Aquatic insect β‐diversity is not dependent on elevation in Southern Rocky Mountain streams

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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.     

Agriculture erases climate‐driven β‐diversity in Neotropical bird communities

Earth is experiencing multiple global changes that will, together, determine the fate of many species. Yet, how biological communities respond to concurrent stressors at local‐to‐regional scales remains largely unknown. In particular, understanding how local habitat conversion interacts with regional climate change to shape patterns in β‐diversity—differences among sites in their species compositions—is critical to forecast communities in the Anthropocene. Here, we study patterns in bird β‐diversity across land‐use and precipitation gradients in Costa Rica. We mapped forest cover, modeled regional precipitation, and collected data on bird community composition, vegetation structure, and tree diversity across 120 sites on 20 farms to answer three questions. First, do bird communities respond more strongly to changes in land use or climate in northwest Costa Rica? Second, does habitat conversion eliminate β‐diversity across climate gradients? Third, does regional climate control how communities respond to habitat conversion and, if so, how? After correcting for imperfect detection, we found that local land‐use determined community shifts along the climate gradient. In forests, bird communities were distinct between sites that differed in vegetation structure or precipitation. In agriculture, however, vegetation structure was more uniform, contributing to 7%–11% less bird turnover than in forests. In addition, bird responses to agriculture and climate were linked: agricultural communities across the precipitation gradient shared more species with dry than wet forest communities. These findings suggest that habitat conversion and anticipated climate drying will act together to exacerbate biotic homogenization.     

The spatial configuration of taxonomic biodiversity along a tropical elevational gradient: α‐, β‐, and γ‐partitions

Biodiversity at larger spatial scales (γ) can be driven by within‐site partitions (α), with little variation in composition among locations, or can be driven by among‐site partitions (β) that signal the importance of spatial heterogeneity. For tropical elevational gradients, we determined the (a) extent to which variation in γ is driven by α‐ or β‐partitions; (b) elevational form of the relationship for each partition; and (c) extent to which elevational gradients are molded by zonation in vegetation or by gradual variation in climatic or abiotic characteristics. We sampled terrestrial gastropods along two transects in the Luquillo Mountains. One passed through multiple vegetation zones (tabonuco, palo colorado, and elfin forests), and one passed through only palm forest. We quantified variation in hierarchical partitions (α, β, and γ) of species richness, evenness, diversity, and dominance, as well as in the content and quality of litter. Total gastropod abundance linearly decreased with increasing elevation along both transects, but was consistently higher in palm than in other forest types. The gradual linear decline in γ‐richness was a consequence of opposing patterns with regard to α‐richness (monotonic decrease) and β‐richness (monotonic increase). For evenness, diversity, and dominance, α‐partitions and γ‐partitions evinced mid‐elevational peaks. The spatial organization of gastropod biodiversity did not mirror the zonation of vegetation. Rather, it was molded by: (a) elevational variation in productivity or nutrient characteristics, (b) the interspersion of palm forest within other forest types, and (c) the cloud condensation point acting as a transition between low and high elevation faunas. Abstract in Spanish is available with online material.     

Environmental heterogeneity and dispersal limitation explain different aspects of β‐diversity in Neotropical fish assemblages

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Not all non‐natives are equally unequal: reductions in herbivore β‐diversity depend on phylogenetic similarity to native plant community

Effects of host plant α‐ and β‐diversity often confound studies of herbivore β‐diversity, hindering our ability to predict the full impact of non‐native plants on herbivores. Here, while controlling host plant diversity, we examined variation in herbivore communities between native and non‐native plants, focusing on how plant relatedness and spatial scale alter the result. We found lower absolute magnitudes of β‐diversity among tree species and among sites on non‐natives in all comparisons. However, lower relative β‐diversity only occurred for immature herbivores on phylogenetically distinct non‐natives vs. natives. Locally in that comparison, non‐native gardens had lower host specificity; while among sites, the herbivores supported were a redundant subset of species on natives. Therefore, when phylogenetically distinct non‐natives replace native plants, the community of immature herbivores is likely to be homogenised across landscapes. Differences in communities on closely related non‐natives were subtler, but displayed community shifts and increased generalisation on non‐natives within certain feeding guilds.     

