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139 results for “species turnover”

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Data from: Opportunistic data reveal widespread species turnover in Enallagma damselflies at biogeographical scales

An information tradeoff exists between systematic presence/absence surveys and purely opportunistic (presence-only) records for investigating the geography of community structure. Opportunistic species occurrence data may be of relatively limited quality, but typically involves numerous observations and species. Given the quality-quantity tradeoff, what can opportunistic data reveal about spatial patterns in community structure? Here we explore opportunistic data in describing geographic patterns of species composition, using over 4,600 occurrence records of Enallagma damselflies in the United States. We tested phylogenetic scale (genus level, Enallagma major clades, Enallagma subclades) and spatial extent (U.S. vs. watershed regions), hypothesizing that nonrandom structure is more likely at larger spatial extents. We also used three sets of systematic presence/absence surveys as a benchmark for validating opportunistic presence-only records. Null model analysis of matrix coherence and species replacements showed many cases of nonrandom structure and widespread species turnover. This outcome was repeated across spatial and environmental gradients and community composition scenarios. Turnover dominated across the U.S. and two watersheds spanning biogeographic boundaries, but random assemblages were prevalent in a third watershed with limited longitudinal extent. Turnover also pervaded each level of phylogeny. Opportunistic presence-only datasets showed identical patterns as systematic presence/absence datasets. These results indicate that extensive opportunistic data can be used to detect species turnover, especially at geographic scales where range margins are crossed.

opencc-zeroDec 2016View details →

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Data from: Evaluating temporal turnover in avian species richness in a Mediterranean semiarid region: different responses to elevation and forest cover

Aim. When studying the effects of global change on biodiversity, it is far more common for the effects of climate change and land-use changes to be assessed separately rather than jointly. However, the effects of land-use changes in recent decades on species richness in areas affected by climate change have been less studied. We assess the temporal turnover in species richness of an avian community between a historical period and a modern one as a consequence of global change. Location. Semiarid Mediterranean ecosystem (Southeastern Spain). Method. We fitted a hierarchical multi-species occupancy model for each period (1991-1992, and 2012-2017), obtaining avian species-specific estimates of occupancy probability in relation to environmental covariates (elevation and forest cover). We analyze the relationships between changes in the bird community and environmental variables, analysing the temporal turnover of the species richness and the richness-based species-exchange ratio. Results. The estimated species richness accounting for detectability was higher than observed species richness, and decreased in the more recent period. Following our hypotheses, we observed a dual pattern of species richness increase associated with different elevations, showing different species turnover rates due to the joint effects of climate change and land-use change. There is a trend toward greater species richness with higher elevations that is associated with climate change, where the species turnover rate is low. Also, species richness increased towards lower elevations, but with a high turnover rate. The latter can be due to species expansions throughout new habitat configurations in bordering forest systems associated with anthropic land-use changes. Conclusions. Our study is of great interest to understand the temporal turnover of avian species richness associated with areas experiencing both climate and land-use change.

opencc-zeroOct 2023View details →

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Incorporating plant phenological responses into species distribution models (SDMs) reduces estimates of future species loss and turnover

Anthropogenetic climate change has caused distribution shifts of many species, and species distribution models (SDMs) are central for documenting this relationship. However, most SDMs rarely consider the evolution of climate-sensitive functional traits, such as phenology, which strongly affect species fitness. Using >120,000 herbarium specimens representing 360 plant species across the eastern United States, we developed a novel "phenology-informed" SDM that integrates dynamic phenological responses to changing climates. Compared to standard SDMs, our phenology-informed SDMs forecast lower species habitat loss and less species turnover under climate change. These results suggest that phenotypic plasticity or local adaptation in phenology may help species adjust their ecological niches and persist in their habitats under rapid environmental change. Our findings reveal how phenology variation mediates species distributions and affects regional biodiversity patterns. Our newly developed model also circumvents the need for mechanistic models, facilitating the deployment of trait-based SDMs across unprecedented spatial and taxonomic scales.

