 697 forests across China from 2008 to 2020. This study examined the elevational patterns of Specific Leaf Area (SLA, m²/kg), Leaf Dry Matter Content (LDMC, g/g), Leaf Nitrogen (LN, mg/g), and Leaf Phosphorus (LP, mg/g), and their responses to climate, soil nutrients, and stand factors. The results showed distinct differences in these key leaf traits at different elevational gradients. Generally, as elevation increased, SLA decreased, while LDMC significantly increased (P < 0.001), and LN first increase and then decreased (P < 0.001). The direct influence of elevation on the spatial variation of key leaf traits was greater than its indirect effects (through environmental and stand factors). The elevational patterns of leaf traits related to resource utilization strategies (SLA and LDMC) were mainly influenced by climate (temperature and precipitation) and soil nutrient factors, showing opposite trends in response to environmental changes. The patterns of leaf nutrient traits (LN and LP) along elevational gradients were primarily influenced by climatic factors, with LN exhibiting greater environmental plasticity. Compared to other stand factors, forest age predominantly influenced the spatial variation of key leaf traits, especially SLA. These findings have significant theoretical implications for revealing how plants adapt to global change.

Mountain ecosystems, contributing substantially to the global carbon (C) and nitrogen (N) biogeochemical cycles, are heavily impacted by global changes. Although soil respiration and microbial activities have been extensively studied at different elevation, little is known on the relationships between environmental drivers, microbial functions, and greenhouse gas fluxes (GHGs; carbon dioxide [CO2], methane [CH4] and nitrous oxide [N2O]) in soils of different elevation. Here, we measured how in situ GHG fluxes were linked to soil properties, soil organic matter (SOM) quantity and composition (the proportion of humic-like vs. protein-like OM), microbial biomass, enzyme activities and functional gene abundances in natural soils spanning an elevational gradient of ∼2400 m in Switzerland. Soil CO2 fluxes did not significantly vary from low (lowland zone) to higher (montane and subalpine zones) elevation forests, but decreased significantly (P

A better understanding of the spatiotemporal dynamics of species composition and biodiversity provides significant insights into the distribution patterns of biodiversity and the prediction of biodiversity fate in a global change context. However, how species and phylogenetic diversity change along elevational gradient with temporal scale in mountain ecosystems is still unknown. In this study, we used census data (2004, 2008 and 2013) of an elevational transect (elevational range 960 - 2 878 m) covering eastern and western slopes of Gaoligong Mountains, SW China, to investigate the spatiotemporal dynamics of forest arbor layer (DBH≥5 cm) species composition, species diversity and phylogenetic diversity. The results were as follows: (1) Species diversity was hump-shaped along the elevational gradient, while the phylogenetic diversity increased with increasing elevation. Clustering phylogenetic structure was observed at low elevations, and over dispersed or random structure was detected at high elevations. (2) Overall, temporal species and phylogenetic beta diversity analysis showed no significant difference among these three investigation time points. However, we found a higher clustering of phylogenetic structure along the temporal scale. (3) Spatial beta diversity showed that there was a significant loss of species at low elevations (960 - 1 381 m) on the eastern slope, where the vegetation had been disturbed or completely converted into farmland. The main lost species including Terminalia chebula, Quercus acutissima, Pistacia weinmanniifolia, Hovenia acerba and Ilex wattii. In contrast, the change in the western slope was mild at low elevations, only observing species abundance increasing, which including Cyclobalanopsis oxyodon, Symplocos chinensis, and Taiwania cryptomerioides. Therefore, we speculated that the dynamic changes in species and phylogenetic diversity of the arbor layer of subtropical evergreen broadleaf forest might be related to communities succession process and climatic change in middle and high elevations, while the communities at low elevations were seriously impacted by human activities in Gaoligong Mountains. The results deepen the understanding of the mechanisms of plant community dynamics in Gaoligong Mountains, and provide new insights to guide precise conservation strategies in the region.

Abstract Key message In European mountain forests, the growth of silver fir (Abies alba Mill.), sycamore maple (Acer pseudoplatanus L.), European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.) seedlings is more strongly affected by ungulate browsing than by elevation. But, the constraint exerted by ungulates, in particular the probability for seedlings to be browsed, increases with elevation for most species. Context While concerns about mountain forest regeneration rise due to their high vulnerability to climate change, the increase in wild ungulate populations and the expansion of their range in the last decades exert an additional constraint on the survival and growth of young trees. Understanding how this constraint can vary with elevation is thus a key to assess the consequences of this population increase for the regeneration of mountain forests. Aims In this study, we investigate the effect of elevation on (i) the occurrence of browsing for seedlings and on (ii) the reduction in seedling growth induced by ungulate browsing. Methods We monitored height growth and browsing occurrence on silver fir, sycamore maple, European beech and Norway spruce seedlings across seven elevation gradients (from 400 to 2013 m) located from France to northern Sweden. Results Seedlings of the two most palatable species—fir and maple—were more likely to be browsed at high elevation while the opposite effect was observed for spruce. Browsing strongly reduced seedling growth for all species but Norway spruce, while elevation had no direct effect on seedling growth. This browsing-induced growth reduction was stronger at high elevation for fir seedlings. Conclusions Browsing is overall a stronger constraint on seedling growth than elevation for four dominant species of European mountain forests. Elevation can, however, affect both browsing probability and the effect of browsing on seedling growth. Our results highlight the importance of taking into account ungulate pressure and its interactive effect with elevation when forecasting the regeneration of mountain forests under a changing climate.

