Biome: evolution of a crucial ecological and biogeographical concept

Seven ways to prevent biomism

Biomism, the pervasive prejudice, discrimination or antagonism against a given biome, highlights critical and overlooked dimensions of human behavior biases that have consequences for real-world conservation. Here, I propose seven ways to end biomism in educational, scientific and conservation arenas, including (1) the recognition and value of all biomes, (2) use of inclusive language that acknowledges diverse perspectives, (3) preventing research prioritization based on colonial legacies, (4) tailoring biome-specific conservation, management and restoration, (5) adapting legislation to embrace all biomes, (6) developing inclusive regulatory measures and (7) equalizing funding opportunities. Recognizing and addressing biases against specific biomes is essential for fostering a more inclusive and equitable approach to conservation arenas and abandoning long-standing prejudices rooted in colonial legacies, aesthetic preferences and utilitarian views of nature.

Biome evolution in subfamily Cercidoideae (Leguminosae): a tropical arborescent clade with a relictual depauperate temperate lineage

Some plant lineages remain within the same biome over time (biome conservatism), whereas others seem to adapt more easily to new biomes. The c. 398 species (14 genera) of subfamily Cercidoideae (Leguminosae or Fabaceae) are found in many biomes around the world, particularly in the tropical regions of South America, Asia and Africa, and display a variety of growth forms (small trees, shrubs, lianas and herbaceous perennials). Species distribution maps derived from cleaned occurrence records were compiled and compared with existing biome maps and with the literature to assign species to biomes. Rainforest (144 species), succulent (44 species), savanna (36 species), and temperate (10 species) biomes were found to be important in describing the global distribution of Cercidoideae, with many species occurring in more than one biome. Two phylogenetically isolated species-poor temperate (Cercis) and succulent (Adenolobus) biome lineages are sister to two broadly distributed species-rich tropical clades. Ancestral state reconstructions on a time-calibrated phylogeny suggest biome shifts occurred throughout the evolutionary history of the subfamily, with shifts between the succulent and rainforest biomes, from the rainforest to savanna, from the succulent to savanna biome, and one early occurring shift into (or from) the temperate biome. Of the 26 inferred shifts in biome, three are closely associated with a shift from the ancestral tree/shrub growth form to a liana or herbaceous perennial habit. Only three of the 13 inferred transcontinental dispersal events are associated with biome shifts. Overall, we find that biome shifts tend to occur within the same continent and that dispersals to new continents tend to occur within the same biome, but that nonetheless the biome-conserved and biogeographically structured Cercidoideae have been able to adapt to different environments through time.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40415-024-01058-z.

In defence of the entity of Macaronesia as a biogeographical region

Since its coinage ca. 1850 AD by Philip Barker Webb, the biogeographical region of Macaronesia, consisting of the North Atlantic volcanic archipelagos of the Azores, Madeira with the tiny Selvagens, the Canaries and Cabo Verde, and for some authors different continental coastal strips, has been under dispute. Herein, after a brief introduction on the terminology and purpose of regionalism, we recover the origins of the Macaronesia name, concept and geographical adscription, as well as its biogeographical implications and how different authors have positioned themselves, using distinct terrestrial or marine floristic and/or faunistic taxa distributions and relationships for accepting or rejecting the existence of this biogeographical region. Four main issues related to Macaronesia are thoroughly discussed: (i) its independence from the Mediterranean phytogeographical region; (ii) discrepancies according to different taxa analysed; (iii) its geographical limits and the role of the continental enclave(s), and, (iv) the validity of the phytogeographical region level. We conclude that Macaronesia has its own identity and a sound phytogeographical foundation, and that this is mainly based on three different floristic components that are shared by the Macaronesian core (Madeira and the Canaries) and the outermost archipelagos (Azores and Cabo Verde). These floristic components are: (i) the Palaeotropical-Tethyan Geoflora, formerly much more widely distributed in Europe and North Africa and currently restricted to the three northern archipelagos (the Azores, Madeira and the Canaries); (ii) the African Rand Flora, still extant in the coastal margins of Africa and Arabia, and present in the southern archipelagos (Madeira, the Canaries and Cabo Verde), and (iii) the Macaronesian neoendemic floristic component, represented in all the archipelagos, a result of allopatric diversification promoted by isolation of Mediterranean ancestors that manage to colonize Central Macaronesia and, from there, the outer archipelagos. Finally, a differentiating floristic component recently colonized the different archipelagos from the nearest continental coast, providing them with different biogeographic flavours.

Macroecology of Abiotic Stress Tolerance in Woody Plants of the Northern Hemisphere: Tolerance Biomes and Polytolerance Hotspots

Understanding the main ecological constraints on plants' adaptive strategies to tolerate multiple abiotic stresses is a central topic in plant ecology. We aimed to uncover such constraints by analysing how the interactions between climate, soil features and species functional traits co-determine the distribution and diversity of stress tolerance strategies to drought, shade, cold and waterlogging in woody plants of the Northern Hemisphere. Functional traits and soil fertility predominantly determined drought and waterlogging/cold tolerance strategies, while climatic factors strongly influenced shade tolerance. We describe the observed patterns by defining 'stress tolerance biomes' and 'polytolerance hotspots', that is, geographic regions where woody plant assemblages have converged to specific tolerance strategies and where the coexistence of multiple tolerance strategies is frequent. The depiction of these regions provides the first macroecological overview of the main environmental and functional requirements underlying the ecological limits to the diversity of abiotic stress tolerance strategies in woody plants.

A Phylogenetic Model of Established and Enabled Biome Shifts

Where each species actually lives is distinct from where it could potentially survive and persist. This suggests that it may be important to distinguish established from enabled biome affinities when considering how ancestral species moved and evolved among major habitat types. We introduce a new phylogenetic method, called RFBS, to model how anagenetic and cladogenetic events cause established and enabled biome affinities (or, more generally, other discrete realized versus fundamental niche states) to shift over evolutionary timescale. We provide practical guidelines for how to assign established and enabled biome affinity states to extant taxa, using the flowering plant clade Viburnum as a case study. Through a battery of simulation experiments, we show that RFBS performs well, even when we have realistically imperfect knowledge of enabled biome affinities for most analyzed species. We also show that RFBS reliably discerns established from enabled affinities, with similar accuracy to standard competing models that ignore the existence of enabled biome affinities. Lastly, we apply RFBS to Viburnum to infer ancestral biomes throughout the tree and to highlight instances where repeated shifts between established affinities for warm and cold temperate forest biomes were enabled by a stable and slowly-evolving enabled affinity for both temperate biomes.

