Search

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]

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]

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]

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]

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]

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]

Purpose: Carbohydrate-active enzymes (CAZymes) mediate carbohydrate turnover and play vital roles in plant- and microbial-derived carbon decomposition. However, the changes of genes that encoding enzymes for plant- and microbial-derived carbon decomposition along environmental gradients remains unclear. Methods: We used metagenomic sequencing to explore changes in genes encoding enzymes for carbon decomposition in five forest sites along an elevational gradient (1503–3182 m) on Qinling Mountain, China. Results: The genes encoding CAZymes showed various patterns along the elevational gradient. In particular, the abundance of genes encoding auxiliary enzymes and glycoside hydrolases decreased with increasing elevation. The abundance of genes encoding enzymes for plant- and fungi-derived carbon decomposition was higher at low elevations than at high elevations, whereas the abundance of genes encoding enzymes for bacteria-derived carbon decomposition was higher at high elevations than at low elevations. The results indicate contrasting patterns of fungal- and bacterial-derived carbon decomposition with elevation. Proteobacteria and Acidobacteria were the dominant species that decomposed dead plant and microbial biomass. Moreover, our results reveal that soil properties (i.e., ammonium nitrogen and bulk density) and vegetation properties dominated the CAZymes gene distribution along the elevational gradient. Conclusion: Bacteria- and fungi-derived carbon decomposition potentials show contrasting elevational patterns in forest soils; soil and vegetation properties are common controls for the elevational patterns. [ABSTRACT FROM AUTHOR]

Aims: Although studies have investigated how nitrogen (N) and phosphorus (P) deposition alone alter terrestrial ecosystems, the responses of soil microorganisms and their functions to interaction of N and P deposition have not been studied across an elevational gradient in subtropical forests. Methods: By conducting N and P deposition experiments at three elevational levels in subtropical forests, we determined how the responses of soil microorganisms and their functions to N and P deposition differ at low (1300 m), moderate (1800 m), and high (2350 m) elevations. Results: Microbial biomass of most functional groups differed among the three elevations; microbial biomass was lowest at the moderate elevation, and the elevation-induced changes in microbial biomass were positively correlated with soil substrate quality (e.g., soil N/P). After two years of treatment, N deposition had negative effects on microbial biomass and interacted with P deposition at the low elevation, while N or P deposition had positive effects on microbial biomass at the moderate elevation. N deposition decreased SOM-C decomposition at the low (16%) and moderate (8%) elevations; N deposition decreased SOM-N decomposition (10%) at the low elevation but increased SOM-N decomposition (16%) at the moderate elevation. P deposition increased SOM-C decomposition (14%) at the low elevation but decreased SOM-C decomposition (6%) at the high elevation. Conclusions: Our results evidenced that short-term effects of nutrient deposition on soil microorganisms and SOM decomposition were altered by elevational gradient in subtropical forests, suggesting that the effect of nutrient deposition on belowground communities and functions are environmental context-dependent. [ABSTRACT FROM AUTHOR]

Background: Empirical 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. Results: The 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. Conclusions: While 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. [ABSTRACT FROM AUTHOR]

With increasing elevation, trees in tropical montane forests have to invest larger fractions of their resources into their fine roots in order to compensate for increasingly unfavorable soil conditions. It is unclear how elevation and related edaphic changes influence the variability in tree fine root traits and belowground functional diversity. We measured six fine root traits related to resource acquisition on absorptive fine roots of 288 trees from 145 species along an elevational gradient from 1000 m to 3000 m a.s.l. in tropical montane forests of the Ecuadorian Andes. We analyzed trait relationships with elevation and soil nutrient availability, and tested whether root functional diversity varied along these gradients. Fine roots at higher elevations and at more nutrient‐poor sites were thicker, had higher tissue densities, and lower specific root length and nutrient concentrations than at lower elevations. These trends were diluted by the coexistence of tree species with a broad range of different root traits within communities particularly towards lower elevations, where root functional diversity was significantly higher. We conclude that nutrient limitation and potentially further adverse conditions at higher elevations are strong environmental filters that lead to trait convergence towards a conservative resource use strategy, whereas different trait syndromes are equally successful at lower elevations. [ABSTRACT FROM AUTHOR]

Aim: The biotic interactions hypothesis predicts that interactions between species are stronger at lower elevations compared to higher elevations. We tested whether this prediction is met by examining elevational patterns in avian haemosporidian infections in New Guinean birds. Location: YUS Conservation Area, Papua New Guinea. Taxon: Birds and haemosporidia. Methods: We collected blood samples from 2268 individuals of 66 bird species along a reef‐to‐ridgetop tropical elevational gradient covering ~3000 m of elevation. We used molecular methods to screen samples for haemosporidian parasites, and sequenced 70% of positive infections to determine the identity of parasite genera. We fit a phylogenetic generalized mixed‐effects model to test whether infection prevalence was higher at low elevations, as predicted by the biotic interactions hypothesis. Finally, we tested for phylogenetic signal in parasite prevalence and in host elevational distribution using Pagel's λ. Results: Overall parasite prevalence was 45%. Infection prevalence decreased with elevation, though prevalence remained above ~30% even for high‐elevation communities between 2000 and 3000 m. We found strong phylogenetic signal in infection prevalence, but no phylogenetic signal in host elevational distribution. Nearly all sequenced infections (97%) were of Haemoproteus. Main Conclusions: Our results are consistent with predictions arising from the biotic interactions hypothesis. However, phylogenetic relationships among hosts are a much better predictor of infection prevalence than is elevational position: closely related bird species tend to have similar infection prevalence regardless of the elevations where they live. [ABSTRACT FROM AUTHOR]

Summary: Knowledge about the distribution and local diversity patterns of arbuscular mycorrhizal (AM) fungi are limited for extreme environments such as the Arctic, where most studies have focused on spore morphology or root colonization. We here studied the joint effects of plant species identity and elevation on AM fungal distribution and diversity.We sampled roots of 19 plant species in 18 locations in Northeast Greenland, using next generation sequencing to identify AM fungi. We studied the joint effect of plant species, elevation and selected abiotic conditions on AM fungal presence, richness and composition.We identified 29 AM fungal virtual taxa (VT), of which six represent putatively new VT. Arbuscular mycorrhizal fungal presence increased with elevation, and as vegetation cover and the active soil layer decreased. Arbuscular mycorrhizal fungal composition was shaped jointly by elevation and plant species identity.We demonstrate that the Arctic harbours a relatively species‐rich and nonrandomly distributed diversity of AM fungi. Given the high diversity and general lack of knowledge exposed herein, we encourage further research into the diversity, drivers and functional role of AM fungi in the Arctic. Such insight is urgently needed for an area with some of the globally highest rates of climate change. [ABSTRACT FROM AUTHOR]