opencc-zeroMar 2024View details →

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Nectar values from: Turnover in floral composition explains species diversity and temporal stability in the nectar supply of urban residential gardens

Residential gardens are a valuable habitat for insect pollinators worldwide, but differences in individual gardening practices substantially affect their floral composition. It is important to understand how the floral resource supply of gardens varies in both space and time so we can develop evidence-based management recommendations to support pollinator conservation in towns and cities. We surveyed 59 residential gardens in the city of Bristol, UK, at monthly intervals from March to October. For each of 472 garden surveys, we combined floral abundances with nectar sugar data to quantify the nectar production of each garden, investigating the magnitude, temporal stability, and diversity and composition of garden nectar supplies. We found that individual gardens differ markedly in the quantity of nectar sugar they supply (from 2 g to 1662 g), and nectar production is higher in more affluent neighbourhoods, but not in larger gardens. Nectar supply peaks in July (mid-summer), when more plant taxa are in flower, but temporal patterns vary among individual gardens. At larger spatial scales, temporal variability averages out through the portfolio effect, meaning insect pollinators foraging across many gardens in urban landscapes have access to a relatively stable and continuous supply of nectar through the year. Turnover in species composition among gardens leads to an extremely high overall plant richness, with 636 taxa recorded flowering. The nectar supply is dominated by non-natives, which provide 91% of all nectar sugar, while shrubs are the main plant life form contributing to nectar production (58%). Two thirds of nectar sugar is only available to relatively specialised pollinators, leaving just one third that is accessible to all. Synthesis and applications. By measuring nectar supply in residential gardens, our study demonstrates that pollinator-friendly management, affecting garden quality, is more important than the size of a garden, giving every gardener an opportunity to contribute to pollinator conservation in urban areas. For gardeners interested in increasing the value of their land to foraging pollinators we recommend planting nectar-rich shrubs with complementary flowering periods and prioritising flowers with an open structure in late summer and autumn.

opencc-zeroJan 2022View details →

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Data from: Turnover in floral composition explains species diversity and temporal stability in the nectar supply of urban residential gardens

opencc-zeroJan 2022View details →

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Fig. 1 in Species turnover between the northern and southern part of the South China Sea in the Elaphropeza Macquart mangrove fly communities of Hong Kong and Singapore (Insecta: Diptera: Hybotidae)

Fig. 1. Distribution of the Malaise traps around Hong Kong (map by C. Taylor and U. Chang).

opencc-by-4.0Sep 2019View details →

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The role of island physiography and oceanographic factors in shaping species richness and turnover of nesting seabird assemblages on islands across the southeastern Pacific

For seabirds, food supplies and nest sites are largely driven by oceanographic gradients and island habitats, respectively. Research into seabirds' ecological roles in insular ecosystems is crucial to understanding processes that structure seabird nesting assemblages. We examined the influence of island physiography and oceanographic factors on the spatial variation in α and β-diversity of nesting seabird assemblages. Location Southeastern Pacific Ocean. Taxon Birds Methods We compiled data from 53 seabirds breeding on 41 coastal and oceanic islands using different sources: our field records, online databases, environmental reports, and literature. We used generalized linear models (GLM) to describe the effect of island physiography (area, elevation, and isolation) and oceanographic factors (surface temperature, salinity, and primary productivity) on seabird species richness (α-diversity). We applied multivariate GLM to test the effects of physiographic and oceanographic predictors on species composition (β-diversity). We used Jaccard dissimilarities on species occurrences per island to calculate β-diversity partitioned into turnover and nestedness. Polynomial models allowed us to model these metrics against geographical and environmental gradients and so analyze patterns in seabird β-diversity across spatial scales. Results Species richness was highest in Galápagos, Pitcairn, and Rapa Nui. Changes in seabird α-diversity across islands were determined by island area and distance to South America but not by oceanographic variables. Physiographic and oceanographic factors were significant in determining β-diversity. Changes in β-diversity were mostly due to species replacement (β-turnover) across three major island Systems (Galápagos Archipelago, Chilean coastal islands, and oceanic islands of the southeastern Pacific). The contribution of β-nestedness was restricted to small scales (within archipelagos). Main conclusions Physiographic and oceanographic factors explain species diversity of seabird assemblages on islands of the southeastern Pacific. Oceanographic variables did not affect species richness but significantly influenced species composition. Change in species composition reflects gradients across three marine biogeographical realms: Temperate South, Eastern Indo-Pacific, and Tropical Eastern Pacific. The low degree of species nestedness may reflect multiple evolutionary origins.