BackgroundEmpirical field studies allow us to view how ecological and environmental processes shape the biodiversity of our planet, but collecting samples in situ creates inherent challenges. The majority of empirical vertebrate gut microbiome research compares multiple host species against abiotic and biotic factors, increasing the potential for confounding environmental variables. To minimize these confounding factors, we focus on a single species of passerine bird found throughout the geologically complex island of Sulawesi, Indonesia. We assessed the effects of two environmental factors, geographic Areas of Endemism (AOEs) and elevation, as well as host sex on the gut microbiota assemblages of the Sulawesi Babbler, Pellorneum celebense, from three different mountains across the island. Using cloacal swabs, high-throughput-amplicon sequencing, and multiple statistical models, we identified the core microbiome and determined the signal of these three factors on microbial composition.ResultsThe five most prevalent bacterial phyla within the gut microbiome of P. celebense were Proteobacteria (32.6%), Actinobacteria (25.2%), Firmicutes (22.1%), Bacteroidetes (8.7%), and Plantomycetes (2.6%). These results are similar to those identified in prior studies of passeriform microbiomes. Overall, microbiota diversity decreased as elevation increased, irrespective of sex or AOE. A single ASV of Clostridium was enriched in higher elevation samples, while lower elevation samples were enriched with the genera Perlucidibaca (Family Moraxellaceae), Lachnoclostridium (Family Lachnospiraceae), and an unidentified species in the Family Pseudonocardiaceae.ConclusionsWhile the core microbiota families recovered here are consistent with other passerine studies, the decreases in diversity as elevation increases has only been seen in non-avian hosts. Additionally, the increased abundance of Clostridium at high elevations suggests a potential microbial response to lower oxygen levels. This study emphasizes the importance of incorporating multiple statistical models and abiotic factors such as elevation in empirical microbiome research, and is the first to describe an avian gut microbiome from the island of Sulawesi.

The El Niño 2015 event, most extreme since 1997, led to severe droughts in tropical wet Papua New Guinea (PNG), reducing May to October dry season rainfall by 75% in the lowlands and 25% in the highlands. Such droughts are likely to have significant effects on terrestrial ecosystems, but they have been poorly explored in Papua New Guinea. Here, we report changes in bird community composition prior to, during, and after the 2015 El Niño event along the elevational gradient ranging from 200 m to 2700 m a.s.l. at the Mt. Wilhelm rainforest in PNG. The abundance of birds in the lowlands dropped by 60% but increased by 40% at elevations above 1700 m during El Niño year. In the following year, the individual bird species reached mean population sizes similar to pre‐El Niño years but did not fully recover. Species richness roughly followed the pattern of observed abundance and quickly and fully re‐established after the event to the pre‐ El Niño values. Thus, at least some terrestrial birds seem to react quickly to the extreme droughts in lowlands and shift to less affected mountain habitats. We recorded upper elevational range limits to shifts by more than 500 m a.s.l. in 22 bird species (out of 237 recorded in total) during El Niño year, in contrast to their typical ranges. Our study suggests that a strong El Niño event can have strong but reversible effects on bird communities as long as they have an opportunity to move to more favorable sites through undisturbed habitats. [ABSTRACT FROM AUTHOR]

Plants require a number of essential elements in different proportions for ensuring their growth and development. The elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental conditions. However, less is known about how the spectrum of leaf elements associated with resource acquisition, photosynthesis and growth regulates forest biomass along broad elevational gradients. We examined the influence of leaf element distribution and diversity on forest biomass by analyzing ten elements (C, N, P, K, Ca, Mg, Zn, Fe, Cu, and Mn) in tree communities situated every 100 meters along an extensive elevation gradient, ranging from the tropical forest (80 meters above sea level) to the alpine treeline (4200 meters above sea level) in the Kangchenjunga Landscape in eastern Nepal Himalayas. We calculated community-weighted averages (reflecting dominant traits governing biomass, i.e., mass-ratio effect) and functional divergence (reflecting increased trait variety, i.e., complementarity effect) for leaf elements in a total of 1,859 trees representing 116 species. An increasing mass-ratio effect and decreasing complementarity in leaf elements enhance forest biomass accumulation. A combination of elements together with elevation explains biomass (52.2% of the variance) better than individual elemental trait diversity (0.05% to 21% of the variance). Elevation modulates trait diversity among plant species in biomass accumulation. Complementarity promotes biomass at lower elevations, but reduces biomass at higher elevations, demonstrating an interaction between elevation and complementarity. The interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation gradient. Our research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation zones. While higher trait variation enhances the adaptation of species to environmental changes, it reduces biomass accumulation, especially at higher elevations. [ABSTRACT FROM AUTHOR]

A better understanding of the spatiotemporal dynamics of species composition and biodiversity provides significant insights into the distribution patterns of biodiversity and the prediction of biodiversity fate in a global change context. However, how species and phylogenetic diversity change along elevational gradient with temporal scale in mountain ecosystems is still unknown. In this study, we used census data (2004, 2008 and 2013) of an elevational transect (elevational range 9602878 m) covering eastern and western slopes of Gaoligong Mountains, SW China, to investigate the spatiotemporal dynamics of forest arbor layer (DBH≥5 cm) species composition, species diversity and phylogenetic diversity. The results were as follows: (1) Species diversity was hump-shaped along the elevational gradient, while the phylogenetic diversity increased with increasing elevation. Clustering phylogenetic structure was observed at low elevations, and over dispersed or random structure was detected at high elevations. (2) Overall, temporal species and phylogenetic beta diversity analysis showed no significant difference among these three investigation time points. However, we found a higher clustering of phylogenetic structure along the temporal scale. (3) Spatial beta diversity showed that there was a significant loss of species at low elevations (960 1 381 m) on the eastern slope, where the vegetation had been disturbed or completely converted into farmland. The main lost species including Terminalia chebula, Quercus acutissima, Pistacia weinmanniifolia, Hovenia acerba and Ilex wattii. In contrast, the change in the western slope was mild at low elevations, only observing species abundance increasing, which including Cyclobalanopsis oxyodon, Symplocos chinensis, and Taiwania cryptomerioides. Therefore, we speculated that the dynamic changes in species and phylogenetic diversity of the arbor layer of subtropical evergreen broadleaf forest might be related to communities succession process and climatic change in middle and high elevations, while the communities at low elevations were seriously impacted by human activities in Gaoligong Mountains. The results deepen the understanding of the mechanisms of plant community dynamics in Gaoligong Mountains, and provide new insights to guide precise conservation strategies in the region. [ABSTRACT FROM AUTHOR]