The response of communities to environmental change is expected to vary among feeding guilds. To evaluate the response of guilds to environmental factors without considering the taxonomic specificities, it is useful to examine Aculeata bees and wasps, which consist of closely related taxa including different guilds, pollinators, predators, and parasitoids. In this study, we evaluated changes in species diversity (SD) and functional traits of each feeding guild along an elevational gradient in a boreal forest in northern Japan. We used yellow pan traps to collect Aculeata bees and wasps at 200–1600 m above sea level. We investigated six functional traits (trophic level, seasonal duration, body size, elevational range, nesting position, and soil dependency) and the horizontal distribution of the species. The SD of all Aculeata, predators, and parasitoids decreased with an increase in elevation; however, the SD of pollinators did not show any specific trend. Although the functional trait composition of all Aculeata species did not show any trend, that of each feeding guild responded to elevation in different ways. Pollinators increased in body size and showed a decrease in seasonal duration with increasing elevation, suggesting that tolerance and seasonal escape from physical stress at high elevations are important for shaping pollinator communities. Predators increased their elevational range and the proportion of above‐ground nesting species increased with increasing elevation, suggesting that the ability to live in a wider range of environments and avoid unsuitable soil environments at high elevations might be important. Parasitoids changed their hosts and displayed variable traits with increasing elevation, suggesting that brood parasitoids have difficulty in surviving at high elevation. The traits for each guild responded in different ways, even if they were dominated by the same environmental factors. Our findings imply that differences in the responses of functional traits would produce different community assembly patterns in different guilds during further climate change. [ABSTRACT FROM AUTHOR]

Elevational and latitudinal gradients in species diversity may be mediated by biotic interactions that cause density‐dependent effects of conspecifics on survival or growth to differ from effects of heterospecifics (i.e. conspecific density dependence), but limited evidence exists to support this. We tested the hypothesis that conspecific density dependence varies with elevation using over 40 years of data on tree survival and growth from 23 old‐growth temperate forest stands across a 1,000‐m elevation gradient. We found that conspecific‐density‐dependent effects on survival of small‐to‐intermediate‐sized focal trees were negative in lower elevation, higher diversity forest stands typically characterised by warmer temperatures and greater relative humidity. Conspecific‐density‐dependent effects on survival were less negative in higher elevation stands and ridges than in lower elevation stands and valley bottoms for small‐to‐intermediate‐sized trees, but were neutral for larger trees across elevations. Conspecific‐density‐dependent effects on growth were negative across all tree size classes and elevations. These findings reveal fundamental differences in biotic interactions that may contribute to relationships between species diversity, elevation and climate. [ABSTRACT FROM AUTHOR]

Local adaptations of host plants to climatic conditions along an elevation gradient can affect insect-plant interactions. Using local accessions sampled from different elevations within South America, plant defense responses and herbivore growth were evaluated on two host plants: a) cherry tomato, Solanum lycopersicum var. cerasiforme, and b) wild tomato, Solanum pimpinellifolium. The elevational origin of the accessions ranged from 100 to 3000 m above sea level. We hypothesized a higher level of defensive compounds in plants originating from lower elevations and, consequently, stronger resistance to insect herbivory. Interestingly, plant resistance to insect herbivory, as demonstrated by a reduction in Helicoverpa zea growth, was stronger for middle and high-elevation accessions. Total phenolic content increased with elevation in both herbivore-damaged and undamaged leaves, augmenting plant resistance. However, an elevational gradient was not evident for plant defensive proteins (polyphenol oxidase and trypsin protease inhibitors) or the density of leaf trichomes. Tradeoffs between constitutive and induced defenses were evident in both tomato genotypes. Future studies should test the role of plasticity in plant defense systems in restricting or facilitating range expansion of insect herbivores with climate change. [ABSTRACT FROM AUTHOR]

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

Question: The distribution and interactions of terrestrial biodiversity are influenced by environmental gradients. In general, tropical species present a hump‐shaped altitudinal species richness pattern related to gradients of temperature and precipitation. However, the effects of the elevational and environmental gradients on the co‐occurrence of species that form specialized mutualisms in the lowland tropical forest canopy and the relative importance of these species in interaction networks are unknown. We studied ant‐gardens, which are constituted by vascular epiphytes that inhabit ant nests exclusively. Our main question was: do the vegetation type, elevation, temperature, and precipitation alter the diversity and interactions of the associated species in ant‐gardens? Location: Southeastern Mexico. Methods: We recorded epiphytes and ants associated with ant‐gardens in 21 sites in southeastern Mexico (elevational range of 23–643 m a.s.l.), which is located on the northern limit of the distribution of Neotropical ant‐gardens. We tested whether the vegetation type and gradients of elevation, temperature and precipitation influence the diversity (richness and composition) and interactions (centrality, i.e., relative importance of each species in epiphyte–epiphyte interaction networks) of the ant‐gardens. Results: We found a total of 126 ant‐gardens formed by 15 epiphyte species and two ant species. Seven epiphytes and only one ant (Azteca gnava) are specialists of ant‐gardens (true ant‐garden epiphyte and ant species respectively). Neither vegetation type nor elevational and environmental gradients influenced the richness, composition and centrality of the epiphytes, although some species only occurred in sites with greater precipitation. The true ant‐garden epiphytes were more central than the non‐true ant‐garden epiphytes, with the orchid Epidendrum flexuosum being the most frequent and central epiphytic species in Mexican ant‐gardens. Conclusions: Unlike guilds of epiphytes and ants considered individually, the ant‐gardens represent a mutualism that maintains their patterns of diversity and interspecific interactions along gradients of elevation, temperature and precipitation. [ABSTRACT FROM AUTHOR]

The integration of phylogenetic methods and species distribution can really help in the investigation of biogeographic patterns and to fill gaps in evolutionary ecology. Here we investigated how the vascular flora of the Brazilian ancient Cipó Mountains, an alleged OCBIL (old, climatic buffered infertile landscape) with a high diversity of species and endemism, evolved across that harsh archipelago-like system and altitudinal gradient. We used a node-based analysis of species distributions that follows the concepts of over- and underrepresentation and takes into account the relationship between sister clades, to yield two very statistically tractable metrics: the geographical node divergence and specific over-representation score. We collected and identified plant species along an elevational gradient ranging from 800 to 1400 m a.s.l. We also collected environmental variables such as elevation and soil properties. We found three allopatric nodes, which revealed the major biogeographic shifts in this tropical mountaintop vegetation. We found evidence to support the idea that environmental filtering is significantly shaping the distribution of biological communities and is restraining clades in the phylogeny. We argue that our study offers new insights into the biogeographic history and distributional shifts of the ancient rocky grasslands flora and to mountaintop vegetation systems in general. [ABSTRACT FROM AUTHOR]

