Ecological Uniqueness Research Articles

Sequential decline in cyanobacterial, total prokaryotic, and eukaryotic responses to backward flow in a river connected to Lake Taihu

River ecosystems face escalating challenges due to altered flow regimes from human activities, such as urbanization with hydrological modifications. Understanding the role of microbial communities for ecosystems with changing flow regimes is still incomplete and remains at the frontier of aquatic microbial ecology. In particular, influences of riverine backward flow on the aquatic biota remain largely unknown. Therefore, we examined the impact of backward flow on the cyanobacterial, total prokaryotic, and eukaryotic communities in the Changdougang River, which naturally flows into Lake Taihu, through environmental DNA metabarcoding. We analyzed the differences in community diversity, assembly, and ecological network stability among groups under backward, weak, and forward flow direction conditions. Non-metric multidimensional scaling showed higher variations in communities of groups across flow direction conditions than seasonal groups. Variations in alpha and beta diversity showed that cyanobacterial and total prokaryotic communities experienced strong homogenization under backward flow conditions, whereas the ecological uniqueness of the eukaryotic community decreased. Assembly of the three flow-related communities was primarily governed by drift and dispersal limitation in stochastic processes. However, in the cyanobacterial community, homogeneous selection in deterministic processes increased from 22.79% to 42.86% under backward flow, aligning with trends observed in the checkerboard score (C-score). More importantly, the topological properties of ecological networks and the degree of average variation revealed higher stability in the cyanobacterial community compared to total prokaryotic and eukaryotic communities. Considering the variations in cohesion, the network stability in the cyanobacterial community decreased under backward flow. Our findings emphasize the distinct and sequentially diminishing responses of cyanobacterial, total prokaryotic, and eukaryotic communities to backward flowing rivers. This knowledge is crucial for maintaining ecological health of rivers, assessing the complex ecological impacts on hydrological engineering, and formulating sustainable water management strategies.

A macroecological analysis of ecological uniqueness of freshwater macrophyte assemblages across Europe and North America

Abstract Understanding spatial variation of species composition at different scales is essential for efficient conservation planning. Here, we investigate ecological uniqueness patterns of freshwater macrophyte assemblages at continental extents. We explored the similarities and differences in the patterns of ecological uniqueness between Europe and North America in relation to species richness and environmental variables using macrophyte presence–absence data in 50 × 50 km grid cells. To describe the ecological uniqueness of macrophyte assemblages, we used an index called ‘local contribution to beta diversity’ (LCBD). First, we used linear regression to evaluate the relationship between ecological uniqueness and species richness. Second, the variation of ecological uniqueness was modelled using environmental variables in generalized additive modelling (GAM). Third, boosted regression tree (BRT) analysis was performed with the same environmental variables to compare BRT results with the results from GAM. The results revealed relatively similar patterns of ecological uniqueness in both continents. The relationship between species richness and ecological uniqueness was overall negative but showed differences in the form and degree of the relationship between Europe and North America. The main driver of ecological uniqueness in both continents was mean annual temperature, with further effects associated with annual precipitation, elevation range, alkalinity and the proportion of freshwaters in a grid cell. Synthesis. Our results showed that species richness and ecological uniqueness may be negatively correlated at large spatial extents, and that the form of the relationship is likely to depend on the species richness profile of the area. The significant influence of climate on the ecological uniqueness of macrophyte assemblages suggests that changes in climate and land use may shape unique macrophyte assemblages. Thus, conservation strategies should consider protection measures, especially in the northern areas with unique macrophyte species assemblages, as they are expected to face many changes in the future. Identifying areas with high ecological uniqueness at different scales is important for efficient implementation of biodiversity conservation practices.

Fungi contribute more than bacteria to the ecological uniqueness of soil microbial communities in alpine meadows

Understanding the ecological uniqueness of soil bacterial and fungal communities and their driving factors can provide more targeted protection for soil microbial diversity. In this study, spatial multi-site sampling was conducted in a wide range of alpine meadows to reveal the patterns of ecological uniqueness of soil bacterial and fungal communities and the driving factors. The results showed that the soil fungal community contributed 62.3 % to the ecological uniqueness of the microbial community, compared to 37.7 % for bacteria, emphasizing the importance of protecting soil fungal diversity to maintain microbial diversity in the region. Soil bacterial diversity had a positive effect on ecological uniqueness, while fungi had an opposite pattern. Interactions of climate conditions, soil properties, plant and microbial diversity explain most of the variation in the ecological uniqueness of bacterial and fungal communities. Plant community played a key mediating role in maintaining the ecological uniqueness of soil bacterial and fungal communities in alpine meadows. This study proposed to maintain the diversity of soil microbial communities in alpine meadows by protecting sites with high ecological uniqueness of soil bacterial and fungal communities, and restoring sites with low ecological uniqueness.

Spatial patterns of coastal dune plant diversity reveal conservation priority hotspots in and out a network of protected areas

Effective conservation planning requires identifying priority hotspots to allocate resources. To preserve biodiversity, it is crucial to consider α, β and γ-diversity and protect the irreplaceable sites with high ecological uniqueness, which can host uncommon species assemblages that would be lost if only species-rich sites were protected. Coastal dunes, hosting highly specialized plant communities, are among the most threatened ecosystems worldwide. In this study, we identified conservation priority hotspots to assess the effectiveness of the network of protected areas in coastal dunes of Tuscany (central Italy), using data on plant communities collected in 506 plots. We additively partitioned γ-diversity in its α and β components, observing a significant variation at all spatial levels only for dune species. In terms of α-diversity, we found that Northern protected sites were richer in dune species, while synanthropic and alien species were equally present inside and outside protected areas of the region. By partitioning the total β-diversity into its components (replacement and richness difference), we found a prevalence of replacement for dune species, indicating the most unique sites as the ones to favor for conservation. Unique sites were identified through Local Contributions to Beta Diversity and their conservation value was determined by their species composition and the relationship with landscape variables. Unique sites with high conservation value were only partly protected, while some protected sites were altered and required restoration. Our approach proved effective for identifying the most unique sites, indicating some issues in the existing protected network, while providing valuable information on sites to prioritize for future conservation actions.

Multiple processes jointly determine ecological uniqueness across forest plant life‐forms in Northeast China

AbstractAimEcological uniqueness is an essential component of biodiversity. However, the mechanisms underlying patterns of ecological uniqueness remain unresolved. This study aims to assess the relative importance as well as interactive roles of four hypothesized processes (regional climate filtering, local environmental filtering, biotic heterogeneity and disturbance intensity [DI]) in shaping ecological uniqueness across three forest plant life‐forms (trees, shrubs and herbs) in a large temperate forest region.LocationNortheast China.MethodsWe quantified ecological uniqueness as abundance and incidence‐based local relative contributions to beta diversity (i.e. LCBD indices) in the study region. Multiple beta regression analyses and piecewise structural equation models were used to determine the relative direct and interactive effects of four processes in shaping ecological uniqueness across forest plant life‐forms.ResultsThe southern area of the region exhibited consistently greater LCBD values across plant life‐forms, highlighting its importance for conservation. All four processes jointly affected ecological uniqueness but their relative importance varied across plant life‐forms. Generally, regional climate had the dominant effect on tree LCBD while biotic heterogeneity was the most important process driving shrub and herb LCBDs. Local environmental filtering was less important in driving LCBD of all life‐forms. The significant direct effect of DI was only found in the herb group. Despite its weak direct effect, DI could indirectly shape tree and shrub LCBDs via biotic heterogeneity.Main ConclusionsOur study suggests that current patterns of ecological uniqueness (i.e. LCBD) across forest plant life‐forms result from multiple processes, with regional climate filtering and biotic heterogeneity having the strongest effects on uniqueness patterns across all life‐forms. Meanwhile, DI is more critical for shaping ecological uniqueness of herbs than trees or shrubs. We highlight the interactive roles of biotic and abiotic filtering in shaping biologically distinct communities important for biodiversity conservation.

Tree mycorrhizal associations determine how biodiversity, large trees, and environmental factors drive aboveground carbon stock in temperate forests

Biodiversity, large trees, and environmental conditions such as climate and soil have important effects on forest carbon stocks. However, recent studies in temperate forests suggest that the relative importance of these factors depends on tree mycorrhizal associations, whereby large-tree effects may be driven by ectomycorrhizal (EM) trees, diversity effects may be driven by arbuscular mycorrhizal (AM) trees, and environment effects may depend on differential climate and soil preferences of AM and EM trees. To test this hypothesis, we used forest-inventory data consisting of over 80,000 trees from 631 temperate-forest plots (30 m ​× ​30 ​m) across Northeast China to examine how biodiversity (species diversity and ecological uniqueness), large trees (top 1% of tree diameters), and environmental factors (climate and soil nutrients) differently regulate aboveground carbon stocks of AM trees, EM trees, and AM and EM trees combined (i.e. total aboveground carbon stock). We found that large trees had a positive effect on both AM and EM tree carbon stocks. However, biodiversity and environmental factors had opposite effects on AM vs. EM tree carbon stocks. Specifically, the two components of biodiversity had positive effects on AM tree carbon stocks, but negative effects on EM tree carbon stocks. Environmental heterogeneity (mean annual temperature and soil nutrients) also exhibited contrasting effects on AM and EM tree carbon stocks. Consequently, for the total carbon stock, the positive large-tree effect far surpasses the diversity and environment effect. This is mainly because when integrating AM and EM tree carbon stock into total carbon stock, the opposite diversity-effect (also environment-effect) on AM vs. EM tree carbon stock counteracts each other while the consistent positive large-tree effect on AM and EM tree carbon stock is amplified. In summary, this study emphasized a mycorrhizal viewpoint to better understand the determinants of overarching aboveground carbon profile across regional forests.

Taxonomic and functional diversity of subtidal benthic communities associated with hard substrates at Crozet archipelago (sub-Antarctic, Southern Ocean)

Sub-Antarctic coastal marine ecosystems harbor rich and diverse benthic communities. Despite their ecological uniqueness and vulnerability to global changes, studies on benthic communities remain limited. Using underwater video-imagery, we investigated the taxonomic and functional diversity of benthic communities associated with hard substrates at Baie du Marin (Ile de la Possession, Crozet archipelago). The Baie du Marin species richness and diversity were additively partitioned to evaluate spatial patterns of species through the following spatial scales: within images, among images within transects, and among transects. We analyzed imagery data from seven transects located at different sites inside Baie du Marin and covering contrasting natural rocky habitats and underwater artificial cable substrates. A total of 50 faunal (mainly represented by Echinodermata and Porifera phyla) and 14 algae (mainly represented by Rhodophyta phylum) taxa were identified. Rocky substrates were dominated by high densities of the polychaetes Parasabella sp. and Lanice marionensis, whereas submarine cables were dominated by high densities of the bivalve Kidderia sp. attached to macroalgae. Our results show contrasted distribution patterns in the faunal and algal assemblages within the Baie du Marin, with significant ecological differences between submarine cables and natural rocky substrates. Larger spatial scale (i.e., among transects) accounted for most of the bay richness and diversity, highlighting a high-level of habitat heterogeneity within the bay. Through a trait-based approach, our findings revealed that Crozet benthic communities are characterized by low functional richness, evenness, and redundancy, highlighting a potential vulnerability to current and future natural and anthropogenic changes. This study provides a novel bentho-ecological baseline for future assessments of natural and anthropogenic impacts on the marine environment of the Crozet archipelago; and for the conservation management of these remote habitats that make part of the French Southern Territories Marine Protected Area, recently inscribed on the UNESCO World Heritage list.

Eutrophication increases the similarity of cyanobacterial community features in lakes and reservoirs

Eutrophication of inland waters is a mostly anthropogenic phenomenon impacting aquatic biodiversity worldwide, and might change biotic community structure and ecosystem functions. However, little is known about the patterns of cyanobacterial community variations and changes both on alpha and beta diversity levels in response to eutrophication. Here, we investigated cyanobacterial communities sampled at 140 sites from 59 lakes and reservoirs along a strong eutrophication gradient in eastern China through using CPC-IGS and 16S rRNA gene amplicon sequencing. We found that taxonomic diversity increased, but phylogenetic diversity decreased significantly along the eutrophication gradient. Both niche width and niche overlap of cyanobacteria significantly decreased from low- to high-nutrient waterbodies. Cyanobacterial community distance-decay relationship became weaker from mesotrophic to hypereutrophic waterbodies, while ecological uniqueness (i.e., local contributions to beta diversity) tended to increase in high-nutrient waterbodies. Latitude and longitude were more important in shaping cyanobacterial community structure than other environmental variables. These findings suggest that eutrophication affects alpha and beta diversity of cyanobacterial communities, leading to increasingly similar community structures in lakes and reservoirs with a higher level of eutrophication. Our work highlights how cyanobacterial communities respond to anthropogenic eutrophication and calls for an urgent need to develop conservation and management strategies to control lake eutrophication and protect freshwater biodiversity.

Environmental correlates of aquatic macroinvertebrate diversity in garden ponds: Implications for pond management

Abstract Garden ponds are a ubiquitous feature of urban landscapes and have the potential to be an important resource for biodiversity. However, the environmental and spatial factors influencing ecological communities within garden ponds have been poorly quantified to date, despite such evidence being critical to the development of effective management strategies that support biodiversity. This study aims to identify the environmental and spatial factors influencing macroinvertebrate richness, abundance and compositional variation among garden ponds and provide management recommendations at the local and landscape scale. In total, 99 macroinvertebrate taxa were recorded from 30 garden ponds. A negative association was recorded between ecological uniqueness (measured as the Local Contribution to Beta‐Diversity) and taxonomic richness among the garden ponds, and those ponds with high ecological uniqueness typically displayed high replacement (turnover) values. Surface area, total plant richness and non‐native plant richness were positively associated with macroinvertebrate richness. Taxonomic richness and abundance predominantly displayed a negative association with conductivity levels. Current management practices for garden ponds are highly variable, often focussed on individual ponds. Based on the findings of this study, we recommend that management should focus on making garden pond surface areas as large as possible, ensure that there is a wide variety of native aquatic plant species present and manage conductivity levels. Garden ponds likely comprise a significant component of the urban freshwater network, and considering their management at both local and landscape scales will ensure that biotic communities inhabiting urban landscapes can be more effectively supported.

Controlling for the effects of environmental availability when testing how the environment determines community compositional uniqueness

Abstract Identifying the drivers that promote unique species compositions (i.e. ecological uniqueness) is crucial to understanding the mechanisms underpinning diversity patterns and for effective conservation planning. Environmental conditions are often sampled differentially in datasets, which can lead to rarer environments having unique species compositions, provided that environmental differences increase compositional differences. This effect, however, will be undesirable when a study aims to test the direct impact of environments rather than their availability. We developed an approach to reduce the effects of environmental availability in ecological uniqueness analyses through calculating expected pairwise compositional dissimilarities for each unique environmental condition. We further used simulations to assess the performance of our methods by randomly generating communities from two hypothetical environments with non‐overlapping species pools. Additionally, we used a dataset of 50 tree communities to demonstrate how environmental availability could impact relationships between environmental conditions and ecological uniqueness in empirical studies. Our simulations revealed that uniqueness metrics based on observed values are sensitive to environmental availability, while our approach correctly concluded that there were no differences among environments under the unbalanced design. Our analysis of tree communities produced divergent conclusions between the two approaches, as increasing slope reduced ecological uniqueness after controlling for their low availability in the dataset only. This suggests that low environmental availability inflated the ecological uniqueness of sites with high slope, which opposed its direct negative effects on ecological uniqueness, leading to a weak relationship based on observed values. To achieve a more mechanistic understanding of ecological uniqueness patterns, the effects of environmental availability must be considered. We recommend that studies use both uncorrected and corrected analyses to identify not only the direct effects of environmental conditions but also the degree to which their availability influences the observed relationships between ecological uniqueness and environment conditions. Our approach should be most necessary and applicable in unbalanced designs, which is a common characteristic in empirical studies.

