From plots to islands: species diversity at different scales

Aim To investigate how plant diversity of whole islands (‘gamma’) is related to alpha and beta diversity patterns among sampling plots within each island, thus exploring aspects of diversity patterns across scales. Location Nineteen islands of the Aegean Sea, Greece. Methods Plant species were recorded at both the whole‐island scale and in small 100 m² plots on each island. Mean plot species richness was considered as a measure of alpha diversity, and six indices of the ‘variation’‐type beta diversity were also applied. In addition, we partitioned beta diversity into a ‘nestedness’ and a ‘replacement’ component, using the total species richness recorded in all plots of each island as a measure of ‘gamma’ diversity. We also applied 10 species–area models to predict the total observed richness of each island from accumulated plot species richness. Results Mean alpha diversity was not significantly correlated with the overall island species richness or island area. The range of plot species richness for each island was significantly correlated with both overall species richness and area. Alpha diversity was not correlated with most indices of beta diversity. The majority of beta diversity indices were correlated with whole‐island species richness, and this was also true for the ‘replacement’ component of beta diversity. The rational function model provided the best prediction of observed island species richness, with Monod’s and the exponential models following closely. Inaccuracy of predictions was positively correlated with the number of plots and with most indices of beta diversity. Main conclusions Diversity at the broader scale (whole islands) is shaped mainly by variation among small local samples (beta diversity), while local alpha diversity is not a good predictor of species diversity at broader scales. In this system, all results support the crucial role of habitat diversity in determining the species–area relationship.     

Partitioning species diversity across landscapes and regions: a hierarchical analysis of alpha, beta, and gamma diversity

Species diversity may be additively partitioned within and among samples (alpha and beta diversity) from hierarchically scaled studies to assess the proportion of the total diversity (gamma) found in different habitats, landscapes, or regions. We developed a statistical approach for testing null hypotheses that observed partitions of species richness or diversity indices differed from those expected by chance, and we illustrate these tests using data from a hierarchical study of forest-canopy beetles. Two null hypotheses were implemented using individual- and sample-based randomization tests to generate null distributions for alpha and beta components of diversity at multiple sampling scales. The two tests differed in their null distributions and power to detect statistically significant diversity components. Individual-based randomization was more powerful at all hierarchical levels and was sensitive to departures between observed and null partitions due to intraspecific aggregation of individuals. Sample-based randomization had less power but still may be useful for determining whether different habitats show a higher degree of differentiation in species diversity compared with random samples from the landscape. Null hypothesis tests provide a basis for inferences on partitions of species richness or diversity indices at multiple sampling levels, thereby increasing our understanding of how alpha and beta diversity change across spatial scales.     

Hierarchical partitioning of ant diversity: implications for conservation of biogeographical diversity in arid and semi‐arid areas

Aim The scale of observation is important in detecting the spatial variation of biological assemblages, which should be taken into consideration for an appropriate plan of biogeographical conservation. We investigated whether (1) World Wildlife Fund’s ecoregion units are the appropriate scale for conserving ant diversity in Iran, (2) each ecoregion represents a distinct ant community composition and (3) patterns of diversity partitioning differ among four ecoregions. Location Iran, a sampling transect along four arid and semi‐arid ecoregions. Methods We applied hierarchical partitioning to data collected from a nested sampling design including four hierarchical levels: ‘local’, ‘landscape’, ‘ecoregional’ and ‘whole‐region’. Observed alpha and beta diversity components were compared with values of null distributions. Hierarchical cluster analysis was applied to evaluate similarity of ant species composition among ecoregions. Results Partitioning of whole‐region species richness showed that 85% of the species richness was generated by beta diversity among ecoregions and landscapes. The highest value of diversity was generated by beta diversity among ecoregions. Unlike whole‐region partitioning, separate partitioning within each ecoregion revealed that beta component among localities contributed to species richness of each ecoregion. Ecoregions showed different patterns of diversity partitioning. The alpha component contributed largely to the total diversity of two ecoregions, but for two other ecoregions, beta component contributed more than alpha component. Cluster analysis identified four discrete ant species compositions; however, it split landscapes of one ecoregion into two distinct groups. Main conclusions Whole‐region diversity partitioning indicates that ecoregions represent the appropriate scale for conserving ant diversity and that each ecoregion has a distinct ant fauna. However, different conservation strategies should be considered for different ecoregions owing to the differing scales of variation within them. Boundaries of ecoregions remain a subject for further studies. The influence of climate change on ecoregional boundaries should be considered and should be predicted with respect to future conservation maps.     