The Andean forests of northern Ecuador are known for their high levels of plant diversity relative to the area they occupy. Typically, these forests grow on steep slopes that lead to dramatic habitat gradients across short distances. These extreme habitat gradients make the Andean forest ecosystem an excellent natural laboratory for understanding the effect of elevation on forest community diversity, structure and composition. We established 31 plots (50 m × 5 m) which are divided between two elevational transects in the cloud forest of the Siempre Verde Reserve in the western foothills of the Andes Mountains of northern Ecuador. All trees and tree ferns with a diameter at breast height (dbh) ≥ 5 cm were measured and identified. We examined changes in community composition, structure, and diversity along and between the elevational transects and three elevational zones: low (2437–2700 m), middle (2756–3052 m), and high (3163–3334 m). We found four main trends associated with the elevational gradients at this site: (1) community composition differed between the two transects and among the three elevational zones according to N-MDS, ANOSIM, and percentage of shared species, with some species having limited distributions, (2) metrics of community structure showed opposite relationships with elevation, depending on the transect, with the only significant relationship (negative) found between basal area and elevation in the open trail transect, (3) alpha diversity, in general, peaked at mid-elevations, and (4) beta diversity consistently increased with distance between plots along elevation. The complexity of changes in community composition, structure, and alpha diversity along elevation may be related to the heterogeneity of the environment on a local scale, such as topography, soil composition, and even human impact, or to dispersal limitation and should be investigated further. These changes in community composition and the relatively high beta diversity found at this site exemplify the biological complexity of montane forest, reinforcing arguments from other studies on the importance of their conservation. [ABSTRACT FROM AUTHOR]

Elevational gradients strongly affect the spatial distribution and structure of soil bacterial communities. However, our understanding of the effects and determining factors is still limited, especially in the deep soil layer. Here, we investigated the diversity and composition of soil bacterial communities in different soil layers along a 1,500-m elevational gradient in the Taibai Mountain. The variables associated with climate conditions, plant communities, and soil properties were analyzed to assess their contributions to the variations in bacterial communities. Soil bacterial richness and α-diversity showed a hump-shaped trend with elevation in both surface and deep layers. In the surface layer, pH was the main factor driving the elevational pattern in bacterial diversity, while in the deep layer, pH and soil carbon (C) availability were the two main predictors. Bacterial community composition differed significantly along the elevational gradient in all soil layers. In the surface layer, Acidobacteria, Delta-proteobacteria, and Planctomycetes were significantly more abundant in the lower elevation sites than in the higher elevation sites; and Gemmatimonadetes, Chloroflexi, and Beta-proteobacteria were more abundant in the higher elevation sites. In the deep layer, AD3 was most abundant in the highest elevation site. The elevational pattern of community composition co-varied with mean annual temperature, mean annual precipitation, diversity and basal area of trees, pH, soil C availability, and soil C fractions. Statistical results showed that pH was the main driver of the elevational pattern of the bacterial community composition in the surface soil layer, while soil C fractions contributed more to the variance of the bacterial composition in the deep soil layer. These results indicated that changes in soil bacterial communities along the elevational gradient were driven by soil properties in both surface and deep soil layers, which are critical for predicting ecosystem functions under future climate change scenarios. [ABSTRACT FROM AUTHOR]

As woody plants provide much of the trophic basis for food webs in forests their species richness, but also stand age and numerous further variables such as vegetation structure, soil properties and elevation can shape assemblages of ground beetles (Coleoptera: Carabidae). However, the combined impact of these numerous variables on ground beetle diversity and community structure has rarely been studied simultaneously. Therefore, ground beetles were studied in 27 plots in a highly diverse and structurally heterogeneous subtropical forest ecosystem, the Gutianshan National Park (southeast China) using pitfall traps and flight interception traps. Both trapping methods collected partly overlapping species spectra. The arboreal fauna was dominated by lebiines and to a smaller extent by tiger beetles and platynines; the epigeic fauna comprised mostly representatives of the genus Carabus and numerous tribes, especially anisodactylines, pterostichines, and sphodrines. Ground beetle species richness, abundance, and biomass of the pitfall trap catches were analyzed with generalized linear mixed models (GLMMs), fitted with seven environmental variables. Four of these variables influenced the ground beetle assemblages: Canopy cover, herb cover, pHvalue of the topsoil and elevation. Contrary to our expectations, woody plant species richness and stand age did not significantly affect ground beetle assemblages. Thus, ground beetles seem to respond differently to environmental variables than ants and spiders, two other predominantly predatory arthropod groups that were studied on the same plots in our study area and which showed distinct relationships with woody plant richness. Our results highlight the need to study a wider range of taxa to achieve a better understanding of how environmental changes affect species assemblages and their functioning in forest ecosystems. [ABSTRACT FROM AUTHOR]

Aim: Anticipating and mitigating the impacts of climate change on species diversity in montane ecosystems requires a mechanistic understanding of drivers of current patterns of diversity. We documented the shape of elevational gradients in avian species richness in North America and tested a suite of a priori predictions for each of five mechanistic hypotheses to explain those patterns. Location: United States Methods: We used predicted occupancy maps generated from species distribution models for each of 646 breeding birds to document elevational patterns in avian species richness across the six largest U.S. mountain ranges. We used spatially explicit biotic and abiotic data to test five mechanistic hypotheses proposed to explain geographic variation in species richness. Results: Elevational gradients in avian species richness followed a consistent pattern of low elevation plateau‐mid‐elevation peak (as per McCain, 2009). We found support for three of the five hypotheses to explain the underlying cause of this pattern: the habitat heterogeneity, temperature, and primary productivity hypotheses. Main Conclusions: Species richness typically decreases with elevation, but the primary cause and precise shape of the relationship remain topics of debate. We used a novel approach to study the richness‐elevation relationship and our results are unique in that they show a consistent relationship between species richness and elevation among 6 mountain ranges, and universal support for three hypotheses proposed to explain the underlying cause of the observed relationship. Taken together, these results suggest that elevational variation in food availability may be the ecological process that best explains elevational gradients in avian species richness in North America. Although much attention has focused on the role of abiotic factors, particularly temperature, in limiting species' ranges, our results offer compelling evidence that other processes also influence (and may better explain) elevational gradients in species richness. [ABSTRACT FROM AUTHOR]

Elevation gradients are drivers of species diversity, and, recently, studies have considered the evolutionary process in shaping community assembly patterns. Patterns of plant species richness across elevational gradients have been studied in different parts of the Atlantic Forest; however, little is known about plant phylogenetic diversity patterns. Thus, we aimed to analyse the phylogenetic diversity of angiosperm trees along an elevation gradient in southern Brazilian Plateau, in the subtropical portion of the Atlantic Forest. We expected a decrease in phylogenetic diversity along the elevation gradient, from lowlands towards to highlands, where species may be evolutionary closely related as many tropical lineages are not capable to inhabit colder conditions. We also investigated the distribution of phylogenetic clades along the elevation gradient through principal coordinates of phylogenetic structure. Data were obtained from 28 phytosociological surveys distributed across different elevation levels, ranging from 40 to 975 m. We found a negative association between phylogenetic diversity and the elevation gradient. The representativeness of families Myrtaceae and Lauraceae increased with elevation, while most of the families decreased in species richness and are replaced by temperate families such as Winteraceae (Drimys) in higher elevations. The decrease in phylogenetic diversity with increasing elevation may be linked to niche conservatism of tropical lineages that retain their historical climatic niches and thus many species are not capable to inhabit colder environments. Most tropical clades are restricted to lower elevations; however, Myrtaceae and Lauraceae probably evolved tolerance to colder temperatures during glacial cycles. Furthermore, the probably long‐term climate stability in lowlands than highland areas may have promoted the co‐occurrence of distantly related species, resulting in higher phylogenetic diversity. Finally, we observed how historical imprints and current environmental conditions shape the phylogenetic diversity of angiosperm tree species in subtropical Atlantic Forest. [ABSTRACT FROM AUTHOR]

