Elevational Bands Research Articles

Effects of spatial fragmentation on the elevational distribution of bird diversity in a mountain adjacent to urban areas.

The biodiversity in mountainous ecosystems is high but is threatened by rapid environmental change. Urbanization and other anthropogenic factors in the mountains can affect land use and spatial fragmentation. Moreover, patterns of habitat are closely related to elevation and have a major effect on montane biodiversity. The aim of this study was to analyze the effects of spatial fragmentation on the vertical distribution pattern of bird diversity by characterizing the structure of the bird community, species diversity, and landscape factors at different altitudes. From 2016 to 2019, this study made a four years of continuous monitoring of the breeding birds. The result indicated that Mount Tai harbored a high bird diversity. Bird richness, abundance, and Shannon‐Wiener index decreased with latitude in Mount Tai monotonically. Moreover, the structure of bird communities varied along altitudinal gradients, and some special species were supported in different elevational bands due to the environmental filtering. Road density, number of habitat patches, patch density, and the percentage of forest were significantly related to bird diversity. Sufficient habitat and more patches in the low‐mountain belt supported higher bird diversity. The middle‐mountain belt and high‐mountain belt showed contrasting patterns. Our results highlight the effects of on‐going urbanization and human activities on montane biodiversity and emphasize the need for artificial habitats in the mountains to be managed.

Ecological constraints on elevational gradients of bird species richness in Tajikistan

The avifauna in Tajikistan has been widely studied for the last century, but specific work on species richness pattern along elevation gradients in Tajikistan is rarely investigated. Here, we reported the first study of bird species richness (BSR) in the high-altitude mountain systems (Tien Shan and Pamir-Alay) of Tajikistan which are very sensitive to the recent climate changes. We aim to explore the relationship of BSR pattern with elevation gradient and to determine the potential drivers underlying the patterns. We collected occurrence data from field surveys, published articles, and open access websites to compile a list of bird species along elevational gradients across the whole country. The BSR was counted by 100 ​m elevational bands ranging from 294 ​m to 5146 ​m. The patterns of BSR were calculated separately for five groups: all breeding birds, Passeriformes, Non-Passeriformes, large elevational range species, and small elevational range species. We calculated ecological and climatic factors of planimetric area, mid-domain effect (MDE), habitat heterogeneity (HH), mean annual temperature (MAT), temperature annual range (TAR), annual precipitation (AP), normalized difference vegetation index (NDVI), human influence index (HII), and human disturbance (HD) in each elevational band. A combination of polynomial regression, Pearson's correlation, and general least squares model analyses were used to test the effects of these factors on the BSR. A unimodal distribution pattern with a peak at 750–1950 m was observed for all breeding birds. The similar pattern was explored for Passeriformes and Non-Passeriformes, while species with different elevational range sizes had different shapes and peak elevations. For all the breeding birds and Passeriformes, BSR was significantly related to spatial, climate and human influence factors, while BSR of Non-Passeriformes positively correlated with all the given factors. First, second and fourth range classes of birds were significantly correlated with human influence factors. Moreover, large-ranged species had positive correlations with the mid-domain effect and weakly with habitat heterogeneity. We found that area, MAT and AP were the main factors to explain the richness pattern of birds, and the species richness increases with these three factors increasing. Multiple factors such as area and climate explain 84% of the variation in richness. Bivariate and multiple regression analyses revealed a consistent influence of spatial and climate factors in shaping the richness pattern for nearly all bird groups.

Ecological traits affect the seasonal migration patterns of breeding birds along a subtropical altitudinal gradient

Altitudinal bird migration involves seasonal shifts up and down the altitude gradient annually. Asia as the place with the largest number of altitudinal migrants, has quite few related studies, especially for montane and temperate avifaunas. To explore the potential drivers of seasonal altitudinal migration for birds in the middle of Hengduan Mountains, we conducted a three-year investigation on breeding and non-breeding season bird communities at eight elevational bands (1200–4200 ​m) in the Gongga Mountains. We examined the altitudinal migration patterns and relationships between seasonal distribution shifts and species' traits of 50 species with sufficient data recorded in both seasons. We found that a large proportion of breeding birds underwent altitudinal migration and showed three migration patterns (downslope shift, upslope shift, no shift). Seasonal distribution shifts were mainly correlated with certain ecological traits. Species breeding at high and mid-elevations, nesting in scrub and being omnivorous are more likely to show downslope movements during the non-breeding season. In addition, territorially weaker species exhibited more diverse migration patterns. Notably, we found the hand-wing index (HWI) was actually more convincing than body mass in explaining altitudinal migration. These results consolidate the studies of seasonal altitudinal migration in montane birds. Our study could be used to bridge existing knowledge gaps that currently impeding effective conservation for montane avifaunas in the Hengduan Mountains.