Contrasting effects of mosaic structure on alpha and beta diversity of bird assemblages in a human‐modified landscape

Habitat loss and fragmentation are key processes causing biodiversity loss in human‐modified landscapes. Knowledge of these processes has largely been derived from measuring biodiversity at the scale of ‘within‐habitat’ fragments with the surrounding landscape considered as matrix. Yet, the loss of variation in species assemblages ‘among’ habitat fragments (landscape‐scale) may be as important a driver of biodiversity loss as the loss of diversity ‘within’ habitat fragments (local‐scale). We tested the hypothesis that heterogeneity in vegetation cover is important for maintaining alpha and beta diversity in human‐modified landscapes. We surveyed bird assemblages in eighty 300‐m‐long transects nested within twenty 1‐km² vegetation ‘mosaics’, with mosaics assigned to four categories defined by the cover extent and configuration of native eucalypt forest and exotic pine plantation. We examined bird assemblages at two spatial scales: 1) within and among transects, and 2) within and among mosaics. Alpha diversity was the mean species diversity within‐transects or within‐mosaics and beta diversity quantified the effective number of compositionally distinct transects or mosaics. We found that within‐transect alpha diversity was highest in vegetation mosaics defined by continuous eucalypt forest, lowest in mosaics of continuous pine plantation, and at intermediate levels in mosaics containing eucalypt patches in a pine matrix. We found that eucalypt mosaics had lower beta diversity than other mosaic types when ignoring relative abundances, but had similar or higher beta diversity when weighting with species abundances. Mosaics containing both pine and eucalypt forest differed in their bird compositional variation among transects, despite sharing a similar suite of species. This configuration effect at the mosaic scale reflected differences in vegetation composition among transects. Maintaining heterogeneity in vegetation cover could help to maintain variation among bird assemblages across landscapes, thus partially offsetting local‐scale diversity losses due to fragmentation. Critical to this is the retention of remnant native vegetation.     

Diversity partitioning confirms the importance of Beta components in tropical rainforest lepidoptera

Abstract Tropical beta diversity, and particularly that of herbivorous insects in rainforests, is often considered to be enormous, but this notion has recently been challenged. Because tropical beta diversity is highly relevant to our view on biodiversity, it is important to gain more insights and to resolve methodological problems that may lead to contradictions in different studies. We used data on two ecologically distinct moth families from Southeast Asia and analyzed separately the contribution of beta components to overall species richness at three spatial scales. Observed diversity partitions were compared under different types of null models. We found that alpha diversity was lower than expected on the basis of null models, whereas hierarchical beta components were larger than expected. Beta components played a significant role in shaping gamma diversity, and their contribution can be high (multiplicative beta >5). We found a reduction in beta components when comparing primary forests to agricultural sites (cf. "biotic homogenization"), but even in these habitats, beta components were still substantial. Our analyses show that beta components do play an important role in our data on tropical herbivorous insects and that these results are not attributable to lumping different habitats when sampling environmental gradients.     

