Insect herbivory and herbivores of Ficus species along a rain forest elevational gradient in Papua New Guinea

Classic research on elevational gradients in plant–herbivore interactions holds that insect herbivore pressure is stronger under warmer climates of low elevations. However, recent work has questioned this paradigm, arguing that it oversimplifies the ecological complexity in which plant–insect herbivore interactions are embedded. Knowledge of antagonistic networks of plants and herbivores is however crucial for understanding the mechanisms that govern ecosystem functioning. We examined herbivore damage and insect herbivores of eight species of genus Ficus (105 saplings) and plant constitutive defensive traits of two of these species, along a rain forest elevational gradient of Mt. Wilhelm (200–2,700 m a.s.l.), in tropical Papua New Guinea. We report overall herbivore damage 2.4% of leaf area, ranging from 0.03% in Ficus endochaete at 1,700 m a.s.l. to 6.1% in F. hombroniana at 700 m a.s.l. Herbivore damage and herbivore abundances varied significantly with elevation, as well as among the tree species, and between the wet and dry season. Community-wide herbivore damage followed a hump-shaped pattern with the peak between 700 and 1,200 m a.s.l. and this pattern corresponded with abundance of herbivores. For two tree species surveyed in detail, we observed decreasing and hump-shaped patterns in herbivory, in general matching the trends found in the set of plant defenses measured here. Our results imply that vegetation growing at mid-elevations of the elevational gradient, that is at the climatically most favorable elevations where water is abundant, and temperatures still relatively warm, suffers the maximum amount of herbivorous damage which changes seasonally, reflecting the water availability.     

Patterns of an elevational gradient affecting moths across the South Korean mountains: effects of geometric constraints,plants, and climate

We investigated elevational richness patterns of three moth groups (Erebidae, Geometridae, and Noctuidae) along four elevational gradients located on one northern and three southern mountains in South Korea, as well as the effects of plants and climatic factors on the diversity patterns of moths. Moths were collected with an ultraviolet light trap at 32 sites from May through October, 2013. Plant species richness and mean temperatures for January and June were acquired. Observed and estimated moth species richness was calculated and the diversity patterns with null models were compared. Species richness along four elevational gradients peaked at mid-elevations, whereas deviations occurred at elevations below mid-peak in the southern mountains and elevations higher than mid-peak on the northern mountain. Species richness curves of three moth groups also peaked at mid-elevations throughout South Korea. However, the species richness curves for Erebidae were positively skewed, indicating that a preference for lowlands, whereas curves of the Geometridae were negatively skewed, indicating a preference for highlands. The mid-peak diversity pattern between plants and moths on the Korean mountains showed an elevational breadth that overlapped between 800 and 900 m. Multiple regression analysis revealed that plant species richness and January mean temperature significantly influenced moth species richness and abundance. The rapid increase in mean annual temperature in the Korean peninsula and the unimodal elevational gradients of moths across the country suggest that an uphill shift in peak optimum elevation and changes in the highest peak of the curve will occur in the future.     

Elevation and experimental snowmelt manipulation affect emergence phenology and abundance of soil‐hibernating arthropods

1. Effects of climate change, such as higher average temperatures and earlier snowmelt, are already apparent, especially in alpine regions. However, community responses of functionally important arthropod taxa to changing climatic conditions are mostly unknown. 2. In this study, an earlier snowmelt was simulated at 15 plots along an elevational gradient in the German Alps. At each study site, soil emergence traps were established for sampling soil‐hibernating arthropods on earlier and control snowmelt treatments during the growing season. The abundance and emergence phenology of the five most common arthropod orders (Araneae, Coleoptera, Diptera, Hemiptera, Hymenoptera) were analysed, as well as the species richness of Coleoptera. 3. There was increasing abundance and species richness of Coleoptera along the elevational gradient, indicating that at higher altitudes more individuals and species hibernate in the soil. Abundances of Diptera also increased with elevation. By contrast, abundances of Hemiptera declined with increasing elevation, while abundances of Araneae and Hymenoptera did not show significant elevational patterns. Arthropods at higher elevations emerged, on average, 5 weeks later than arthropods at lower elevations, because of a longer‐lasting snow cover. The earlier snowmelt treatment resulted in higher abundances of Araneae and Hymenoptera compared with the control plots, indicating that the time of snowmelt influenced the abundance of predators, such as spiders or parasitic wasps, more than that of herbivores. 4. An earlier emergence of certain arthropod guilds and a change in relative abundance of guilds might desynchronise species interactions, leading to a possible loss of biodiversity.     