Seasonal variation in community composition and distributional ranges of birds along a subtropical elevation gradient in China

AbstractAimSeasonal variation in community composition and species distributional ranges along elevational gradients remain poorly known but are essential to inform conservation. In this study, we aim to understand how species richness, community composition and elevational ranges of montane birds change between the breeding and the non‐breeding season.LocationThe east slope of the southern Gaoligong Mountains, Yunnan, southwest China, elevational range: 700–3,400 m a.s.l.; latitudinal range: 24°56′–26°09′N.MethodsWe compared species richness and community composition of birds in nine 300‐m elevational bands in the breeding (April–May) and non‐breeding (December–January) seasons. We also calculated seasonal elevational shifts of 97 species with sufficient data recorded in both seasons and assessed how species' traits influenced these shifts.ResultsSpecies richness declined in high and low elevations between the breeding and the non‐breeding season. The temporal beta diversity shift from the breeding to the non‐breeding season was mainly caused by species losses rather than species gains in high‐ and low‐elevation communities. Communities in middle elevations showed a contrasting pattern, with seasonal composition change resulting mainly from species gains. We also found that species' seasonal distribution shifts were mainly associated with breeding elevation and diet. Notably, high‐ and middle‐elevation breeders and insectivores significantly shifted their elevational ranges downslope in the non‐breeding season. In addition, species that participate in mixed‐species flocks and that rely on forests also showed significant downslope shifts in the non‐breeding season.Main conclusionsThese results show complex patterns of the interconnectedness of bird communities along the elevational gradient. Keeping forests at middle elevations intact appears especially important as they are used in winter by species that breed at both high and middle elevations. Furthermore, our results suggested conservation actions maintaining connectedness in low and middle elevations are urgently needed to conserve regional biodiversity and highlight the importance of seasonality in montane ecosystem research.

Do sub-groups of butterflies display different elevational distribution patterns in the Eastern Himalaya, India?

Understanding the pattern of biodiversity along environmental gradients helps in identifying diversity hotspot areas that can be prioritized for conservation. While the elevational distribution of several taxa has been studied, responses of the sub-groups within a taxon to elevation and its associated factors are not properly understood. Here we study species richness and butterfly density along an elevation gradient in Sikkim, Eastern Himalaya, India and explore the underlying causes of the patterns. We sampled butterflies using a fixed-width point count method in 16 elevational bands (150–200 m intervals), between a range of 300 and 3300 m a.s.l. We categorized butterflies into various sub-groups based on family, range size, biogeographic affinity, and host-plant specialization. We recorded 3603 individuals and 253 species of butterflies after the completion of 1860 point counts. Overall, species richness in the majority of the sub-groups (except for Riodinidae and Palearctic species) declines with elevation, as does the density of almost all the sub-groups. From a selection of environmental factors, annual actual evapotranspiration has the strongest effect on the species richness pattern of butterflies as well as on the density of the overall butterfly community, especially the Lycaenidae family. The richness and density of butterfly groups display varied responses to the richness and density of trees and shrubs. The conducive climatic conditions and diverse habitats in the lower valleys of the Eastern Himalaya support a high diversity of butterflies (with majority of small range species) and thus warrants conservation attention.