Diversity patterns in upper Cambrian to Lower Ordovician trilobite communities of north‐western Argentina

The hierarchical structure of biodiversity from a regional scale analysis has received much attention as an alternative approach to unravelling the principal drivers of biodiversification. To better understand the processes that control the diversification of Cambro‐Ordovician trilobite communities from the Argentine Cordillera Oriental, we explore patterns of occupancy and diversity trajectories at the local and regional scales through seven intervals (Furongian, loTr1, upTr1, loTr2, upTr2, Tr3 and Fl2–3), and across an onshore‐offshore profile. Our results indicate: (1) a decrease in regional diversity from the upper Tr2 onwards, mainly caused by a reduction in the number of rare taxa, coupled with stable beta diversity at regional scale and a constant rise in beta diversity in deep subtidal environments; (2) a higher proportion of regional diversity allocated to the within‐habitat beta component; and (3) that changes in gamma diversity are driven primarily by changes in alpha diversity during the Furongian–Tr3, whereas in the Floian, beta diversity seems to modulate regional diversity. These trends and associated patterns indicate increasing ecological differences among taxa, shifting from metacommunities where most taxa have similar ecological preferences or ‘Hubbell type’ to metacommunities with high niche differentiation or ‘Hutchinson type’. Interestingly, the timing of this shift coincides with the regional‐scale turnover between trilobite evolutionary faunas suggesting that the rise in niche differentiation among these genera may be related to the transition. Superimposed on this general trend, particular diversity structures can be understood in the light of metacommunity dynamics, such as dispersal limitation and mass effect.     

Fish species diversity among spatial scales of altered temperate rivers

Aim The alteration of flowing systems over the past century has led to significant changes to the processes that drive these complex environments as well as to the scales at which these processes act. Recently, efforts have begun in earnest to restore some semblance of ecosystem diversity, but there is little understanding of exactly on what spatial scale or scales biotic diversity is responding. We investigated the manner in which fish diversity is partitioned at multiple spatial scales in two rivers in the central United States. Location The Missouri and Illinois rivers of the central United States. Methods We analysed how fish diversity was partitioned within the Illinois River and Missouri River systems by sampling each river under hierarchical frameworks that allowed analysis at section (large), reach (intermediate), and site (small) scales. We tested the hypothesis that there are scale‐dependent responses of fish diversity using an additive partitioning approach. Results Site alpha diversity was significantly higher than expected in both the Illinois and Missouri rivers. The relative contribution of alpha diversity to total diversity at a given spatial scale increased for the Illinois River, but not for the Missouri River, in that the highest alpha diversity contribution peaked at the reach scale. Diversity patterns from both rivers suggest that diversity at the site scale plays a significant role in determining the overall diversity in these systems. However, there is a substantial contribution at larger scales that warrants consideration when attempts are being made to protect or restore diversity and other ecosystem parameters. Main conclusions Understanding the variation of diversity in riverine systems is crucial for providing insight not only into how biotic communities respond to scale‐dependent factors, but also into the underlying abiotic and biotic factors that generate patterns of diversity across scales. These insights, in turn, are important for ensuring that restoration and management activities are targeting the appropriate scales for remediation. A lack of understanding of this issue could have negative outcomes for the recovery of a community in a restoration scenario, as well as resulting in a low economic return on restoration investments, which could hinder future efforts.     

Scale-dependent effects of landscape pattern on plant diversity in Hunshandak Sandland

The influence of landscape pattern on plant diversity has strong scale-dependent effects. However, the relationship is still unclear for sandy land, which covers more than one-third of the world’s land mass. Aiming at exploring such scale-dependent effects in sandy land, we conducted a case study in Hunshandak Sandland, northern China. Principal component analysis (PCA) and Redundancy Analysis (RDA) was used to disentangle the relations between landscape pattern and alpha and beta plant diversity. Our results show that landscape pattern has an important influence on plant diversity, however, there existed scale effects. Landscape diversity enhanced the alpha diversity, conversely, reduced the beta diversity for all scales. PSSD (Patch Size Standard Deviation) positively related with alpha diversity whilst negatively related with beta diversity on moderate and large spatial scales, same as LPI (Largest Patch Index) on moderate scales. Shape complexity of patches can slightly increase both alpha and beta diversity at large scales. The adjustment of landscape pattern based on different spatial scales can enhance plant diversity. It is useful to improve plant diversity conservation in sandy land.     

