W.D. Hawthorne's research while affiliated with University of Oxford and other places

Publications (44)

Article
Full-text available
Aim Existing phytogeographical frameworks for tropical Africa lack either spatial completeness, unit definitions smaller than the regional scale or a quantitative approach. We investigate whether physical environmental variables can be used to interpolate floristically defined vegetation units, presenting an interpolated, hierarchical, quantitative...
Article
Full-text available
Phylogenies are a central and indispensable tool for evolutionary and ecological research. Even though most angiosperm families are well investigated from a phylogenetic point of view, there are far less possibilities to carry out large-scale meta-analyses at order level or higher. Here, we reconstructed a large-scale dated phylogeny including near...
Preprint
Full-text available
Phylogenies are a central and indispensable tool for evolutionary and ecological research. Even though most angiosperm families are well investigated from a phylogenetic point of view, there are far less possibilities to carry out large-scale meta-analyses at order level or higher. Here, we reconstructed a large-scale dated phylogeny including near...
Technical Report
Full-text available
A review of species records for Atewa Range Forest Reserve to establish the biological richness and number of globally threatened species known from the forest.
Article
Identifying areas of high biodiversity is an established way to prioritize areas for conservation [1-3], but global approaches have been criticized for failing to render global biodiversity value at a scale suitable for local management [4-6]. We assembled 3.1 million species distribution records for 40,401 vascular plant species of tropical Africa...
Article
To answer new scientific and ecological questions and monitor multiple forest changes, a fine scale characterization of these ecosystems is needed, and could imply the mapping of specific species, of detailed forest types, and of functional composition. This characterization can be now provided by the novel Earth Observation tools. This study aims...
Article
Although the publication of the vascular flora of the Caribbean islands of Trinidad and Tobago extended from 1928–1992, it is incomplete with the family Poaceae still outstanding. Many of the early recorded families are in need of extensive revision. Therefore, this checklist is intended to fill these gaps by providing a comprehensive list of the v...
Article
Full-text available
Degradation, a reduction of the ecosystem’s capacity to supply goods and services, is widespread in tropical forests and mainly caused by human disturbance. To maintain the full range of forest ecosystem services and support the development of effective conservation policies, we must understand the overall impact of degradation on different forest...
Article
Full-text available
We evaluated the relative importance of annual rainfall, temperature and their seasonality to tree species distribution in Ghana. We used species presence/absence data from 2505 1-ha plots systematically distributed over Ghana's forests. Logistic regression was used to determine species responses to four climatic variables generated from the Worldc...
Article
Background and aims - Botanical surveys in Ghana yielded numerous new species, including saplings of what proved to be a tall, canopy tree. After several years, adults with flowers and fruits were found. Key results - Synsepalum ntimii, a new species similar to S. afzelii, is described and its affinities are discussed. Conservation status - Upper G...
Article
We designed 3 image-based field guides to tropical forest plant species in Ghana, Grenada, and Cameroon and tested them with 1095 local residents and 20 botanists in the United Kingdom. We compared users' identification accuracy with different image formats, including drawings, specimen photos, living plant photos, and paintings. We compared users'...
Article
Six new species of Pavetta L. are described from the Wet Evergreen forests of Ghana, Ivory Coast and Liberia: Pavetta sonjae, P. bomiensis, P. abujuamii, P. ankasensis, P. quasidigita and P. sapoensis, the first of these with ornamental potential. The last three are considered ‘litter-bin’ species, a morphological syndrome whereby forest understore...
Article
Regeneration Ecology of the Useful Flora of the Putu Range Rainforest, Liberia. We test the hypothesis that useful plants in general, and medicines in particular, are more likely to be pioneer and herbaceous species than any other guild or habit, using data from six communities in southeastern Liberia. Of 624 surveyed species from seven locally def...
Article
We analyse data from 12 permanent sample plots (PSPs) in Ghana to determine recovery rates of skid trails and gaps in forest logged 10–30 years previously. We examine four key indicators of recovery – basal area, mortality rate, diameter increment and changes in the balance of tree guilds (Pioneer Index) – to compare the forest directly affected by...
Article
Gilbertiodendron tonkolili Burgt & Estrella sp. nov. (LeguminosaeCaesalpinioideae) is described and illustrated. The new species is endemic to a small area in central Sierra Leone. Gilbertiodendron tonkolili is characterised by leaves bearing 46 pairs of leaflets; stipules comprising a lower auriculate and an upper linear part, creamwhite coloured...
Conference Paper
Background/Question/Methods Plant functional traits play an important role in shaping species distribution patterns relative to environmental-gradients. Despite fast growing knowledge on role of functional traits in structuring plant communities, surprisingly few studies have tested their importance at large scales in wet-tropics. This study desc...
Article
Full-text available
Aim Our aim was to evaluate the extent to which we can predict and map tree alpha diversity across broad spatial scales either by using climate and remote sensing data or by exploiting spatial autocorrelation patterns. Location Tropical rain forest, West Africa and Atlantic Central Africa. Methods Alpha diversity estimates were compiled for trees w...
Article
Plant morphological and physiological traits affect the way plants tolerate environmental stresses and therefore play an important role in shaping species distribution patterns in relation to environmental gradients. Despite our growing knowledge on the role of functional traits in structuring plant communities, few studies have tested their import...
Article
Plant morphological and physiological traits affect the way plants tolerate environmental stresses and therefore play an important role in shaping species distribution patterns in relation to environmental gradients. Despite our growing knowledge on the role of functional traits in structuring plant communities, few studies have tested their import...
Article
Full-text available
The intermediate disturbance hypothesis (IDH) predicts local species diversity to be maximal at an intermediate level of disturbance. Developed to explain species maintenance and diversity patterns in species-rich ecosystems such as tropical forests, tests of IDH in tropical forest remain scarce, small-scale and contentious. We use an unprecedented...
Article
Numerous linear taxon sequences can be generated from large phylogenetic trees raising questions about what criteria should be used to select an optimal sequence for collections of specimens and published taxonomic outputs including field guides. Possible criteria and ways to implement them are discussed in relation to the sequence of Angiosperm fa...
Article
Full-text available
The diversity and structure of communities are partly determined by how species partition resource gradients. Plant size is an important indicator of species position along the vertical light gradient in the vegetation. 2. Here, we compared the size distribution of tree species in 44 Ghanaian tropical forest communities, using data from 880 one-hec...
Article
Summary 1. Comparative analyses of diversity variation among and between regions allow testing of alternative explanatory models and ideas. Here, we explore the relationships between the tree α -diversity of small rain forest plots in Africa and in Amazonia and climatic
Article
Full-text available
A more general explanation for differences amongst communities lies in the costs and benefits of adult tree size under real conditions. We already noted that species will evolve to be bigger only while the advantages of additional size are not outweighed by their costs. Tree size has various costs in addition to energetic demands (Smith & Huston 19...
Conference Paper
Full-text available
This is the first step of a multi-scale analysis of the patterns of the diversity of the African rainforest. Data from over 1200 forest plots have been assembled. We aim to model the nowadays diversity-climate relationship and to investigate the potential effects of past and future climate change.
Chapter
Based on original research, this book presents information on the flora (including a checklist), diversity (with overviews at several levels of integration), ecology (distribution, characteristics in relation to environment, their role in forest ecosystems) and ethnobotany. Forestry aspects, such as their impact on tree growth and development, and...
Chapter
Based on original research, this book presents information on the flora (including a checklist), diversity (with overviews at several levels of integration), ecology (distribution, characteristics in relation to environment, their role in forest ecosystems) and ethnobotany. Forestry aspects, such as their impact on tree growth and development, and...
Article
Tropical dry forests, with their distinct and economically important diversity, are acknowledged conservation priorities because of alarming rates of forest conversion. Whilst it is realised that terrestrial conservation requires an understanding of landscape level patterns of diversity, forests are rarely assessed accordingly. Here we demonstrate...
Chapter
This book focuses on the biodiversity and ecology of West African forests. The first part of the book includes 8 chapters which analyse the factors that give rise to biodiversity and structure tropical plant communities. It emphasizes the distribution and state of the forests and analyses vegetation gradients, determines hotspots of plant diversity...
Chapter
This book focuses on the biodiversity and ecology of West African forests. The first part of the book includes 8 chapters which analyse the factors that give rise to biodiversity and structure tropical plant communities. It emphasizes the distribution and state of the forests and analyses vegetation gradients, determines hotspots of plant diversity...
Chapter
This book focuses on the biodiversity and ecology of West African forests. The first part of the book includes 8 chapters which analyse the factors that give rise to biodiversity and structure tropical plant communities. It emphasizes the distribution and state of the forests and analyses vegetation gradients, determines hotspots of plant diversity...
Article
The potential of the dry zone agro-ecosystem of southern Honduras to contribute to the conservation of Mesoamerican dry forest tree diversity is evaluated. Four rural communities containing eight land uses were surveyed using rapid botanical sampling resulting in the identification of 241 tree and shrub species. As a result of ordination analysis,...