Disentangling the effects of host relatedness and elevation on haemosporidian parasite turnover in a clade of songbirds

AbstractThe persistence of a parasite species in an ecological community is determined both by its environmental tolerance and host breadth. The relative contribution of these niche characteristics to parasite community structure is challenging to parse because host persistence is also a consequence of extrinsic environmental factors. We investigated haemosporidian parasites (genera Plasmodium, Leucocytozoon, and Haemoproteus) in a clade of avian hosts in eastern North America. Species in this clade of Catharus thrushes occupy specific elevational bands in a non‐phylogenetically determined manner. This allowed us to tease apart the effects of host relatedness and elevation on parasite community structure, diversity, and infection prevalence. We screened blood and tissue samples from 414 adult birds from four mountain ranges in the Appalachian Highlands for blood parasites using a cytochrome‐b‐nested PCR protocol and identified parasite lineages by sequencing. We found an overall infection prevalence of 88.4% and identified a total of 38 parasite lineages including six novel lineages. Parasite community patterns varied by genus. Host relatedness rather than elevational zone predicted the beta turnover and phylobeta turnover of Leucocytozoon parasites, indicating that closely related rather than geographically proximate host species had more similar parasites. This pattern was not seen in Plasmodium parasites because the diversity of this parasite genus varied considerably in the high elevational zones among mountain ranges, that is, a sky‐island effect. Haemoproteus parasites were rare in this study system. Our study suggests that the mechanisms that underlie community structuring vary between haemosporidian genera due to differences in the degree of host sharing among lineages.

The importance of the standardizing sampling methodology to detect altitudinal gradients in mountains: A study case for the resident bird community in a hotspot (Atlantic forest) and the Middle Domain Effect

Among the theories that attempt to explain the elevational distribution of metazoan species along elevational gradients, the Mid-Domain Effect (MDE) is one of most debated and criticized. Here, we test whether the diversity of birds along elevational gradients in the Serra do Caparaó, a mountain of the Brazilian Atlantic Forest, is explicable by the MDE. We sampled an elevational gradient between 970 m.a.s.l. and 1970 m.a.s.l. of forest vegetation, with elevational bands every 100 m. We observed a hump-shaped richness pattern of birds along the gradient, with more species in intermediate elevations. It decreased at lower and higher elevations, thereby following a unimodal distribution. Distribution of species richness indicated a high correlation with the tested MDE null model. The result was the same for endemic species. Considering the total bird species registered, up to 30% are endemic and 9 are endangered. Threatened species richness followed a different elevational distribution along the gradient: three species occurred at the lower elevations, two at the interquartile elevations and four at the highest elevations. Despite finding more species in the intermediate elevations, the areas of low and high elevations are also important for the maintenance of endemic and threatened species. To test the MDE theory and compare our results with other studies, we highlight the importance of standardized samplings and habitats. Moreover, we focus on the characterization of the surrounding landscape, which can also influence the richness of bird species diversity.

Species richness patterns of vascular plants and their drivers along an elevational gradient in the central Himalayas

How and why biodiversity varies along the elevational gradients is fundamental yet controversial topics in ecology. To advance our understanding on these questions and provide insight into biological conservation, we explore the elevational patterns of vascular plant richness and their drivers in the Gyirong Valley, the longest valley in China’s Himalayas. Elevational richness patterns of vascular plant were documented by 96 sampling plots along 12 elevational bands of 300-m ranging from 1800 to 5400 m above sea level. We related the elevational patterns of vascular plant richness to the climate, spatial, historical, and disturbance factors, and assessed the relative importance of these factors in explaining above patterns using the Random Forest model. Overall, the species richness of vascular plant showed a hump-shaped pattern along the elevational gradient in the Gyirong Valley, although the life form and endemism of species in combination with the scale effect modified the patterns observed. Climate factors played a greater role than other environmental factors in explaining the elevational pattern of vascular plant richness. Such strong climate-species relationship was nicely interpreted by the water-energy dynamic hypothesis, indicating the combined effect of energy and water is the major driver that shaped vascular plant richness along elevational gradient. The climate-driven hump-shaped pattern of vascular plant in the Gyirong Valley is aligned with most of previous report from different part of the Himalayas, highlighting the need for more conservation effort at the intermediate elevations of this region, and calling for more scientific concern on the impact of climate change on elevational pattern of biodiversity.