Elevational climatic heterogeneity, complex terrains, and varying subsurface properties affect the sensitivity of evapotranspiration (ET) in dryland mountain forests to hydrometeorological changes. However, the elevational distribution of ET sensitivity and its major influencing factors remain poorly understood. This study focused on the mid-altitude zone (1000–3500 m) forests in the Chinese Western Tianshan Mountains and assessed ET sensitivity to multiple climate variables, including precipitation (P) and potential evapotranspiration (PET), from 2000 to 2020. To evaluate the multi-year mean and trends in ET sensitivity, multi-source remote sensing data and regional survey data were analyzed using Spearman's correlation coefficient, the sliding window method, and Kendall's test. Furthermore, the relative importance of environmental variables (topography, geology, soil, and vegetation) was investigated. P and PET showed no significant trends, while ET exhibited a significant increasing trend (5.81 mm/yr, p < 0.01), particularly at elevations above 2000 m. Most forests (93.5%) showed a positive sensitivity of ET to P, and 70.0% showed a positive sensitivity of ET to PET, mainly at elevations of 1500–2500 m. Additionally, the trend in ET sensitivity to P decreased with an increasing elevation, with 64.5% showing a positive trend. Meanwhile, the trend in ET sensitivity to PET increased with elevation, with 88.1% showing a positive trend. Notably, 53.2% of the forests showed increasing ET sensitivity trends to both P and PET, primarily at elevations of 2000–3000 m with a mean normalized difference vegetation index (NDVI) of 0.56. Geological factors, particularly the hydrological properties of weathered bedrock, contributed the most (~47%) to mean sensitivity. However, geological and vegetative factors, including the NDVI and root zone water availability, were the main contributors (35% each) to the sensitivity. This study highlights the elevation-dependent sensitivity of dryland mountain forests to hydrothermal changes, with higher-elevation forests (>2000 m) being more sensitive to global warming. [ABSTRACT FROM AUTHOR]

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

One of the most vulnerable phases in the plant life cycle is sexual reproduction, which depends on effective pollen transfer, but also on the thermotolerance of pollen grains. Pollen thermotolerance is temperature-dependent and may be reduced by increasing temperature associated with global warming. A growing body of research has focused on the effect of increased temperature on pollen thermotolerance in crops to understand the possible impact of temperature extremes on yield. Yet, little is known about the effects of temperature on pollen thermotolerance of wild plant species. To fill this gap, we selected Lotus corniculatus s.l. (Fabaceae), a species common to many European habitats and conducted laboratory experiments to test its pollen thermotolerance in response to artificial increase in temperature. To test for possible local adaptation of pollen thermal tolerance, we compared data from six lowland (389=451 m a.s.l.) and six highland (841=1,030 m a.s.l.) populations. We observed pollen germination in vitro at 15 °C, 25 °C, 30 °C, and 40 °C. While lowland plants maintained a stable germination percentage across a broad temperature range (15=30 °C) and exhibited reduced germination only at extremely high temperatures (40 °C), highland plants experienced reduced germination even at 30 °C=temperatures commonly exceeded in lowlands during warm summers. This suggests that lowland populations of L. corniculatus may be locally adapted to higher temperature for pollen germination. On the other hand, pollen tube length decreased with increasing temperature in a similar way in lowland and highland plants. The overall average pollen germination percentage significantly differed between lowland and highland populations, with highland populations displaying higher germination percentage. On the other hand, the average pollen tube length was slightly smaller in highland populations. In conclusion, we found that pollen thermotolerance of L. corniculatus is reduced at high temperature and that the germination of pollen from plant populations growing at higher elevations is more sensitive to increased temperature, which suggests possible local adaptation of pollen thermotolerance. [ABSTRACT FROM AUTHOR]

Key message: In European mountain forests, the growth of silver fir (Abies alba Mill.), sycamore maple (Acer pseudoplatanus L.), European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.) seedlings is more strongly affected by ungulate browsing than by elevation. But, the constraint exerted by ungulates, in particular the probability for seedlings to be browsed, increases with elevation for most species. Context: While concerns about mountain forest regeneration rise due to their high vulnerability to climate change, the increase in wild ungulate populations and the expansion of their range in the last decades exert an additional constraint on the survival and growth of young trees. Understanding how this constraint can vary with elevation is thus a key to assess the consequences of this population increase for the regeneration of mountain forests. Aims: In this study, we investigate the effect of elevation on (i) the occurrence of browsing for seedlings and on (ii) the reduction in seedling growth induced by ungulate browsing. Methods: We monitored height growth and browsing occurrence on silver fir, sycamore maple, European beech and Norway spruce seedlings across seven elevation gradients (from 400 to 2013 m) located from France to northern Sweden. Results: Seedlings of the two most palatable species—fir and maple—were more likely to be browsed at high elevation while the opposite effect was observed for spruce. Browsing strongly reduced seedling growth for all species but Norway spruce, while elevation had no direct effect on seedling growth. This browsing-induced growth reduction was stronger at high elevation for fir seedlings. Conclusions: Browsing is overall a stronger constraint on seedling growth than elevation for four dominant species of European mountain forests. Elevation can, however, affect both browsing probability and the effect of browsing on seedling growth. Our results highlight the importance of taking into account ungulate pressure and its interactive effect with elevation when forecasting the regeneration of mountain forests under a changing climate. [ABSTRACT FROM AUTHOR]