Ecotones as Windows into Organismal-to-Biome Scale Responses across Neotropical Forests

Tropical forests are incredibly diverse in structure and function. Despite, or perhaps because of, this diversity, tropical biologists often conduct research exclusively in one or perhaps a few forest types. Rarely do we study the ecotone-the interstitial region between forest types. Ecotones are hyper-diverse, dynamic systems that control the flow of energy and organisms between adjacent ecosystems, with their locations determined by species' physiological limits. In this review, we describe how studying ecotones can provide key indicators for monitoring the state of Neotropical forests from organisms to ecosystems. We first describe how ecotones have been studied in the past and summarize our current understanding of tropical ecotones. Next, we provide three example lines of research focusing on the ecological and evolutionary dynamics of the ecotone between tropical dry forests and desert; between tropical dry and rainforests; and between Cerrado and Atlantic rainforests, with the latter being a particularly well-studied ecotone. Lastly, we outline methods and tools for studying ecotones that combine remote sensing, new statistical techniques, and field-based forest dynamics plot data, among others, for understanding these important systems.

Fire-modulated fluctuations in nutrient availability stimulate biome-scale floristic turnover in time, and elevated species richness, in low-nutrient fynbos heathland

BACKGROUND AND AIMS

In many systems, postfire vegetation recovery is characterized by temporal changes in plant species composition and richness. We attribute this to changes in resource availability with time since fire, with the magnitude of species turnover determined by the degree of resource limitation. Here, we test the hypothesis that postfire species turnover in South African fynbos heathland is powered by fire-modulated changes in nutrient availability, with the magnitude of turnover in nutrient-constrained fynbos being greater than in fertile renosterveld shrubland. We also test the hypothesis that floristic overlaps between fynbos and renosterveld are attributable to nutritional augmentation of fynbos soils immediately after fire.

METHODS

We use vegetation survey data from two sites on the Cape Peninsula to compare changes in species richness and composition with time since fire.

KEY RESULTS

Fynbos communities display a clear decline in species richness with time since fire, whereas no such decline is apparent in renosterveld. In fynbos, declining species richness is associated with declines in the richness of plant families having high foliar concentrations of nitrogen, phosphorus and potassium and possessing attributes that are nutritionally costly. In contrast, families that dominate late-succession fynbos possess adaptations for the acquisition and retention of sparse nutrients. At the family level, recently burnt fynbos is compositionally more similar to renosterveld than is mature fynbos.

CONCLUSIONS

Our data suggest that nutritionally driven species turnover contributes significantly to fynbos community richness. We propose that the extremely low baseline fertility of fynbos soils serves to lengthen the nutritional resource axis along which species can differentiate and coexist, thereby providing the opportunity for low-nutrient extremophiles to coexist spatially with species adapted to more fertile soil. This mechanism has the potential to operate in any resource-constrained system in which episodic disturbance affects resource availability.

Reassessment of the risks of climate change for terrestrial ecosystems

Forecasting the risks of climate change for species and ecosystems is necessary for developing targeted conservation strategies. Previous risk assessments mapped the exposure of the global land surface to changes in climate. However, this procedure is unlikely to robustly identify priority areas for conservation actions because nonlinear physiological responses and colimitation processes ensure that ecological changes will not map perfectly to the forecast climatic changes. Here, we combine ecophysiological growth models of 135,153 vascular plant species and plant growth-form information to transform ambient and future climatologies into phytoclimates, which describe the ability of climates to support the plant growth forms that characterize terrestrial ecosystems. We forecast that 33% to 68% of the global land surface will experience a significant change in phytoclimate by 2070 under representative concentration pathways RCP 2.6 and RCP 8.5, respectively. Phytoclimates without present-day analogue are forecast to emerge on 0.3-2.2% of the land surface and 0.1-1.3% of currently realized phytoclimates are forecast to disappear. Notably, the geographic pattern of change, disappearance and novelty of phytoclimates differs markedly from the pattern of analogous trends in climates detected by previous studies, thereby defining new priorities for conservation actions and highlighting the limits of using untransformed climate change exposure indices in ecological risk assessments. Our findings suggest that a profound transformation of the biosphere is underway and emphasize the need for a timely adaptation of biodiversity management practices.

Vrba was right: Historical climate fragmentation, and not current climate, explains mammal biogeography

Climate plays a crucial role in shaping species distribution and evolution over time. Dr Vrba's Resource-Use hypothesis posited that zones at the extremes of temperature and precipitation conditions should host a greater number of climate specialist species than other zones because of higher historical fragmentation. Here, we tested this hypothesis by examining climate-induced fragmentation over the past 5 million years. Our findings revealed that, as stated by Vrba, the number of climate specialist species increases with historical regional climate fragmentation, whereas climate generalist species richness decreases. This relationship is approximately 40% stronger than the correlation between current climate and species richness for climate specialist species and 77% stronger for generalist species. These evidences suggest that the effect of climate historical fragmentation is more significant than that of current climate conditions in explaining mammal biogeography. These results provide empirical support for the role of historical climate fragmentation and physiography in shaping the distribution and evolution of life on Earth.

Biogeographical ‍distributions of trickster animals

Human language encompasses almost endless potential for meaning, and folklore can theoretically incorporate themes beyond time and space. However, actual distributions of the themes are not always universal and their constraints remain unclear. Here, we specifically focused on zoological folklore and aimed to reveal what restricts the distribution of trickster animals in folklore. We applied the biogeographical methodology to 16 taxonomic categories of trickster (455 data) and real (93 090 848 data) animals obtained from large databases. Our analysis revealed that the distribution of trickster animals was restricted by their presence in the vicinity and, more importantly, the presence of their corresponding real animals. Given that the distributions of real animals are restricted by the annual mean temperature and annual precipitation, these climatic conditions indirectly affect the distribution of trickster animals. Our study, applying biogeographical methods to culture, paves the way to a deeper understanding of the interactions between ecology and culture.

Fossil-informed biogeographic analysis suggests Eurasian regionalization in crown Squamata during the early Jurassic

Background

Squamata (lizards, snakes, and amphisbaenians) is a Triassic lineage with an extensive and complex biogeographic history, yet no large-scale study has reconstructed the ancestral range of early squamate lineages. The fossil record indicates a broadly Pangaean distribution by the end- Cretaceous, though many lineages (e.g., Paramacellodidae, Mosasauria, Polyglyphanodontia) subsequently went extinct. Thus, the origin and occupancy of extant radiations is unclear and may have been localized within Pangaea to specific plates, with potential regionalization to distinct Laurasian and Gondwanan landmasses during the Mesozoic in some groups.

Methods

We used recent tectonic models to code extant and fossil squamate distributions occurring on nine discrete plates for 9,755 species, with Jurassic and Cretaceous fossil constraints from three extinct lineages. We modeled ancestral ranges for crown Squamata from an extant-only molecular phylogeny using a suite of biogeographic models accommodating different evolutionary processes and fossil-based node constraints from known Jurassic and Cretaceous localities. We hypothesized that the best-fit models would not support a full Pangaean distribution (i.e., including all areas) for the origin of crown Squamata, but would instead show regionalization to specific areas within the fragmenting supercontinent, likely in the Northern Hemisphere where most early squamate fossils have been found.