The campo rupestre sensu lato is a vegetation type that occurs in South American mountains, supports a distinctive flora characterized by high rates of endemism, high herbaceous species richness and often-neglected but also species-rich of the arboreal stratum. We aimed to investigate how environmental factors and elevation are associated with the distribution and diversity of woody species in different rupestrian vegetation types across South America. Using a database of 2,049 woody species from 185 sites across four vegetation types within the campo rupestre, we assessed how the vegetation types were grouped according to their floristic composition and number of shared indicator species, as well as by using different beta diversity indices. The most important variables from a set of 27 variables (e.g. altitude, geo-edaphic and climatic) explaining species distribution were identified using redundancy analysis (RDA) and variation partitioning methods. The distribution of vegetation types was related to both environmental and spatial fractions, with a set of 17 variables retained (e.g. rockiness, grass cover and temperature seasonality as the most important variables). There was an association between the floristic composition of each vegetation type and the elevation range. Although the identified vegetation types are floristically related, they are distinguished by exclusive and habitat-specialist woody species. This uniqueness of vegetation types should be considered in terms of complementarity for the conservation of campos rupestres. [ABSTRACT FROM AUTHOR]

Tropical mountains encompass a wide range of environmental conditions and are useful models for studying drivers of community structure. Invertebrate species richness and abundance show various elevational patterns. However, the drivers of these differences are not well understood, although microhabitat complexity is potentially important. We studied ground‐dwelling ants using pitfall trapping and hand collection on Mt. Wilhelm (Papua New Guinea) from 169 to 3,795 m a. s. l. We tested for the effects of elevation and leaf litter depth (as a measure of microhabitat complexity) on ant abundance, species richness, and composition. We sampled 118 species, with ants present up to 2,331 m a. s. l. Species richness peaked at mid‐elevation (~700 m), but the elevational pattern for abundance varied depending on sampling scale. Leaf litter depth negatively affected abundance once elevation had been accounted for, while elevation and litter depth had an interactive effect on species richness. Species richness was positively related to litter depth at lower elevations, but negatively above ~ 700 m. Species composition varied with elevation and less strongly with leaf litter depth. We speculate that in the lowlands, litter depth rather than temperature limits ant communities. At high elevations, the deeper litter decreases temperature of the litter layer, and temperature becomes limiting. At mid‐elevations, temperature is not yet too low, and litter is still relatively deep, hence generating a mid‐elevation peak in ant richness. Our results may explain differing richness‐elevation patterns of litter arthropods around the world and provide testable predictions for future studies on this topic. [ABSTRACT FROM AUTHOR]

Aim: In response to warming, species are shifting their ranges towards higher elevations. These elevational range shifts have been documented in a variety of taxonomic groups across latitude. However, the rate and direction of species range shifts in response to warming vary, potentially as a consequence of variation in species traits across elevation. Specifically, diurnal and seasonal climates are often more variable at higher elevations, which results in high-elevation species that have broader thermal physiologies relative to low-elevation species. High-elevation species that are thermal generalists might not need to move as far to track their thermal niche as lowelevation thermal specialists. We investigated whether rates of range shifts varied systematically with increasing elevation across taxa and regions. Location: Sixteen montane regions world-wide. Time period: 1850-2013. Taxon: Nine hundred and eighty-seven species of plants and animals. Methods: We gathered published data on elevational range shifts from 20 transect studies comparing historical and recent distributions and examined how rates of range shifts changed across elevation. Specifically, we performed a meta-analysis to calculate the pooled effect of elevation on species range shifts. Results: We found that rates of range shifts show a negative relationship with elevation such that low-elevation species have moved upslope farther than high-elevation species on the same transect. This finding was primarily a result of shifts in the upper range limits. We also found that 28% of species shifted downslope against predictions, but elevation did not show a relationship with downslope range shifts. Main conclusions: Idiosyncratic range shifts will significantly alter montane ecological communities, which are home to some of the greatest biodiversity on Earth. Our results demonstrate that species range shifts vary with elevation and might be a consequence of differences in species traits that also vary along montane gradients. [ABSTRACT FROM AUTHOR]

The merging of community ecology and phylogenetic biology allows us to link broader evolutionary processes to local ecological processes, thereby increasing our understanding of community assembly. A recurrent way to test how species assemblages respond to different abiotic conditions and evaluate the role of evolutionary constraints in community assembly is through using environmental gradients as natural treatments. Here, we combine phylogenetic and trait-based methods to evaluate how the phylogenetic diversity and composition of bird assemblages and their community-weighted traits vary along an elevational gradient in the Swiss Alps. For this purpose, we used four life-history traits considered to be key indicators of individual species response to environmental changes: clutch size, number of breeding attempts, dispersal capacity and lifespan. Controlling for phylogeny, we determined whether environmental filters (elevation, habitat type) act on these traits independently of the level of relatedness among species. We found that phylogenetic dispersion decreases with elevation, but the signature of phylogenetic clustering was weak. Phylogenetic fuzzy weighting showed that the distribution of bird species across plots was related to the two environmental gradients; nonetheless, such influence was not determined by the phylogenetic relationships in either case. That is, there are no specific clades associated with particular elevation or habitat types. We also found that high elevation communities around the treeline were composed of species with lower reproductive rates, reduced lifespan, and lower dispersal capacity, which would make them less resilient to environmental change. Although traits showed moderate phylogenetic signal, only the lifespan was phylogenetically structured. In the remaining cases, the trait-environment association was not mediated by the phylogenetic relationships among taxa. Our study indicates that evolutionary constraints do not represent a significant driver of community assembly in Alpine bird communities and support the notion that phylogeny may often not be a good proxy for traits subject to environmental filtering. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMFs) play a vital role in ecosystems, especially in ecosystem variability, diversity, and function. Understanding the AMF diversity, distribution, and their driver at different altitudinal gradients is a benefit for understanding the ecological function of AMF in mountain ecosystems. In this study, we explored the AMF molecular diversity and their distribution from 660 to 3,500 m a.s.l. in Mount Taibai of Qinling Mountains based on high-throughput sequencing technology. A total of 702 operational taxonomic units (OTUs) in 103 species of AMF are isolated from soil samples, which belong to 18 identified and 1 unidentified genus in 10 families. The fungi in the genus of Glomus is the most dominant, with the occurrence frequency of 100% and the relative abundance of 42.268% and 33.048% on the species and OTU level, respectively. The AMF colonization in root could be simulated by a cubic function with the change of altitudes with the peak and trough at a.s.l. 1,170 and 2,850 m, respectively. Further, AMF diversity indices including Sob, Shannon diversity, and Pielou evenness also showed the same cubic function change trends with increasing altitude at OTU and species levels. However, the average values of diversity indices at OTU level are always higher than these at the species level. Based on the OTU level, the highest and lowest values of Shannon and Pielou indices are observed at the altitudes of 1,400 and 2,800 m, respectively. The pattern of AMF community distribution in Mt. Taibai is driven by altitude with the characteristics of more abundance in the medium- to low-altitude than high-altitude areas. In general, abundant AMF molecular diversity and species exit in different elevations of Mt. Taibai, which indicate gradient changes with elevations. [ABSTRACT FROM AUTHOR]