Elevational patterns of fern species assemblages and richness in central Japan

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.     

Elevational gradients of small mammal diversity on the northern slopes of Mt. Qilian, China

Aim Small mammal species richness and relative abundance vary along elevational gradients, but there are different patterns that exist. This study reports the patterns of distribution and abundance of small mammals along the broader elevational gradient of Mt. Qilian range. Location The study was conducted in the Mt. Qilian range, north‐western China, from June to August 2001. Methods Removal trapping was conducted using a standardized technique at 7 sites ranging between 1600 and 3900 m elevation within three transects. Correlation, regression and graphical analyses were used to evaluate the diversity patterns along this elevational gradient. Results In total, 586 individuals representing 18 nonvolant small mammal species were collected during 20 160 trap nights. Species composition was different among the three transects with 6 (33%) of the species found only within one transect. Elevational distribution and relative abundance of small rodents showed substantial spatial variation, with only 2 species showing nonsignificant capture frequencies across elevations. Despite these variations, some general patterns of elevational distribution emerged: humped‐shape relationships between species diversity and elevation were noted in all three transects with diversity peaks at middle elevations. In addition, relative abundance was negatively correlated with elevation. Conclusions Results indicate that maximum richness and diversity of nonvolant small mammals occurred at mid‐elevations where several types of plants reached their maximum diversity and primary productivity, and where rainfall and humidity reached a maximum. It is demonstrated that the mid‐elevation bulge is a general feature of at least a large portion of the biota on the Mt. Qilian range.     

Elevational patterns of frog species richness and endemic richness in the Hengduan Mountains, China: geometric constraints, area and climate effects

We studied frog biodiversity along an elevational gradient in the Hengduan Mountains, China. Endemic and non-endemic elevational diversity patterns were examined individually. Competing hypotheses were also tested for these patterns. Species richness of total frogs, endemics and non-endemics peaked at mid-elevations. The peak in endemic species richness was at higher elevations than the maxima of total species richness. Endemic species richness followed the mid-domain model predictions, and showed a nonlinear relationship with temperature. Water and energy were the most important variables in explaining elevational patterns of non-endemic species richness. A suite of interacting climatic and geometric factors best explained total species richness patterns along the elevational gradient. We suggest that the mid-domain effect was an important factor to explain elevational richness patterns, especially in regions with high endemism.     

Influence of niche characteristics and forest type on fern species richness,abundance and plant size along an elevational gradient in Costa Rica

An analysis of the fern vegetation on 156 plots along an elevational gradient (45-3400 m) in undisturbed forests in Costa Rica, Central America, showed a hump-shaped pattern of species richness with a maximum of up to 68 species per 400 m2 at mid-elevations. This study documents the contribution of specific habitats (forest types: ridges, ravines) and niches within them (dead wood, rocks, growth zones in trees) to the local fern richness and the relation of species richness to elevation and climatic variables. Forests along ravines showed significantly higher species richness, presumably caused by high environmental humidity. The mean number of individuals of occupied niches per species increased significantly with elevation, suggesting that the niche breadth of species increased and that the differentiation of niches decreased with elevation. Both findings may explain the reduced fern species richness towards and above the upper treeline, but not at low elevations. The key factors for the decreases of species richness at the extremes of the gradient are likely to involve climatic conditions.     