Taxonomic,functional, and phylogenetic β‐diversity patterns of stream fish assemblages in tropical agroecosystems

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Environmental and biotic drivers of soil microbial β‐diversity across spatial and phylogenetic scales

Soil microbial communities play a key role in ecosystem functioning but still little is known about the processes that determine their turnover (β‐diversity) along ecological gradients. Here, we characterize soil microbial β‐diversity at two spatial scales and at multiple phylogenetic grains to ask how archaeal, bacterial and fungal communities are shaped by abiotic processes and biotic interactions with plants. We characterized microbial and plant communities using DNA metabarcoding of soil samples distributed across and within eighteen plots along an elevation gradient in the French Alps. The recovered taxa were placed onto phylogenies to estimate microbial and plant β‐diversity at different phylogenetic grains (i.e. resolution). We then modeled microbial β‐diversities with respect to plant β‐diversities and environmental dissimilarities across plots (landscape scale) and with respect to plant β‐diversities and spatial distances within plots (plot scale). At the landscape scale, fungal and archaeal β‐diversities were mostly related to plant β‐diversity, while bacterial β‐diversities were mostly related to environmental dissimilarities. At the plot scale, we detected a modest covariation of bacterial and fungal β‐diversities with plant β‐diversity; as well as a distance–decay relationship that suggested the influence of ecological drift on microbial communities. In addition, the covariation between fungal and plant β‐diversity at the plot scale was highest at fine or intermediate phylogenetic grains hinting that biotic interactions between those clades depends on early‐evolved traits. Altogether, we show how multiple ecological processes determine soil microbial community assembly at different spatial scales and how the strength of these processes change among microbial clades. In addition, we emphasized the imprint of microbial and plant evolutionary history on today's microbial community structure.     

The differences of butterfly (Lepidoptera, Papilionoidea) communities in habitats with various degrees of disturbance and altitudes in tropical forests of Vietnam

A survey was conducted on the species composition, richness and abundance of Papilionoidea (excluding Lycaenidae) butterfly fauna in habitats with various degrees of disturbance and altitudes in tropical forests at Tam Dao National Park, northern Vietnam in 2001. The transect method was used to collect data in the survey. Six transects representing different habitat types at two sites, one site located at a low elevation of 200–250 m a.s.l., and the other located at a high elevation of 950–1000 m a.s.l., were chosen: three transects for each site, with a length of 500 m for each transect. A total of 3594 individuals of 127 species in 240 sets of data were recorded from various habitats. The differences in butterfly composition, species richness, abundance and diversity in different habitat types and altitudes were analyzed. The results showed significant differences of butterfly diversity among the different habitat types and between the low and high altitude sites. The butterfly diversity, species richness and species abundance in the low elevation habitats were higher than in the high elevation habitats. The highest diversity of butterflies occurred in the mixed habitats of agriculture, scrub and clearing lands of high disturbance. However, butterflies most important for conservation are associated with undisturbed or moderately disturbed forests only.     

Linking woody species diversity with plant available water at a landscape scale in a Brazilian savanna

Question: How is the diversity of woody species in a seasonally dry savanna related to plant available water (PAW)? Location: Savannas in central Brazil. Methods: Two‐dimensional soil resistivity profiles to 10‐m depth previously measured along three 10 m × 275 m replicate transects revealed differences in belowground water resources among and within transects: (1) driest/most heterogeneous; (2) wettest/least heterogeneous; and (3) PAW‐intermediate. All woody plants along these transects were identified to species, and height and basal circumference measured. Species diversity was evaluated for the whole transect (total diversity), 100‐m² plots (alpha‐diversity) and dissimilarity among 100‐m² plots within transects (beta‐diversity). Correlation analyses were conducted between PAW and vegetation variables at the 100‐m² scale. Results: The driest/most heterogeneous transect had the lowest total species diversity, while the wettest/least heterogeneous transect showed the lowest beta‐diversity. Floristic variation was correlated with PAW in all transects. In the most heterogeneous transect, species density was positively correlated with PAW in the 0‐400 cm soil layer. Evenness and Simpson's diversity were negatively correlated with PAW in the 700‐1000 cm soil layer. Conclusion: Woody species diversity was related to PAW at a fine spatial scale. Abundant PAW in the top 4 m of soil may favour many species and increase species total diversity. Conversely, abundant PAW at depth may result in lower evenness and total diversity, probably because the few species adapted to obtaining deep soil water can become dominant. Environmental changes altering soil water availability and partitioning in soil layers could affect the diversity of woody plants in this savanna.     