Mountain systems are exceptionally species rich, yet the associated elevational gradients in functional and phylogenetic diversity and their consistency across latitude remain little understood. Here, we document how avian functional and phylogenetic diversity and structure vary along all major elevational gradients worldwide and uncover strong latitudinal differences. Assemblages in warm tropical lowlands and cold temperate highlands are marked by high functional overdispersion and distinctiveness, whereas tropical highlands and temperate lowlands appear strongly functionally clustered and redundant. We additionally find strong geographic variation in the interplay of phylogenetic and functional structure, with strongest deviations between the two in temperate highlands. This latitudinal and elevational variation in assemblage functional structure is underpinned by nuanced shifts in the position, shape and composition of multivariate trait space. We find that, independent of latitude, high‐elevation assemblages emerge as exceptionally susceptible to functional change. [ABSTRACT FROM AUTHOR]

Seeds are the colonizing propagules for many plants and may therefore contribute to the filtering of species during the process of colonization and community assembly. Environmental filtering of seed traits may occur among species and influence community composition, or within species and influence the environmental breadth that a given species inhabits. To test for evidence of such filtering of seed traits, we measured morphological and germination traits of seeds of 408 angiosperm species collected across an elevational gradient in the eastern Tibetan Plateau grasslands. We tested for elevational filtering of traits at the species level, as well as within 22 of those species that occurred at different elevations, in order to test whether within‐species variation reflected among‐species patterns. Elevational patterning occurred in both seed morphology and seed germination. Seeds were smaller, more elongated and had a higher surface area:volume ratio and shorter germination times at higher elevation. Seed morphology was associated with germination such that more elongated and smaller seeds with a higher surface area:volume ratio germinated faster, leading to earlier germination in seeds from high elevation. Within species, elevational variation in seed traits was observed in several species, but species differed in how those traits were distributed across elevation. These results suggest that taxonomic differences in seed traits may contribute to elevational variation in the species composition of plant communities, but that seed traits may be variably selected by elevation within species. [ABSTRACT FROM AUTHOR]

The mountain ecosystem is a perfect podium to investigate the impact of climate change on overall community structure and species composition. The Potohar region in Pakistan was chosen to study changes in grass-species diversity and the distributional pattern along an altitudinal range of 1000 m (from 400 m to 1400 m). The major objectives of the study were to prepare grass-species listing and species composition, and patterns of their dominance and distribution at various habitats. Three sites separated by a distance of 50 km were selected at each altitude and three transect lines (each of 100 m) were laid at a distance of 500 m. Then five sub-transect lines were laid at distance of 50 m on which five quadrats (1 × 1 m2) were laid systematically with a distance of 10 m between the successive quadrats. The diversity of the grass species is high and 114 species were recorded therein. Six grasses, Aristida adscensionis, Cynodon dactylon, Chrysopogon serrulatus, Cymbopogon jwarancusa, Dichanthium annulatum and Panicum orientale, are widely distributed at all altitudinal ranges. Species like A. adscensionis, Cenchrus ciliaris, C. jwarancusa, C. dactylon, Ochthochloa compressa, Panicum antidotale, Paspalum distichum and Phragmites karka dominate because of their high degree of tolerance to multiple stresses. These dominant grasses are highly palatable and support livestock and endemic wildlife species. The distributional range of other grasses is altitudinal-specific and is directly linked to the physiographic parameters and climate variables that influence species richness, dominance, community structure and species distributional pattern along altitudinal gradients. Over-harvesting for essential oil and other medicinal purposes are identified as major threats to species like Cymbopogon martini and Chrysopogon zizanioides. The findings of this study are useful in investigating the composition of grass species of the sub-mountainous rangelands and in developing conservation strategies for rare and endangered species in future studies. [ABSTRACT FROM AUTHOR]

We evaluated the spatial characteristics of the first day of peak leaf colouring (PLCstart) and their relationships with air temperature along latitudinal and elevational gradients in Japan from 2015 to 2017. Leaf colouring information collected from more than 740 sites via citizen science was analysed, representing elevations from 0 to 2800 m and latitudes from 32°N to 44°N. We found that locations with earlier PLCstart dates (day of year 265–294) displayed steeper slopes in elevation per degree of latitude than locations with later PLCstart dates (day of year 295–314). This statistically significant result indicates that the influence of elevation on PLCstart (vertical gradient) weakened as the leaf colouring season progressed in Japan. In addition to these spatial characteristics, the PLCstart and the warmth index (based on monthly mean air temperature) showed significant linear correlations for latitudinal and elevational gradients. This result suggests that the sensitivity of PLCstart to air temperature, as manifested in both latitudinal and elevational gradients, is constant. This study suggests that online phenological data may provide more accurate results for a regional scale (100–1000 km) than the datasets used by previous studies. [ABSTRACT FROM AUTHOR]

Key adaptations enabling mammals to cope with oxygen deficiency at high elevations relate to oxygen transfer into the blood. Among others, the efficiency of this mechanism depends on haematocrit (Hct, the volumetric fraction of red blood cells in blood). Although blood of high-elevation mammals is usually characterised by normal or slightly increased Hct, there are contradictory findings from studies along different elevational gradients. The aim of this study was to explore variability of Hct at both inter- and intraspecific levels in six rodent species from lower and higher elevations of Choke Mountain in Ethiopia. We found that Stenocephalemys sp. A from higher elevation had higher Hct than its congener Stenocephalemys albipes from lower elevation and a similar but weaker tendency was observed intraspecifically in Lophuromys simensis. Furthermore, Hct among four species occupying the high-elevation Afroalpine zone was comparable, and higher than in animals from lower elevations. Higher Hct in the three Afroalpine specialists probably contributes to local adaptations for life in high elevation environments under hypobaric hypoxia. [ABSTRACT FROM AUTHOR]

Due to specific habitat preferences and behavioural limitations, black francolin is not uniformly distributed across the northwestern Himalayan landscape, rather is confined to certain land mosaic. The habitable zones are further reduced due to several manmade threats as logging and forest fire leading to sparse distribution. Overall 54 samples were used for partial sequence analysis of mitochondrial control region. A well evident divergence pattern was observed as individuals collected from low altitude, terrai region significantly distanced from high altitude sampled individuals. Also, the individuals at lower elevation sites exhibited higher genetic diversity in comparison to the samples collected at higher elevations. This indicates that patchy distribution and low dispersal rate have resulted in fine-scale patterns of genetic diversity among the black francolin population. Further, habitat loss and forest fragmentation could lead to more small and isolated populations that could suffer from reduced genetic diversity and may be higher extinction rates. [ABSTRACT FROM AUTHOR]