Diversity of epiphyte ferns along an elevational gradient in El Triunfo Biosphere Reserve, southern Mexico

Background and aims – In the tropics, some studies have found that the richness of epiphytic ferns present a peak at mountain mid-elevations. However, it is not well understood how transitions from tropical to subtropical conditions affect this peak, and even less is known about beta diversity of epiphytic ferns. Thus, the objective is to understand the effect of climatic gradients on the variation of local richness of ferns and beta diversity patterns along an elevational gradient in a mountain system in southern Mexico.Methods – We sampled 32 trees, each in four elevational bands (100–2200 m). Alpha diversity patterns were analysed using linear regression models. We used the Morisita index to quantify species turnover between bands. An additive partitioning approach was used to analyse the degree to which individual trees, plots, and bands contributed to total species richness. We evaluated the influence of climatic variables on species composition via linear regression models.Key results – A total of 30 species in five families were recorded. Each family contributed in different magnitude to the elevational richness pattern, with Polypodiaceae dominating due to its richness and presence along the entire transect. Alpha diversity at the three scales (αtree, αplot, αband) increased with elevation and rainfall, and with decreasing temperature. Species turnover was high along the gradient, but was scale-dependent, with βtransect (65–75%) and βband (14%) with the greatest contributing to total diversity. Although the contribution of the individual trees was lower, it increased with elevation. Conclusions – We emphasize the importance of including different scale levels in analyses of diversity along elevational gradients. In the region, cloud forest on the mountain peaks harbours the highest diversity of epiphytic fern communities. Due to a limited extent of this mountain range, the epiphyte ferns are susceptible to the effects of climate change.

Different responses of dung beetle diversity and feeding guilds from natural and disturbed habitats across a subtropical elevational gradient

Understanding the effects of natural and anthropogenic processes that drives biodiversity is urgently needed to improve conservation strategies at the landscape scale. Although natural drivers on altitudinal gradients have been well studied, the concatenated effect of habitat disturbance across different altitudes over biodiversity is still poorly known. We aimed to test the effect of habitat transformation on assemblage metrics of dung beetles across an altitudinal gradient (between 0 and 3400 m.a.s.l.; 18 elevational bands). Our results highlighted four main findings: (i) dung beetle forests or pastures specialized species changed their habitat specificity depending on the elevation range; (ii) a hump-shaped pattern of dung beetle diversity at intermediate elevations was found both in forests and pastures; (iii) species turnover was the main component of β diversity in both forest and pastures; (iv) presence of crops and human settlements across elevational gradient influenced changes the taxonomical and feeding guild composition of dung beetle assemblages, but these effects were elevation-site-dependent. These results suggest that the impacts of habitat disturbance on beetle assemblages caused by humans’ activities on mountains are spatial site dependents. We highlight the importance of understanding the effect of environmental disturbance in mountain ecosystems using a wide range of assemblage metrics. This research serves as basis for the development of efficient conservation strategies to protect species and ecosystem functions in these fragile environments.

Small mammal species richness and turnover along elevational gradient in Yulong Mountain, Yunnan, Southwest China.

Understanding the species diversity patterns along elevational gradients is critical for biodiversity conservation in mountainous regions. We examined the elevational patterns of species richness and turnover, and evaluated the effects of spatial and environmental factors on nonvolant small mammals (hereafter “small mammal”) predicted a priori by alternative hypotheses (mid‐domain effect [MDE], species–area relationship [SAR], energy, environmental stability, and habitat complexity]) proposed to explain the variation of diversity. We designed a standardized sampling scheme to trap small mammals at ten elevational bands across the entire elevational gradient on Yulong Mountain, southwest China. A total of 1,808 small mammals representing 23 species were trapped. We observed the hump‐shaped distribution pattern of the overall species richness along elevational gradient. Insectivores, rodents, large‐ranged species, and endemic species richness showed the general hump‐shaped pattern but peaked at different elevations, whereas the small‐ranged species and endemic species favored the decreasing richness pattern. The MDE and the energy hypothesis were supported, whereas little support was found for the SAR, the environmental stability hypothesis, and the habitat complexity. However, the primary driver(s) for richness patterns differed among the partitioning groups, with NDVI (the normalized difference vegetation index) and MDE being the most important variables for the total richness pattern. Species turnover for all small mammal groups increased with elevation, and it supported a decrease in community similarity with elevational distance. Our results emphasized for increased conservation efforts in the higher elevation regions of the Yulong Mountain.

Spatial and climatic variables independently drive elevational gradients in ant species richness in the Eastern Himalaya.