Results

Incorporating fossil data reconstructs a localized origin within Pangaea, with early regionalization of extant lineages to Eurasia and Laurasia, while Gondwanan regionalization did not occur until the middle Cretaceous for Alethinophidia, Scolecophidia, and some crown Gekkotan lineages. While the Mesozoic history of extant squamate biogeography can be summarized as a Eurasian origin with dispersal out of Laurasia into Gondwana, their Cenozoic history is complex with multiple events (including secondary and tertiary recolonizations) in several directions. As noted by previous authors, squamates have likely utilized over-land range expansion, land-bridge colonization, and trans-oceanic dispersal. Tropical Gondwana and Eurasia hold more ancient lineages than the Holarctic (Rhineuridae being a major exception), and some asymmetries in colonization (e.g., to North America from Eurasia during the Cenozoic through Beringia) deserve additional study. Future studies that incorporate fossil branches, rather than as node constraints, into the reconstruction can be used to explore this history further.

Multiple drivers of functional diversity in temperate forest understories: Climate, soil, and forest structure effects

In macroecology, shifting from coarse- to local-scale explanatory factors is crucial for understanding how global change impacts functional diversity (FD). Plants possess diverse traits allowing them to differentially respond across a spectrum of environmental conditions. We aim to assess how macro- to microclimate, stand-scale measured soil properties, forest structure, and management type, influence forest understorey FD at the macroecological scale. Our study covers Italian forests, using thirteen predictors categorized into climate, soil, forest structure, and management. We analyzed five traits (i.e., specific leaf area, plant size, seed mass, belowground bud bank size, and clonal lateral spread) capturing independent functional dimensions to calculate the standardized effect size of functional diversity (SES-FD) for all traits (multi-trait) and for single traits. Multiple regression models were applied to assess the effect of predictors on SES-FD. We revealed that climate, soil, and forest structure significantly drive SES-FD of specific leaf area, plant size, seed mass, and bud bank. Forest management had a limited effect. However, differences emerged between herbaceous and woody growth forms of the understorey layer, with herbaceous species mainly responding to climate and soil features, while woody species were mainly affected by forest structure. Future warmer and more seasonal climate could reduce the diversity of resource economics, plant size, and persistence strategies of the forest understorey. Soil eutrophication and acidification may impact the diversity of regeneration strategies; canopy closure affects the diversity of above- and belowground traits, with a larger effect on woody species. Multifunctional approaches are vital to disentangle the effect of global changes on functional diversity since independent functional specialization axes are modulated by different drivers.

The evolution of ephemeral flora in Xinjiang, China: insights from plastid phylogenomic analyses of Brassicaceae

BACKGROUND

The ephemeral flora of northern Xinjiang, China, plays an important role in the desert ecosystems. However, the evolutionary history of this flora remains unclear. To gain new insights into its origin and evolutionary dynamics, we comprehensively sampled ephemeral plants of Brassicaceae, one of the essential plant groups of the ephemeral flora.

RESULTS

We reconstructed a phylogenetic tree using plastid genomes and estimated their divergence times. Our results indicate that ephemeral species began to colonize the arid areas in north Xinjiang during the Early Miocene and there was a greater dispersal of ephemeral species from the surrounding areas into the ephemeral community of north Xinjiang during the Middle and Late Miocene, in contrast to the Early Miocene or Pliocene periods.

CONCLUSIONS

Our findings, together with previous studies, suggest that the ephemeral flora originated in the Early Miocene, and species assembly became rapid from the Middle Miocene onwards, possibly attributable to global climate changes and regional geological events.

The contribution of plant life and growth forms to global gradients of vascular plant diversity

Plant life and growth forms (shortened to 'plant forms') represent key functional strategies of plants in relation to their environment and provide important insights into the ecological constraints acting on the distribution of biodiversity. Despite their functional importance, how the spectra of plant forms contribute to global gradients of plant diversity is unresolved. Using a novel dataset comprising > 295 000 species, we quantify the contribution of different plant forms to global gradients of vascular plant diversity. Furthermore, we establish how plant form distributions in different biogeographical regions are associated with contemporary and paleoclimate conditions, environmental heterogeneity and phylogeny. We find a major shift in representation of woody perennials in tropical latitudes to herb-dominated floras in temperate and boreal regions, following a sharp latitudinal gradient in plant form diversity from the tropics to the poles. We also find significant functional differences between regions, mirroring life and growth form responses to environmental conditions, which is mostly explained by contemporary climate (18-87%), and phylogeny (6-62%), with paleoclimate and heterogeneity playing a lesser role (< 23%). This research highlights variation in the importance of different plant forms to diversity gradients world-wide, shedding light on the ecological and evolutionary pressures constraining plant-trait distributions.

Biomes of the world under climate change scenarios: increasing aridity and higher temperatures lead to significant shifts in natural vegetation

The global potential distribution of biomes (natural vegetation) was modelled using 8,959 training points from the BIOME 6000 dataset and a stack of 72 environmental covariates representing terrain and the current climatic conditions based on historical long term averages (1979-2013). An ensemble machine learning model based on stacked regularization was used, with multinomial logistic regression as the meta-learner and spatial blocking (100 km) to deal with spatial autocorrelation of the training points. Results of spatial cross-validation for the BIOME 6000 classes show an overall accuracy of 0.67 and R²_logloss of 0.61, with "tropical evergreen broadleaf forest" being the class with highest gain in predictive performances (R²_logloss = 0.74) and "prostrate dwarf shrub tundra" the class with the lowest (R²_logloss = -0.09) compared to the baseline. Temperature-related covariates were the most important predictors, with the mean diurnal range (BIO2) being shared by all the base-learners (i.e.,random forest, gradient boosted trees and generalized linear models). The model was next used to predict the distribution of future biomes for the periods 2040-2060 and 2061-2080 under three climate change scenarios (RCP 2.6, 4.5 and 8.5). Comparisons of predictions for the three epochs (present, 2040-2060 and 2061-2080) show that increasing aridity and higher temperatures will likely result in significant shifts in natural vegetation in the tropical area (shifts from tropical forests to savannas up to 1.7 ×10⁵ km² by 2080) and around the Arctic Circle (shifts from tundra to boreal forests up to 2.4 ×10⁵ km² by 2080). Projected global maps at 1 km spatial resolution are provided as probability and hard classes maps for BIOME 6000 classes and as hard classes maps for the IUCN classes (six aggregated classes). Uncertainty maps (prediction error) are also provided and should be used for careful interpretation of the future projections.

Ecological barriers mediate spatiotemporal shifts of bird communities at a continental scale

Species' range shifts and local extinctions caused by climate change lead to community composition changes. At large spatial scales, ecological barriers, such as biome boundaries, coastlines, and elevation, can influence a community's ability to shift in response to climate change. Yet, ecological barriers are rarely considered in climate change studies, potentially hindering predictions of biodiversity shifts. We used data from two consecutive European breeding bird atlases to calculate the geographic distance and direction between communities in the 1980s and their compositional best match in the 2010s and modeled their response to barriers. The ecological barriers affected both the distance and direction of bird community composition shifts, with coastlines and elevation having the strongest influence. Our results underscore the relevance of combining ecological barriers and community shift projections for identifying the forces hindering community adjustments under global change. Notably, due to (macro)ecological barriers, communities are not able to track their climatic niches, which may lead to drastic changes, and potential losses, in community compositions in the future.