Quantitative classification and ordination are instrumental in improving our understanding of plant community patterns and facilitating effective conservation efforts in national mountain ecosystems worldwide. However, there has been a lack of relevant research focused on arid and semi-arid mountain ecosystems. This study aims to address this gap by investigating the Ningxia Helan Mountain National Nature Reserve (located in Northwest China). We conducted a comprehensive study on the patterns of plant communities and their association with environmental factors across a broad elevation range from 1200 m a.s.l. to 2600 m a.s.l. Our findings revealed the presence of 121 angiosperm species across 41 families, with vegetation classified into six distinct groups through two-way indicator species analysis (TWINSPAN) along the elevational gradient. Notably, the communities of Ulmus, Prunus, and Stipa in the middle elevation range exhibited the highest Shannon–Wiener (SW) and Simpson (SN) diversity indices, and these indices followed a single-peak pattern with increasing elevation. Canonical correspondence analysis (CCA) further revealed six distinct yet interrelated plant communities, revealing elevation (ELE) and the biological aridity index (BK) as the most influential environmental factors influencing plant communities’ distribution. This understanding is critically important for biodiversity conservation and the management of ecosystems in arid and semi-arid mountain ecosystems.

Species richness has been shown to decrease, and elevational range increase (the Rapoport effect), with elevation as a consequence of biotic and abiotic factors, but patterns are inconsistent across taxonomic groups. Despite being an important indicator taxon and a component of local communities, Orthoptera distributions at higher elevations in Europe remain unclear. We investigated the relationship of Orthoptera species richness and elevational range with elevation in the Pyrenees mountains, Europe. We conducted sweepnetting surveys supplemented by hand‐sampling, at 28 sites stratified by elevation, across three study areas. Using generalised linear models, we found that species richness declined with elevation. Elevation was an important predictor of species richness, but sampling effort and vegetation structure (height and cover) also contributed to estimates of species richness. Using a nonlinear regression to model the elevational range of species over the elevational gradient, we did not observe a Rapoport effect, with elevational range peaking at mid‐elevation instead. Smaller elevational ranges of species found at high elevations may be due to a combination of sampling over a restricted elevational range and the presence of specialist high‐elevation species. We argue that our findings are useful for understanding species distributions with elevation at the interface between local and regional scales. Clarifying the biotic and abiotic predictors of species distribution is important for informing conservation efforts and predicting consequences of climate change. [ABSTRACT FROM AUTHOR]

Background: In September 2012, a comprehensive survey of Pico Island was conducted along an elevational transect, starting at Manhenha (10 m a.s.l.) and culminating at the Pico Mountain caldera (2200 m a.s.l.). The primary objective was to systematically inventory the bryophytes inhabiting the best-preserved areas of native vegetation environments. Twelve sites were selected, each spaced at 200 m elevation intervals. Within each site, two 10 m x 10 m plots were established in close proximity (10-15 m apart). Within these plots, three 2 m x 2 m quadrats were randomly selected and sampled for bryophytes using microplots measuring 10 cm x 5 cm, which were then collected into paper bags. Six substrates were surveyed in each quadrat: rock, soil, humus, organic matter, tree bark and leaves/fronds. Three replicates were obtained from all substrates available and colonised by bryophytes, resulting in a maximum of 18 microplots per quadrat, 54 microplots per plot, 108 microplots per site, and a total of 1296 microplots across the 12 sites on Pico Island. New information: Two-thirds of the maximum expected number of microplots (n = 878; 67.75%) were successfully collected, yielding a total of 4896 specimens. The vast majority (n = 4869) were identified at the species/subspecies level. The study identified a total of 70 moss and 71 liverwort species or subspecies. Elevation levels between 600-1000 m a.s.l., particularly in the native forest plots, exhibited both a higher number of microplots and greater species richness. This research significantly enhanced our understanding of Azorean bryophyte diversity and distribution, contributing valuable insights at both local and regional scales. Notably, two new taxa for the Azores were documented during the MOVECLIM study, namely the pleurocarpous mosses Antitrichia curtipendula and Isothecium interludens. [ABSTRACT FROM AUTHOR]

Aim: Andean forests are a global biodiversity hotspot. They harbour many species living within narrow climate ranges and a high functional diversity of trees. It remains still unclear how such hotspots respond to climatic changes over time. We investigated whether Andean forests are changing their functional composition over time along an elevational gradient by assessing changes in species composition, abundance and functional traits. Location: An elevational gradient in Colombia's northern Andes. Time Period: Species composition changes were studied two to four times from 2006 to 2017, and functional composition from 2016 to 2017. Major Taxa Studied: A total of 1104 tropical tree species with in situ traits characterization. Methods: We used seven morphological leaf traits and wood density values to analyse the functional trait dynamic over 10 years along an elevational gradient. By analysing changes in species composition, abundance and trait representation, we inferred the magnitude and direction of changes in functional composition. Then, we assessed if the functional change was related to climate change and demography. Results: With increased minimum temperature and vapour‐pressure deficit, we found a decrease over time in mean values for leaf area and specific leaf area and increases in leaf thickness and leaf dry matter content. Long‐term temperature increases are smaller with increasing elevation, but the magnitude of trait changes is greater than in lowlands. Main Conclusions: The functional composition is changing towards more conservative strategies over time across the elevation gradient, with the strongest changes observed at the highest elevations. This pattern is explained by the change in species turnover within communities due to higher recruitment rates of species with high leaf dry matter content values and low leaf area values. These shifts may be related to communities' responses to higher evapotranspiration demand and thermal stress, mainly at higher elevations. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms of biological invasions (e.g., competitive exclusion) is a key conservation challenge, especially on islands. Many mechanisms have been tested by comparing the characteristics of native and alien species, but few studies have considered ecological strategies. Here we aim at comparing the competitive ability, stress tolerance, and ruderalism (CSR) of native and alien trees in the tropical rainforests of Réunion Island. A total of sixteen 100 m2 plots (eight 'near-trail' and eight 'off-trail', at less disturbed sites) were established over a 2100 m elevational gradient. Three traits were measured in 1093 leaves from 237 trees: leaf area, leaf dry matter content and specific leaf area. They were converted into a CSR score assigned to each of the 80 surveyed tree species (70 native and 10 alien) using the 'Stratefy' ordination approach. C scores increased with basal area and S scores with elevation, but R scores were not higher along the trail, thus only partially validating Stratefy. Native and alien trees had similar CS strategies, thus challenging invasion hypotheses predicting a difference in ecological strategies and rather demonstrating the importance of environmental filtering. However, other differences falling outside the CSR theory may also explain the success of alien species on Réunion. [ABSTRACT FROM AUTHOR]

