Royal Botanic Garden Edinburgh

The distribution range of Erica sicula Guss. sensu lato spans the central and eastern Mediterranean Basin, but shows a significantly fragmented pattern, and its populations are locally subject to multiple threats inducing continuous regression. The species is distributed across five countries, Italy, Libya, Cyprus, Türkiye and Lebanon, and includes two subspecies, subsp. sicula and subsp. bocquetii, currently represented by 31 and 8 stands, respectively. This study provides an updated overview of the distribution, ecology, and conservation status of both subspecies. New distribution data and ecological information were gathered through fieldwork, literature, and herbarium specimens. In Sicily (Italy), unmanned aerial systems and high-resolution digital elevation models were employed to perform a detailed census of the last extant stand, mapping its distribution and calculating its 3D occupation surface. Based on our analyses, Erica sicula is evaluated as Least Concern (LC) at the global level, even though each subspecies and subpopulation are nationally endangered. In fact, 19 locations of E. sicula subsp. sicula were not confirmed recently, and this subspecies should be considered as Critically Endangered (CR) in Italy and Vulnerable (VU) in Lebanon, Cyprus and Türkiye. In Libya, E. sicula subsp. sicula is VU due to severe habitat degradation. E. sicula subsp. bocquetii, formerly known from a few locations in the mountains of SW Anatolia, Türkiye, has been found at lower altitudes in several new locations and is also assessed as VU. Further fieldwork is recommended to better assess the demographic trends of the different subpopulations. Genetic analyses are needed to clarify the taxonomic value of infraspecific taxa previously described and to guide future conservation efforts of the most unique and genetically rich stands, both in-situ and ex-situ. Improving the conservation strategies for taxa like Erica sicula s. l. requires the collaboration of specialists from all involved countries, making it crucial to maintain networks of experts in the Mediterranean.

Accurate biome delineation is difficult where biomes occupy the same climatic space, as is the case for tropical dry forest and savanna. The resulting confusion limits our ability to understand and manage impacts of global change on these biomes. To address this, we developed an unsupervised, repeatable method to delineate biomes and their component functional ecosystems, based on landscape-level vegetation structure measured using remote sensing and an understanding of the ecology of the region. This approach contrasts with previous definitions, based on climate differences amongst savanna, dry forest and rain forest. Using the heterogeneous north-east Brazil, where several biomes interdigitate, as a case study, a hierarchical functional ecosystem classification is proposed that aligns with both the IUCN Global Ecosystem Typology (GET) and previous work. Based on fuzzy clustering of remotely sensed vegetation attributes, seven groups were found, identified as rain forest, cerrado (savanna) and five caatinga vegetation groups. These groups broadly align with the literature, for example, sedimentary and arboreal caatinga. These groups align with three ‘Ecosystem Functional Groups’ (EFGs) described by the IUCN GET and, additionally, suggest there is a new, fourth EFG in the region: non-pyric shrublands. Random Forest models showed soil pH was the most important environmental variable distinguishing these vegetation groups. These results suggest a remotely sensed structure-based approach is an effective method for operationalising the IUCN GET. North-East Brazil – where many EFGs are interdigitated – serves as a challenging case study and, therefore, we hope our approach will have generality for other regions globally. There are seven vegetation groups in northeast Brazil, including savanna, rain forest and five types of caatinga. Most of these vegetation groups align with the IUCN Global Ecosystem Typology 2.0, but non-pyric shrubland (caatinga) vegetation may represent a new Ecosystem Functional Group. Soil pH is the strongest determinant of vegetation distribution in northeast Brazil. Remote sensing can provide objective, spatially explicit information on vegetation types in the region, largely consistent with previous vegetation classifications. Accurate biome mapping is vital for management, as biomes differ in ecosystem function and consequently require different management.