Iterative mapping of marine ecosystems for spatial status assessment, prioritization, and decision support

South Africa has taken an iterative approach to marine ecosystem mapping over 18  years that has provided a valuable foundation for ecosystem assessment, planning and decision-making, supporting improved ecosystem-based management and protection. Iterative progress has been made in overcoming challenges faced by developing countries, especially in the inaccessible marine realm. Our aim is to report on the approach to produce and improve a national marine ecosystem map to guide other countries facing similar challenges, and to illustrate the impact of even the simplest ecosystem map. South Africa has produced four map versions, from a rudimentary map of 34 biozones informed by bathymetry data, to the latest version comprising 163 ecosystem types informed by 83 environmental and biodiversity datasets that aligns with the IUCN Global Ecosystem Typology. Data were unlocked through academic and industry collaborations; multi-disciplinary, multi-realm and multi-generational networks of practitioners; and targeted research to address key gaps. To advance toward a more transparent, reproducible and data-driven approach, limitations, barriers and opportunities for improvement were identified. Challenges included limited human and data infrastructure capacity to collate, curate and assimilate many data sources, covering a variety of ecosystem components, methods and scales. Five key lessons that are of relevance for others working to advance ecosystem classification and mapping, were distilled. These include (1) the benefits of iterative improvement; (2) the value of fostering relationships among a co-ordinated network of practitioners including early-career researchers; (3) strategically prioritizing and leveraging resources to build and curate key foundational biodiversity datasets and understand drivers of biodiversity pattern; (4) the need for developing, transferring and applying capacity and tools that enhance data quality, analytical workflows and outputs; and (5) the application of new technology and emerging statistical tools to improve the classification and prediction of biodiversity pattern. South Africa’s map of marine ecosystem types has been successfully applied in spatial biodiversity assessment, prioritization to support protected area expansion and marine spatial planning. These successes demonstrate the value of a co-ordinated network of practitioners who continually build an evidence base and iteratively improve ecosystem mapping while simultaneously growing ecological knowledge and informing changing priorities and policy.

Temperature predicts maximum tree-species richness and water availability and frost shape the residual variation

The kinetic hypothesis of biodiversity proposes that temperature is the main driver of variation in species richness, given its exponential effect on biological activity and, potentially, on rates of diversification. However, limited support for this hypothesis has been found to date. I tested the fit of this model to the variation of tree-species richness along a continuous latitudinal gradient in the Americas. I found that the kinetic hypothesis accurately predicts the upper bound of the relationship between the inverse of mean annual temperature (1/kT) and the natural logarithm of species richness, at a broad scale. In addition, I found that water availability and the number of days with freezing temperatures explain part of the residual variation of the upper bound model. The finding of the model fitting on the upper bound rather than on the mean values suggest that the kinetic hypothesis is modeling the variation of the potential maximum species richness per unit of temperature. Likewise, the distribution of the residuals of the upper bound model in function of the number of days with freezing temperatures suggest the importance of environmental thresholds rather than gradual variation driving the observable variation in species richness.

Forest bathing and hiking benefits for mental health during the COVID-19 pandemic in Mediterranean regions

Forest bathing (FB) has evidenced positive effects on individuals' mental health and well-being, but its benefits have mainly been studied in Asian biomes. The present study aimed to evaluate whether its benefits are also generalisable to other forests and biomes of the world, such as the Mediterranean. Eighty-six healthy adults of the general population were assessed before and after a FB near Barcelona (Spain) during the COVID-19 pandemic. A control-hiking group of participants was also analysed to contrast the FB effects on anxiety, affect, mood states and mindfulness. Results show that the guided practice of FB in Mediterranean-Catalan forests increases mindfulness states and positive affect and reduces anxiety and negative affect, with effect sizes being large to very large. Hiking also induced significant changes in all variables tested, but FB showed higher effect sizes. An exploratory analysis also revealed a different profile of the FB participants compared to the hiking practitioners, being highly educated women living in urban areas and with lower basal levels of psychological well-being. Accordingly, it is concluded that both Mediterranean FB and hiking (to a lesser degree) might be cost-effective strategies to promote and restore psychological well-being after the COVID-19 pandemic and to promote sustainable tourism in Mediterranean biomes of the European forested and protected areas.

Toward a forest biomass reference measurement system for remote sensing applications

Forests contribute to climate change mitigation through carbon storage and uptake, but the extent to which this carbon pool varies in space and time is still poorly known. Several Earth Observation missions have been specifically designed to address this issue, for example, NASA's GEDI, NASA-ISRO's NISAR and ESA's BIOMASS. Yet, all these missions' products require independent and consistent validation. A permanent, global, in situ, site-based forest biomass reference measurement system relying on ground data of the highest possible quality is therefore needed. Here, we have assembled a list of almost 200 high-quality sites through an in-depth review of the literature and expert knowledge. In this study, we explore how representative these sites are in terms of their coverage of environmental conditions, geographical space and biomass-related forest structure, compared to those experienced by forests worldwide. This work also aims at identifying which sites are the most representative, and where to invest to improve the representativeness of the proposed system. We show that the environmental coverage of the system does not seem to improve after at least the 175 most representative sites are included, but geographical and structural coverages continue to improve as more sites are added. We highlight the areas of poor environmental, geographical, or structural coverage, including, but not limited to, Canada, the western half of the USA, Mexico, Patagonia, Angola, Zambia, eastern Russia, and tropical and subtropical highlands (e.g. in Colombia, the Himalayas, Borneo, Papua). For the proposed system to succeed, we stress that (1) data must be collected and processed applying the same standards across all countries and continents; (2) system establishment and management must be inclusive and equitable, with careful consideration of working conditions; and (3) training and site partner involvement in downstream activities should be mandatory.

Relationship between Phytocenotic Diversity of the Northeastern Transbaikal Orobiome and Bioclimatic Parameters

The most important spatial patterns of plant cover of the Northern Transbaikalia, its regional features being represented by the structure of altitudinal zonality of the Northeastern Transbaikal orobiome, have been determined in relationship with the climatic factor. The regional climate assessment of the altitudinal belt structure of the plant cover of the orobiome has been performed for typological subdivisions of the highest hierarchic level (phratries of the classes of plant formations) using the BioClim global climate model. Principal component analysis, discriminant and cluster analysis were used to demonstrate that the summer ombrothermic index, continentality and climate moisture indices and the mean annual rainfall of many years are the most significant bioclimatic parameters determining the spatial structure of plant cover in the mountain taiga, subgoletz, mountain tundra and goletz belts. The background communities of orobiome belts develop under the conditions of continental climate (continentality index from 36 to 50). Heat supply parameters, first of all, in the vegetation period, are crucial for the spatial differentiation of altitudinal subelts, characterizing the change of light forest and dwarf pine communities in the subgoletz belt, larch, larch-pine and dark-coniferous forests in the mountain taiga belt. Moisture supply is related to the regional differences in the typological diversity of the belts, which are manifested in the development of more moisture-demanding fir-spruce forests in the low parts of the Patom Highland (rainfall amount more than 450 mm per year) and pine forests in the intermountain basins of the Stanovoy Highlands, existing under the conditions with the maximum annual temperature amplitude and low rainfall levels (up to 400 mm per year).