Environmental drivers of ant species richness and composition across the Argentine Pampas grassland

Understanding the underlying mechanisms causing diversity patterns is a fundamental objective in ecology and science‐based conservation biology. Energy and environmental‐heterogeneity hypotheses have been suggested to explain spatial changes in ant diversity. However, the relative roles of each one in determining alpha and beta diversity patterns remain elusive. We investigated the main factors driving spatial changes in ant (Hymenoptera, Formicidae) species richness and composition (including turnover and nestedness components) along a 500 km longitudinal gradient in the Pampean region of Argentina. Ants were sampled using pitfall traps in 12 sample sites during the summer. We performed a model selection approach to analyse responses of ant richness and composition dissimilarity to environmental factors. Then, we computed a dissimilarity partitioning of the contributions of spatial turnover and nestedness to total composition dissimilarity. Temporal habitat heterogeneity and temperature were the primary factors explaining spatial patterns of epigean ant species richness across the Pampas. The distance decay in species composition similarity was best accounted by temperature dissimilarity, and turnover had the greatest contribution to the observed beta diversity pattern. Our findings suggest that both energy and environmental‐heterogeneity‐related variables are key factors shaping richness patterns of ants and niche‐based processes instead of neutral processes appear to be regulating species composition of ant assemblages. The major contribution of turnover to the beta diversity pattern indicated that lands for potential reconversion to grassland should represent the complete environmental gradient of the Pampean region, instead of prioritizing a single site with high species richness.     

Environmental change and predator diversity drive alpha and beta diversity in freshwater macro and microorganisms

Global biodiversity is eroding due to anthropogenic causes, such as climate change, habitat loss, and trophic simplification of biological communities. Most studies address only isolated causes within a single group of organisms; however, biological groups of different trophic levels may respond in particular ways to different environmental impacts. Our study used natural microcosms to investigate the predicted individual and interactive effects of warming, changes in top predator diversity, and habitat size on the alpha and beta diversity of macrofauna, microfauna, and bacteria. Alpha diversity (i.e., richness within each bromeliad) generally explained a larger proportion of the gamma diversity (partitioned in alpha and beta diversity). Overall, dissimilarity between communities occurred due to species turnover and not species loss (nestedness). Nevertheless, the three biological groups responded differently to each environmental stressor. Microfauna were the most sensitive group, with alpha and beta diversity being affected by environmental changes (warming and habitat size) and trophic structure (diversity of top predators). Macrofauna alpha and beta diversity was sensitive to changes in predator diversity and habitat size, but not warming. In contrast, the bacterial community was not influenced by the treatments. The community of each biological group was not mutually concordant with the environmental and trophic changes. Our results demonstrate that distinct anthropogenic impacts differentially affect the components of macro and microorganism diversity through direct and indirect effects (i.e., bottom‐up and top‐down effects). Therefore, a multitrophic and multispecies approach is necessary to assess the effects of different anthropogenic impacts on biodiversity.     

Multiple‐scale assessment of understory herb species diversity in pine plantations after long‐term restoration

Plantations are established for a variety of purposes including wood production, soil and water conservation, and carbon sequestration. However, their implications for species diversity are considerably debated. To assess restoration effect of species diversity in plantations after 50 years’ natural restoration, understory herb species diversity of Chinese pine (Pinus tabulaeformis) plantations were characterized and compared with secondary growth oak (Quercus wutaishanica) forests by additive partitioning across three different nested spatial scales (subplot, plot and site scales) in the middle of the Loess Plateau, northwestern China. Whether these two forest types demonstrate different structuring processes was also examined by quantifying the relative contributions of space and the environment on community composition. Overall, the two forests displayed similar accumulation of species diversity across spatial scales. The contribution of species diversity components increased with the spatial scale, and both forests displayed lower alpha diversity at the subplot scale but higher beta diversity at the plot and site scales. There was no significant difference in alpha or beta diversity between the two forests at any of the three scales, but in species compositions at the subplot and plot scales (p < 0.05). The diversity of both forest types were simultaneously governed by environmental and spatial processes, with the exception of a greater contribution of each component in the secondary growth oak forests, but both forests were dominated by environmental processes. Our study highlight the significant role of spatial scales in assessing the result of biodiversity restoration of plantations. These results suggest that pine plantations function in a similar manner as secondary growth oak forests for understory herb diversity, albeit with different community compositions.     