Abstract The El Niño 2015 event, most extreme since 1997, led to severe droughts in tropical wet Papua New Guinea (PNG), reducing May to October dry season rainfall by 75% in the lowlands and 25% in the highlands. Such droughts are likely to have significant effects on terrestrial ecosystems, but they have been poorly explored in Papua New Guinea. Here, we report changes in bird community composition prior to, during, and after the 2015 El Niño event along the elevational gradient ranging from 200 m to 2700 m a.s.l. at the Mt. Wilhelm rainforest in PNG. The abundance of birds in the lowlands dropped by 60% but increased by 40% at elevations above 1700 m during El Niño year. In the following year, the individual bird species reached mean population sizes similar to pre‐El Niño years but did not fully recover. Species richness roughly followed the pattern of observed abundance and quickly and fully re‐established after the event to the pre‐ El Niño values. Thus, at least some terrestrial birds seem to react quickly to the extreme droughts in lowlands and shift to less affected mountain habitats. We recorded upper elevational range limits to shifts by more than 500 m a.s.l. in 22 bird species (out of 237 recorded in total) during El Niño year, in contrast to their typical ranges. Our study suggests that a strong El Niño event can have strong but reversible effects on bird communities as long as they have an opportunity to move to more favorable sites through undisturbed habitats.

Abstract Background Soil fauna is an important driver of carbon (C) and nitrogen (N) release from decomposing litter in forest ecosystems. However, its role in C and N cycling concerning climate and litter traits remains less known. In a 4-year field experiment, we evaluated the effects of soil fauna on litter C and N release across an elevation gradient (453, 945, 3023, and 3582 m) and litter traits (coniferous vs. broadleaf) in southwestern China. Results Our results showed that N was retained by –0.4% to 31.5%, but C was immediately released during the early stage (156–516 days) of decomposition for most litter species. Soil fauna significantly increased the peak N content and N retention across litter species, but reduced the C/N ratio for certain species (i.e., Juniperus saltuaria, Betula albosinensis, Quercus acutissima, and Pinus massoniana litter), leading to more C and N being released from decomposing litter across the elevation gradient. Contributions of soil fauna to C and N release were 3.87–9.90% and 1.10–8.71%, respectively, across litter species after 4 years of decomposition. Soil environment and initial litter quality factors caused by elevation directly affected litter C and N release. Changes in soil fauna resulting from elevation and fauna exclusion factors had a direct or indirect impact on C and N release during litter decomposition. Conclusions Our findings suggest that soil fauna promote C and N release from decomposing litter in different magnitudes, mainly controlled by environmental conditions (i.e., temperature and moisture), litter quality (i.e., lignin and cellulose content, and lignin/cellulose), and its diversity across the elevation gradient.

Abstract We developed an approach to distinguish among 3 alternative strategies that birds may employ relating the timing of egg laying across elevations to annual variation in spring temperature (phenological reaction norms), which we applied to analyze the breeding phenology of 2 species over an elevational gradient in the Sierra Nevada, California. In a “simple-offset” strategy, birds at different elevations initiate breeding relative to environmental temperature in a consistent manner, in that breeding onset is triggered by a critical temperature regardless of when it occurs in the spring. Elevation-specific reaction norms based on multiple years are offset (high-elevation birds start breeding later) but parallel. In a “delay” strategy, in cooler springs, populations at higher elevations that are sensitive to early-season weather-related risks delay laying onset relative to those at lower elevations, yielding a high-elevation reaction norm that diverges from a low-elevation one at cooler temperatures. Conversely, high-elevation populations in cooler springs that are sensitive to the risk of having insufficient time to complete a breeding cycle advance laying onset relative to lower populations (“advance” strategy), yielding a high-elevation reaction norm than converges with a low-elevation one. Both delay and advance strategies imply an elevation-dependent interaction between temperature and date (photoperiod) in influencing laying onset. Examined across 3 elevation groupings, phenological reaction norms of Mountain Chickadees (Poecile gambeli) were essentially parallel, consistent with simple offset, whereas Dusky Flycatchers (Empidonax oberholseri) relationships were more complex. In cooler springs, mid-elevation flycatchers bred comparatively late relative to lowest-elevation birds (delay), implying greater sensitivity to early-season risks, but still with sufficient time to complete a breeding cycle. However, high-elevation flycatchers bred comparatively early relative to mid-elevation populations (advance); delaying at these highest elevations may not be an option. Our approach revealed differences in risk sensitivity that were consistent with other ecological differences between the 2 species.