The biome inventory – Standardizing global biogeographical land units

Motivation

The subdivision of the Earth's terrestrial surface into different biomes, ecozones, bio‐climatic realms or other large ecological land units is an essential reference for global biogeographical and ecological studies. Various classification schemes exist. These differ significantly in terms of the considered criteria for classification and the underlying methodology of class assignments. Evident divergences between global biome concepts are elusive, weakening hereon based analyses and assumptions. Compilation and standardization are essential for obtaining a framework that enables the comparison of different products. To address this need, we created a catalogue of standardized categorial biome maps comprising 31 different global products based on various methodological approaches. These products were processed individually to facilitate their use in large‐scale biogeographical and ecological analyses.

Main types of variables contained

We provide a unified RasterStack containing 31 terrestrial biome and land‐cover classifications in different layers. Additional ancillary and processing information is allocated.

Spatial location and grain

Global, 10 km × 10 km grain size in equal‐area Mollweide projection.

Major taxa and level of measurement

Biomes, ecozones, bio‐climatic zones, and ecological land units.

Software format

GeoTiff.

Phylogenetic biome conservatism as a key concept for an integrative understanding of evolutionary history: Galliformes and Falconiformes as study cases

Biomes are climatically and biotically distinctive macroecological units that formed over geological time scales. Their features consolidate them as ‘evolutionary scenarios’, with their own diversification dynamics. Under the concept of phylogenetic niche conservatism, we assessed, for the first time, the evolution of biome occupation in birds. We aimed to analyse patterns of adaptation to different climatic regimes and the determinant factors for colonization of emerging biomes by clades from different ancestral biomes. In this work, we reconstructed the biome occupation history of two clades of birds (Galliformes and Falconiformes) under an integrative perspective through a comprehensive review of ecological, phylogenetic, palaeontological and biogeographical evidence. Our findings for both groups are consistent with a scenario of phylogenetic biome conservatism and highlight the importance of changes in climate during the Miocene in the adaptation and evolution of climatic niches. In particular, our results indicate high biome conservatism associated with biomes situated in some of the extremes of the global climate gradient (evergreen tropical rainforest, steppe and tundra) for both bird taxa. Finally, the historical dynamics of tropical seasonal biomes, such as tropical deciduous woodlands and savannas, appear to have played a preponderant role during the diversification processes of these bird lineages.

Wood stock in neotropical streams: Quantifying and comparing instream wood among biomes and regions

Instream wood plays important chemical, physical and ecological functions in aquatic systems, benefiting biota directly and indirectly. However, human activities along river corridors have disrupted wood recruitment and retention, usually leading to reductions in the amount of instream wood. In the tropics, where wood is believed to be more transient, the expansion of agriculture and infrastructure might be reducing instream wood stock even more than in the better studied temperate streams. However, research is needed to augment the small amount of information about wood in different biomes and ecosystems of neotropical streams. Here we present the first extensive assessment of instream wood loads and size distributions in streams of the wet-tropical Amazon and semi-humid-tropical Cerrado (the Brazilian savanna). We also compare neotropical wood stocks with those in temperate streams, first comparing against data from the literature, and then from a comparable dataset from temperate biomes in the USA. Contrary to our expectations, Amazon and Cerrado streams carried similar wood loads, which were lower than the world literature average, but similar to those found in comparable temperate forest and savanna streams in the USA. Our results indicate that the field survey methods and the wood metric adopted are highly important when comparing different datasets. But when properly compared, we found that most of the wood in temperate streams is made-up of a small number of large pieces, whereas wood in neotropical streams is made up of a larger number of small pieces that produce similar total volumes. The character of wood volumes among biomes is linked more to the delivery, transport and decomposition mechanisms than to the total number of pieces. Future studies should further investigate the potential instream wood drivers in neotropical catchments in order to better understand the differences and similarities here detected between biomes and climatic regions.

A function-based typology for Earth's ecosystems

As the United Nations develops a post-2020 global biodiversity framework for the Convention on Biological Diversity, attention is focusing on how new goals and targets for ecosystem conservation might serve its vision of 'living in harmony with nature'1,2. Advancing dual imperatives to conserve biodiversity and sustain ecosystem services requires reliable and resilient generalizations and predictions about ecosystem responses to environmental change and management3. Ecosystems vary in their biota4, service provision5 and relative exposure to risks6, yet there is no globally consistent classification of ecosystems that reflects functional responses to change and management. This hampers progress on developing conservation targets and sustainability goals. Here we present the International Union for Conservation of Nature (IUCN) Global Ecosystem Typology, a conceptually robust, scalable, spatially explicit approach for generalizations and predictions about functions, biota, risks and management remedies across the entire biosphere. The outcome of a major cross-disciplinary collaboration, this novel framework places all of Earth's ecosystems into a unifying theoretical context to guide the transformation of ecosystem policy and management from global to local scales. This new information infrastructure will support knowledge transfer for ecosystem-specific management and restoration, globally standardized ecosystem risk assessments, natural capital accounting and progress on the post-2020 global biodiversity framework.

Co-evolution assists geographic dispersal: the case of Madagascar

Interspecific associations may limit the dispersal of individual species, but may also facilitate it when entire co-evolved systems expand their geographic ranges. We tested the recent proposal that episodic land bridges linked Africa and Madagascar at three stages during the Cenozoic by comparing divergence estimates of Madagascar’s angiosperm taxa with their dispersal mechanisms. Plants that rely on gravity for seed dispersal indicate at least two episodes of land connection between Africa and Madagascar, in the Early Palaeocene and Early Oligocene. Seed dispersal by strepsirrhine primates possibly evolved in the Palaeocene, with the divergence of at least one endemic Malagasy angiosperm genus, Burasaia (Menispermaceae). This genus may have facilitated the lemur colonization of Madagascar. Frugivory, nectarivory and gummivory probably generalized in the Oligocene, with the co-evolution of modern lemurs and at least 10 new Malagasy angiosperm families. In the Late Miocene, more angiosperms were probably brought from Africa by birds via a discontinuous land connection, and radiated on Madagascar in diffuse association with birds (asities) and dwarf nocturnal lemurs (cheirogaleids). During the same connective episode, Madagascar was probably colonized by hippopotamuses, which both followed and re-seeded a variety of plants, forming the grassy Uapaca ‘tapia’ forest and ericoid ‘savoka’ thicket.

Global variation in diversification rate and species richness are unlinked in plants

Species richness varies immensely around the world. Variation in the rate of diversification (speciation minus extinction) is often hypothesized to explain this pattern, while alternative explanations invoke time or ecological carrying capacities as drivers. Focusing on seed plants, the world's most important engineers of terrestrial ecosystems, we investigated the role of diversification rate as a link between the environment and global species richness patterns. Applying structural equation modeling to a comprehensive distribution dataset and phylogenetic tree covering all circa 332,000 seed plant species and 99.9% of the world's terrestrial surface (excluding Antarctica), we test five broad hypotheses postulating that diversification serves as a mechanistic link between species richness and climate, climatic stability, seasonality, environmental heterogeneity, or the distribution of biomes. Our results show that the global patterns of species richness and diversification rate are entirely independent. Diversification rates were not highest in warm and wet climates, running counter to the Metabolic Theory of Ecology, one of the dominant explanations for global gradients in species richness. Instead, diversification rates were highest in edaphically diverse, dry areas that have experienced climate change during the Neogene. Meanwhile, we confirmed climate and environmental heterogeneity as the main drivers of species richness, but these effects did not involve diversification rates as a mechanistic link, calling for alternative explanations. We conclude that high species richness is likely driven by the antiquity of wet tropical areas (supporting the "tropical conservatism hypothesis") or the high ecological carrying capacity of warm, wet, and/or environmentally heterogeneous environments.

Net plant interactions are highly variable and weakly dependent on climate at the global scale

Although plant-plant interactions (i.e. competition and facilitation) have long been recognised as key drivers of plant community composition and dynamics, their global patterns and relationships with climate have remained unclear. Here, we assembled a global database of 10,502 pairs of empirical data from the literature to address the patterns of and climatic effects on the net outcome of plant interactions in natural communities. We found that plant interactions varied among plant performance indicators, interaction types and biomes, yet competition occurred more frequently than facilitation in plant communities worldwide. Unexpectedly, plant interactions showed weak latitudinal pattern and were weakly related to climate. Our study provides a global comprehensive overview of plant interactions, highlighting competition as a fundamental mechanism structuring plant communities worldwide. We suggest that further investigations should focus more on local factors (e.g. microclimate, soil and disturbance) than on macroclimate to identify key environmental determinants of interactions in plant communities.

Evolutionary Genetics of Cacti: Research Biases, Advances and Prospects

Here, we present a review of the studies of evolutionary genetics (phylogenetics, population genetics, and phylogeography) using genetic data as well as genome scale assemblies in Cactaceae (Caryophyllales, Angiosperms), a major lineage of succulent plants with astonishing diversity on the American continent. To this end, we performed a literature survey (1992-2021) to obtain detailed information regarding key aspects of studies investigating cactus evolution. Specifically, we summarize the advances in the following aspects: molecular markers, species delimitation, phylogenetics, hybridization, biogeography, and genome assemblies. In brief, we observed substantial growth in the studies conducted with molecular markers in the past two decades. However, we found biases in taxonomic/geographic sampling and the use of traditional markers and statistical approaches. We discuss some methodological and social challenges for engaging the cactus community in genomic research. We also stressed the importance of integrative approaches, coalescent methods, and international collaboration to advance the understanding of cactus evolution.

Biome boundary maintained by intense belowground resource competition in world's thinnest-rooted plant community

The distribution and stability of biomes are critical for understanding, modeling, and managing the land biosphere. While studies have emphasized abiotic factors such as climate, geology, or fire regimes, we here identify a biological mechanism—plant–plant competition for belowground resources—as critical for maintaining the boundary between the Fynbos and Afrotemperate Forest biomes in South Africa. We demonstrate an apparent general mechanism in which local competition triggers a biome-scale feedback between plant traits and soil resources, which, in turn, stabilizes the biome boundary by allowing plants to maintain their own preferred soil conditions. Our findings are of general importance for understanding the organization of biodiversity across landscapes, for managing alien plant invasions, and for modeling the future of biome boundaries.

Recent findings point to plant root traits as potentially important for shaping the boundaries of biomes and for maintaining the plant communities within. We examined two hypotheses: 1) Thin-rooted plant strategies might be favored in biomes with low soil resources; and 2) these strategies may act, along with fire, to maintain the sharp boundary between the Fynbos and Afrotemperate Forest biomes in South Africa. These biomes differ in biodiversity, plant traits, and physiognomy, yet exist as alternative stable states on the same geological substrate and in the same climate conditions. We conducted a 4-y field experiment to examine the ability of Forest species to invade the Fynbos as a function of growth-limiting nutrients and belowground plant–plant competition. Our results support both hypotheses: First, we found marked biome differences in root traits, with Fynbos species exhibiting the thinnest roots reported from any biome worldwide. Second, our field manipulation demonstrated that intense belowground competition inhibits the ability of Forest species to invade Fynbos. Nitrogen was unexpectedly the resource that determined competitive outcome, despite the long-standing expectation that Fynbos is severely phosphorus constrained. These findings identify a trait-by-resource feedback mechanism, in which most species possess adaptive traits that modify soil resources in favor of their own survival while deterring invading species. Our findings challenge the long-held notion that biome boundaries depend primarily on external abiotic constraints and, instead, identify an internal biotic mechanism—a selective feedback among traits, plant–plant competition, and ecosystem conditions—that, along with contrasting fire regime, can act to maintain biome boundaries.

Global taxonomic and phylogenetic assembly of AM fungi

Arbuscular mycorrhizal (AM) fungi are a ubiquitous group of plant symbionts, yet processes underlying their global assembly - in particular the roles of dispersal limitation and historical drivers - remain poorly understood. Because earlier studies have reported niche conservatism in AM fungi, we hypothesized that variation in taxonomic community composition (i.e., unweighted by taxon relatedness) should resemble variation in phylogenetic community composition (i.e., weighted by taxon relatedness) which reflects ancestral adaptations to historical habitat gradients. Because of the presumed strong dispersal ability of AM fungi, we also anticipated that the large-scale structure of AM fungal communities would track environmental conditions without regional discontinuity. We used recently published AM fungal sequence data (small-subunit ribosomal RNA gene) from soil samples collected worldwide to reconstruct global patterns in taxonomic and phylogenetic community variation. The taxonomic structure of AM fungal communities was primarily driven by habitat conditions, with limited regional differentiation, and there were two well-supported clusters of communities - occurring in cold and warm conditions. Phylogenetic structure was driven by the same factors, though all relationships were markedly weaker. This suggests that niche conservatism with respect to habitat associations is weakly expressed in AM fungal communities. We conclude that the composition of AM fungal communities tracks major climatic and edaphic gradients, with the effects of dispersal limitation and historic factors considerably less apparent than those of climate and soil.

Plastid phylogenomics of tribe Perseeae (Lauraceae) yields insights into the evolution of East Asian subtropical evergreen broad-leaved forests

BACKGROUND

The East Asian subtropical evergreen broad-leaved forests (EBLFs) harbor remarkable biodiversity. However, their historical assembly remains unclear. To gain new insights into the assembly of this biome, we generated a molecular phylogeny of one of its essential plant groups, the tribe Perseeae (Lauraceae).