Beta diversity of stream diatoms at two hierarchical spatial scales: implications for biomonitoring

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Agriculture erases climate constraints on soil nematode communities across large spatial scales

Anthropogenic conversion of natural to agricultural land reduces aboveground biodiversity. Yet, the overall consequences of land‐use changes on belowground biodiversity at large scales remain insufficiently explored. Furthermore, the effects of conversion on different organism groups are usually determined at the taxonomic level, while an integrated investigation that includes functional and phylogenetic levels is rare and absent for belowground organisms. Here, we studied the Earth's most abundant metazoa—nematodes—to examine the effects of conversion from natural to agricultural habitats on soil biodiversity across a large spatial scale. To this aim, we investigated the diversity and composition of nematode communities at the taxonomic, functional, and phylogenetic level in 16 assemblage pairs (32 sites in total with 16 in each habitat type) in mainland China. While the overall alpha and beta diversity did not differ between natural and agricultural systems, all three alpha diversity facets decreased with latitude in natural habitats. Both alpha and beta diversity levels were driven by climatic differences in natural habitats, while none of the diversity levels changed in agricultural systems. This indicates that land conversion affects soil biodiversity in a geographically dependent manner and that agriculture could erase climatic constraints on soil biodiversity at such a scale. Additionally, the functional composition of nematode communities was more dissimilar in agricultural than in natural habitats, while the phylogenetic composition was more similar, indicating that changes among different biodiversity facets are asynchronous. Our study deepens the understanding of land‐use effects on soil nematode diversity across large spatial scales. Moreover, the detected asynchrony of taxonomic, functional, and phylogenetic diversity highlights the necessity to monitor multiple facets of soil biodiversity in ecological studies such as those investigating environmental changes.     

Biodiversity and ecosystem stability across scales in metacommunities

Although diversity–stability relationships have been extensively studied in local ecosystems, the global biodiversity crisis calls for an improved understanding of these relationships in a spatial context. Here, we use a dynamical model of competitive metacommunities to study the relationships between species diversity and ecosystem variability across scales. We derive analytic relationships under a limiting case; these results are extended to more general cases with numerical simulations. Our model shows that, while alpha diversity decreases local ecosystem variability, beta diversity generally contributes to increasing spatial asynchrony among local ecosystems. Consequently, both alpha and beta diversity provide stabilising effects for regional ecosystems, through local and spatial insurance effects respectively. We further show that at the regional scale, the stabilising effect of biodiversity increases as spatial environmental correlation increases. Our findings have important implications for understanding the interactive effects of global environmental changes (e.g. environmental homogenisation) and biodiversity loss on ecosystem sustainability at large scales.     

Loss of small glaciers will diminish beta diversity in Pyrenean streams at two levels of biological organization