opencc-zeroAug 2021View details →

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Data from: Low species turnover of upland Amazonian birds in the absence of physical barriers

Aim: One of the oldest and most powerful ways for ecologists to explain distinct biological communities is to invoke underlying environmental differences. But in hyper-diverse systems, which often display high species richness and low species abundance, these sorts of community comparisons are especially challenging. The classic view for Amazonian birds posits that riverine barriers and habitat specialization determine local and regional community composition. We test the tacit, complementary assumption that similar bird communities should therefore permeate uniform habitat between major rivers, regardless of distance. Location: Upland (terra firme) rainforests of central Amazonia. Results: In all, we detected 244 forest-dependent birds, with an average of 190 species (78%) per plot. Species turnover was negligible, no unique indicator species were found among plot pairs, and all documented species were already known from a complete inventory at one of the three sites. Main conclusions: Our study corroborates the classic biogeographical pattern and suggests that turnover contributes little to regional avian diversity within upland forests. Using a grain size of 100 ha, this implies that upland birds perceive the environment as uniform, at least over distances of ~60 km. Therefore, to maximize both local species richness and population persistence, our findings support the conservation of very large tracts of upland rainforest. Our analyses also revealed that the avifauna at Reserva Ducke, encroached by urban sprawl from the city of Manaus, shows the hallmarks of a disturbed community, with fewer vulnerable insectivores. This defaunation signals that even an enormous preserve (10 × 10 km) in lowland Amazonia is not insulated from anthropogenic degradation within the surrounding landscape.

opencc-zeroNov 2022View details →

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Mapping trait versus species turnover reveals spatiotemporal variation in functional redundancy and network robustness in a plant‐pollinator community

1. Functional overlap among species (redundancy) is considered important in shaping competitive and mutualistic interactions that determine how communities respond to environmental change. Most studies view functional redundancy as static, yet traits within species – which ultimately shape functional redundancy – can vary over seasonal or spatial gradients. We therefore have limited understanding of how trait turnover within and between species could lead to changes in functional redundancy or how loss of traits could differentially impact mutualistic interactions depending on where and when the interactions occur in space and time. 2. Using an Arctic bumblebee community as a case study, and 1,277 individual measures from 14 species over three annual seasons, we quantified how inter- and intraspecific body-size turnover compared to species turnover with elevation and over the season. Coupling every individual and their trait with a plant visitation, we investigated how grouping individuals by a morphological trait or by species identity altered our assessment of network structure and how this differed in space and time. Finally, we tested how the sensitivity of the network in space and time differed when simulating extinction of nodes representing either morphological trait similarity or traditional species groups. This allowed us to explore the degree to which trait-based groups increase or decrease interaction redundancy relative to species-based nodes. 3. We found that i) groups of taxonomically and morphologically similar bees turn over in space and time independently from each other, with trait turnover being larger over the season; ii) networks composed of nodes representing species versus morphologically similar bees were structured differently; and iii) simulated loss of bee trait groups caused faster coextinction of bumblebee species and flowering plants than when bee taxonomic groups were lost. Crucially, the magnitude of these effects varied in space and time, highlighting the importance of considering spatiotemporal context when studying the relative importance of taxonomic and trait contributions to interaction network architecture. 4. Our finding that functional redundancy varies spatiotemporally demonstrates how considering the traits of individuals within networks is needed to understand the impacts of environmental variation and extinction on ecosystem functioning and resilience.

opencc-zeroDec 2022View details →

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Data from: A case for the "Competitive exclusion – tolerance rule" as a general cause of species turnover along environmental gradients

Closely-related, ecologically-similar species often segregate their distributions along environmental gradients of time, space, and resources, but previous research suggests diverse underlying causes. Here, we review reciprocal removal studies in nature that experimentally test the role of interactions among species in determining their turnover along environmental gradients. We find consistent evidence for asymmetric exclusion coupled with differences in environmental tolerance causing the segregation of species pairs, where a dominant species excludes a subordinate from benign regions of the gradient, but is unable to tolerate challenging regions to which the subordinate species is adapted. Subordinate species were consistently smaller and performed better in regions of the gradient typically occupied by the dominant species compared to their native distribution. These results extend previous ideas contrasting competitive ability with adaptation to abiotic stress to include a broader diversity of species interactions (intraguild predation, reproductive interference) and environmental gradients, including gradients of biotic challenge. Collectively, these findings suggest that adaptation to environmental challenge compromises performance in antagonistic interactions with ecologically-similar species. The consistency of this pattern across diverse organisms, environments, and biomes suggests generalizable processes structuring the segregation of ecologically-similar species along disparate environmental gradients, a phenomenon that we propose should be named the Competitive exclusion – tolerance rule.

opencc-zeroDec 2022View details →

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Spatial genetic differentiation correlates with species assemblage turnover across tropical reef fish lineages

Aim: Evaluating the similarity of diversity patterns across micro- to macroevolutionary scales in natural communities, such as species-genetic diversity correlations (SGDC), may inform on processes shaping community assembly. However, whether SGDCs not only hold across communities but also across lineages has never been explored so far. Here we investigated SGDCs across co-distributed taxa for different spatial components (α, β, γ), and formally tested the influence of dispersal traits on β SGDCs. Location: Western Indian Ocean Time period: 2016–2017 Major taxa studied: Tropical reef fish species with contrasting dispersal traits Methods: Using ddRADseq single nucleotide polymorphism (SNP) data for 20 tropical reef fishes and distribution data of 2,446 species belonging to 12 families, we analysed the correlations between within-species genetic diversity and within-family species diversity (i.e., lineage diversity) for the three spatial components (α, β, γ SGDCs). We then related the strength of β-SGDCs per species to proxies of larval dispersal abilities. Results: We detected positive and significant lineage-based SGDC only for the β component, i.e., the families showing the greatest level of species turnover among sites contains the species with the greatest levels of genetic differentiation. We showed that the Monsoon drift mainly explained the β diversity patterns at both intraspecific and interspecific levels. Higher β-SGDCs were found for species with short pelagic larval duration and weak larval swimming capacity. Main conclusions: Our study reveals a strong correlation between genetic and species β diversity, a result explained by the presence of a 'soft' barrier and mediated by larval dispersal processes. This suggests that vicariance and dispersal limitation are major processes shaping β-diversity patterns from microevolutionary to macroevolutionary scales in tropical reef fishes.

opencc-zeroJan 2023View details →

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High species turnover and unique plant–pollinator interactions make a hyperdiverse mountain

1. We studied α- and β-diversity of pollinators, flowering plants, and plant–pollinator interactions along the altitudinal gradient of Mt. Olympus, a legendary mountain and biodiversity hotspot in Central Greece. 2. We explored ten study sites located on the north-eastern slope of the mountain, from 327 to 2,596 m a.s.l. Insect surveys were conducted once a month using hand netting (years 2013, 2014, and 2016), and they were combined with recordings of flowering plant diversity (species richness and flower cover). We then calculated α- and β-diversity of pollinators, plants in flower, and plant–pollinator interactions, and explored their demographic response along the altitudinal gradient. 3. Alpha‐diversity of pollinators, plants, and plant–pollinator interactions were altitude-dependent; α‐diversity of all pollinators, bees, non-bumblebee bees, bee flies, and butterflies showed linear declines with altitude, whereas those of hoverflies and bumblebees showed unimodal patterns. Beta-diversity and its turnover component of all pollinators, hoverflies, bees, bumblebees, non-bumblebee bees, butterflies, and plants showed linear increases, whereas those of bee flies and of plant–pollinator interactions varied independently from the pairwise altitudinal difference. 4. The high dissimilarity and uniqueness of pollination networks, which is probably a result of the high biodiversity and endemism of Mt. Olympus, is driven by species turnover and the formation of new interactions between new species. Contrasting to the monotonic decline of the remaining groups, the unimodal patterns of hoverfly and bumblebee α‐diversity are probably the effect of a higher tolerance of these groups to high-altitude environmental conditions. Our findings highlight that the high turnover of species and of pollination interactions along the altitudinal gradient is the mainstay of hyperdiverse mountains, a fact that conveys important historical, ecological, and conservational implications.

