Browsing by Autor "R. Toby Pennington"

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A 45kyr palaeoclimate record from the lowland interior of tropical South America
(Elsevier BV, 2011) Bronwen S. Whitney; Francis E. Mayle; Surangi W. Punyasena; Katharine Anne Fitzpatrick; Michael J. Burn; René Guillén; Ezequiel Chavez; David G. Mann; R. Toby Pennington; Sarah E. Metcalfe
Characterisation of Bolivian savanna ecosystems by their modern pollen rain and implications for fossil pollen records
(Elsevier BV, 2011) Huw T. Jones; Francis E. Mayle; R. Toby Pennington; Timothy J. Killeen
Comment on “The extent of forest in dryland biomes”
(American Association for the Advancement of Science, 2017) Daniel M. Griffith; Caroline E. R. Lehmann; Caroline A. E. Strömberg; Catherine L. Parr; R. Toby Pennington; Mahesh Sankaran; Jayashree Ratnam; Christopher J. Still; Rebecca Powell; Niall P. Hanan
Bastin <i>et al</i> (Reports, 12 May 2017, p. 635) infer forest as more globally extensive than previously estimated using tree cover data. However, their forest definition does not reflect ecosystem function or biotic composition. These structural and climatic definitions inflate forest estimates across the tropics and undermine conservation goals, leading to inappropriate management policies and practices in tropical grassy ecosystems.
Evolutionary diversity is associated with wood productivity in Amazonian forests
(Nature Portfolio, 2019) Fernanda Coelho de Souza; Kyle G. Dexter; Oliver L. Phillips; R. Toby Pennington; Danilo M. Neves; Martin J. P. Sullivan; Esteban Álvarez‐Dávila; Atila Indalecio Marques Alves; Iêda Leão do Amaral; Ana Andrade
Evolutionary heritage influences Amazon tree ecology
(Royal Society, 2016) Fernanda Coelho de Souza; Kyle G. Dexter; Oliver L. Phillips; Roel J. W. Brienen; