Nestedness Components Research Articles

Dispersal ability is associated with contrasting patterns of beta diversity in African small mammal communities

AbstractAimSpatial processes and environmental filtering are important factors shaping community composition, but their effects are rarely tested across all aspects and components of beta diversity. We investigate both of these factors to explain patterns of taxonomic, functional and phylogenetic beta diversity of small mammals across Sub‐Saharan Africa. We predict that groups with poorest dispersal ability will experience the highest taxonomic and phylogenetic turnover but a nesting of functional diversity independent of dispersal.LocationAfrica.TaxaRodents, bats, shrews.MethodsWe amassed a continent‐spanning dataset of 97 bat assemblages, 166 rodent assemblages and 153 shrew assemblages comprising a total of 183, 225 and 109 species, respectively, from six bioregions of Sub‐Saharan Africa. We calculated three aspects of beta diversity: taxonomic, functional and phylogenetic. For each of these, we first calculated total beta diversity based on the Sørensen index (βsor) and then decomposed this into turnover (βsim) and nestedness (βnes) components. We then used Moran's Eigenvector Maps to examine the relationships between each aspect of beta diversity and environmental gradients (environmental filtering) and geographical distance between sites (spatial processes).ResultsWe found consistent patterns across the three taxa in all aspects of beta diversity, with taxonomic beta diversity being greatest and phylogenetic beta diversity being lowest. The turnover component was typically greater than the nestedness component for taxonomic and functional beta diversity, but not for phylogenetic beta diversity, for all three groups. Beta diversity was also linked with the dispersal ability of the three groups, with the highest levels of beta diversity found in shrews, intermediate levels in rodents and the lowest levels in bats.Main ConclusionsSpatial processes, which are linked to the dispersal abilities of the three taxa of small mammal, dominate environmental drivers in structuring African small‐mammal communities with phylogenetic comparisons suggesting a relatively permeable continent.

β-diversity Patterns of Bird Communities in Natural Protected Areas in Anhui by Separating the Turnover and Nestedness Components

β-diversity Patterns of Bird Communities in Natural Protected Areas in Anhui by Separating the Turnover and Nestedness Components

Shrubs alter alpha and beta diversity of soil fauna in a semiarid grassland

Shrubs are widely distributed in semi-arid and arid ecosystems. Understanding shrub effects on alpha and beta diversity of soil fauna in arid and semiarid ecosystems could lead to promotion of biodiversity conservation and sustainable management. Yet the extent to which shrubs can influence beta diversity of soil fauna and different body size in arid and semiarid ecosystems is unknown. An investigation of soil fauna, macrofauna, and mesofauna beneath shrub canopy and in open spaces was conducted in the Donddashan Nature Reserve (a semiarid grassland ecosystem in China). Shrubs significantly increased the alpha diversity (richness and Shannon index), but significantly decreased the beta diversity and the nestedness component. Moreover, shrub effects differed among soil fauna of different body size. Shrubs significantly increased the abundance and Shannon index of mesofauna, whereas there were no significant effects on macrofauna between shrubs and open spaces. Shrubs significantly decreased the beta diversity of mesofauna, but significantly increased beta diversity and the turnover component of macrofauna. Piecewise structural equation modelling (SEM) showed that shrubs had an indirect effect on soil fauna diversity through mesofauna diversity. Results highlighted the crucial role that shrubs have in maintaining alpha diversity of soil fauna in arid ecosystem, and also demonstrated the divergent shrub effects on beta diversity of soil fauna, mesofauna, and macrofauna. This suggests a need to examine different taxonomic groups to gain a better understanding of ecological consequences of shrubs.

Discrepancies of fungi and plants in the pattern of beta-diversity with environmental gradient imply a comprehensive community assembly rule.