Species Diversity and Altitudinal Gradient Patterns of Evergreen Broad leaved Forest in MeihuashanNational Natural Reserve,Fujian Province

In China, evergreen broad leaved forests (EBLFs) is one of the most important vegetation types which was widly distributed in subtropical area, and it plays a very important role in the global biological diversity and natural environment conservation also. In order to reveal species diversity and altitudinal gradient patterns of evergreen broad leaved forest in Meihuashan National Natural Reserve, Fujian Province. Five altitude transects were set up at a vertical interval of 200m between 375m and 1300m above sea level in the EBLFs distribution areas, and twenty four quadrats(14400m2) had been surveyed. Species richness(S), species richness index (dGl), Simpson index (D), Shannon Wiener index (H′), Pielou evenness index (J) had been used for analysis of species diversity and altitudinal gradient pattern of EBLFs. The average value of S, dGl, H′,J and D were 64.42, 10.75, 5.75, 3.50, 0.58 respectively. The difference of community species diversity index(S, dGl, D, H′, and J) was extremely significant between transects, and the altitudinal gradient patterns of species diversity presented the unimodal variable trend, with a peak in the mid altitude(700m-900m). The species richness and Shannon Wiener index of different layer were ranked as shrub layer (include young tree and the plants between layers)>arbor layer>herb layer. The species richness of tree and shrub layer, and Shannon Wiener index of tree layer were significantly different between at transects, and trends of altitude gradient was similar to community. The Shannon Wiener index of shrub layer and herb layer, and the species richness of herb layer did not change significantly along elevation gradient. Therefore, plant species diversity distribution pattern presented a unimodal variable trend along an elevation gradient, and supported “mid domain model” in EBLFs of Meihuashan National Nature Reserve.     

The influence of historical dispersal on the phylogenetic structure of tree communities in the tropical Andes

We test for evidence of the Tropical Niche Conservatism or the Out of The Tropics hypotheses in structuring patterns of tree community composition along a 2000 + meter elevational gradient in the northern tropical Andes. By collecting and integrating data on the presence–absence of tree species within plots with phylogenetic information, we analyzed the following: (a) patterns of phylogenetic dispersion and species diversity along the elevational gradient based on indexes of net relatedness, nearest taxon relatedness, and species richness (α‐diversity); and (b) the replacement of lineages along the gradient using the PhyloSorensen metric (β‐diversity). More specifically, we established 20 0.25‐ha permanent tree inventory plots between 750 and 2,802 m asl where all individuals with diameter at breast height (DBH) ≥ 10 cm were measured and identified. We then used a series of linear models to test for changes in α and β diversity between plots in relation to elevation. Neither the net relatedness index nor the nearest taxon index showed a significant relationship with elevation. However, there was greater phylogenetic overdispersion at intermediate elevations; this likely reflects the mixing of species with contrasting origins from tropical and temperate lineages. β‐diversity between plots was negatively related to the corresponding difference in elevation, indicating that closely related lineages occupy similar ranges of elevation and temperature. We conclude that the immigration of lineages from extra‐tropical regions has significant effects in determining the phylogenetic structure of tree communities in tropical Andean forests. Abstract in Spanish is available with online material.     

Turnover and nestedness in subtropical dung beetle assemblages along an elevational gradient

Aim

We investigated changes in dung beetle β‐diversity components along a subtropical elevational gradient, to test whether turnover or nestedness‐related processes drive the dissimilarity of assemblages at spatial and temporal scales.

Location

An elevational gradient (200–1,600 m a.s.l.) of the Atlantic Forest in southern Brazil.

Methods

We investigated the extent to which β‐diversity varied along the elevational gradient (six elevations) at both spatial (among sites at different elevations) and temporal (different months at the same site) scales. We compared both the turnover and nestedness‐related dissimilarity of species and genera using multiple‐site or multiple‐month measures and tested whether these measurements were different from random expectations.

Results

A mid‐elevation peak in species richness along the elevational gradient was observed, and the lowest richness occurred at the highest elevations. We found two different groups of species, lowland and highland species, with a mixing of groups at intermediate elevations. The turnover component of β‐diversity was significantly higher for both spatial (i.e. elevational) and temporal changes in species composition. However, when the data for genera by site were considered, the elevational turnover value decreased in relative importance. Nestedness‐related processes are more important for temporal dissimilarity patterns at higher elevation sites.