Elevational plant species richness patterns and their drivers across non-endemics,endemics and growth forms in the Eastern Himalaya

Despite decades of research, ecologists continue to debate how spatial patterns of species richness arise across elevational gradients on the Earth. The equivocal results of these studies could emanate from variations in study design, sampling effort and data analysis. In this study, we demonstrate that the richness patterns of 2,781 (2,197 non-endemic and 584 endemic) angiosperm species along an elevational gradient of 300–5,300 m in the Eastern Himalaya are hump-shaped, spatial scale of extent (the proportion of elevational gradient studied) dependent and growth form specific. Endemics peaked at higher elevations than non-endemics across all growth forms (trees, shrubs, climbers, and herbs). Richness patterns were influenced by the proportional representation of the largest physiognomic group (herbs). We show that with increasing spatial scale of extent, the richness patterns change from a monotonic to a hump-shaped pattern and richness maxima shift toward higher elevations across all growth forms. Our investigations revealed that the combination of ambient energy (air temperature, solar radiation, and potential evapo-transpiration) and water availability (soil water content and precipitation) were the main drivers of elevational plant species richness patterns in the Himalaya. This study highlights the importance of factoring in endemism, growth forms, and spatial scale when investigating elevational gradients of plant species distributions and advances our understanding of how macroecological patterns arise.     

Heterogeneous patterns of abundance of epigeic arthropod taxa along a major elevation gradient

Species diversity is the variable most commonly studied in recent ecological research. Ecological processes, however, are driven by individuals and affected by their abundances. Understanding the variation in animal abundances along climatic gradients is important for predicting changes in ecosystem processes under global warming. High abundances make arthropods, despite their small body sizes, important actors in food webs, yet abundance distributions of major arthropod taxa along climatic gradients remain poorly documented. We sampled arthropod assemblages in disturbed and undisturbed vegetation types along an elevational gradient of 860–4550 m asl on the southern slopes of Mt. Kilimanjaro, Tanzania. In our analysis, we focused on 13 taxa of arthropods that represented three major functional groups: predators, herbivores, and decomposers. Abundance patterns were unimodal for most of the taxa and functional groups, including decomposer arthropods, and most of them peaked at low elevations in lower montane forest. When we assigned beetles to functional groups, however, decomposer beetle abundances declined almost linearly, and abundances of predator beetles (ca. 2400 m asl) and herbivore beetles (ca. 3000 m asl, undisturbed vegetation) peaked at higher elevations and exhibited unimodal patterns. Temperature, not primary productivity, was the best predictor of abundance for most of the taxa and groups. Disturbance was only of minor importance. Our results revealed different trends in the response of arthropod abundance along the elevational gradient that depended on the level of taxonomic and functional resolution. This highlights the need for more comparisons of different taxa along the same climatic gradients.     

Epiphytic bryophyte diversity and range distributions along an elevational gradient in Marojejy,Madagascar

Describing spatial variation in species richness and understanding its links to ecological mechanisms are complementary approaches for explaining geographical patterns of richness. The study of elevational gradients holds enormous potential for understanding the factors underlying global diversity. This paper investigates the pattern of species richness and range-size distribution of epiphytic bryophytes along an elevational gradient in Marojejy National Park, northeast Madagascar. The main objectives are to describe bryophyte species composition and endemism in Marojejy National Park, to describe the species richness and distribution patterns of epiphytic bryophytes along an elevational gradient from 250 m to 2050 m and to evaluate the explanatory value of environmental variables for the observed patterns. Bryophyte samples were collected following a nested design with four hierarchical levels: elevational belts, plots, quadrats, and microplots. In total, 254 epiphytic bryophyte species were recorded, comprising 157 liverworts and 97 mosses. Twenty-three of these are endemic to Madagascar. Species richness exhibits a hump-shaped pattern along the elevational gradient, peaking at 1,250 m. Eighty-seven percent of the total recorded species have a range distribution lower than 1,000 m, at which point 36% are restricted to these single elevations. Our results suggest that mean temperature, relative humidity, and vapor pressure deficit play important roles in shaping the richness pattern observed in this study. While the liverwort richness pattern did not correlate to vapor pressure deficit and responded only weakly to relative humidity, the richness pattern shown by mosses correlates well with mean temperature, relative humidity, and vapor pressure deficit.     