Beta-diversity partitioning has shown that the nestedness component is developed with environmental stress in a variety of taxa. However, soil fungal community may maintain its turnover components in contrast with the development of plants' nestedness component, and the potential causes remain unclear. To investigate the process of species turnover of soil fungi along a stress gradient in the Arctic, we divided species turnover component into sub-components; βsim_hete and βsim_homo representing species turnover with and without a change in the guilds, respectively. The results indicate that fungal communities maintain their turnover components unlike plant communities; however, their βsim_hete increased under stressful conditions. Additionally, GDM analysis showed that βsim_hete was mainly explained by stress gradient and plant nestedness, suggesting that functionality of soil fungi was ecologically filtered by environmental stress and plant community structure. The discordant trend of beta-diversity values between plant and fungi (i.e. development of plant nestedness and maintenance of fungal turnover) is possibly not caused by different assembly rules working in parallel on the two taxa, but according to an ecological rule that reflects plant-fungal interaction.

Geographic patterns of taxonomic and phylogenetic β-diversity of aquatic angiosperms in China

China covers a vast territory harbouring a large number of aquatic plants. Although there are many studies on the β-diversity of total, herbaceous or woody plants in China and elsewhere, few studies have focused on aquatic plants. Here, we analyse a comprehensive data set of 889 aquatic angiosperm species in China, and explore the geographic patterns and climatic correlates of total taxonomic and phylogenetic β-diversity as well as their turnover and nestedness components. Our results show that geographic patterns of taxonomic and phylogenetic β-diversity are highly congruent for aquatic angiosperms, and taxonomic β-diversity is consistently higher than phylogenetic β-diversity. The ratio between the nestedness component and total β-diversity is high in northwestern China and low in southeastern China. The geographic patterns of taxonomic and phylogenetic β-diversity of aquatic angiosperms in China are obviously affected by geographic and climatic distances, respectively. In conclusion, the geographic patterns of taxonomic and phylogenetic β-diversity of aquatic angiosperms are consistent across China. Climatic and geographic distances jointly affect the geographic patterns of β-diversity of aquatic angiosperms. Overall, our work provides insight into understanding the large-scale patterns of aquatic angiosperm β-diversity, and is a critical addition to previous studies on the macroecological patterns of terrestrial organisms.

Taxonomic dependency of beta diversity for bacteria, archaea, and fungi in a semi-arid lake

Microbial beta diversity has been recently studied along the water depth in aquatic ecosystems, however its turnover and nestedness components remain elusive especially for multiple taxonomic groups. Based on the beta diversity partitioning developed by Baselga and Local Contributions to Beta Diversity (LCBD) partitioning by Legendre, we examined the water-depth variations in beta diversity components of bacteria, archaea and fungi in surface sediments of Hulun Lake, a semi-arid lake in northern China, and further explored the relative importance of environmental drivers underlying their patterns. We found that the relative abundances of Proteobacteria, Chloroflexi, Euryarchaeota, and Rozellomycota increased toward deep water, while Acidobacteria, Parvarchaeota, and Chytridiomycota decreased. For bacteria and archaea, there were significant (p < 0.05) decreasing water-depth patterns for LCBD and LCBDRepl (i.e., species replacement), while increasing patterns for total beta diversity and turnover, implying that total beta diversity and LCBD were dominated by species turnover or LCBDRepl. Further, bacteria showed a strong correlation with archaea regarding LCBD, total beta diversity and turnover. Such parallel patterns among bacteria and archaea were underpinned by similar ecological processes like environmental selection. Total beta diversity and turnover were largely affected by sediment total nitrogen, while LCBD and LCBDRepl were mainly constrained by water NO2 --N and NO3 --N. For fungal community variation, no significant patterns were observed, which may be due to different drivers like water nitrogen or phosphorus. Taken together, our findings provide compelling evidences for disentangling the underlying mechanisms of community variation in multiple aquatic microbial taxonomic groups.

Local environmental conditions influence species replacement in Great Lakes interdunal wetland macroinvertebrate communities

Abstract Understanding the role of environmental filtering and spatial processes along environmental gradients in assembling and maintaining aquatic communities in rare habitats is crucial for land management and biological conservation. We investigated the relative roles of environmental and spatial factors influencing beta (β) diversity of aquatic macroinvertebrate assemblages in 36 interdunal wetlands from five freshwater sand dune areas across two ecoregions spanning the latitudinal gradient of Lake Michigan. We hypothesised that aquatic macroinvertebrate diversity and composition would vary along the coastline because of an underlying environmental gradient. We predicted high species replacement correlated with environmental (local and regional) conditions and increasing species diversity with decreasing latitude. We calculated sample completeness, obtained diversity estimates based on Hill numbers and used abundance‐based β partitioning and multivariate analysis to examine β diversity, and its replacement and nestedness components in relation to local and regional predictors. Despite a short latitudinal gradient, we detected a significant increase in species richness with decreasing latitude, underpinned by a strong temperature and precipitation gradient. Species replacement (balanced variation in abundance) was high at all spatial scales (wetland, dune area, ecoregion and coastline), and correlated with local and regional environmental variables. Community dissimilarity showed no marked increase with spatial extent, which suggests a system where local‐scale environmental filtering prevents dispersal driven homogenisation. Both local and bioclimatic factors were correlated with aquatic macroinvertebrate dissimilarity, but local factors played a larger role. This study simultaneously examined the response of alpha and β diversity to geographical and environmental variables. Our results indicate that macroinvertebrates respond to abiotic factors by tracking suitable environmental conditions among locally variable interdunal wetlands. Thus, high dispersal along the coastline conveys resiliency to a hydrologically dynamic wetland system, which allows aquatic macroinvertebrates to contribute an integral portion of sand dune biodiversity within the Laurentian Great Lakes region. The high species turnover found suggests that conservation strategies should consider coastline connectivity among dune areas to maintain freshwater biodiversity.

Bird Beta Diversity in Sharp Contrasting Altai Landscapes: Locality Connectivity Is the Influential Factor on Community Composition.

Simple SummaryUnderstanding the ecological processes involved in establishing a metacommunity, a collection of small communities linked by species dispersal, could help with biodiversity conservation. In this work, we examine how local community connectivity affects the distributional patterns of various bird species across metacommunities in the strikingly different Altai landscapes. We discovered that connectivity was most important for determining community composition in metacommunities. High beta diversity and a high turnover component in the research region showed that regional-scale conservation efforts should consider overall biodiversity. Although they are not part of the Altai-Sayan biodiversity ecoregion, the riparian and desert landscapes are essential to the birds that reside in the mountain ranges and should be regarded as integral parts of the ecoregion, and high connectivity stepping-stone habitats in these landscapes should be protected.Located on the southwest slope and plain areas of the Altai Mountains in China, this study aims to explore bird composition variation (beta diversity) in mountain landscape (metacommunity M), riparian landscape (metacommunity R), desert landscape (metacommunity D) and across the three landscapes (metacommunity A), and to assess how patch connectivity with environmental and spatial factors influence species distributional patterns across multiple metacommunities. In 78 transect lines over the study area, 9724 detections of 139 bird species were detected. We calculated the beta diversity, its turnover and nestedness components in four metacommunities. We used the variation partitioning method to investigate the relative importance between the environment, spatial variation and locality connectivity in driving bird community composition variation. We found high beta diversities with a small contribution of nestedness components in all four metacommunities. When only a single set of predictors is contained in the model, the predictor that best explains the variation of bird community composition is connectivity in metacommunity M, R and D and spatial predictor in metacommunity A. In all three sets of predictors, 73.8~85.4% of variations of community composition can be explained in the four metacommunities, and connectivity always contributed the most. High beta diversity and a high turnover component imply that regional-scale conservation efforts should be thought of as preserving overall biodiversity. A conservation strategy is to keep stepping-stone habitats with good connectivity in the middle of the riparian landscape. Along with the Altai-Sayan biodiversity ecoregion, the desert and riparian environments are essential for birds residing in the mountainous terrain. Furthermore, they should be regarded as integral parts of the ecoregion.