Main conclusions

Spatial and temporal turnover of dung beetle species is the most important component of β‐diversity along the elevational gradient. High‐elevation assemblages are not subsets of assemblages that inhabit lower elevations, but this relationship ceases when β‐diversity is measured at the generic level. Environmental changes across elevations may be the cause of the differential establishment of distinctive species, but these species typically belong to the same higher taxonomic rank. Conservation strategies should consider elevational gradients in case‐specific scenarios as they may contain distinct species assemblages in lowlands vs. highlands.

     

Spatiotemporal dynamics of α‐ and β‐diversity across topographic gradients in the herbaceous layer of an old‐growth deciduous forest

Understanding the factors that regulate biodiversity over spatial and temporal gradients is an important scientific objective with ramifications for theory and conservation. Species composition is known to vary across spatial gradients, but how this spatial variation is linked to temporal dynamics is less well studied. Our objective was to understand how Shannon (α) diversity, spatial species turnover (Bray–Curtis dissimilarity), and temporal species turnover (Bray–Curtis dissimilarity) varied with regard to three topographic gradients (aspect, slope and elevation) over one growing season. In April, June and August of 2011, the herbaceous layer was sampled in 320 1‐m² plots within Big Everidge Hollow, an old‐growth forest in southeastern Kentucky. Multiple regression models revealed that Shannon diversity was linearly related to aspect (negative) and slope (positive), but unimodally related to elevation, indicating steep, mid‐elevation, and south‐facing plots were most diverse. Distance decay analysis showed that significant spatial species turnover occurred across all three topographic gradients, but aspect and elevation had a greater influence on compositional dissimilarity than slope. Mean temporal species turnover was significantly greater (p < 0.001) between April and June (0.39 ± 0.02 SE) than between June and August (0.20 ± 0.01). April‐to‐June turnover was related to aspect (linear) and elevation (quadratic; r²= 0.23, p < 0.0001), suggesting greater temporal species turnover occurred on north‐facing and mid‐elevation plots during this period; however, June‐to‐August turnover was weakly related to slope only (positive linear; r²= 0.08, p = 0.006). Environmental heterogeneity generated by topography is one of many factors that may constrain or promote biodiversity through space and across time, and a solid understanding of these spatiotemporal patterns of diversity can benefit both conservation and ecological theory.     

Environmental filtering explains a U‐shape latitudinal pattern in regional β‐deviation for eastern North American trees

The underlying drivers of β‐diversity along latitudinal gradients have been unclear. Previous studies have focused on β‐diversities calculated at a local scale and shed limited light on regional β‐diversity. We tested the much‐debated effects of range size vs. environmental filtering on the β‐gradient using data from the US Forest Inventory Analysis Program. We showed that the drivers of the β‐gradient were scale dependent. At the local scale species spatial patterns contributed little to the β‐gradient, whereas at the regional scale spatial patterns dominated the gradient and a U‐shape latitudinal relationship for the standardised β‐diversity deviation was revealed. The relationship can be explained by spatial variation in climate and soil texture, thus supporting the environmental filtering hypothesis. But it is inconsistent with Rapoport's rule about the effect of range size on β‐gradient. These results resolve the debate on whether species spatial distributions contribute to β‐gradient and attest the importance of environmental filtering in determining regional β‐diversity.     

Phylogenetic diversity of macromycetes and woody plants along an elevational gradient in Eastern Mexico

Phylogenetic information provides insight into the ecological and evolutionary processes that organize species assemblages. We compared patterns of phylogenetic diversity among macromycete and woody plant communities along a steep elevational gradient in eastern Mexico to better understand the evolutionary processes that structure their communities. Macrofungi and trees were counted and identified in eight sites from 100 to 3500 m asl, and sequence data retrieved from GenBank for the same or closely related species were used to reconstruct their phylogenies. Patterns of species richness and phylogenetic diversity were similar for both macrofungi and trees, but macromycete richness and diversity peaked at mid‐elevations, whereas woody plant richness and diversity did not show significant trends with elevation. Phylogenetic similarity among sites was low for both groups and decreased as elevational distance between sites increased. Macromycete communities displayed phylogenetic overdispersion at low elevations and phylogenetic clustering at high elevations; the latter is consistent with environmental filtering at high elevation sites. Woody plants generally exhibited phylogenetic clustering, consistent with the potential importance of environmental filtering throughout the elevational gradient.     