RESULTS

Our plastid tree topologies were robust to analyses based on different plastid regions and different strategies for data partitioning, nucleotide substitution saturation, and gap handling. We found that tribe Perseeae comprised six major clades and began to colonize the subtropical EBLFs of East Asia in the early Miocene. The diversification rates of tribe Perseeae accelerated twice in the late Miocene.

CONCLUSIONS

Our findings suggest that the intensified precipitation in East Asia in the early Miocene may have facilitated range expansions of the subtropical EBLFs and establishment of tribe Perseeae within this biome. By the late Miocene, species assembly and diversification within the EBLFs had become rapid.

Global Forest Types Based on Climatic and Vegetation Data

Forest types are generally identified using vegetation or land-use types. However, vegetation classifications less frequently consider the actual forest attributes within each type. To address this in an objective way across different regions and to link forest attributes with their climate, we aimed to improve the distribution of forest types to be more realistic and useful for biodiversity preservation, forest management, and ecological and forestry research. The forest types were classified using an unsupervised cluster analysis method by combining climate variables with normalized difference vegetation index (NDVI) data. Unforested regions were masked out to constrict our study to forest type distributions, using a 20% tree cover threshold. Descriptive names were given to the defined forest types based on annual temperature, precipitation, and NDVI values. Forest types had distinct climate and vegetation characteristics. Regions with similar NDVI values, but with different climate characteristics, which would be merged in previous classifications, could be clearly distinguished. However, small-range forest types, such as montane forests, were challenging to differentiate. At macroscale, the resulting forest types are largely consistent with land-cover types or vegetation types defined in previous studies. However, considering both potential and current vegetation data allowed us to create a more realistic type distribution that differentiates actual vegetation types and thus can be more informative for forest managers, conservationists, and forest ecologists. The newly generated forest type distribution is freely available to download and use for non-commercial purposes as a GeoTIFF file via doi: 10.13140/RG.2.2.19197.90082).

Defining Biologically Meaningful Biomes Through Floristic, Functional, and Phylogenetic Data

While we have largely improved our understanding on what biomes are and their utility in global change ecology, conservation planning, and evolutionary biology is clear, there is no consensus on how biomes should be delimited or mapped. Existing methods emphasize different aspects of biomes, with different strengths and limitations. We introduce a novel approach to biome delimitation and mapping, based upon combining individual regionalizations derived from floristic, functional, and phylogenetic data linked to environmentally trained species distribution models. We define “core Biomes” as areas where independent regionalizations agree and “transition zones” as those whose biome identity is not corroborated by all analyses. We apply this approach to delimiting the neglected Caatinga seasonally dry tropical forest biome in northeast Brazil. We delimit the “core Caatinga” as a smaller and more climatically limited area than previous definitions, and argue it represents a floristically, functionally, and phylogenetically coherent unit within the driest parts of northeast Brazil. “Caatinga transition zones” represent a large and biologically important area, highlighting that ecological and evolutionary processes work across environmental gradients and that biomes are not categorical variables. We discuss the differences among individual regionalizations in an ecological and evolutionary context and the potential limitations and utility of individual and combined biome delimitations. Our integrated ecological and evolutionary definition of the Caatinga and associated transition zones are argued to best describe and map biologically meaningful biomes.

Grade of Membership models reveal geographical and environmental correlates of floristic structure in a temperate biodiversity hotspot

Identifying the contours and correlates of species turnover is central to understanding the nature of biogeographical regions. The Hengduan Mountains region of south-central China (HMR) is well known for its high diversity of plants, but its boundaries and internal floristic structure are poorly understood, especially in relation to geographical and environmental factors. With data on occurrences and elevational ranges of seed plants across the HMR and adjacent areas of the greater Qinghai-Tibet Plateau, we identified motifs (distinct species assemblages) by Grade of Membership models, and characterized relative contributions of geography, elevation, and climate to their spatial patterns. Motifs segregate primarily by latitude, elevation, and correlated environmental variables, most sharply across the tropical-temperate divide. Secondarily, they segregate by longitude and geographical features, and reveal a novel divide across the Jinsha River. A core set of motifs corresponds to previous delineations of the HMR. The HMR biodiversity hotspot is more a mosaic of floristic elements than a cohesive entity. Grade of Membership models effectively reveal the geographical contours of biotic structure, and are a valuable new tool for biogeographical analysis.

The influence of urban, socio-economic, and eco-environmental aspects on COVID-19 cases, deaths and mortality: A multi-city case in the Atlantic Forest, Brazil

Urban, socio-economic and eco-environmental influences on people's health are widely studied and well-known. Their relation to COVID-19, however, is still a novel research topic. Thus, we investigated if COVID-19 parameters are higher in cities with higher urbanization, worst socio-economic conditions, and less vegetation cover, considering 3,052 municipalities in the Atlantic Forest, Brazil. Brazil is the second country most affected by COVID-19, and the Atlantic Forest is its most urbanized, populous, and deforested region. Indexes were created through multivariate principal components analysis using secondary official data: population, demographic density, absolute built area, and relative built area as urbanization parameters; average per capita income, relative people vulnerable to poverty, illiteracy rate of the population aged 18 or over, and human development index (HDI) as socio-economic parameters; and absolute and relative vegetation cover, absolute and relative forest cover as eco-environmental parameters. These indexes were correlated with absolute and relative confirmed COVID-19 cases, absolute and relative confirmed deaths, and mortality rate via Spearman's and Kendall's coefficients. Strong correlations (>0.50) were found between COVID-19 and urbanization. Socio-economic and eco-environmental aspects, although weaker predictors of COVID-19, presented meaningful relations with the health parameters. This study contributes to the evidence regarding COVID-19 incidence in the Brazilian population.

Targeting Conservation Actions at Species Threat Response Thresholds

Given the failure of the world's governments to improve the status of biodiversity by 2020, a new strategic plan for 2030 is being developed. In order to be successful, a step-change is needed to not just simply halt biodiversity loss, but to bend the curve of biodiversity loss to stable or increasing species' populations. Here, we propose a framework that quantifies species' responses across gradients of threat intensity to implement more efficient and better targeted conservation actions. Our framework acknowledges the variation in threat intensities as well as the differences among species in their capacity to respond, and is implemented at a relevant scale for national and international policy-making.

A brief history of research in campo rupestre: identifying research priorities and revisiting the geographical distribution of an ancient, widespread Neotropical biome

Few ecologists and evolutionary biologists are familiar with the ecology and evolution of the campo rupestre, an ancient azonal peinobiome characterized by a fire-prone, nutrient-impoverished, montane vegetation mosaic, home to thousands of endemics and climate refugia. With the goal of providing a synthetic view of the campo rupestre, we provide a brief historical account of the biological research, revisit its geographical distribution and identify knowledge gaps. The azonal campo rupestre is distributed as isolated and naturally fragmented sky islands, mostly in Central and Eastern Brazil and in the Guyana Shield, with significant areas across the Amazon, Cerrado, Atlantic Forest, Caatinga and Pantanal. Our proposal to elevate campo rupestre to the level of biome is expected to improve communication among scientists and consolidate the use of the term campo rupestre in the ecological and evolutionary literature, as is the case for analogous ecosystems, such as kwongan, fynbos, páramos and tepuis. Based on the identification of knowledge gaps, we propose a research programme comprising ten key topics that can foster our understanding of the ecology and evolution of campo rupestre and, potentially, support conservation strategies.