Multi‐trophic guilds respond differently to changing elevation in a subtropical forest

Negative relationships between species richness and elevation are common and attributed to changes in single environmental properties associated to elevation, such as temperature and habitat area. However, research has lacked taxonomic breadth and comprehensive elevation studies that consider multiple groups from different trophic levels are rare. We thus analysed 24 groups of plants, arthropods, and microorganisms grouped into six trophic guilds (predators, detritivores, herbivores, plants, bacteria and fungi) along a relatively short elevational gradient (~600 m) in a subtropical forest in south‐east China. The total species richness of all organisms was not related to elevation, nor was the richness of plants, herbivores or microorganisms. However, species richness and abundance in two major trophic guilds of arthropods changed with elevation, which was mediated by changes in elevation‐associated habitat properties. Specifically, deadwood mass increased with elevation, which increased detritivore richness indirectly via detritivore abundance, thus supporting the ‘more individuals hypothesis’. In contrast, lower predator richness at higher elevations was directly related to lower mean temperatures, which had no effect on abundance. Our study demonstrates that even along relatively short gradients, elevation can have strong direct and abundance‐mediated effects on species richness, but with effects varying from positive to negative signs depending on local resource availability and the characteristics of groups or trophic guilds. If elevation positively influences local environmental properties that benefit a given group, richness can increase towards higher elevations. Thus, the effect of global change in mountainous regions should be evaluated within the local environmental context using multi‐taxon approaches.     

广东象头山国家级自然保护区兰科植物垂直分布格局

于2019～2022年对广东象头山国家级自然保护区内的兰科植物进行专项调查,记录兰科植物种类、数量、生活型、海拔、生境等信息,分析保护区内兰科植物的垂直分布格局,并根据《广东高等植物红色名录》和《国家重点保护野生植物名录》对各海拔高度兰花濒危等级的物种数量进行统计。结果显示：(1) 实地记录兰科植物33属48种,多数种类种群数量较少;(2) 随着海拔上升,各海拔梯度的兰科植物总种数和不同生活型的种数均呈现“中间高度膨胀型”分布特点,峰值在中低海拔区域;(3) 濒危物种主要集中在海拔200～500 m区间;(4) 相邻海拔段的兰科植物种类相似性系数较高,垂直梯度差异越大,相似性系数越小。低海拔地区可能由于人为干扰频繁,兰科植物物种多样性较低;中海拔物种多样性最丰富;高海拔地区生长环境较苛刻,物种数量较少。     

Ant Diversity and Abundance along an Elevational Gradient in the Philippines1

Ant communities were surveyed along an elevational gradient in the Philippines extending from lowland dipterocarp forest (250 m elevation) to mossy forest (1750 m). Standardized pitfall trapping in arboreal and terrestrial microhabitats at seven sites yielded 51 species. Collecting by hand at five of the sites yielded 48 species. The two methods produced substantially different assemblages, with only 22 species (29%) taken in common. Only a fraction of the total ant community appeared to be sampled at most of the sites. Measures of species richness and relative abundance peaked at mid-elevations and declined sharply with increasing elevation. Ants were extremely rare above 1500 m elevation. Arboreal ants were trapped much less frequently than terrestrial ants at all sites. Ant species that were abundant had broader elevational distributions than those that were less common, but most species were rare and occurred at only one or two sites. The elevational patterns for ants are largely the inverse of those documented for Philippine small mammals which reach their greatest diversity and abundance at high elevations where ants are rare. This suggests that the two groups may interact competitively. Some of the patterns observed or inferred from this study may apply to tropical ant communities in general, and are presented as series of testable hypotheses as a guide and stimulus for future research.     

Phylogenetic diversity,structure and diversification patterns of endemic plants along the elevational gradient in the Eastern Himalaya

ABSTRACT

Background: Several studies have documented the variation in species diversity patterns along elevational gradients in the Himalaya, but few have reported the evolutionary and biogeographic processes behind these patterns.

Aims: To understand whether evolutionary history and phylogeny have any role in structuring plant species communities along an elevational gradient in the Sikkim Himalaya.

Methods: We used data on endemic plant species occurrence from primary and secondary sources to construct family-level phylogenetic supertrees for different growth forms with the help of Phylomatic tool of Phylocom. These phylogenetic supertrees were used as a base for testing phylogenetic diversity (PD), niche conservatism, diversification time patterns and phylogenetic structure of various plant growth forms along an elevational gradient.