Elevational gradients are considered important for understanding causes behind gradients in species richness due to the large variation in climate and habitat within a small spatial extent. Geometric constraints are thought to interact with environmental variables and influence elevational patterns in species richness. However, the geographic setting of most mountain ranges, particularly continuity with low elevation areas may reduce the effect of geometric constraints at lower elevations. In the present study, we test the effects of climatic gradients and continuity with the low elevation plains of the eastern Himalayan mountain range on patterns of species richness. We studied species richness of ants (Hymenoptera: Formicidae) on an elevational gradient between 600m and 2400m in the Eastern Himalaya–part of Himalaya biodiversity hotspot. Ants were sampled in nine elevational bands of 200m with four transects in each band using pitfall and Winkler traps. We used regression models to identify the most important environmental variables that predict species richness and used constrained null models to test the effects of contiguity between the mountain range and plains. We find a monotonic decline in species richness of ants with elevation. Temperature was a more important predictor of species richness than habitat complexity. Geometric constraints model weighted by temperature with a soft lower boundary and hard upper boundary best explained the species richness pattern. This suggests that a combination of climate and geometric constraints drive the elevational species richness patterns of ants.

Disentangling elevational and vegetational effects on ant diversity patterns

When aiming to assess the effects of elevation on animal diversity, many studies have been carried out in different vegetation types occurring across elevational gradients. Thus, it remains unclear if any changes observed in species richness are caused by factors directly associated with elevation or are caused by vegetation change across the gradient. Here, we disentangled the effects of elevation from changes in vegetation by assessing ant diversity patterns along an elevational gradient. We analyzed patterns of ant diversity utilizing two different sampling approaches across the elevational gradient: (1) a standardized sampling including only forest formations and (2) a non–standardized sampling including forest (low elevational bands) and grasslands (high elevational bands). We sampled ants at eight elevational bands of Atlantic Forest in Brazil, and the highest three bands were sampled at both forest and grassland habitat. We found that the two approaches produce contrasting patterns of alpha and beta diversity, but the same pattern of gamma diversity. However, in the non–standardized sampling approach, the regression analysis produced a reduced explanation of the species richness gradient and a decrease in the elevational effect size. Different patterns found in the two approaches could be due to distinct environmental conditions in these habitats. In conclusion, our results highlight the potential bias of non–standardizing vegetation type across elevational gradients when assessing elevational patterns of species diversity.

Plant species richness across the Himalaya driven by evolutionary history and current climate

AbstractThe Himalaya, the world's largest mountain chain, spans a wide variety of climates. Further, different locations have historically experienced climatic perturbations to different degrees. This makes it the ideal region to assess roles of contemporary climate, diversification (speciation minus extinction), and dispersal barriers in affecting local species richness. Based on a review of all available Himalayan floras, we determined that 8765 native angiosperm species are presently documented and recorded their location and elevational distributions. We compared species richness and measures of phylogenetic structure in 100‐m elevational bands for all species combined and for three major life‐forms separately (trees, shrubs, and herbs) across the Himalaya. Species richness declines threefold from the east to the northwest of the Himalaya. Along elevational gradients, tree richness monotonically declines in the northwest, but peaks at ~1000 m in the east. Shrubs and herbs peak in richness at mid‐elevations (~2000 m). Mean temperature and annual precipitation together explain ~60% of the variation in species richness. The general phylogenetic pattern observed in this study is that phylogenetic clustering (i.e., more closely related species on fewer long branches) increases from low to high elevations, but with a dip at mid‐elevations (2000–3000 m), which may result from a mixing of distinct floras, but is not associated with exceptionally high richness. High clustering at higher elevations (3000–4500 m) and in the drier northwest suggests ongoing diversification dynamics limit richness in these harsher environments. The effects of diversification dynamics appear to be smaller than those of contemporary climate in limiting buildup of species numbers.