New insights into the formation of biodiversity hotspots of the Kenyan flora

AbstractAimThis study aimed to investigate the distribution patterns of plant diversity in Kenya, how climatic fluctuations and orogeny shaped them, and the formation of its β‐diversity.LocationKenya, East Africa.TaxonAngiosperms.MethodsWe quantified patterns of turnover and nestedness components of phylogenetic β‐diversity for angiosperm species among neighbouring sites using a well‐resolved phylogenetic tree and extensive distribution records from public databases and other published sources. We applied clustering methods to delineate biota based on pairwise similarities among multiple sites and used a random assembly null model to assess the effects of species abundance distribution on phylogenetic β‐diversity.ResultsThe phylogenetic turnover of the Kenyan flora, intersecting with the biodiversity hotspots Eastern Afromontane, Coastal Forests of Eastern Africa, and Horn of Africa, shows a non‐monotonic pattern along a latitudinal gradient that is strongly structured into volcanic and coastal areas. The other areas are mainly dominated by phylogenetic nestedness, even in the eastern part of the equatorial region parallel to the volcanic area. Phylogenetic diversity and phylogenetic structure analyses explain the mechanism of the observed phylogenetic turnover and nestedness patterns. We identified five phytogeographical regions in Kenya: the Mandera, Turkana, Volcanic, Pan Coastal and West Highland Regions.ConclusionsVariations in turnover gradient and coexistence are highly dependent on the regional biogeographical history resulting from climatic fluctuations and long‐lasting orogeny, which jointly shaped the biodiversity patterns of the Kenyan flora. The nestedness component dominated climatically unstable regions and is presumed to have been caused by heavy local species extinction and recolonization from the Volcanic Region. The high turnover component in climatically stable regions may have preserved old lineages and the prevalence of endemic species within narrow ranges.

Understanding the drivers of β-diversity improves conservation prioritization for Central European dung beetles

The conversion and degradation of natural habitats has caused global declines in terrestrial insect diversity. Conserving insect diversity has therefore gained increasing attention in international conservation agendas. Dung beetles (Geotrupidae, Scarabaeidae) are diverse and abundant coprophagous insects who remove dung and enhance nutrient cycling. Today, half of Central European dung beetle species are threatened. While past research has concentrated on local (α-diversity) of dung beetles, the compositional differences between sites (β-diversity) have been largely neglected. However, maximizing the overall outcome of conservation measures requires a detailed understanding of the factors determining compositional differences between sites. We separated β-diversity of dung beetle communities, sampled across the Czech Republic, into independent components of spatial turnover and nestedness. We tested the relative importance of space, temperature, precipitation, elevation, season, grazing herbivore and antiparasitic treatment via multiple regressions for distance matrices to reveal which factors drive the β-diversity of dung beetle communities. Our results show that β-diversity of dung beetle communities is mostly driven by spatial distance, followed by similarly strong effects of season and mean temperature. Herbivore type and antiparasitic treatment had lesser influence than environment but can be influenced by conservation management. Nevertheless, antiparasitic treatment increased nestedness and resulted in an overall lower γ-diversity. Based on the principle of complementarity, we recommend – in order of decreasing importance – giving (1) conservation priority to the most distant sites, under (2) the largest differences in mean annual temperature, ensure (3) year-round grazing by (4) multiple herbivore species, and (5) avoid using antiparasitics.

Beta diversities of grassland birds indicate the importance of pastoralism for nature conservation of the Qinghai–Tibetan plateau

The post-2020 global biodiversity framework calls for a transformative change in food systems. Promoting agricultural multifunctionality is a viable approach to this sustainability transformation. The eastern Qinghai–Tibetan Plateau (QTP) is both one of the world’s largest livestock grazing systems and a hotspot of endemic birds in Asia. In this research, we aim to investigate the impact of livestock grazing on alpine bird assemblages at the local scale (alpha diversity) and their variation across the pastoral landscape (beta diversity). In the study area Nyanpo Yutse, we conducted surveys of 126 bird sample plots during two breeding seasons to acquire bird assemblage data. Meanwhile, we employed unmanned aerial vehicles to measure 2D and 3D habitat features within the 150-m radius. We investigated the key habitat variables driving the spatial distributions of both alpha and beta diversities of birds. Particularly, we partitioned beta diversity into its turnover and nestedness components and tested their patterns across sites of four levels of livestock grazing intensities (LGIs). Our results found no significant correlation between LGIs with species richness of birds, while 2D and 3D habitat complexity and built structure were positively correlated with alpha diversity (p &amp;lt; 0.05). At the landscape scale, pairwise LGI differences had no significant correlation (p &amp;gt; 0.05) with any pairwise beta diversity. The ordination plotting detected distinguished habitat preferences among 12 common birds and eight endemic birds. The multiple-site beta diversity of the 126 plots showed high species turnover (&amp;gt;0.871) where LGI was lower than 1.065 sheep units/ha, indicating the importance of moderate grazing for the conservation of diverse avian assemblages at the landscape scale. Our study demonstrated that extensive pastoralism is important for both maintaining the mosaic landscape and conserving avian biodiversity on the eastern QTP. We unveiled one of the ecological mechanisms through which synergies can be realized to support both agricultural production and biodiversity conservation in the Tibetan grazing system.