Aim: What factors set species' range edges? One general hypothesis, often attributed to Darwin and MacArthur, is that interspecific competition prevents species from inhabiting the warmest portions along geographic gradients (i.e., low latitudes or low elevations). A prediction arising from this Darwin–MacArthur hypothesis is that lower elevation species are better competitors than related higher elevation species. An alternative prediction is that higher elevation animal taxa will tend to be better competitors because they will tend to be larger (Bergmann's rule). Here, I test these opposing predictions. Location: Global. Time period: 1971–2019. Major taxa studied: Birds, mammals, amphibians, fishes. Methods: I conducted a meta‐analysis of studies that measured pairwise behavioural aggression between species‐pairs of closely related animals where the two species inhabit divergent elevational distributions. Results: I found that (a) interspecific aggression appears to be a reliable indicator of interspecific competition; (b) elevational position was not consistently linked to interspecific aggression—while lower elevation songbird species in the tropics showed stronger interspecific aggression in response to playback experiments, higher elevation species showed stronger interspecific aggression in direct observations of interspecific aggression across a range of taxa and latitudes; (c) body size was a good predictor of pairwise interspecific aggression and (d) there was limited evidence for Bergmann's rule. Main conclusions: My results do not support the longstanding prediction that lower elevation animals are generally better competitors than their higher elevation relatives. Instead, patterns of interspecific aggression are linked to body size, with larger animals showing more aggression towards smaller relatives than vice versa. Hence, a trait—body size—that is idiosyncratically related to elevational position appear to determine the outcome of pairwise behavioural interactions. Last, I consider these results in the context of the hypothesis that behavioural interactions may impact rates of upslope range shifts associated with recent warming. [ABSTRACT FROM AUTHOR]

The dependence of air temperature on elevation (i.e., its elevational gradient) in the mountains is well known. However, the elevational gradient of near-surface ground temperatures and derived thermal parameters is much less understood. In this study, we investigated how these parameters depend on elevation by one-year temperature measurements along a transect in the Valais Alps (Switzerland) between 700 and 2,600 ma.s.l. In addition, we studied the effect of differences in slope aspect (north/ south) and land cover (open field/forest). Air temperatures were measured as a reference. The results show that the ground thermal regime distinctly differs from that of the air. These differences could mainly be attributed to radiation, snow cover, and ground heat transfer. Our findings have farreaching implications for ecosystems, agriculture, and forestry in mountains because a large portion of the living biomass is underground and thus affected by ground thermal processes. [ABSTRACT FROM AUTHOR]

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

Questions: Studies on bryophyte and lichen diversity patterns along elevational gradients are scarce, although this approach can serve as space‐for‐time substitution to predict diversity changes because of climate warming. Therefore, we investigated bryophytes and macrolichens in disturbed and undisturbed stands along an elevational gradient in the unique laurel forest of Madeira island by addressing the following questions: (a) how does the species richness of functional‐taxonomic bryophyte and macrolichen groups differ with elevation; (b) how is the species richness of these groups affected by disturbances? Location: UNESCO World Natural Heritage site laurel forest of Madeira island (Madeira, Portugal). Methods: We analyzed species richness of bryophytes and macrolichens in 92 plots in response to elevation and to disturbances. Results: Bryophyte species richness showed a mid‐elevational peak, while macrolichen richness increased with elevation. Disturbed plots harbored on average 20% less bryophyte and macrolichen species than undisturbed plots. Conclusions: The laurel forest of Madeira island is a bryophyte and lichen diversity hotspot. Our findings indicate future biodiversity threats by changing environmental conditions. This calls for the need for a strict protection status of the laurel forest on Madeira island to minimize human‐related disturbances, for the development of management measures that could mitigate climate change effects by maximizing habitat suitability and for the implementation of species conservation programs to prevent future extinctions, in particular of endemic species. [ABSTRACT FROM AUTHOR]

Aims: We aimed to compare uptake and litter flux of silicon (Si) across tropical tree species and sites on Mt. Kinabalu, Borneo. Methods: Si flux components were measured at eight plots in tropical forests at four altitudes (700–3,100 m above sea level) on two types of parent materials (acidic sedimentary/granite rock and ultramafic igneous rock, paired at each elevation). Results: Leaf Si concentration differed substantially among tree species (0.24–13.6 mg g−1). Species with high leaf Si concentrations occurred mostly in the lowest elevation plots on both parent materials. The abundance-weighted community means of live-leaf Si concentrations, as well as Si concentration in leaf litter, declined with increasing elevation. Annual leaf-litter Si flux and water extractable Si per unit air-dried soil also decreased with increasing elevation, whereas parent material type had little influence despite consistently higher pH by 0.5–1.0 unit in ultramafic soil. Conclusions: Si uptake and litter Si flux were greater in lower elevation forests regardless of parent material types, most likely because Si accumulating species are more abundant in lowland tropical forests. These results suggest a stronger role of biota than the geochemistry of parent material and rock weathering in Si cycling in the forests on Mt. Kinabalu. [ABSTRACT FROM AUTHOR]

Mountains offer replicated units with large biotic and abiotic gradients in a reduced spatial scale. This transforms them into well-suited scenarios to evaluate biogeographic theories. Mountain biogeography is a hot topic of research and many theories have been proposed to describe the changes in biodiversity with elevation. Geometric constraints, which predict the highest diversity to occur in mid-elevations, have been a focal part of this discussion. Despite this, there is no general theory to explain these patterns, probably because of the interaction among different predictors with the local effects of historical factors. We characterize the diversity of small non-volant mammals across the elevational gradient on Mount (Mt.) Kinabalu (4,095 m) and Mt. Tambuyukon (2,579 m), two neighboring mountains in Borneo, Malaysia. We documented a decrease in species richness with elevation which deviates from expectations of the geometric constraints and suggests that spatial factors (e.g., larger diversity in larger areas) are important. The lowland small mammal community was replaced in higher elevations (from above ~1,900 m) with montane communities consisting mainly of high elevation Borneo endemics. The positive correlation we find between elevation and endemism is concordant with a hypothesis that predicts higher endemism with topographical isolation. This supports lineage history and geographic history could be important drivers of species diversity in this region. [ABSTRACT FROM AUTHOR]