Ecological uniqueness across multiple levels of biodiversity in a Chilean watershed

Ecological uniqueness across multiple levels of biodiversity in a Chilean watershed

Diversity of early flowering plants of the Ulytau mountains (Central Kazakhstan)

Early flowering plants (ephemers and ephemeroids) are an important component of the biosystem of steppes and deserts. These species form perennial pasture communities, for early grazing. The present work was conducted to evaluate the floristic checklist and ecological uniqueness of early flowering plants of Central Kazakhstan, in the forest-steppe regions of Em-Bulak region and Edige mountains, during 2021 and 2022. A total of 26 species of ephemers and ephemeroids were recorded, which belong to 16 families: Liliaceae – 3 species, Asteraceae – 3 species, Ranunculaceae – 3 species, Rosaceae – 3 species, Brassicaceae – 2 species, Boraginaceae – 2 species, the other families are represented by one species. According to ecomorphological characteristics: 8 species (31%) belong to the xerophyte group, 6 (23%) to the xeromesophyte group, 7 (27%) to the mesoxerophyte group and 5 (19%) to the mesophyte group. Also, as a result of our research we found two species of plants which are included in the Red Book of the Republic of Kazakhstan – Pulsatilla patens (L.) Mill. and Tulipa patens Agardh. ex Schult. f. The data obtained can be used for environmental monitoring and issues of rational nature management of wild plants of Central Kazakhstan.

Using plant community uniqueness and floristic quality assessment in management decision-making in an urban park setting

With the densification of cities, it is imperative to identify urban ecosystems that should be protected or restored. We aimed to determine the conservation and restoration needs in a large urban park (1,35 km2) in Quebec City (Canada), based on site history, current species richness, floristic uniqueness, and floristic quality assessment of its diverse ecosystems: forest, swamp, wooded peatland, open peatland, and marsh. We evaluated the cover of all vascular species in 70 plots (400 m2) and assessed 18 environmental variables. We found that forest and swamp plots were the richest while peatland plots were the poorest, with marsh plots showing intermediate values. Ecological uniqueness (LCBD) was not correlated with richness (ρ = 0.17; p > 0.05), with marsh and peatland plots showing the highest and lowest uniqueness, respectively. With a regression tree, we identified canopy openness as the most influential variable explaining plot uniqueness across all ecosystems, especially in the peatland, indicating that future recreational development should be avoided in open ecosystems. By plotting ecological uniqueness (LCBD) with tolerance to disturbance (Mean C) values, we identified areas that could benefit from conservation or restoration, and areas that could sustain future development for recreational use. For each area, floristic composition, site characteristics, and past land-use history were investigated further to identify appropriate actions. The open peatland was identified as the main conservation priority, but actions will be needed to limit rapid tree encroachment. Three marshes were identified as areas that would floristically benefit from restoration actions. Still, since they also act as natural retention basins hosting species adapted to the soil conditions, we suggested monitoring the expansion of exotic and invasive species. Approaches developed and lessons learned from this project will serve as guidelines for municipalities aiming to implement a restoration and management plan in urban parks.

Rainfall Influences the Patterns of Diversity and Species Distribution in Sandy Beaches of the Amazon Coast

The Amazon region is one of the Earth’s hotspots of biodiversity and has a pivotal role in climate regulation. Yet, little is known about its coastal biodiversity. Here, we performed the first assessment of macrobenthic diversity and ecological patterns of sandy beaches north of the Amazon River delta, the world’s largest freshwater input into the oceans. By assessing spatial and temporal changes in the soft-bottom biodiversity and environmental variables of three beaches (Goiabal, Nazaré, and Sumaúma) in the northernmost stretch of the Brazilian coast, we found low richness (14 taxa, overall; Goiabal: 3.27 ± 1.78; Nazaré: 2.34 ± 1.29; Sumaúma: 2 ± 0.67) and diversity (Goiabal: 0.72 ± 0.52; Nazaré: 0.62 ± 0.46; Sumaúma: 0.55 ± 0.39) across 2949 individuals with great dominance of estuarine species (notably Nephthys fluviatis and Sphaeromopsis mourei). Abundance was higher during rainy periods, and the same pattern was observed for richness and diversity in comparison to transitional periods, at least on Nazaré Beach. Environmental heterogeneity was reduced during rainy periods, resulting in a higher abundance of dominant species and lower beta diversity. Most species presented aggregated distribution at the upper intertidal zone, and changes in macrobenthic assemblages were linked to variations in rainfall and organic matter content in the sediment. Given the ecological uniqueness and the severe erosional process affecting the northern coast of the Amazon region, our results provide essential baseline knowledge to better understand the patterns and processes influencing its understudied biodiversity. We advocate that further studies expand our findings to support the conservation of this region.

Minimizing Data Waste: Conservation in the Big Data Era

Minimizing Data Waste: Conservation in the Big Data Era

Uncovering the dynamic evolution of microbes and n-alkanes: Insights from the Kuroshio Extension in the Northwest Pacific Ocean

Biomarkers offer unique insights into the state of the environment, but little is known about how they interact with microbial communities in the open ocean. This study investigated the correlative effects between microbial communities and n-alkane distribution in surface seawater and sediments from the Kuroshio Extension in the Northwest Pacific Ocean. The n-alkanes in both surface seawater and surface sediments were mostly derived from algae and higher plants, with some minor contributions from anthropogenic and biological sources. The composition of microbial communities in surface seawater and sediments was different. In surface seawater, the dominant taxa were Vibrio, Alteromonas, Clade_Ia, Pseudoalteromonas, and Synechococcus_CC9902, while the taxa in the sediments were mostly unclassified. These variations/fluctuations of n-alkanes in three areas caused the aggregation of specialized microbial communities (Alteromonas). As the characteristic composition indexes of two typical n-alkanes, Short-chain n-alkane carbon preference index (CPI-L) and long-chain n-alkane carbon preference index (CPI-H) significantly influenced the microbial community structure in surface seawater, but not in surface sediments. Effect of CPI on microbial communities may be attributed to anthropogenic inputs or petroleum pollution. The abundance of hydrocarbon degradation genes also varied across the three different areas. Our work underscores that n-alkanes in the oceans alter the microbial community structure and enrich associated degradation genes. The functional differences in microbial communities within different areas contribute to their ecological uniqueness.

Invasion by an exotic grass species homogenizes native freshwater plant communities

Abstract A growing body of evidence has shown that biological invasions cause shifts in species composition of communities in space and time. Although biological invasions are considered a major driver of biotic homogenisation worldwide, most previous studies were conducted at small spatial scales and over short time periods, which may have underestimated the impacts of exotic species on native communities. Using a unique dataset of aquatic plants sampled in 235 sites over 12 years (2007–2010 and 2015–2019) in a large reservoir (Itaipu Reservoir; 1350 km2), we analysed how the invasion of a non‐native grass Urochloa arrecta affects the species richness, ecological uniqueness (i.e. local contribution to beta diversity—LCBD) and temporal β–diversity of native plant communities. From 3934 surveyed plant communities, U. arrecta was recorded in 2888 samples and it was absent from 1046 samples. Overall, species richness and ecological uniqueness of native plant communities were markedly lower in sites invaded than non‐invaded by U. arrecta. From 2007 to 2019, the ecological uniqueness of native plants was 60% lower in the invaded than non‐invaded sites. Whereas in invaded sites species loss was the dominant process driving native communities over time, in non‐invaded sites gain of new native species was the primary process underlying community trajectories. Moreover, comparing native plant communities before and after the invasion of U. arrecta, species richness, ecological uniqueness and species gains of native plant communities decreased, whereas species losses increased after the invasion of U. arrecta. Finally, the positive relationship between native biodiversity and precipitation was stronger in non‐invaded than invaded sites. Synthesis. Our findings provide comprehensive evidence that an invasive plant is decreasing the spatial and temporal β–diversity of native plant communities through declining species richness, rather than simply correlating with them. This suggests that U. arrecta is driving native plants to become less diverse and homogeneous after the invasion, both spatially and temporally. Our findings illustrate that at broad scales, aquatic plant communities may become increasingly homogeneous with the increasing number of biological invasion events taking place worldwide.

The offshore Foraminifera of the Togean Islands, Tomini Gulf; distribution and ecological significance

The hydrological complexity, the gulf shape, and the undeveloped geological setting of the Togean Islands in the middle of the waters assembled the area to be such an interesting place to discover its ecological uniqueness. Foraminifera was widely used as proxies for various ecological aspects. Real time and retrospective studies of the vertical and horizontal distribution of foraminiferal communities on such waters are the reflection of many ecological factors in the area. The purpose of the Foraminiferal research on the offshore Togean Islands is to discover the ecological roles that directly and indirectly affect the characteristics of the vertical and horizontal distribution. The study was also referring various ecological aspects from previous studies at the research site. Sampling was carried out in September 2015 using the Baruna Jaya VIII RV in the Togean Islands waters, Tomini Gulf, through a gravity core. Foraminifera analysis was carried out at four core samples from the adjacent waters of four reef islands; Una-una, Pengempang, Togean, and Kalla at 5 m to 455 m water depths. Core samples of various lengths, from 8 cm to 34 cm were dominated by planktonic foraminifera. The dominance of planktonic taxa in reef waters indicates a robust oceanic influence to the reef islands. Upwelling events in several locations in the region as well as volcanic processes that are ongoing also play a role in the distribution of the bulk of planktonic taxa in the reef waters of Togean Islands.

The ecological uniqueness of plant communities and their determinants across the temperate deserts of China

The ecological uniqueness of plant communities and their determinants across the temperate deserts of China

Elevated pan traps optimise the sampling of bees, including when the availability of floral resources is high

Abstract To sample bee communities, a combination of methods is necessary, the most common being hand netting (HN) and pan traps (PT). However, there has been little exploration into how vertical distribution of PT can improve their sampling efficiency, also taking the temporal variation of floral resources into account. Here, we analysed the properties of bee communities sampled with PT at different heights (1.6 and 4.0 m) compared with PTs close to the ground, HN and large blue bucket trap (BB). In addition, we tested the effect of variation in the availability of floral resources on the performance of each method. Bees were collected in fragments of the Brazilian Caatinga. We captured 60 bee species with PTs, HN and BB, with significant increases in the sample coverage with elevated bowls (BB = 56.7%, HN = 60.0%, PT0.3 m = 23.3%, PT1.6 m = 36.7%, PT4.0 m = 50.0%). Elevating the bowls increased the sampling of bees with larger body size. Considering the three heights, PTs registered similar richness compared to HN and BB, but differed in the composition of species and ecological traits. When floral resource availability was greater, the abundance and richness of bees caught in PTs decreased, however, the elevated PT increased their ecological uniqueness (degree of uniqueness of the samples in terms of community composition). Thus, elevating PTs enables the capture of bees that forage at a specific height when floral resources increase. Our results highlight the importance of the vertical distribution of PT for sampling bees, since it improves their performance and its complementarity with other methods.