Formation mechanism of plant diversity in mechanical sand‐control technique‐implemented dunes in China

AbstractAlthough the influence of mechanical sand control techniques on vegetation on degraded sand dunes has received much attention for a long time, our understanding of the underlying processes of plant community formation is not yet strong. Analyses of trends in the turnover and nestedness components of beta diversity can be informative of the process of response to sand dune stabilization. In this study, we applied a field investigation of sand dunes at different stabilization stages in northern China. We then used Baselga's method to calculate total beta diversity and partition it into spatial turnover and nestedness to clarify the underlying community change processes. Our study indicated that the implementation of straw checkerboard techniques significantly increased the beta diversity of the community, leading to species heterogeneity. Species turnover was the main contributor to species beta diversity, and it was caused by high environmental heterogeneity with sand dune stabilization. The contribution of the nestedness component to beta diversity decreased with dune stabilization, indicating that with stabilization, dissimilarity was largely driven by variation in community composition rather than differences in taxonomic richness. This study provides insights into the underlying variation in species composition among sites where mechanical sand fixation engineering has been implemented and important guidelines for combating desertification.

Multifaceted fish diversities respond differently to impounding age and longitudinal location along a reservoir cascade

Damming usually modifies riverine habitats, which affects various aspects of fish diversity, especially in a reservoir cascade. Their influence on fish assemblage has been studied widely, but a lack of data from the diversity perspective remains. The Gezhouba Reservoir and Three Gorges Reservoir are two of the largest cascaded reservoirs located on the upper Yangtze River. In this study, we investigated the current fish assemblages in 2020∼2021 and retrieved 22 previous investigations in different sections of this cascade system to analyze how fish taxonomic, functional, and phylogenetic alpha- and beta-diversity change with the distance from the dams and the impounding age during 1998∼2021, and all sampling sites are located in the upper section of the dams. The total species richness and phylogenetic diversity increased significantly with the distance from the dams, but the functional diversity did not change substantially. No significant difference was found in the influence of impounding age on the three aspects of fish diversity. We observed a noticeable increase in non-indigenous fish species richness, functional diversity, and phylogenetic diversity over time, these effects were similar in areas at different distances from the dams. The species richness and phylogenetic diversity of lotic fish decreased from the lotic to lentic zones, whereas the functional and phylogenetic diversities decreased significantly with impounding age. The taxonomic beta-diversity was remarkably higher than the functional and phylogenetic beta-diversities. The differences among the three facets of beta-diversity were driven by a lower functional turnover than the taxonomic and phylogenetic turnovers, and their nestedness components were low without exception. The present study suggests that trade-offs should be considered when designing policies to protect fish diversity based on different objectives.