Understanding the different patterns of plant diversity and distribution along the environmental gradients is essential for managing ecosystems, especially in fragmented habitats due to intensive human pressure. The Darkash area is located in the western Aladagh Mountains in Khorassan-Kopet Dagh Floristic Province. The easternmost patches of the Hyrcanian montane forests grow in this area. The three main vegetation types in the area are shrublands/scrub forests, oak forests (Quercus castaneifolia), and subalpine vegetation. In this study, we aimed to evaluate the plant diversity in the understory of plant communities along the elevational gradient. We sampled 187 vegetation plots (2m x 2m) along a 1300m elevational gradient (in 100-m classes) using the stratified-random method and estimated the abundance and canopy cover of the species. Floristic characteristics and different diversity indices were measured. In total, 252 plant species belonging to 161 genera and 44 families were identified. Of these, 41 species were found to be endemic or semi-endemic. Hemicryptophytes and therophytes are the dominant life-forms in the study area. The Irano-Turanian elements (46.8%) make the major chorotype in the flora of the area, followed by Bi-regional (17.5%), Tri-regional (17.5%), Pluri-regional (11.5%), and Euro-Siberian (6.7%) elements. The shrubland understory has the highest Hill's and beta diversity indices, followed by the oak forest and the subalpine understory. The biodiversity changes sinusoidally along the elevation. In order to protect plant species, especially young oak seedlings, it is recommended to create a protective corridor along the elevational gradient in this area. This strategy is essential to protect plant diversity in these habitats.

Abstract Species richness has been shown to decrease, and elevational range increase (the Rapoport effect), with elevation as a consequence of biotic and abiotic factors, but patterns are inconsistent across taxonomic groups. Despite being an important indicator taxon and a component of local communities, Orthoptera distributions at higher elevations in Europe remain unclear. We investigated the relationship of Orthoptera species richness and elevational range with elevation in the Pyrenees mountains, Europe. We conducted sweepnetting surveys supplemented by hand‐sampling, at 28 sites stratified by elevation, across three study areas. Using generalised linear models, we found that species richness declined with elevation. Elevation was an important predictor of species richness, but sampling effort and vegetation structure (height and cover) also contributed to estimates of species richness. Using a nonlinear regression to model the elevational range of species over the elevational gradient, we did not observe a Rapoport effect, with elevational range peaking at mid‐elevation instead. Smaller elevational ranges of species found at high elevations may be due to a combination of sampling over a restricted elevational range and the presence of specialist high‐elevation species. We argue that our findings are useful for understanding species distributions with elevation at the interface between local and regional scales. Clarifying the biotic and abiotic predictors of species distribution is important for informing conservation efforts and predicting consequences of climate change.

The Chinese pangolin (Manis pentadactyla) confronts challenges from illegal hunting, trading, and habitat degradation. Therefore, it is imperative to establish and implement effective conservation strategies at both local and regional levels. However, there is limited information, particularly within the Kathmandu Valley of Nepal, underscoring the significance of local-level habitat characterization for burrowing animals like pangolins. In this context, our study aimed to assess how anthropogenic and environmental factors influence the presence of Chinese pangolins along the elevational gradients of Chandragiri-Champadevi Hills, renowned for the scenic beauty and popular hiking trails within the valley. We conducted surveys of foraging and resting burrows at 72 plots distributed along 12 elevational line transects from 1500 to 2100 m elevational gradients of Chandragiri-Champadevi Hills. Notably, we observed pangolin burrows spanning from 1550 m to 2095 m. With increasing elevation, we recorded a decline in both foraging and resting burrow numbers. Furthermore, our findings indicated an increase in burrow numbers with increasing the distances from roads, whereas burrow numbers decreased with increasing proximity to human settlements. Interestingly, foraging burrows exhibited an increase with noise but a decrease with slope, while resting burrows showed an increase association with higher canopy and ground cover percentages. Our study shows the substantial anthropogenic disturbances in the habitats of Chinese pangolins in the Chandragiri-Champadevi Hills. We recommend managing the human-associated threats to ensure the species conservation at this site-specific area.

Establishing how environmental gradients and host ecology drive spatial variation in infection rates and diversity of pathogenic organisms is one of the central goals in disease ecology. Here, we identified the predictors of concomitant infection and lineage richness of blood parasites in New Word bird communities. Our multi-level Bayesian models revealed that higher latitudes and elevations played a determinant role in increasing the probability of a bird being co-infected with Leucocytozoon and other haemosporidian parasites. The heterogeneity in both single and co-infection rates was similarly driven by host attributes and temperature, with higher probabilities of infection in heavier migratory host species and at cooler localities. Latitude, elevation, host body mass, migratory behavior, and climate were also predictors of Leucocytozoon lineage richness across the New World avian communities, with decreasing parasite richness at higher elevations, rainy and warmer localities, and in heavier and resident host species. Increased parasite richness was found farther from the equator, confirming a reverse Latitudinal Diversity Gradient pattern for this parasite group. The increased rates of Leucocytozoon co-infection and lineage richness with increased latitude are in opposition with the pervasive assumption that pathogen infection rates and diversity are higher in tropical host communities. [ABSTRACT FROM AUTHOR]

Data from existing monitoring schemes point to a global crisis of butterflies across Europe, with habitat loss/degradation, climate change and chemical pollution as the main drivers of decline.The existing butterfly time series from Western Europe come from densely populated, relatively flat areas. However, population trends from less populated areas, such as mountain ranges in the south of Europe, have been less studied, despite these areas harbouring one of the highest butterfly biodiversity of the continent.Here, we analyse trends for butterfly populations in a Southwestern Europe mountain range (Picos de Europa, Northwest Spain), for the last 9 years (2013–2021), across an altitudinal gradient (80–2000 m). We show that this region, protected as National Park more than 100 years ago, is nonetheless under a great threat, with a decline in butterfly abundance of, on average, 5.7% per year (45.7% cumulative decline in the last 9 years).Species at higher elevations are faring worse than those at low elevations and communities at mid‐elevations (below the tree line) are changing towards higher abundance of species with a preference from closed habitats. Combined effects of amplified climate change in mountains and habitat loss, due to abandonment of traditional management, appear to be affecting both individual species and community composition of butterflies in our study area. [ABSTRACT FROM AUTHOR]