Lianas are important components of tropical forest diversity and dynamics, yet little is known about the drivers of their community structure and composition. Combining extensive field and LiDAR data, we investigated the influence of local topography, forest structure, and tree composition on liana community structure, and their floristic and functional composition, in a moist forest in northern Republic of Congo. We inventoried all lianas ≥ 1 cm in diameter in 144 20 × 20‐m quadrats located in four 9‐ha permanent plots, where trees and giant herbs were inventoried. We characterized the functional strategies of selected representatives of the main liana taxa using a set of resource‐use leaf and wood traits. Finally, we used complementary statistical analyses, including multivariate and randomization approaches, to test whether forest structure, topography, and tree composition influence the structure, floristic composition, and functional composition of liana communities. The structure of liana communities was strongly shaped by local forest structure, with higher abundances and total basal areas in relatively open‐canopy forests, where lianas competed with giant herbs. Liana floristic composition exhibited a weak spatial structure over the study site but was marginally influenced by the local forest structure and topography. Only forest structure had a weak but significant effect on liana functional composition, with more conservative strategies—higher stem tissue density and lower PO4 leaf concentration and SLA values—in tall and dense forests. Finally, we found evidence of host specificity with significant attraction/repulsion for 19% of the tested liana and tree species associations, suggesting that the unexplained floristic variation may be partly attributed to these host‐species‐specific associations, although the underlying mechanisms behind remain elusive. Overall, our findings demonstrate that liana communities' structure can be much better predicted than their composition, calling for a better understanding of the implications of the large functional diversity observed in liana communities.

Background and aims – As currently circumscribed, Diospyros ferrea represents one of the most geographically widespread species in the genus and had previously been described as an ochlospecies because of its particularly challenging morphological complexity. Recent studies have shown that it likely contains multiple species that differ from populations in SW India and Sri Lanka corresponding to the type, which was collected on the Malabar coast in India. Here we present the second in a series of papers that aim to revise the taxonomy of D. ferrea, treating material from Africa. Material and methods – This study was based on measurements and observations of herbarium specimens from K, MO, and P as well as scanned images from BM, BR, C, COI, EA, FHO, LISC, US, and WAG. Species were delimited based on a combination of fruit and leaf characters, in conjunction with eco-geographic distribution. Specimen records were georeferenced, mapped, and used to conduct risk of extinction assessments based on the IUCN Red List criteria. Key results – Five well-delimited and geographically coherent species are recognized among the African material previously ascribed to Diospyros ferrea, including three described as new (D. angolensis, D. moutsambotei, and D. suaheliensis) and two for which new combinations are made (D. guineensis and D. smeathmannii). We provide a diagnostic key along with detailed morphological descriptions and photos illustrating the principal characters that distinguish the five species. Preliminary risk of extinction assessments indicate that only one of them is Least Concern, whereas three are Vulnerable, and one is Endangered. Conclusion – This revision demonstrates that taxonomically challenging ochlospecies can be resolved by careful analysis of morphological characters and geographic distribution, provided adequate material is available. Studies to clarify the nature, evolutionary history, and taxonomic status of other ochlospecies recognized by Frank White (viz. D. natalensis and D. mespiliformis) should be undertaken, but may also require additional phylogenetic and/or phylogeographic data.

Wood density is a critical control on tree biomass, so poor understanding of its spatial variation can lead to large and systematic errors in forest biomass estimates and carbon maps. The need to understand how and why wood density varies is especially critical in tropical America where forests have exceptional species diversity and spatial turnover in composition. As tree identity and forest composition are challenging to estimate remotely, ground surveys are essential to know the wood density of trees, whether measured directly or inferred from their identity. Here, we assemble an extensive dataset of variation in wood density across the most forested and tree-diverse continent, examine how it relates to spatial and environmental variables, and use these relationships to predict spatial variation in wood density over tropical and sub-tropical South America. Our analysis refines previously identified east-west Amazon gradients in wood density, improves them by revealing fine-scale variation, and extends predictions into Andean, dry, and Atlantic forests. The results halve biomass prediction errors compared to a naïve scenario with no knowledge of spatial variation in wood density. Our findings will help improve remote sensing-based estimates of aboveground biomass carbon stocks across tropical South America.

Premise Pteridophytes—vascular land plants that disperse by spores—are a powerful system for studying plant evolution, particularly with respect to the impact of abiotic factors on evolutionary trajectories through deep time. However, our ability to use pteridophytes to investigate such questions—or to capitalize on the ecological and conservation‐related applications of the group—has been impaired by the relative isolation of the neo‐ and paleobotanical research communities and by the absence of large‐scale biodiversity data sources. Methods Here we present the Pteridophyte Collections Consortium (PCC), an interdisciplinary community uniting neo‐ and paleobotanists, and the associated PteridoPortal, a publicly accessible online portal that serves over three million pteridophyte records, including herbarium specimens, paleontological museum specimens, and iNaturalist observations. We demonstrate the utility of the PteridoPortal through discussion of three example PteridoPortal‐enabled research projects. Results The data within the PteridoPortal are global in scope and are queryable in a flexible manner. The PteridoPortal contains a taxonomic thesaurus (a digital version of a Linnaean classification) that includes both extant and extinct pteridophytes in a common phylogenetic framework. The PteridoPortal allows applications such as greatly accelerated classic floristics, entirely new “next‐generation” floristic approaches, and the study of environmentally mediated evolution of functional morphology across deep time. Discussion The PCC and PteridoPortal provide a comprehensive resource enabling novel research into plant evolution, ecology, and conservation across deep time, facilitating rapid floristic analyses and other biodiversity‐related investigations, and providing new opportunities for education and community engagement.

Conservation and research of highly diverse plant taxa can be a considerable challenge due to unmanageable numbers of species with potentially complex relationships often resulting in difficulties in species identification. Cyrtandra, the largest genus of the family Gesneriaceae, exemplifies these challenges. The lack of identification resources for the ca. 170 species of Bornean Cyrtandra has left many specimens unidentified, slowing down the research efforts in the area. This project addresses this by constructing the first taxonomic key to all Bornean Cyrtandra and by describing the workflow of creating identification resources for highly diverse taxa, using the online biodiversity data management platform Xper3 (https://app.xper3.fr/). The key is now published and freely accessible online. Online multi-access taxonomic keys provide a promising tool for biodiversity research by combining an accessible user-friendly platform with dynamic tools for taxonomic research, making them particularly well suited for tackling highly diverse taxonomic groups.

Studies of rock outcrops in tropical South America have increased in recent years, but they have often been restricted to individual countries, single biomes or single disciplines (e.g. through a floristic, functional or genetic lens), limiting their generality. We review the current state of knowledge on the geological and floristic diversity of rock outcrops in tropical South America to identify knowledge gaps and generate testable hypotheses for future research into the biogeography and evolution of their plant communities. We find that the diversity of lowland rock outcrop vegetation is disparately documented and we know less about the evolutionary and biogeographic history of these island-like systems. Based on geological and edaphic factors, we classify South American rock outcrops into four main groups: granite/gneiss, quartzite/metamorphosed sandstone, limestone and ironstone. We hypothesise that these lithologies influence the floristic and evolutionary lineage composition of outcrop floras. However, elevation also plays a role through creating microclimatic conditions and by influencing the degree of insularity from the surrounding vegetation. Our literature review suggests that these lithologies support different floras, but confirming this requires further floristic surveys across the full geological diversity of outcrops. We suggest a research framework to: (i) improve knowledge of outcrop floras and how they relate to floras of surrounding biomes; (ii) investigate the relative roles of niche conservatism and evolution using floristic and phylogenetic approaches; and (iii) assess how outcrop species cope with living in naturally fragmented habitats through analysis of recruitment and gene flow using population genetics. Understanding the biogeography of rock outcrop floras can help provide information for conservation planning and decisions. Highlights Rock outcrops are in urgent need of study because they possess a distinctive and highly specialised flora that is threatened by climate and land-use changes. There is a need to increase the number of studies in some Latin American countries (e.g. Bolivia, Paraguay, Guyana, French Guiana and Suriname) and lithologies (e.g. limestone). We suggest that the major determinant of floristic composition on rock outcrops is lithology and outline how this can be tested using community-level floristic data. Inferring the phylogenetic relationships of the species endemic to rock outcrops and establishing the environments where their closest relatives occur will be a powerful approach to address questions of niche evolution and niche conservatism in the historical assembly of outcrop floras. Population genetic approaches focusing on plant species that occur both in outcrop habitats and the surrounding vegetation will elucidate their connectivity and, therefore, how insular and vulnerable these environments are.

Understanding the capacity of forests to adapt to climate change is of pivotal importance for conservation science, yet this is still widely unknown. This knowledge gap is particularly acute in high-biodiversity tropical forests. Here, we examined how tropical forests of the Americas have shifted community trait composition in recent decades as a response to changes in climate. Based on historical trait-climate relationships, we found that, overall, the studied functional traits show shifts of less than 8% of what would be expected given the observed changes in climate. However, the recruit assemblage shows shifts of 21% relative to climate change expectation. The most diverse forests on Earth are changing in functional trait composition but at a rate that is fundamentally insufficient to track climate change.