Changes in the abundance and species diversity of Collembola community along with dwarf bamboo density gradient in a mountainous temperate forest of Japan

Understory vegetation plays an important role in forest ecosystems by providing protection from soil physicochemical stresses or disturbance. Consequently, this type of vegetation may help maintain soil biodiversity and functions. However, the effects of understory degradation on soil faunal communities is not well understood. This study investigated the effects of the declining understory dwarf bamboo density in cool-temperate Japanese deciduous forests on the community composition of soil Collembola; by comparing partitioned community dissimilarity indices and trait components to detect the processes shaping community under understory degradation. For the species richness and diversity of Collembola community, unimodal quadratic model to dwarf bamboo density was selected as best model among all measured environmental properties, whereas, for Collembola abundance, linear negative relationship to dwarf bamboo density was selected as best model. For Collembola trait compositions, dwarf bamboo density model was not selected, although those of soil C and hardness were selected. The nestedness component in community dissimilarity increased with greater dwarf bamboo density differences between plots, whereas the replacement component was not significant. This suggests that the decreasing dwarf bamboo density might induce reduced niche space of whole Collembola community. In the range of mid to high density of dwarf bamboo, the higher density of dwarf bamboo declined the species diversity of the Collembola community, whereas the abundance still increased, probably because of the competitive exclusion by the dominant Folsomia octoculata under less disturbed habitat condition in high understory and litter coverage. Our results implied that the changes in the abundance and species diversity of Collembola community to understory density gradient were controlled both by abiotic niche reduction and biotic competitive exclusion without life-form trait selection.

Functional and taxonomic beta diversity of butterfly assemblages in an archipelago: relative importance of island characteristics, climate, and spatial factors

Islands host a disproportionate fraction of global biodiversity and provide ideal systems for investigating the factors affecting patterns of biodiversity. However, islands are also vulnerable systems and epicenters of biodiversity loss. Clarifying the processes that affect patterns of island biodiversity is important for achieving biodiversity conservation goals. Here, we studied the biodiversity of butterfly assemblages in Zhoushan Archipelago of China. Specifically, we evaluated i) whether functional and taxonomic beta diversity of butterfly communities provides complementary ecological insights; ii) the extent to which nestedness and turnover components contribute to total functional and taxonomic beta diversity; and iii) the relative contributions of island characteristics, spatial and climate factors to shaping functional and taxonomic beta diversity and its components. The contributions of the nestedness and turnover components to total taxonomic beta diversity were similar; by contrast, the relative contribution of the nestedness component to total functional beta diversity was much larger than that of the turnover component. A high nestedness component of both functional and taxonomic beta diversity reflected a nested spatial distribution of butterfly assemblages in Zhoushan Archipelago. Beta diversity decomposition and variation partitioning analysis (VPA) revealed that both functional and taxonomic beta diversity components provided complementary ecological insights. Taxonomic beta diversity and its turnover component were more strongly correlated with island isolation, while functional beta diversity and its turnover component were correlated more strongly with fine-scale spatial factors. VPA showed that island characteristics (e.g., perimeter-to-area ratio and isolation), climatic factors (e.g., temperature and precipitation), and broad-scale and some fine-scale spatial factors jointly contributed to shaping patterns of functional and taxonomic beta diversity of butterfly assemblages and their components. Lower functional beta diversity, especially low functional turnover, in our study indicated functional convergence. This was caused by the high abundance of dominant species. However, rare species can promote trait diversity, trait divergence, and convergence in functional biodiversity. Our study demonstrated that taxonomic and functional beta diversity can provide distinct insights into variation in butterfly communities. Island communities are affected by biogeographical, climate, and historical events. Studies of island communities that consider temporal variation in communities, including the effects of historical events, are needed to achieve a comprehensive understanding of patterns of biodiversity in island communities.

Pattern of β-Diversity and Plant Species Richness along Vertical Gradient in Northwest Himalaya, India.