Patterns of species diversity have been associated with changes in climate across latitude and elevation. However, the ecological and evolutionary mechanisms underlying these relationships are still actively debated. Here, we present a complementary view of the well-known tropical niche conservatism (TNC) hypothesis, termed the multiple zones of origin (MZO) hypothesis, to explore mechanisms underlying latitudinal and elevational gradients of phylogenetic diversity in tree communities. The TNC hypothesis posits that most lineages originate in warmer, wetter, and less seasonal environments in the tropics and rarely colonize colder, drier, and more seasonal environments outside of the tropical lowlands, leading to higher phylogenetic diversity at lower latitudes and elevations. In contrast, the MZO hypothesis posits that lineages also originate in temperate environments and readily colonize similar environments in the tropical highlands, leading to lower phylogenetic diversity at lower latitudes and elevations. We tested these phylogenetic predictions using a combination of computer simulations and empirical analyses of tree communities in 245 forest plots located in six countries across the tropical and subtropical Andes. We estimated the phylogenetic diversity for each plot and regressed it against elevation and latitude. Our simulated and empirical results provide strong support for the MZO hypothesis. Phylogenetic diversity among co-occurring tree species increased with both latitude and elevation, suggesting an important influence on the historical dispersal of lineages with temperate origins into the tropical highlands. The mixing of different floras was likely favored by the formation of climatically suitable corridors for plant migration due to the Andean uplift. Accounting for the evolutionary history of plant communities helps to advance our knowledge of the drivers of tree community assembly along complex climatic gradients, and thus their likely responses to modern anthropogenic climate change. [ABSTRACT FROM AUTHOR]

Documenting and understanding sex-specific variation in migratory phenology is important for predicting avian population dynamics. In spring, males often arrive on the breeding grounds before females (protandry), though whether these patterns result from fitness benefits vs. sexspecific constraints on arrival timing remains poorly understood. Sex-specific variation in the timing of fall migration is less well-documented than in spring, in part because documenting fall departures is often limited by cryptic behaviors, lower vocalization rates, and shifting territory boundaries during this time of year. We used 2 years of high-resolution encounter data from radio-frequency identification (RFID)-equipped bird feeders to monitor the daily presence of male and female Lazuli Buntings (Passerina amoena) throughout the breeding season at a high and a low-elevation site in Cache County, Utah, USA. These encounter data were used to estimate daily arrival and departure probabilities and to investigate possible differences in migration timing in relation to sex and elevation. At low elevation, male arrival (n = 15) preceded female arrival (n = 16) by ~1 week, consistent with previous research that has documented protandry in other migratory songbirds. At high elevation, however, no significant differences were found between male (n = 19) and female arrival (n = 6). In fall, we found little difference in departure dates between elevation or sex, or between years. Our observations are most consistent with constraint-based hypotheses explaining protandry, possibly relating to sex-specific constraints operating during the nonbreeding period. We additionally emphasize the need for quantifying uncertainty in phenological estimates and importance of addressing potential differences across demographic groups. [ABSTRACT FROM AUTHOR]

The relative contribution of adaptation and phenotypic plasticity can vary between core and edge populations, with implications for invasive success. We investigated the spread of the invasive yellow monkeyflower, Erythranthe gutatta in New Zealand, where it is spreading from lowland agricultural land into high‐elevation conservation areas. We investigated the extent of phenotypic variation among clones from across the South Island, looked for adaptation and compared degrees of plasticity among lowland core versus montane range‐edge populations. We grew 34 clones and measured their vegetative and floral traits in two common gardens, one in the core range at 9 m a.s.l. and one near the range‐edge at 560 m a.s.l. Observed trait variation was explained by a combination of genotypic diversity (as identified through common gardens) and high phenotypic plasticity. We found a subtle signature of local adaptation to lowland habitats but all clones were plastic and able to survive and reproduce in both gardens. In the range‐edge garden, above‐ground biomass was on average almost double and stolon length almost half that of the same clone in the core garden. Clones from low‐elevation sites showed higher plasticity on average than those from higher elevation sites. The highest performing clones in the core garden were also top performers in the range‐edge garden. These results suggest some highly fit general‐purpose genotypes, possibly pre‐adapted to New Zealand montane conditions, best explains the spread of E. gutatta from lowland to higher elevation areas. [ABSTRACT FROM AUTHOR]