Aim Small (< 1 km²) alpine glaciers are likely to disappear in this century, resulting in decreased regional habitat heterogeneity in associated streams. Both heterogeneity within and spatial isolation among glacier‐influenced streams can enhance beta diversity of stream‐dwelling organisms. We measured beta at both community and population‐genetic levels within and among streams currently influenced by small Pyrenean glaciers. We aimed to evaluate whether patterns are analogous between the two levels, to apply various approaches for characterizing beta, and to infer the outcome of future glacier loss on regional biodiversity. Location Four glacier‐fed basins in the Parc National des Pyrénées, France. Methods We classified each of 18 stream reaches across the basins into either high‐, mid‐ or low‐‘glaciality’ (glacial influence) groups according to four physicochemical characteristics. At each reach, we collected macroinvertebrate communities and evaluated mitochondrial DNA haplotypes for 11–13 individuals of Baetis alpinus Pictet. Using taxa/haplotypes as basic units, we evaluated community and population‐genetic beta diversity simultaneously. We measured beta diversity in three major ways: as multivariate (Sørensen's dissimilarity, Jost D) and ‘classical’ (gamma/alpha) variation to compare among glaciality groups, and as turnover along the glaciality gradient within each basin. Results For most approaches at both organizational levels, beta was greatest among high‐glaciality reaches, absolute values of variation of beta in high‐glaciality streams were strikingly similar between levels, and the steepest turnover within basins occurred between high‐ and mid‐glaciality reaches. Therefore, high‐glaciality reaches contained assemblages and populations that were unique both within that stream type (among basins) and compared with other stream types within basins. Main conclusions Parallel beta diversity patterns at population‐genetic and community levels suggested that environmental drivers influence these levels analogously. Extreme conditions (e.g. low temperature, high instability, isolation) in high‐glaciality streams probably enhance beta at both levels. Stream beta diversity is likely to decrease substantially with continued glacial reduction in this system.     

Non-Native Plants Disrupt Dual Promotion of Native Alpha and Beta Diversity

Non-native species can alter patterns of species diversity at multiple spatial scales, but the processes that underlie multi-scale effects remain unclear. Here we show that non-native species reduce native diversity at multiple scales through simultaneous disruption of two processes of native community assembly: species immigration, which enhances alpha diversity, and community divergence, which enhances beta diversity. Community divergence refers to the process in which local communities diverge over time in species composition because the history of species immigration and, consequently, the way species affect one another within communities are variable among communities. Continuous experimental removal of species over four years of floodplain succession revealed that, when non-native species were excluded, stochastic variation in the timing of a dominant native species’ arrival allowed local communities to diverge, thereby enhancing beta diversity, without compromising promotion of alpha diversity by species immigration. In contrast, when non-native species were allowed to enter experimental plots, they not only reduced native alpha diversity by limiting immigration, but also diminished the dominant native species’ role in enhancing native beta diversity. Our results highlight the importance of community assembly and succession for understanding multi-scale effects of non-native species.     

Species turnover in lake littorals: spatial and temporal variation of benthic macroinvertebrate diversity and community composition

Aims Despite wide consensus that ecological patterns and processes should be studied at multiple spatial scales, the temporal component of diversity variation has remained poorly examined. Specifically, rare species may exhibit patterns of diversity variation profoundly different from those of dominant taxa. Location Southern Finland. Methods We used multiplicative partitioning of true diversities (species richness, Shannon diversity) to identify the most important scale(s) of variation of benthic macroinvertebrate communities across several hierarchical scales, from individual samples to multiple littorals, lakes and years. We also assessed the among‐scale variability of benthic macroinvertebrate community composition by using measures of between‐ and within‐group distances at hierarchical scales. Results On average, a single benthic sample contained 23% of the total regional macroinvertebrate species pool. For both species richness and Shannon diversity, beta‐diversity was clearly the major component of regional diversity, with within‐littoral beta‐diversity (β₁) being the largest component of gamma‐diversity. The interannual component of total diversity was small, being almost negligible for Shannon index. Among‐sample (within‐littoral) diversity was related to variation of substratum heterogeneity at the same scale. By contrast, only a small proportion of rare taxa was found in an average benthic sample. Thus, dominant species among lakes and years were about the same, whereas rare species were mostly detected in a few benthic samples in one lake (or year). For rare species, the temporal component of diversity was more important than spatial turnover at most scales. Main conclusions While individual species occurrences and abundances, particularly those of rare taxa, may vary strongly through space and time, patterns of dominance in lake littoral benthic communities are highly predictable. Consequently, many rare species will be missed in temporally restricted samples of lake littorals. In comprehensive biodiversity surveys, interannual sampling of littoral macroinvertebrate communities is therefore needed.     