Aim: Climate change is driving many species towards higher latitudes and higher elevations. However, empirical studies documenting these changes have largely focused on presence/absence based range shifts in temperate regions. Studies in lowland tropical ecosystems that control for detection probabilities are especially lacking. Location: Hong Kong SAR, China. Methods: By analysing a 15‐year trapping dataset of geometrid moths along a lowland elevation gradient (0–600 m) in Hong Kong, we used multiple metrics and approaches to estimate occurrence shifts with elevation, changes to range limits, and community‐wide shifts in elevation. Our approaches used Bayesian occupancy models to account for false absences, which may bias naïve measures of range shifts over time. Results: Over the study period, we detected only subtle changes in forest cover but a notable increase in maximum temperatures (~0.5°C per decade) and extreme weather events. Of geometrid moths, one out of the 123 examined species exhibited increased occurrence probabilities across all elevations after accounting for uncertainty in detection; all other species exhibited no significant change in occupancy with elevation. However, at least two species became newly established in Hong Kong over the decade, and 32 species showed significant elevational shifts in lower or upper range limits. At the community level, geometrid moths showed a noticeable upslope shift at all but one of the examined sites. Main conclusions: The complex patterns observed highlight the difficulties and limitations in detecting climate change impacts on diverse tropical communities. Our conservative results indicate early responses of tropical species over a relatively short timespan to a decade of environmental change, and the necessity of long‐term monitoring for providing insights into the management and conservation of vulnerable species. [ABSTRACT FROM AUTHOR]

Question: The composition of fruit types, fleshy vs dry fruits, greatly influences the functioning of plant communities. Literature documenting spatial patterns of fruit types at fine scale is abundant. However, studies at larger geographical scale remain scarce, especially on high‐elevation oceanic islands that provide a great environmental heterogeneity. Here, we investigated how abiotic factors explained the proportion of fleshy‐fruited species (pFF) on Réunion. We asked (a) which abiotic factors were most related to pFF, (b) if fleshy‐fruited canopy species were more sensitive than fleshy‐fruited shrubs to harsh climatic conditions and (c) what are the relationships between pFF, endemism and phylogenetic relatedness. Location: Réunion (3,070 m a.s.l), Mascarene archipelago, South‐West Indian Ocean. Methods: We used a dataset of 429 vegetation plots and assigned fruit types, growth forms and geographical distribution to 213 native woody species. Phylogenetic trees were constructed for each plot. We used GLMs to measure the relationship between pFF and abiotic factors, controlling for spatial autocorrelation. We then assessed the relationship between pFF, the standardized net relatedness index and the proportion of endemic species. Results: The top model explained 78% of the variation in pFF. Elevation was by far the best predictor, with pFF decreasing from 81% at 50 m a.s.l to 0% at 3,000 m a.s.l. At low elevations, pFF was higher on the wet windward (81%) than on the leeward (70%) where phylogenetic clustering was evident. Almost half (48%) of woody plants was fleshy‐fruited trees at low elevations. The proportion of fleshy‐fruited trees declined sharply with elevation and was significantly related to precipitation of the driest month contrary to the proportion of fleshy‐fruited shrubs that showed a hump shaped pattern along elevational gradient and no correlation with precipitation of the driest month. At high elevations, most plant assemblages were phylogenetically clustered and strongly dominated by single‐island endemic dry‐fruited plants. Conclusions: The striking relationship between pFF and elevation, the shift among fleshy‐fruited growth forms along climatic gradients and the phylogenetic clustering of assemblages subjected to harsh climatic conditions, suggested that climatic factors were the main drivers of the distribution of fruit types on Réunion. To explain the absence of fleshy‐fruited species at high elevations, we hypothesized that native fleshy‐fruited lineages lacked the evolutionary potential to adapt and fleshy‐fruited cold‐adapted lineages had major difficulties reaching Réunion. The composition of fruit types has never been investigated at landscape scale on oceanic islands. We showed on Réunion a tremendous decrease of the proportion of fleshy‐fruited plants with elevation and a large dominance of radiated dry‐fruited plants in subalpine shrubland. Climatic factors were major drivers, but the lack of cold‐adapted fleshy‐fruited lineages because of biogeographic constraints may strongly influence this pattern. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Since Darwin, ecologists have assumed that species tend to be abundant in the centre of their geographic distributions and rare at their range edges. We test two predictions of this abundant centre hypothesis: (a) that species are common in the centre of their range and rare at the edges and (b) that empirical distributions along environmental gradients are well described by symmetric bell‐shaped curves. Location: A reef‐to‐ridgetop elevational gradient in the Yopno–Urawa–Som Conservation Area (YUS CA) on the Huon Peninsula in Papua New Guinea. Taxon: Birds. Methods: We use mist net capture rates to quantify species’ abundances as a function of range position, then fit a series of models with different shapes, including symmetric curves, to species’ empirical abundance distributions. Results: Species peak abundances were located near species’ low elevation range edges, high elevation range edges and everywhere in between. Real abundance distributions were fit well by symmetric curves in fewer than half of the species we analysed. Most lowland species have high abundances at their low elevation margin near sea level. Main conclusions: We find only limited support for the abundant centre hypothesis. Most lowland species appear to currently occupy a “truncated” realized niche, suggesting that they will be able to persist at low elevations even as temperatures increase and that lowland biotic attrition is unlikely. In addition to analyses, we present (a) a full species list for the 256 species recorded thus far within the YUS CA, with elevational limits for all forest species and (b) the raw data from our extensive mist net surveys. This information provides valuable baseline data that can be used by future biodiversity scientists to evaluate the changes in the YUS avifauna and will be generally useful to biodiversity scientists studying tropical elevational gradients. [ABSTRACT FROM AUTHOR]

Non-structural carbohydrate (NSC), a major substrate of primary metabolism, has been implicated in mediating cold-induced termination of tree growth, particularly in the alpine environment. Despite its functional significance, NSC pattern as well as its partitioning between sugar and starch in response to elevation across the globe remains unclear. Here, we compiled data from 67 studies encompassing 90 elevational transects worldwide and conducted a meta-analysis to evaluate the responses of NSC (including sugar, starch, and total NSC concentrations) as well as sugar:starch ratio in mountain trees to increasing elevation at organ scale. Our results showed that declining temperature with increasing elevation promoted NSC accumulation in aboveground organs, but did not affect the sugar:starch ratio in all organs analysed, implying that the remarkably significant role of NSC in both short-term cellular metabolism and long-term recalcitrant storage. Trees grown within warmer mountain regions (i.e., regions with relatively higher mean temperature during the growing season) stored more NSC in leaf in response to elevation than those grown within colder mountain regions. We also found that the observed increasing pattern of NSC with elevation occurred only in treeline tree species but not in non-treeline trees (i.e., tree taxa that do not reach the alpine treeline). Additionally, a significant negative effect of elevation on NSC revealed an unbalanced carbon supply in the roots of angiosperms tree species, indicating that the growth inhibition of belowground organ with increasing elevation occurred mainly in angiosperms rather than in gymnosperms. Our findings suggest that a sugar-starch partitioning pattern, which remains essentially stable over a wide range of climates and functional type species, predominately modulates the balance of carbon assimilates between supply and demand in responding to cold stress in the mountain trees worldwide. • Elevation promoted NSC accumulation in aboveground organs of mountain trees. • Trees grown within warmer climates stored more NSC in leaf in response to elevation. • The increase of NSC with elevation only appeared in treeline tree species but not in non-treeline trees. • The negative effect of elevation on NSC revealed an unbalanced carbon supply in the roots of angiosperms trees. • Sugar-starch partitioning pattern remains stable over a wide range of climates and functional types. [ABSTRACT FROM AUTHOR]