Temperate rainforests are globally rare, covering less than 1% of the Earth’s surface, with 15% of their suitable climate space located in Europe. These ecosystems are uniquely defined by diverse cryptogamic species, particularly epiphytic lichens, which play crucial roles in forest biodiversity, trophic interactions, and biogeochemical processes. However, the ecophysiology of temperate rainforest lichens, with the potential to explain their regional to local distribution, their primary productivity, growth rates and biomass accumulation, remains under researched. This study asked whether the coexistence of morphologically different species within Scotland’s temperate rainforest is driven by adaptation and subsequent species-sorting into contrasting microclimatic moisture environments. We examined seven species, analysing their biogeographic distributions and physiological responses to controlled moisture and light gradients to understand their degree of association with the temperate rainforest habitat. Our results indicated that species with the strongest temperate rainforest association had higher thallus water requirements (OptWC, MinWC and MaxWC) to achieve maximal photosynthesis (MaxNP) and that these appeared mediated by morphological traits. We found that, when morphological traits relating to water capture and retention, including layers of rhizine and tomentum, are linked to physiological optima, they can begin to explain how species across a spectrum of morphologies are differentially adapted or acclimated and associated to different degrees with the temperate rainforest climate. These findings also underscore the significance of ecophysiological knowledge for predicting the impacts of climate change on temperate rainforest biodiversity, since species’ microhabitat responses will be pivotal in understanding broader ecological shifts.

Pan-genomics and genome-editing technologies are revolutionizing breeding of global crops1,2. A transformative opportunity lies in exchanging genotype-to-phenotype knowledge between major crops (that is, those cultivated globally) and indigenous crops (that is, those locally cultivated within a circumscribed area)3, 4–5 to enhance our food system. However, species-specific genetic variants and their interactions with desirable natural or engineered mutations pose barriers to achieving predictable phenotypic effects, even between related crops6,7. Here, by establishing a pan-genome of the crop-rich genus Solanum⁸ and integrating functional genomics and pan-genetics, we show that gene duplication and subsequent paralogue diversification are major obstacles to genotype-to-phenotype predictability. Despite broad conservation of gene macrosynteny among chromosome-scale references for 22 species, including 13 indigenous crops, thousands of gene duplications, particularly within key domestication gene families, exhibited dynamic trajectories in sequence, expression and function. By augmenting our pan-genome with African eggplant cultivars⁹ and applying quantitative genetics and genome editing, we dissected an intricate history of paralogue evolution affecting fruit size. The loss of a redundant paralogue of the classical fruit size regulator CLAVATA3 (CLV3)10,11 was compensated by a lineage-specific tandem duplication. Subsequent pseudogenization of the derived copy, followed by a large cultivar-specific deletion, created a single fused CLV3 allele that modulates fruit organ number alongside an enzymatic gene controlling the same trait. Our findings demonstrate that paralogue diversifications over short timescales are underexplored contingencies in trait evolvability. Exposing and navigating these contingencies is crucial for translating genotype-to-phenotype relationships across species.

Tropical forest canopies are the biosphere’s most concentrated atmospheric interface for carbon, water and energy1,2. However, in most Earth System Models, the diverse and heterogeneous tropical forest biome is represented as a largely uniform ecosystem with either a singular or a small number of fixed canopy ecophysiological properties³. This situation arises, in part, from a lack of understanding about how and why the functional properties of tropical forest canopies vary geographically⁴. Here, by combining field-collected data from more than 1,800 vegetation plots and tree traits with satellite remote-sensing, terrain, climate and soil data, we predict variation across 13 morphological, structural and chemical functional traits of trees, and use this to compute and map the functional diversity of tropical forests. Our findings reveal that the tropical Americas, Africa and Asia tend to occupy different portions of the total functional trait space available across tropical forests. Tropical American forests are predicted to have 40% greater functional richness than tropical African and Asian forests. Meanwhile, African forests have the highest functional divergence—32% and 7% higher than that of tropical American and Asian forests, respectively. An uncertainty analysis highlights priority regions for further data collection, which would refine and improve these maps. Our predictions represent a ground-based and remotely enabled global analysis of how and why the functional traits of tropical forest canopies vary across space.

Plants cope with the environment by displaying large phenotypic variation. Two spectra of global plant form and function have been identified: a size spectrum from small to tall species with increasing stem tissue density, leaf size, and seed mass; a leaf economics spectrum reflecting slow to fast returns on investments in leaf nutrients and carbon. When species assemble to communities it is assumed that these spectra are filtered by the environment to produce community level functional composition. It is unknown what are the main drivers for community functional composition in a large area such as Amazonia. We use 13 functional traits, including wood density, seed mass, leaf characteristics, breeding system, nectar production, fruit type, and root characteristics of 812 tree genera (5211 species), and find that they describe two main axes found at the global scale. At community level, the first axis captures not only the ‘fast-slow spectrum’, but also most size-related traits. Climate and disturbance explain a minor part of this variance compared to soil fertility. Forests on poor soils differ largely in terms of trait values from those on rich soils. Trait composition and soil fertility exert a strong influence on forest functioning: biomass and relative biomass production.