Results: PD was the highest at mid-elevations for all growth forms and PD had a significant positive correlation with endemic species richness. Species at mid-elevations were dominated by the ancestral/primitive taxa. There was phylogenetic clustering at higher elevations and phylogenetic overdispersion at lower and mid-elevations for the majority of the growth forms.

Conclusions: Time-for-speciation effect and niche conservatism along elevation (retention of niche-related ancestral elevational distribution over evolutionary time scale by species) together determine plant species diversity patterns in the Himalaya.     

The same but different: equally megadiverse but taxonomically variant spider communities along an elevational gradient

Spatial variation in biodiversity is one of the key pieces of information for the delimitation and prioritisation of protected areas. This information is especially important when the protected area includes different climatic and habitat conditions and communities, such as those along elevational gradients. Here we test whether the megadiverse communities of spiders along an elevational gradient change according to two diversity models – a monotonic decrease or a hump-shaped pattern in species richness. We also measure compositional variation along and within elevations, and test the role of the preference of microhabitat (vegetation strata) and the functional (guild) structure of species in the changes. We sampled multiple spider communities using standardised and optimised sampling in three forest types, each at a different elevation along a climatic gradient. The elevational transects were at increasing horizontal distances (between 0.1 and 175 km) in the Udzungwa Mountains, Eastern Arc Mountains, Tanzania. The number of species was similar between plots and forest types, and therefore the pattern did not match either diversity model. However, species composition changed significantly with a gradual change along elevations. Although the number of species per microhabitat and guild also remained similar across elevations, the number of individuals varied, e.g. at higher elevations low canopy vegetation was inhabited by more spiders, and the spiders belonging to guilds that typically use this microhabitat were more abundant. Our findings reflex the complex effects of habitat-microhabitat interactions on spider communities at the individual, species and guild levels. If we aim to understand and conserve some of the most diverse communities in the world, researchers and managers may need to place more attention to small scale and microhabitat characteristics upon which communities depend.     

Climate and history explain the species richness peak at mid-elevation for Schizothorax fishes (Cypriniformes: Cyprinidae) distributed in the Tibetan Plateau and its adjacent regions

Aim  We studied elevational species richness patterns of Schizothorax fishes and identified the roles of ecological and evolutionary factors in shaping the patterns of elevational diversity.
Location  The Tibetan Plateau and its adjacent regions.
Methods  We assembled distribution and altitude data for all Schizothorax species using the literature. We merged ecological and evolutionary approaches to test the relationships between species richness and ecological factors (climate, area, the mid-domain effect) or evolutionary factors (diversification rates and time of colonization).
Results  We found that species richness of Schizothorax fishes peaked at mid-elevations. Rainfall, area, the mid-domain effect and diversification rate were weak predictors of the richness pattern. Temperature showed a nonlinear relationship with species richness. Temperature and time of colonization were the most important variables in explaining the elevational diversity pattern.
Main conclusion  Our findings indicate that the time-for-speciation effect and niche conservatism play important roles in variation of species richness.     

Elevational changes in vascular plants richness,diversity, and distribution pattern in Abune Yosef mountain range,Northern Ethiopia

The aim of this research is to investigate the patterns of vascular plant species richness,diversity,and distribution along an elevation gradient in the Abune Yosef mountain range,Ethiopia.Preferential systematic sampling was employed to collect vegetation and environmental data along the elevation gradient.We found that plant species richness declines monotonically from low to high elevations.Specifically,vascular plant species richness and diversity were lower in the Afroalpine grassland(high elevation)than in the Dry evergreen Afromontane forest and Ericaceous forest(low elevations).In contrast,endemic vascular plant richness was significantly higher in the Afroalpine grassland than in the Dry evergreen Afromontane forest and Ericaceous forest.Elevation showed a significant impact on the richness,diversity,and endemism of vascular plants.According to Sorensen's coefficient,the similarity between Dry evergreen Afromontane forest and Ericaceous forest vegetation types is higher(32%)than the similarity between Ericaceous forest and Afroalpine grassland(18%).Only 5%similarity was recorded between the Dry evergreen Afromontane forest and Afroalpine grassland.Growth forms showed different elevationai richness patterns.Trees and liana increased monotonically up to 3300 m.Shrub and herb richness patterns followed a hump-shaped and inverted hump-shaped pattern along the elevation gradient.The elevation patterns of vascular plant species richness,diversity,and growth form in the present study may be attributed to differences in management intensity,spatial heterogeneity,microclimatic variations,and anthropogenic disturbances.     