The structural and functional traits of coniferous trees can reflect their growth states and adaptive strategies to a harsh environment. However, it is still unclear if and how hydraulic traits of subalpine conifers change with altitude.Therefore, the changes in stem hydraulic characteristics of Abies fabri along an elevational gradient (2700–3700 m a.s.l.) were identified in a subalpine ecosystem in southwest China and linked to anatomical properties.Xylem hydraulic efficiency decreased with increasing elevation. Surprisingly, higher hydraulic dysfunction and vulnerability to embolism occurred at higher altitudes. The trade‐off between hydraulic efficiency and safety was weak in A. fabri at higher elevations. Low temperature and superfluous precipitation may be the main constraints for hydraulic function and mechanical strength ((t/b)2)) in plants at high elevations (p < 0.05). The strongly limited hydraulic transport system reflected the severe growth constraint of A. fabri at high elevations. Although series of anatomical traits varied with elevation (e.g. smaller mean diameter of tracheid, mean hydraulic conduit diameter and mean pit aperture diameter at higher altitude) and revealed the adaptive strategies to enhance embolism resistance, thickness‐to‐span ratio ((t/b)2) played a dominant role in the trade‐off between hydraulic efficiency and safety. Thickness‐to‐span ratio was positively correlated with stem hydraulic conductivity but negatively correlated with percent loss of conductivity and water potential at 50% loss of conductivity, (t/b)2 and specific leaf area. Therefore, plants with better hydraulic and growth states at low elevations could allocate more resources to building up solid mechanical supporting systems to cope with high wind load, while those at high elevations with impaired growth states and limited hydraulic functions had to invest more resources in leaves under the harsh environment. The weak trade‐off between hydraulic efficiency and safety (lower hydraulic efficiency and high risk of embolism) could limit the growth and distribution of A. fabri at timberlines; however, global warming trends may facilitate hydraulic transport and benefit plants' growth in the future. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Aim: The exceptional turnover in biota with elevation and number of species coexisting at any elevation makes tropical mountains hotspots of biodiversity. However, understanding the historical processes through which species arising in geographical isolation (i.e. allopatry) assemble along the same mountain slope (i.e. sympatry) remains a major challenge. Multiple models have been proposed including (1) the sorting of already elevationally divergent species, (2) the displacement of elevation upon secondary contact, potentially followed by convergence, or (3) elevational conservatism, in which ancestral elevational ranges are retained. However, the relative contribution of these processes to generating patterns of elevational overlap and turnover is unknown. Location: Tropical mountains of Central‐ and South‐America. Time Period: The last 12 myr. Major Taxa Studied: Birds. Methods: We collate a dataset of 165 avian sister pairs containing estimates of phylogenetic age, geographical and regional elevational range overlap. We develop a framework based on continuous‐time Markov models to infer the relative frequency of different historical pathways in explaining present‐day overlap and turnover of sympatric species along elevational gradients. Results: We show that turnover of closely related bird species across elevation can predominantly be explained by displacement of elevation ranges upon contact (81%) rather than elevational divergence in allopatry (19%). In contrast, overlap along elevation gradients is primarily (88%) explained by conservatism of elevational ranges rather than displacement followed by elevational expansion (12%). Main Conclusions: Bird communities across elevation gradients are assembled through a mix of processes, including the sorting, displacement and conservatism of species elevation ranges. The dominant role of conservatism in explaining co‐occurrence of species on mountain slopes rejects more complex scenarios requiring displacement followed by expansion. The ability of closely related species to coexist without elevational divergence provides a direct and faster pathway to sympatry and helps explain the exceptional species richness of tropical mountains. [ABSTRACT FROM AUTHOR]

Background: Soil fauna is an important driver of carbon (C) and nitrogen (N) release from decomposing litter in forest ecosystems. However, its role in C and N cycling concerning climate and litter traits remains less known. In a 4-year field experiment, we evaluated the effects of soil fauna on litter C and N release across an elevation gradient (453, 945, 3023, and 3582 m) and litter traits (coniferous vs. broadleaf) in southwestern China. Results: Our results showed that N was retained by –0.4% to 31.5%, but C was immediately released during the early stage (156–516 days) of decomposition for most litter species. Soil fauna significantly increased the peak N content and N retention across litter species, but reduced the C/N ratio for certain species (i.e., Juniperus saltuaria, Betula albosinensis, Quercus acutissima, and Pinus massoniana litter), leading to more C and N being released from decomposing litter across the elevation gradient. Contributions of soil fauna to C and N release were 3.87–9.90% and 1.10–8.71%, respectively, across litter species after 4 years of decomposition. Soil environment and initial litter quality factors caused by elevation directly affected litter C and N release. Changes in soil fauna resulting from elevation and fauna exclusion factors had a direct or indirect impact on C and N release during litter decomposition. Conclusions: Our findings suggest that soil fauna promote C and N release from decomposing litter in different magnitudes, mainly controlled by environmental conditions (i.e., temperature and moisture), litter quality (i.e., lignin and cellulose content, and lignin/cellulose), and its diversity across the elevation gradient. [ABSTRACT FROM AUTHOR]

Patterns of microbial diversity on elevational gradients have been extensively studied, but little is known about those patterns during the restoration of earthquake-fractured alpine ecosystems. In this study, soil properties, soil enzyme activities, abundance and diversity of soil bacterial and fungal communities at four positions along a 2.6-km elevational gradient in the Snow Treasure Summit National Nature Reserve, located in Pingwu County, Southwest China. Although there were no significant changes in the soil chemical environment, bacterial and fungal communities were significantly different at different elevations. The overall fungal community presented an N-shaped diversity pattern with increasing elevation, while bacterial diversity decreased significantly with elevation. Changes in microbial diversity were associated with soil phosphorus, plant litter, and variations in dominant microbial taxa. Differences in enzyme activities among elevations were regulated by microbial communities, with changes in catalase and acid phosphatase activities mainly controlled by Acidobacteria and Planctomycetaceae bacteria, respectively (catalase: p< 0.001; acid phosphatase: p<0.01), and those in β-glucosidase, sucrase, and urease activities mainly controlled by fungi. The β-glucosidase and sucrase were both positively correlated with Herpotrichiellaceae, and urease was positively correlated with Sebacinaceae (p<0.05). These findings contribute to the conservation and management of mountain ecosystems in the face of changing environmental conditions. Further research can delve into the specific interactions between microbial communities, soil properties, and vegetation to gain deeper insights into the intricate ecological dynamics within earthquake-prone mountain ecosystems. [ABSTRACT FROM AUTHOR]

Grasslands host a significant share of Europe's species diversity but are among the most threatened vegetation types of the continent. Resurvey studies can help to understand patterns and drivers of changes in grassland diversity and species composition. However, most resurveys are based on local or regional data, and hardly reach back more than eight decades. Here, we publish and describe the Historic Square Foot Dataset, comprising 580 0.09‐m2 and 43 1‐m2 vegetation plots carefully sampled between 1884 and 1931, covering a wide range of grassland types across Switzerland. We provide the plots as an open‐access data set with coordinates, relocation accuracy and fractional aboveground biomass per vascular plant species. We assigned EUNIS habitat types to most plots. Mean vascular plant species richness in 0.09 m2 was 19.7, with a maximum of 47. This is considerably more than the present‐day world record of 43 species for this plot size. Historically, species richness did not vary with elevation, differing from the unimodal relationship found today. The data set provides unique insight into how grasslands in Central Europe looked more than 100 years ago, thus offering manifold options for studies on the development of grassland biodiversity and productivity. [ABSTRACT FROM AUTHOR]