Riverine networks constrain β‐diversity patterns among fish assemblages in a large Neotropical river

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Topographic,latitudinal and climatic distribution of Pinus coulteri: geographic range limits are not at the edge of the climate envelope

With changing climate, many species are projected to move poleward or to higher elevations to track suitable climates. The prediction that species will move poleward assumes that geographically marginal populations are at the edge of the species' climatic range. We studied Pinus coulteri from the center to the northern (poleward) edge of its range, and examined three scenarios regarding the relationship between the geographic and climatic margins of a species' range. We used herbarium and iNaturalist.org records to identify P. coulteri sites, generated a species distribution model based on temperature, precipitation, climatic water deficit, and actual evapotranspiration, and projected suitability under future climate scenarios. In fourteen populations from the central to northern portions of the range, we conducted field studies and recorded elevation, slope and aspect (to estimate solar insolation) to examine relationships between local and regional distributions. We found that northern populations of P. coulteri do not occupy the cold or wet edge of the species' climatic range; mid‐latitude, high elevation populations occupy the cold margin. Aspect and insolation of P. coulteri populations changed significantly across latitudes and elevations. Unexpectedly, northern, low‐elevation stands occupy north‐facing aspects and receive low insolation, while central, high‐elevation stands grow on more south‐facing aspects that receive higher insolation. Modeled future climate suitability is projected to be highest in the central, high elevation portion of the species range, and in low‐lying coastal regions under some scenarios, with declining suitability in northern areas under most future scenarios. For P. coulteri, the lack of high elevation habitat combined with a major dispersal barrier may limit northward movement in response to a warming climate. Our analyses demonstrate the importance of distinguishing geographically vs. climatically marginal populations, and the importance of quantitative analysis of the realized climate space to understand species range limits.     

Climate and plant structure determine the spatiotemporal butterfly distribution on a tropical mountain

Mountains are among the most powerful natural gradients for testing ecological and evolutionary responses of biota to environmental influences because differences in climate and plant structure occur over short spatial scales. We describe the spatiotemporal distribution patterns and drives of fruit‐feeding butterfly diversity in the mountainous region of Serra do Cipó, Minas Gerais, Brazil. Seven elevations from 822 to 1,388 m a.s.l. were selected for evaluating the effects of abiotic factors and vegetation characteristics on butterfly diversity. A total of 44 fruit‐feeding butterfly species were recorded in a two‐year study. Species richness (local and regional) of fruit‐feeding butterflies decreased with increasing elevation. The interaction between temperature or humidity and precipitation influenced the abundance and β‐diversity of butterflies in the elevation gradient, whereas β‐diversity decreased with increasing plant richness. Butterfly richness (local and regional) and β‐diversity varied with the sampling period, with fewer species in July (2012 and 2013), the dry period, as expected for Neotropical insects. β‐Diversity in space and time was due to species replacement (turnover), indicating that butterfly composition differs throughout the mountain and over time. In summary, climate and plant richness largely influence butterfly diversity in the elevational gradient. Climatic changes in conjunction with increasing anthropic impacts on mountainous regions of southeast Brazil will likely influence the community of mountaintop butterflies in the Espinhaço Mountain Range. Abstract in Portuguese is available with online material.     

福建梅花山常绿阔叶林植物物种多样性及其海拔梯度格局

常绿阔叶林是福建梅花山国家级自然保护区地带性植被。采用样带与典型群落调查法对区内的常绿阔叶林14400m2样地展开调查,并对植物多样性海拔梯度格局进行分析,结果表明：（1） 群落植物物种丰富度、Gleason丰富度指数、Simpson指数、Shannon Wiener指数和Pielou均匀度指数的均值分别为64.42、10.75、5.75、3.50、0.58,且这5种指数在各样带间差异极为显著,并随海拔的升高均呈单峰曲线变化,峰值出现在海拔700m~900m。（2） 群落各层次的植物物种丰富度、Shannon Wiener指数均呈现灌木层（包括幼树和层间植物）〉乔木层〉草本层的特征。乔木、灌木层物种丰富度与乔木层Shannon Wiener指数在海拔梯度上的样带间差异极显著,变化趋势与群落相似;灌木层与草本层Shannon Wiener指数以及草本层物种丰富度随海拔梯度变化不明显。因此,梅花山自然保护区常绿阔叶林植物物种多样性的海拔梯度格局呈现单峰分布,并支持中间高度膨胀模式（mid domain model）。