Elevational gradients in ant species richness: area, geometry, and Rapoport's rule

Studying the distributions of plants and animals along environmental gradients can illuminate the factors governing and maintaining species diversity. There are two general predictions of how species richness and elevation are related: either species richness decreases monotonically with increasing elevation or richness peaks at mid-elevations. Several processes might contribute to this pattern. In this paper, I examine patterns in ant species richness along elevational gradients in three states in the western US: Colorado, Nevada, and Utah. I test for the effects of available area and the geometric constraints model on species richness patterns. I also test Rapoport's rescue hypothesis, which relates the extent of species' elevational ranges to patterns in species richness. In each state, species richness peaked at mid-elevations. Area explained more variation in species richness than the geometric constraints model in Colorado and Utah, but not in Nevada. Area and geometric constraints together explained 90%, 99%, and 57% of the variation in species richness in Colorado, Nevada, and Utah, respectively. Even though there were peaks at mid-elevations, I still found a strong Rapoport effect. This work suggests that the influences of area and geometric constraints cannot be overlooked when examining patterns in species richness along environmental gradients.     

Elevational Gradient in Species Richness Pattern of Epigaeic Beetles and Underlying Mechanisms at East Slope of Balang Mountain in Southwestern China

We report on the species richness patterns of epigaeic beetles (Coleoptera: Carabidae and Staphylinidae) along a subtropical elevational gradient of Balang Mountain, southwestern China. We tested the roles of environmental factors (e.g. temperature, area and litter cover) and direct biotic interactions (e.g. foods and antagonists) that shape elevational diversity gradients. Beetles were sampled at 19 sites using pitfall traps along the studied elevational gradient ranging from 1500 m–4000 m during the 2004 growing season. A total of 74416 specimens representing 260 species were recorded. Species richness of epigaeic beetles and two families showed unimodal patterns along the elevational gradient, peaking at mid-elevations (c. 2535 m), and the ranges of most beetle species were narrow along the gradient. The potential correlates of both species richness and environmental variables were examined using linear and second order polynomial regressions. The results showed that temperature, area and litter cover had strong explanatory power of beetle species richness for nearly all richness patterns, of beetles as a whole and of Carabidae and Staphylinidae, but the density of antagonists was associated with species richness of Carabidae only. Multiple regression analyses suggested that the three environmental factors combined contributed most to richness patterns for most taxa. The results suggest that environmental factors associated with temperature, area and habitat heterogeneity could account for most variation in richness pattern of epigaeic beetles. Additionally, the mid-elevation peaks and the small range size of most species indicate that conservation efforts should give attention to the entire gradient rather than just mid-elevations.     

Elevational patterns of plant richness and their drivers on an Asian mountain

We examined the elevational patterns of plant species along two transects on Mt Seorak, South Korea, and calculated four richness indices from field survey data: total number of species per 100 m elevational band; mean number of species per plot in each elevational band; total estimated number of species per elevational band; and beta diversity of each elevational band. We evaluated the effects of area, mean distance between plots, climatic variables (mean annual temperature and precipitation), and productivity on the richness patterns along the two transects. In total, 235 plant species belonging to 72 families and 161 genera were recorded from 130 plots along the two transects. The analyses revealed different patterns including monotonic decline, and unimodal and multimodal shapes for richness indices of total, woody, and herbaceous plants with the change in elevation along the two transects. The proportion of suitable area (as opposed to rocky areas) was the best predictor for total number of species per elevational band, mean number of species per plot, and total estimated number of species per elevational band of total and herbaceous plants along the two transects. Mean distance between plots was the most important variable for beta diversity of all plant groups. Although regional area, climatic variables, and productivity were important variables for predicting woody plant richness patterns, the effects were not consistent between the two transects. Our study suggests that elevational species richness patterns may differ not only among different plant groups, but also between nearby elevational transects, and that these differences are explained by differences in the underlying mechanisms shaping these patterns.