opencc-zeroFeb 2023View details →

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Revealing the drivers of parasite community assembly: using avian haemosporidians to model global dynamics of parasite species turnover

Why do some regions share more or fewer species than others? Community assembly relies on the ability of individuals to disperse, colonize, and thrive in new regions. Therefore, many distinct factors, such as geographic distance and environmental features, can determine the odds of a species colonizing a new environment. For parasites, host community composition (i.e., resources) also plays a key role in their ability to colonize a new environment as they rely on their hosts to complete their life cycle. Thus, variation in host community composition and environmental conditions should determine parasite turnover among regions. Here, we explored the global drivers of parasite turnover using avian malaria and malaria-like (haemosporidian) parasites. We compiled global databases on avian haemosporidian lineages distributions, environmental conditions, avian species distributions and functional traits and ran generalized dissimilarity models to uncover the main drivers of parasite turnover. We demonstrated that haemosporidian parasite turnover is mainly driven by geographic distance followed by host functional traits, environmental conditions, and host distributions. The main host functional traits associated with high parasite turnover were the predominance of resident (i.e., non-migratory) species and strong territoriality while the most important climatic drivers of haemosporidian turnover were mean temperature and temperature seasonality. Overall, we establish the importance of geographic distance as a key predictor of ecological dissimilarity and show that host resources influence parasite turnover more strongly than environmental conditions. We also evidenced that parasite turnover is most pronounced among tropical and less interconnected regions (i.e., regions with mostly territorial and non-migratory hosts). Our findings provide a robust foundation for the prediction of avian pathogen spread and the emergence of infectious diseases.

opencc-zeroFeb 2023View details →

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Data from: Chilean bee diversity: Contrasting patterns of species and phylogenetic turnover along a large-scale ecological gradient