Island biogeography in continental areas: inferring dispersal based on distributional patterns of Pronophilina butterflies (Nymphalidae: Satyrinae) in the north Andean massifs

Faunal structure, species relationships and distribution patterns of Pronophilina butterflies, a Neotropical montane section of the Satyrinae (Nymphalidae), of 5 isolated north Andean massifs —Cordillera de Merida, Sierra El Tama, Sierra Nevada de Santa Marta, Cordillera de la Costa and Sierra de Perija— are analyzed from the island biogeography perspective. El Tama range, a part of the “continental” Eastern Cordillera, is considered as the source area of the faunas of the Sierra de Perija and the Cordillera de Merida, which in turn are stepping stones for the dispersal of species to the Sierra Nevada de Santa Marta and the Cordillera de La Costa. The role of major biogeographical variables is evaluated in the process of colonization of these areas. It is conlcuded that the maximum elevation between the neighbouring ranges is the most important variable, not the distance. This is related to the fact that dispersal in this group of butterflies seems to occur by slow expansion through ecological corridors not by long distance flights. Faunal relationships between the 5 ranges and the elevational bands occupied by widespread and endemic species allow inferring the extent of vertical movements of cloud forests in the past.

Elevational patterns of bird species richness on the eastern slope of Mt. Gongga, Sichuan Province, China

BackgroundIn biological systems, biological diversity often displays a rapid turn-over across elevations. This defining feature has made mountains classic systems for studying the spatial variation in diversity. Because patterns of elevational diversity can vary among lineages and mountain systems it remains difficult to extrapolate findings from one montane region to another, or among lineages. In this study, we assessed patterns and drivers of avian diversity along an elevational gradient on the eastern slope of Mt. Gongga, the highest peak in the Hengduan Mountain Range in central China, and a mountain where comprehensive studies of avian diversity are still lacking.MethodsWe surveyed bird species in eight 400-m elevational bands from 1200 to 4400 m a.s.l. between 2012 and 2017. To test the relationship between bird species richness and environmental factors, we examined the relative importance of seven ecological variables on breeding season distribution patterns: land area (LA), mean daily temperature (MDT), seasonal temperature range (STR), the mid-domain effect (MDE), seasonal precipitation (SP), invertebrate biomass (IB) and enhanced vegetation index (EVI). Climate data were obtained from five local meteorological stations and three temperature/relative humidity smart sensors in 2016.ResultsA total of 219 bird species were recorded in the field, of which 204 were recorded during the breeding season (April–August). Species richness curves (calculated separately for total species, large-ranged species, and small-ranged species) were all hump-shaped. Large-ranged species contributed more to the total species richness pattern than small-ranged species. EVI and IB were positively correlated with total species richness and small-ranged species richness. LA and MDT were positively correlated with small-ranged species richness, while STR and SP were negatively correlated with small-ranged species richness. MDE was positively correlated with large-ranged species richness. When we considered the combination of candidate factors using multiple regression models and model-averaging, total species richness and large-ranged species richness were correlated with STR (negative) and MDE (positive), while small-ranged species richness was correlated with STR (negative) and IB (positive).ConclusionsAlthough no single key factor or suite of factors could explain patterns of diversity, we found that MDE, IB and STR play important but varying roles in shaping the elevational richness patterns of different bird species categories. Model-averaging indicates that small-ranged species appear to be mostly influenced by IB, as opposed to large-ranged species, which exhibit patterns more consistent with the MDE model. Our data also indicate that the species richness varied between seasons, offering a promising direction for future work.

Variation of plant species richness at different spatial scales

It is now realized that the variation in species richness is influenced by spatial and temporal scales. Pattern and scale are a central focus in ecology and biogeography. The species richness relationship depends on the scale of study and their correlated factors. The broad objective of this review is to elucidate how different scales are correlated with different explanatory variables to generate patterns of species richness. Addressing the problem of scale has both fundamental and applied importance in understanding variation in species richness along gradients. The understanding of pattern, its causes, and consequences is central to our understanding of processes such as succession, community development, and the spread and persistence of species. According to the hierarchical theory of species diversity there are mainly three categories of scales: local, landscape and regional. The local species richness or α-diversity is the diversity of individual stands. The β-diversity or species change is turnover between two elevational bands or between two plots or two sites. The regional or γ-diversity is the total richness of whole mountains or study systems and it has a combined influence from α- and β-diversity. The local species richness is affected by both local-scale processes (e.g., internal interactions) and broad-scale processes (e.g., evolutionary). Different explanatory variables according to the scales of study are necessary to explain variation at different spatial scales. Local factors (e.g., disturbance, grazing and tree cover) have been used to detect variation at a local scale. Generally, topographical factors are used to detect variation in species richness at a landscape scale; whereas climate, water-energy dynamics and historical processes are used to detect variation at a regional scale. However, it is not easy to separate strictly one scale from other because there is no clear boundary between them. The study of the whole elevation gradient from tropical to alpine zone or long latitude is a broad-scale study. The intermediate scale is a study on a local mountain, which covers the subtropical to warm temperate zones. To explain patterns of species richness, a pluralistic body of hypotheses, which incorporates historical, biological and climatic factors, is needed. This is depicted by the strong relationship between climate, biological interactions, and historical processes in influencing variation in species richness at different spatial scales.Botanica Orientalis – Journal of Plant Science (2017) 11: 49–62