Whole-tree water use of nine Pinus cembra trees was estimated in the treeline ecotone of the Central Austrian Alps. Sap flow density using Granier-type thermal dissipation probes and environmental parameters was monitored along an elevational gradient from the forest limit up to treeline and finally mediating the krummholz limit throughout two growing seasons. Normalized sap flow density ( Q) was significantly correlated with solar radiation ( R) and vapor pressure deficit ( D) throughout the treeline ecotone. Multiple regression analysis indicated that at the forest limit and at treeline, D had a similar effect on Q than R. At the krummholz limit by contrast, D had a greater effect on Q than R due to partially stomatal closure and wind-induced clustering of the needles, which impaired their response to available irradiance. Whole-tree water use scaled to crown surface area estimated for an entire growing (172 days) declined from 449 mm at the forest limit to 274 mm at treeline and was 251 mm at the krummholz limit, which is within the values estimated for other European forest ecosystems. Nevertheless, the observation above the forest limit in the central Tyrolean Alps tree transpiration scaled to crown surface area is comparable to the water use of adjacent low-stature vegetation, which should also be taken into account when forecasting potential effects of global change on the water balance of the treeline ecotone. [ABSTRACT FROM AUTHOR]

We conducted field surveys in 807 quadrats to evaluate the elevational belts, boundary and richness patterns of ferns and lycophytes in the temperate region of central Japan. We analysed fern species assemblages at 100 m elevational steps by cluster analysis and tested the number of upper and lower boundaries for elevational intervals against a null model of random distribution of elevational limits. We compared the pattern of fern species richness along the elevational gradients in central Japan with patterns in several locations to evaluate the fern flora in central Japan in relation to the rest of the world. We recorded 261 ferns species in total, which is one-third of the Japanese ferns. We found clear elevational boundaries of fern assemblages at 900 and 1,800 m and three fern elevational zones, which corresponded well to the elevational limits of forest types in central Japan. The pattern of fern species richness in central Japan was an asymmetric hump-shaped pattern that peaked close to the sea level, with the peak of local richness at lower elevations than that of regional richness. We found that the peak of fern species richness along the elevational gradient in Japan was located at lower elevations than that of fern elevational patterns in several locations around the world. [ABSTRACT FROM AUTHOR]

Aim This study explores the relationship between orchid species richness along elevational gradients in the central and eastern Himalaya. Specifically, we aimed to test predictions of maximum richness at different elevational levels for orchid species geographically restricted to central and eastern Himalaya (endemics), and total orchid richness, including different life forms. We then compared and assessed climatic factors together with area as causal explanations for the observed patterns. Location Nepal (100-5200 m a.s.l.), Bhutan (100-5200 m a.s.l.), and adjacent regions of India, i.e. Sikkim and Darjeeling. Methods We used published data on the distribution of orchids to interpolate presence between maximum and minimum recorded elevations in 100-m elevational zones. These patterns were compared with previously published patterns for other plant groups, which were derived in the same way. Descriptive regressions with metres above sea level (m a.s.l.) as the independent variable were performed using nonparametric generalized additive models (GAMs), whereas tests of the diversity models were carried out using parametric generalized linear models (GLMs). Results A hump-shaped relationship between orchid species richness and elevation was observed in Nepal and Bhutan, with maximum richness at 1600 m a.s.l. corresponding to c. 16 °C mean annual temperature. The richness of orchid species that are endemic to central and eastern Himalaya showed a bimodal pattern. Richness of endemic epiphytes peaked at elevation zones similar to those for total richness, but the peak in numbers of endemic terrestrial species occurred at a higher elevation. Main conclusions This study shows that climatic variables (temperature and precipitation) provide a good potential explanation for orchid species richness along the Himalayan elevational gradient, even when the effect of area is considered. The principal elevational peak in richness of central and eastern Himalayan endemics was consistent with the peak in total orchid richness, but maximum terrestrial endemic richness occurred at higher elevations. [ABSTRACT FROM AUTHOR]

The net primary productivity, carbon (C) stocks and turnover rates (i.e. C dynamics) of tropical forests are an important aspect of the global C cycle. These variables have been investigated in lowland tropical forests, but they have rarely been studied in tropical montane forests (TMFs). This study examines spatial patterns of above- and belowground C dynamics along a transect ranging from lowland Amazonia to the high Andes in SE Peru. Fine root biomass values increased from 1.50 Mg C ha at 194 m to 4.95 ± 0.62 Mg C ha at 3020 m, reaching a maximum of 6.83 ± 1.13 Mg C ha at the 2020 m elevation site. Aboveground biomass values decreased from 123.50 Mg C ha at 194 m to 47.03 Mg C ha at 3020 m. Mean annual belowground productivity was highest in the most fertile lowland plots (7.40 ± 1.00 Mg C ha yr) and ranged between 3.43 ± 0.73 and 1.48 ± 0.40 Mg C ha yr in the premontane and montane plots. Mean annual aboveground productivity was estimated to vary between 9.50 ± 1.08 Mg C ha yr (210 m) and 2.59 ± 0.40 Mg C ha yr (2020 m), with consistently lower values observed in the cloud immersion zone of the montane forest. Fine root C residence time increased from 0.31 years in lowland Amazonia to 3.78 ± 0.81 years at 3020 m and stem C residence time remained constant along the elevational transect, with a mean of 54 ± 4 years. The ratio of fine root biomass to stem biomass increased significantly with increasing elevation, whereas the allocation of net primary productivity above- and belowground remained approximately constant at all elevations. Although net primary productivity declined in the TMF, the partitioning of productivity between the ecosystem subcomponents remained the same in lowland, premontane and montane forests. [ABSTRACT FROM AUTHOR]

Larix principis-rupprechtii is an important afforestation tree species in the North China alpine coniferous forest belt. Studying the correlations and response relationships between Larix principis-rupprechtii radial growth and climatic factors at different elevations is helpful for understanding the growth trends of L. principis-rupprechtiind its long-term sensitivity and adaptability to climate change. Pearson correlation, redundancy (RDA), and sliding analysis were performed to study the correlations and dynamic relationships between radial growth and climatic factors. The main conclusions are as follows: (1) The three-elevation standard chronologies all exhibited high characteristic values, contained rich climate information and were suitable for tree-ring climatological analyses. (2) Both temperature and precipitation restricted low-elevation L. principis-rupprechtii radial growth, while monthly maximum temperatures mainly affected mid-high-elevation L. principis-rupprechtii radial growth. (3) Mid-elevation L. principis-rupprechtii radial growth responded to climate factors with a "lag effect" and was not restricted by spring and early summer drought. (4) Long-term sliding analysis showed that spring temperatures and winter precipitation were the main climatic factors restricting L. principis-rupprechtii growth under warming and drying climate trends at different elevations. The tree-ring width index and Palmer drought severity index (PDSI) were positively correlated, indicating that L. principis-rupprechtii growth is somewhat restricted by drought. These results provide a reference and guidance for L. principis-rupprechtii management and sustainable development in different regions under warming and drying background climate trends. [ABSTRACT FROM AUTHOR]