Spirotropis (Leguminosae, Papilionoideae) is a Neotropical genus of trees that has long remained circumscribed to just one species, S. longifolia. Evidence from previous molecular phylogenetic analyses of nuclear and plastid loci and morphological features supports expanding its circumscription to encompass species from the polyphyletic Clathrotropis s.l. that are widely distributed in the Amazonian forests. Here, we reassess the evolutionary relationships of Spirotropis and Clathrotropis s.l. based on a new plastome-wide phylogenomic analysis of the genistoid legumes. The evolutionary histories of selected morphological characters were estimated through Bayesian stochastic mapping over a robust phylogeny of the Ormosieae clade in order to investigate synapomorphies that define an expanded concept of Spirotropis. The newly circumscribed genus Spirotropis was recovered as a well-supported monophy-letic group comprising five species: the type S. longifolia, three species added from Clathrotropis s.str. (S. nitida, S. paradoxa, S. rosea) and the newly described S. fusca endemic to Venezuela. These species are represented by trees with fragrant flowers and spirally twisted keel petals that grow from tropical lowland rain forests, including seasonally flooded forests, to montane forests. In this study, we present identification keys for the Ormosieae genera and the Spirotropis species, in addition to full taxonomic descriptions , illustrations, maps of geographic distribution, and comments on the morphological distinctiveness, nomenclature, and ecology of each species.

There is growing interest in the ecosystem roles contributed by “nonvascular photoautotrophs” (NVPs). This includes the biomass of epiphytic lichens and bryophytes, which can potentially absorb large amounts of atmospheric moisture (relative to their dry mass) therefore modifying hydrochemical pathways through the forest ecosystem. One further possibility is that NVP epiphytes can access moisture from, or at least have slower drying rates when in contact with, saturated bark surfaces. We tested this by comparing the drying rates for epiphytic lichen thalli positioned onto saturated bark of two types, with or without a conspecific biomass, relative to a free-drying control. We found little or no effect of saturated bark, but a strong effect of the conspecific biomass in slowing the thallus drying rate. The weak bark effect is possibly explained by the hydrophobic lower surface of the lichen species that was investigated (Platismatia glauca (L.) W.L. Culb. & C.F. Culb.), which may act as a barrier to water uptake, and which may—contrary to our original hypothesis—slow bark surface drying. Although it seems highly plausible that bark–lichen hydrological interactions are important for incorporating NVPs into ecosystem models, the nature of these interactions may be more subtle than previously supposed, requiring further investigation.

The diversity of foliar fungal endophyte communities was examined in three economically and ecologically important pine species in Scotland: Scots pine, Corsican pine and lodgepole pine. Two plantation sites comprising all three species were selected in climatically contrasting parts of Scotland and were sampled in late spring by collecting healthy needles from two age classes. Surface sterilisation was carried out before obtaining cultures of fungal isolates, and representatives of common sterile morphotypes were sequenced to determine taxonomic placement. Overall relative proportions of the dominant taxa across sites, tree species and needle age classes were as follows: Anthostomella spp. (52%), Lophodermium seditiosum (17%) and Desmazierella acicola (7%). Many other less frequent taxa were recovered. The results agreed with previous endophyte studies in that the combined effects of site and tree species produced unique endophytic fungal assemblages. Phylogenetic analyses revealed potential sub-species variation associated with site in Anthostomella pinea. Our findings point to the potential naturalisation of European fungal endophytic species (e.g., Anthostomella spp.) in Scottish pine plantations, particularly in association with Corsican pine.

Understanding how the traits of lineages are related to diversification is key for elucidating the origin of variation in species richness. Here, we test whether traits are related to species richness among lineages of trees from all major biogeographical settings of the lowland wet tropics. We explore whether variation in mortality rate, breeding system and maximum diameter are related to species richness, either directly or via associations with range size, among 463 genera that contain wet tropical forest trees. For Amazonian genera, we also explore whether traits are related to species richness via variation among genera in mean species-level range size. Lineages with higher mortality rates—faster life-history strategies—have larger ranges in all biogeographic settings and have higher mean species-level range sizes in Amazonia. These lineages also have smaller maximum diameters and, in the Americas, contain dioecious species. In turn, lineages with greater overall range size have higher species richness. Our results show that fast life-history strategies influence species richness in all biogeographic settings because lineages with these ecological strategies have greater range sizes. These links suggest that dispersal has been a key process in the evolution of the tropical forest flora.