Title of dataset Data from: Chilean bee diversity: Contrasting patterns of species and phylogenetic turnover along a large-scale ecological gradient Authors of dataset Leon Marshall1,2, John S. Ascher3, Cristian Villagra4, Amaury Beaugendre1, Valentina Herrera4, Patricia Henríquez-Piskulich4, Alejandro Vera5, Nicolas J. Vereecken1 <ol> <li>Agroecology Lab, Université libre de Bruxelles (ULB), Boulevard du Triomphe CP 264/2, B 1050 Brussels, Belgium</li> <li>Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands</li> <li>Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore</li> <li>Instituto de Entomología, Universidad Metropolitana de Ciencias de la Educación, Santiago, Región Metropolitana, Chile</li> <li>Departamento de Biología, Universidad Metropolitana de Ciencias de la Educación, Santiago, Región Metropolitana, Chile</li> </ol> Abstract Chile's isolation and varied climates have driven the evolution of a unique biodiversity with a high degree of endemism. As a result, Chile encompasses diverse environments, including the Mediterranean-type ecosystem, a global biodiversity hotspot. These environments are currently threatened by anthropogenic land use change impacting the integrity of local biomes and associated species. This area is the most intensively sampled of the country with high endemicity of native bee species. Characterising habitat requirements of bees is a pressing priority to safeguard these insects and the ecosystem services they provide. We investigated broad-scale patterns of bee (Hymenoptera: Apoidea: Anthophila) diversity using newly accessible expert-validated datasets comprising digitized specimen records from Chilean and US collections, and novel expert-validated type specimen data for the bees of Chile. We used a generalised dissimilarity modelling (GDM) approach to explore both compositional and phylogenetic β-diversity patterns across latitudinal, altitudinal, climate and habitat gradients in well-sampled bee assemblages in Central Chile. Using the GDM measures of increasing compositional and environmental dissimilarity we categorised and compared the most important drivers of these patterns and used them to classify 'wild bee ecoregions' (WBE) representing unique assemblages. Turnover of bee assemblages was explained primarily by latitudinal variation (proxy for climate) from south to north in Chile. However, temperature variations, precipitation and the presence of bare soil also significantly explained turnover in bee assemblages. In comparison, we observed less turnover in phylogenetic biodiversity corresponding to spatial gradients. We identified six de novo ecoregions (WBE), all with distinct taxa, endemic lineages, and representative species. The WBE represent distinct spatial classifications but have similarities to existing biogeographical classifications, ecosystems and bioclimatic zones. This approach establishes the baseline needed to prioritise bee species conservation efforts across this global biodiversity hotspot. We discuss the novelty of this classification considering previous biogeographical characterisations and their relevance in assessing conservation priorities for bee conservation. We argue that Chile's WBE highlight areas in need of funding for bee species surveys and description, distribution mapping and strengthening of conservation policies. Usage notes The dataset contains species occurrence data of chilean bees aggregated to a 5 x 5 km grid shapefile. The shapefile of the grid and the raster mask of the Central Chilean study area are also included. Finally, a database of type specimen data used to supplement the dataset is included here.  The code for the analysis can be found at: <a href="https://github.com/lmar116/ChileanBeeDiversity">https://github.com/lmar116/ChileanBeeDiversity</a>. Shapefiles, rasters, CSV files and code were all loaded and analyzed using R statistics software.  Four files are included: <ol> <li>Marshall-et-al-2023_Ecosphere_DataTable_bee_grid: contains all species occurrence data used in GDM analysis, Grid column refers to cl.5km.shp.</li> <li>cl.5km.shp (and associated files): 5 x 5 km grid shapefile of the Central Chilean study area</li> <li>chile.mask.tif: raster outline of the Central Chilean study area</li> <li>Marshall-et-al-2023_Ecosphere_CentralChileTypeSpecimens.xlsx: contains type specimen data used to supplement species occurrence dataset.</li> </ol>

openother-openApr 2023View details →

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Data for: Increases in functional diversity of mountain plant communities is mainly driven by species turnover under climate change

Warming in mountain regions is projected to be three times faster than the global average. Pronounced climate change will likely lead to species reshuffling in mountain plant communities and consequently change ecosystem resilience and functioning. Yet, little is known about the role of inter- versus intraspecific changes of plant traits and their consequences for functional richness and evenness of mountain plant communities under climate change. We performed a downslope translocation experiment of intact plant-soil mesocosms from an alpine pasture and a subalpine grassland in the Swiss and Austrian Alps to simulate an abrupt shift in climate and removal of dispersal barriers. Translocated plant communities experienced warmer and dryer climatic conditions. We found a considerable shift from resource conservative to resource acquisitive leaf-economy in the two climate change scenarios. However, shifts in leaf-economy were mainly attributable to species turnover, namely colonization by novel lowland species with trait expressions for a wider range of resource use. We also found an increase in vegetative height of the warmed and drought-affected alpine plant community, while trait plasticity to warming and drought was limited to few graminoid species of the subalpine plant community. Our results highlight the contrast between the strong competitive potential of novel lowland species in quickly occupying available niche space and native species' lack of both the intraspecific trait variability and the plant functional trait expressions needed to increase functional richness under warming and drought. This is particularly important for the trailing range of many mountain species (i.e. subalpine zone) where upward moving lowland species are becoming more abundant and abiotic climate stressors are likely to become more frequent in the near future. Our study emphasizes mountain plant communities' vulnerability to novel climates and biotic interactions under climate change and highlights graminoid species as potential winners of a warmer and dryer future.

opencc-zeroJul 2023View details →

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