Article
Elephant populations have declined greatly in the rain forests of Upper Guinea (Africa, west of the Dahomey Gap). Elephants have a number of well-known influences on vegetation, both detrimental and beneficial to trees. They are dispersers of a large number of woody forest species, giving rise to concerns that without elephants the plant diversity...

Citations

... Studies by scientists have suggested that herbalfounded drugs and extracts are healthier and safer (Cragg and Newman, 2005). (Siepel et al., 2004) To ensure that human health complications are treated with plant properties, Alstonia boonei stem bark was extracted with ethanol and use to check for its hematological effect. Alstonia is a genus of the family Apocynaceae where other therapeutic vital floras fit in (Nweze et al., 2004) (Figure 1). ...
... La correction radiométrique a consisté à normaliser l'image selon les propriétés du capteur Landsat 7 ETM+, de convertir les valeurs numériques des images en valeurs de réflectance selon les paramètres du capteur Landsat 7 ETM+ et de minimiser l'impact des December 2021 edition Vol. 17,No.43 www.eujournal.org 6 conditions no-surfaciques sur les valeurs de l'image de 2002. ...
... Climbers are either woody (lianas) or non-woody (vines) plants that constitute one of the most conspicuous elements but are not limited to the tropical forest ecosystems (Emmons and Gentry 1983;Gentry 1991;Pérez-Salicrup et al. 2001). Woody climbers can comprise up to 30% of the woody plant diversity in many tropical forest ecosystems (Jongkind and Hawthorne 2005). Freeze-based embolism may limit their distribution within the tropics, but recent studies have shown their fair representation in temperate (Allen 2015) and subtropical ecosystems (Yuan et al. 2009;Malizia et al. 2015). ...
... Climbers are plants that germinate and grow for part of their life as forest undergrowths by attaching to other plants for support (Jongkind and Hawthorne 2005) to reach a great height in the forest (Swaine et al. 2005). Climbing plants are an important physiognomic feature of tropical forests (Putz and Mooney 1991), differentiating tropical forest from temperate forest (Schnitzer and Bongers 2002). ...
... The flora of these mountain-related AoEs are closely related, as shown by the high number of shared species (Annexe 10) and the clustering and NMDS analyses (Figure IV-1), except for AoE #2 whose flora is more similar to the Congolese flora (i.e. AoE #3; Marshall et al., 2021). It is worth noting that Koumounabouali massif and Monts Doudou are likely too small and too poorly sampled to have a possibility of being identified as distinct bioregions by the bipartite network analysis. ...
... Asterisks indicate nodes without a single significantly supported character state, whereas nodes with a grey circle indicate that the corresponding character state is unknown. At the bottom, a coloured bar is used to highlight the timing of diversification of Euclea (Ebenaceae), based on the study by Janssens et al. (2020). The time scale of rainforest blocks is likely to have had an adverse impact on a wide range of tropical plant lineages (Couvreur et al., 2021), such as palms that are mostly associated with rainforest habitats (Blach-Overgaard et al., 2010). ...
... The Atewa Range Forest Reserve (ARFR) is characterized by a bi-modal rainy season (April-July and September-October) with mean annual rainfall between 1200 mm and 1600 mm, a monthly temperature between 24 C and 29 C, and a relative humidity of 75 -80% (Apeanti, 2014;Ayivor et al., 2011). It is regarded as one of the highest priority ecosystems in West Africa because of its high species diversity (both plants and animals) and level of endemism (Lindsell et al., 2019; Rapid Assessment Bentsi-Enchill et al. Trees, Forests and People 8 (2022) 100238 Program, 2007). ...
... Without giving absolute figures, they estimated a relatively high level of endemism, 19.9%, while Kelbessa and Demissew (2014) gave the absolute number of FEE area endemics at 647. That number infers a relative figure based on the total number of species In a review of the methodological background for their 'bioquality' value, reflecting global rarity, Marshall et al. (2016) and Hawthorne and Marshall (2019) categorised more than 40,000 African plants species by global rarity, using a 'star' rating with four categories (highest to lowest): Black, Gold, Blue and Green stars. Based on the weighted 'star' rating, they calculated community scores on one-degree squares for > 3.1 million botanical records across the African continent, focussing on the high scores from the eastern coast of tropical Africa. ...
... More botanical research is needed, as numerous morphospecies remained unidentified. Marshall et al. (2016) estimated that the completeness of floristic species sampling was <10% for most of central DRC, including ...