Fine‐scale Beta‐diversity Patterns Across Multiple Arthropod Taxa Over a Neotropical Latitudinal Gradient

Documenting how diversity patterns vary at fine‐ and broad scales may help answer many questions in theoretical and applied ecology. However, studies tend to compare diversity patterns at the same scale and within the same taxonomic group, which limits the applicability and generality of the results. Here, we have investigated whether vegetation‐dwelling arthropods from different trophic ranks and with distinct life histories (i.e., ants, caterpillars, cockroaches, and spiders) have different beta‐diversity patterns at multiple scales. Specifically, we compared their beta diversity across architecturally distinct plant species (fine‐scale process) and a latitudinal gradient of sites (broad‐scale process) along 2040 km of coastal restinga vegetation in the Neotropics. Over 50 percent of the compositional changes (β‐diversity) in ants, caterpillars, and spiders and 41 percent of those in cockroaches were explained by plant identity within each site. Even groups that do not feed on plant tissues, such as omnivores and predators, were strongly affected by plant identity. Fine‐scale variation was more important than large‐scale processes for all studied groups. Performing a cross‐scale comparison of diversity patterns of groups with distinct life histories helps elucidate how processes that act at regional scales, such as dispersal, interact with local processes to assemble arthropod communities.     

Plant diversity predicts beta but not alpha diversity of soil microbes across grasslands worldwide

Aboveground–belowground interactions exert critical controls on the composition and function of terrestrial ecosystems, yet the fundamental relationships between plant diversity and soil microbial diversity remain elusive. Theory predicts predominantly positive associations but tests within single sites have shown variable relationships, and associations between plant and microbial diversity across broad spatial scales remain largely unexplored. We compared the diversity of plant, bacterial, archaeal and fungal communities in one hundred and forty‐five 1 m² plots across 25 temperate grassland sites from four continents. Across sites, the plant alpha diversity patterns were poorly related to those observed for any soil microbial group. However, plant beta diversity (compositional dissimilarity between sites) was significantly correlated with the beta diversity of bacterial and fungal communities, even after controlling for environmental factors. Thus, across a global range of temperate grasslands, plant diversity can predict patterns in the composition of soil microbial communities, but not patterns in alpha diversity.     

Fine‐scale heterogeneity in beetle assemblages under co‐occurring Eucalyptus in the same subgenus

Aim Insect biodiversity is often positively associated with habitat heterogeneity. However, this relationship depends on spatial scale, with most studies focused on differences between habitats at large scales with a variety of forest tree species. We examined fine‐scale heterogeneity in ground‐dwelling beetle assemblages under co‐occurring trees in the same subgenus: Eucalyptus melliodora A. Cunn. ex Schauer and E. blakelyi Maiden (Myrtaceae). Location Critically endangered grassy woodland near Canberra, south‐eastern Australia. Methods We used pitfall traps and Tullgren funnels to sample ground‐dwelling beetles from the litter environment under 47 trees, and examined differences in diversity and composition at spatial scales ranging from 100 to 1000 m. Results Beetle assemblages under the two tree species had distinctive differences in diversity and composition. We found that E. melliodora supported a higher richness and abundance of beetles, but had higher compositional similarity among samples. In contrast, E. blakelyi had a lower abundance and species richness of beetles, but more variability in species composition among samples. Main conclusions Our study shows that heterogeneity in litter habitat under co‐occurring and closely related eucalypt species can influence beetle assemblages at spatial scales of just hundreds of metres. The differential contribution to fine‐scale alpha and beta diversity by each eucalypt can be exploited for conservation purposes by ensuring an appropriate mix of the two species in the temperate woodlands where they co‐occur. This would help not only to maximize biodiversity at landscape scales, but also to maintain heterogeneity in species richness, trophic function and biomass at fine spatial scales.