An operational definition of the biome for global change research

Biomes are constructs for organising knowledge on the structure and functioning of the world's ecosystems, and serve as useful units for monitoring how the biosphere responds to anthropogenic drivers, including climate change. The current practice of delimiting biomes relies on expert knowledge. Recent studies have questioned the value of such biome maps for comparative ecology and global-change research, partly due to their subjective origin. Here we propose a flexible method for developing biome maps objectively. The method uses range modelling of several thousands of plant species to reveal spatial attractors for different growth-form assemblages that define biomes. The workflow is illustrated using distribution data from 23 500 African plant species. In an example application, we create a biome map for Africa and use the fitted species models to project biome shifts. In a second example, we map gradients of growth-form suitability that can be used to identify sites for comparative ecology. This method provides a flexible framework that (1) allows a range of biome types to be defined according to user needs and (2) enables projections of biome changes that emerge purely from the individualistic responses of plant species to environmental changes.

Climate change promotes transitions to tall evergreen vegetation in tropical Asia

Vegetation in tropical Asia is highly diverse due to large environmental gradients and heterogeneity of landscapes. This biodiversity is threatened by intense land use and climate change. However, despite the rich biodiversity and the dense human population, tropical Asia is often underrepresented in global biodiversity assessments. Understanding how climate change influences the remaining areas of natural vegetation is therefore highly important for conservation planning. Here, we used the adaptive Dynamic Global Vegetation Model version 2 (aDGVM2) to simulate impacts of climate change and elevated CO₂ on vegetation formations in tropical Asia for an ensemble of climate change scenarios. We used climate forcing from five different climate models for representative concentration pathways RCP4.5 and RCP8.5. We found that vegetation in tropical Asia will remain a carbon sink until 2099, and that vegetation biomass increases of up to 28% by 2099 are associated with transitions from small to tall woody vegetation and from deciduous to evergreen vegetation. Patterns of phenology were less responsive to climate change and elevated CO₂ than biomes and biomass, indicating that the selection of variables and methods used to detect vegetation changes is crucial. Model simulations revealed substantial variation within the ensemble, both in biomass increases and in distributions of different biome types. Our results have important implications for management policy, because they suggest that large ensembles of climate models and scenarios are required to assess a wide range of potential future trajectories of vegetation change and to develop robust management plans. Furthermore, our results highlight open ecosystems with low tree cover as most threatened by climate change, indicating potential conflicts of interest between biodiversity conservation in open ecosystems and active afforestation to enhance carbon sequestration.

Modeling Phylogenetic Biome Shifts on a Planet with a Past

The spatial distribution of biomes has changed considerably over deep time, so the geographical opportunity for an evolutionary lineage to shift into a new biome may depend on how the availability and connectivity of biomes has varied temporally. To better understand how lineages shift between biomes in space and time, we developed a phylogenetic biome shift model in which each lineage shifts between biomes and disperses between regions at rates that depend on the lineage's biome affinity and location relative to the spatial distribution of biomes at any given time. To study the behavior of the biome shift model in an empirical setting, we developed a literature-based representation of paleobiome structure for three mesic forest biomes, six regions, and eight time strata, ranging from the Late Cretaceous (100 Ma) through the present. We then fitted the model to a time-calibrated phylogeny of 119 Viburnum species to compare how the results responded to various realistic or unrealistic assumptions about paleobiome structure. Ancestral biome estimates that account for paleobiome dynamics reconstructed a warm temperate (or tropical) origin of Viburnum, which is consistent with previous fossil-based estimates of ancestral biomes. Imposing unrealistic paleobiome distributions led to ancestral biome estimates that eliminated support for tropical origins, and instead inflated support for cold temperate ancestry throughout the warmer Paleocene and Eocene. The biome shift model we describe is applicable to the study of evolutionary systems beyond Viburnum, and the core mechanisms of our model are extensible to the design of richer phylogenetic models of historical biogeography and/or lineage diversification. We conclude that biome shift models that account for dynamic geographical opportunities are important for inferring ancestral biomes that are compatible with our understanding of Earth history.[Ancestral states; biome shifts; historical biogeography; niche conservatism; phylogenetics].

A grid-based map for the Biogeographical Regions of Europe

Background

Biogeographical units are widely adopted in ecological research and nature conservation management, even though biogeographical regionalisation is still under scientific debate. The European Environment Agency provided an official map of the European Biogeographical Regions (EBRs), which contains the official boundaries used in the Habitats and Birds Directives. However, these boundaries bisect cells in the official EU 10 km × 10 km grid used for many purposes, including reporting species and habitat data, meaning that 6881 cells overlap two or more regions. Therefore, superimposing the EBRs vector map over the grid creates ambiguities in associating some cells with European Biogeographical Regions.

New information

To provide an operational tool to unambiguously define the boundaries of the eleven European Biogeographical Regions, we provide a specifically developed raster map of Grid-Based European Biogeographical Regions (GB-EBRs). In this new map, the borders of the EBRs are reshaped to coherently match the standard European 10 km × 10 km grid imposed for reporting tasks by Article 17 of the Habitats Directive and used for many other datasets. We assign each cell to the EBR with the largest area within the cell.

Exploring patterns of beta-diversity to test the consistency of biogeographical boundaries: A case study across forest plant communities of Italy

AIM

To date, despite their great potential biogeographical regionalization models have been mostly developed on descriptive and empirical bases. This paper aims at applying the beta-diversity framework on a statistically representative data set to analytically test the consistency of the biogeographical regionalization of Italian forests.

LOCATION

Italy.

TAXON

Vascular plants.

METHODS

Forest plant communities were surveyed in 804 plots made in a statistically representative sample of forest communities made by 201 sites of Italian forests across the three biogeographical regions of the country: Alpine, Continental, and Mediterranean. We conducted an ordination analysis and an analysis of beta-diversity, decomposing it into its turnover and nestedness components.

RESULTS

Our results provide only partial support to the consistency of the biogeographical regionalization of Italy. While the differences in forest plant communities support the distinction between the Alpine and the other two regions, differences between Continental and Mediterranean regions had lower statistical support. Pairwise beta-diversity and its turnover component are higher between- than within-biogeographical regions. This suggests that different regional species pools contribute to assembly of local communities and that spatial distance between-regions has a stronger effect than that within-regions.

MAIN CONCLUSIONS

Our findings confirm a biogeographical structure of the species pools that is captured by the biogeographical regionalization. However, nonsignificant differences between the Mediterranean and Continental biogeographical regions suggest that this biogeographical regionalization is not consistent for forest plant communities. Our results demonstrate that an analytical evaluation of species composition differences among regions using beta-diversity analysis is a promising approach for testing the consistency of biogeographical regionalization models. This approach is recommended to provide support to the biogeographical regionalization used in some environmental conservation polices adopted by EU.