Simple SummaryElevation has a significant impact on the distribution of plant species. However, the structure and distribution patterns of Himalayan vegetation are poorly explored, and research on species composition along an elevation gradient in these mountain ranges is still deficient. Plant species richness is supposed to diminish with altitude, although numerous scientists have found a peak in species richness at mid-elevation, yielding a humped relationship. Many studies along the Himalayan altitudinal gradients have been conducted in order to better understand large-scale biogeographical patterns as well as what drives them, but no clear pattern has emerged. In order to understand how elevation affects plant species, we focused on species diversity, species composition and β-diversity, which allow for the interpreting of different patterns along the elevations. It was found that all these components of diversity vary significantly with the change in altitude.The structure and distribution patterns of Himalayan vegetation are poorly explored, and research on species composition along the elevation gradient in these mountain ranges is still deficient. The current study was undertaken to analyze the variation and pattern of plant species composition along a vertical gradient in northwestern Himalaya, India. A total of 18 sites were selected along an elevation gradient ranging from 2200 to 3900 m asl positioned at an interval of 100 m. The Renyi diversity profile, non-metric multidimensional scaling based on the Bray–Curtis dissimilarity metric and beta diversity components among the elevation belts were calculated. Furthermore, to study the influence of altitude on species richness and diversity, a generalized additive model was created. Two hundred and ten plant species representing 66 families and 147 genera were recorded. The Renyi diversity profiles show that the lower and mid-altitudes had rich species diversity. The results of the non-metric multidimensional scaling analysis show a considerable variation in the total plant species composition among the studied elevation belts. The observed multiple-site Sorensen dissimilarity index across the studied elevation belts was very high. The contribution of species replacement or the turnover component to the observed dissimilarity was much higher than the nestedness component. Furthermore, the herbaceous and tree richness showed a significant decrease with increase in elevation; however, the richness of shrubs showed a bimodal pattern. The present study increases our understanding of the trends and patterns of species richness along the vertical gradient in the Himalayan region.

Dominated Taxonomic and Phylogenetic Turnover but Functional Nestedness of Wetland Bird Beta Diversity in North China

The decomposition of taxonomic, phylogenetic, and functional beta diversity into their turnover and nestedness components could provide novel insights into biodiversity conservation, e.g., provide implications for the Single Large Or Several Small reserves debate (SLOSS debate). Due to dramatic climate change and massive anthropogenic activities in recent decades in North China, the wetlands and the associated biodiversity in this region have declined significantly. This study applied the taxonomic, phylogenetic, and functional beta diversity decomposition for the first time in wetland bird communities in North China, aiming to propose scientific and comprehensive suggestions for bird diversity conservation in this region. A paired t-test was used to compare the differences between taxonomic, phylogenetic, and functional turnover, and their nestedness components. In addition, a spearman correlation analysis was used to assess the associations between each explanatory variable (differences in mean annual temperature and mean annual precipitation, as well as spatial distances) and each beta diversity index. A total of 546 bird species were found in 38 wetlands in North China, with three critically endangered species, 19 endangered species, 22 vulnerable species, and 61 near threatened species. The number of threatened species (critically endangered, endangered, and vulnerable) found in these lakes was about 30% of all threatened species in China. The results showed that taxonomic and phylogenetic beta diversity among wetland bird communities in North China was mainly dominated by turnover, while functional beta diversity was mainly dominated by nestedness. Importantly, the phylogenetic and functional results showed similar patterns even after controlling for the effects of taxonomic beta diversity. In addition, the taxonomic and phylogenetic turnover was more associated with both climate variables and spatial distances than other components. The contrasting patterns among the taxonomic, phylogenetic, and functional decompositions of wetland bird communities in North China indicate that distinctive conservation strategies should be considered for different biodiversity dimensions. Specifically, the conservation of taxonomic and phylogenetic bird diversity in this region should focus on multiple wetlands, while the conservation of bird functional diversity should focus on a single wetland with high functional diversity.

Climate change is expected to restructure forest frugivorous bird communities in a biodiversity hot‐point within the Atlantic Forest