Spring warming in Yukon mountains is not amplified by the snow albedo feedback

Decreasing spring snow cover may amplify Arctic warming through the snow albedo feedback. To examine the impact of snowmelt on increasing temperature we used a 5,000 m elevation gradient in Yukon, Canada, extending from valley-bottom conifer forests, through middle elevation tundra, to high elevation icefields, to compare validated downscaled reanalysis air temperature patterns across elevational bands characterized by different patterns of spring snowmelt. From 2000 to 2014 we observed surface warming of 0.01 °C/a·1,000 m in May (0.14 °C/a at 1,000 m to 0.19 °C/a at 5,000 m), and uniform cooling of 0.09 °C/a in June at all elevations. May temperature trends across elevationally dependent land cover types were highly correlated with each other despite large variations in albedo and snow cover trends. Furthermore, a clear dependency of infrared skin temperature on snow cover mediated albedo decline was observed in tundra, but this was insufficient to influence average diurnal air temperature. We observed negative June temperature trends which we attribute to increasing daytime cloud cover because albedo and snow cover trends were unchanging. We conclude that 8-day and monthly averaged Spring air temperature trends are responding to a synoptic external forcing that is much stronger than the snow albedo feedback in sub-Arctic mountains.

The unfolding of plant growth form-defence syndromes along elevation gradients.

Understanding the functional economics that drives plant investment of resources requires investigating the interface between plant phenotypes and the variation in ecological conditions. While allocation to defence represents a large portion of the carbon budget, this axis is usually neglected in the study of plant economic spectrum. Using a novel geometrical approach, we analysed the co-variation in a comprehensive set of functional traits related to plant growth strategies, as well as chemical defences against herbivores on all 15 Cardamine species present in the Swiss Alps. By extracting geometrical information of the functional space, we observed clustering of plants into three main syndromes. Those different strategies of growth form and defence were also distributed within distinct elevational bands demonstrating an association between the functional space and the ecological conditions. We conclude that plant strategies converge into clear syndromes that trade off abiotic tolerance, growth and defence within each elevation zone.

Tropical tree species diversity in a mountain system in southern Mexico: local and regional patterns and determinant factors

AbstractMechanisms explaining patterns of biodiversity along elevation gradients in tropical mountain systems remain controversial. We use a set of climatic, topographic, and soil variables encompassing regional, landscape, and local‐level spatial scales to explain the spatial variation of tree species diversity in the Sierra Madre of Chiapas, Mexico. We sampled 128 circular plots (0.1‐ha each) in four elevational bands along four elevation gradients or transects encompassing 100–2200 m. A total of 12,533 trees belonging to 444 species were recorded. Diversity patterns along the elevation gradient and the explanatory power of independent variables were dependent on spatial scale (regional vs transect) and functional group (total vs late‐successional or pioneer species). Diversity of all species and late‐successional species (1 – proportion of pioneer species) showed a constant pattern at the regional and transect scales, with low predictive power of climatic variables and/or elevation. A linear decrease in either number or proportion of pioneer species diversity was observed with increasing elevation, which was correlated with temperature, rainfall, and human disturbance trends. Total species diversity showed an increase with rainfall of the warmest quarter, indicating a regional‐level limiting effect of seasonality (drought duration). Yet the explanatory power of climatic and topographic variables was higher at the individual transect level than at the regional scale, suggesting the parallel but differential influence of evolutionary and geological history factors on diversification not so far studied to explain elevation patterns of species diversity in tropical mountain systems.