AbstractAimChanges in climatic conditions are predicted to impact species distribution and hence alter their diversity patterns. Modifications in the composition of biological communities are expected as a result of the loss and replacement of species due to global warming. Forest frugivorous birds already suffer from habitat loss and may disappear locally due to suitable area contraction or range shifts to novel areas, disrupting seed dispersal and consequently the functioning of natural ecosystems. Here, we investigate the impacts of different climate scenarios on alpha and beta diversities of forest frugivorous birds.LocationCentral Corridor of the Atlantic Forest (CCAF), Brazil.MethodsWe used ecological niche models to project species distribution of 68 frugivorous birds for the baseline and future (2050 and 2070) scenarios. We generated binary maps of suitable areas for each species by climate scenario to calculate alpha and beta diversities.ResultsMost forest frugivorous birds were projected to lose suitable area, as a consequence of climate change, reducing alpha diversity in future scenarios and increasing temporal beta diversity, which is dominated by the nestedness component. In addition, species richness decreased from the east to the west portion of the CCAF, while differentiation of bird communities increased in the same direction, a pattern consistent across all climate scenarios evaluated.Main conclusionsClimate change may exert drastic alterations in the composition of frugivorous bird communities in the CCAF. As forest frugivorous birds are critical to seed dispersal of forest plant species, impoverishment of their communities can drastically affect forest regeneration, diversity, and structure in the decades to come. Therefore, a better comprehension of spatio‐temporal changes in diversity patterns of frugivorous birds can help us to avoid the disruption of seed dispersal and its consequences, such as cascading effects that will trigger biodiversity loss in the CCAF.

Effects of spatial distance and woody plant cover on beta diversity point to dispersal limitation as a driver of community assembly during postfire succession in a Mediterranean shrubland.

Beta diversity, and its components of turnover and nestedness, reflects the processes governing community assembly, such as dispersal limitation or biotic interactions, but it is unclear how they operate at the local scale and how their role changes along postfire succession. Here, we analyzed the patterns of beta diversity and its components in a herbaceous plant community after fire, and in relation to dispersal ability, in Central Spain. We calculated multiple‐site beta diversity (βSOR) and its components of turnover (βSIM) and nestedness (βSNE) of all herbaceous plants, or grouped by dispersal syndrome (autochory, anemochory, and zoochory), during the first 3 years after wildfire. We evaluated the relationship between pairwise beta diversity (βsor), and its components (βsim, βsne), and spatial distance or differences in woody plant cover, a proxy of biotic interactions. We found high multiple‐site beta diversity dominated by the turnover component. Community dissimilarity increased with spatial distance, driven mostly by the turnover component. Species with less dispersal ability (i.e., autochory) showed a stronger spatial pattern of dissimilarity. Biotic interactions with woody plants contributed less to community dissimilarity, which tended to occur through the nestedness component. These results suggest that dispersal limitation prevails over biotic interactions with woody plants as a driver of local community assembly, even for species with high dispersal ability. These results contribute to our understanding of postfire community assembly and vegetation dynamics.

Partitioning of beta-diversity reveals distinct assembly mechanisms of plant and soil microbial communities in response to nitrogen enrichment.

Nitrogen (N) deposition poses a serious threat to terrestrial biodiversity and alters plant and soil microbial community composition. Species turnover and nestedness reflect the underlying mechanisms of variations in community composition. However, it remains unclear how species turnover and nestedness contribute to different responses of taxonomic groups (plants and soil microbes) to N enrichment. Here, based on a 13‐year consecutive multi‐level N addition experiment in a semiarid steppe, we partitioned community β‐diversity into species turnover and nestedness components and explored how and why plant and microbial communities reorganize via these two processes following N enrichment. We found that plant, soil bacterial, and fungal β‐diversity increased, but their two components showed different patterns with increasing N input. Plant β‐diversity was mainly driven by species turnover under lower N input but by nestedness under higher N input, which may be due to a reduction in forb species, with low tolerance to soil Mn2+, with increasing N input. However, turnover was the main contributor to differences in soil bacterial and fungal communities with increasing N input, indicating the phenomenon of microbial taxa replacement. The turnover of bacteria increased greatly whereas that of fungi remained within a narrow range with increasing N input. We further found that the increased soil Mn2+ concentration was the best predictor for increasing nestedness of plant communities under higher N input, whereas increasing N availability and acidification together contributed to the turnover of bacterial communities. However, environmental factors could explain neither fungal turnover nor nestedness. Our findings reflect two different pathways of community changes in plants, soil bacteria, and fungi, as well as their distinct community assembly in response to N enrichment. Disentangling the turnover and nestedness of plant and microbial β‐diversity would have important implications for understanding plant–soil microbe interactions and seeking conservation strategies for maintaining regional diversity.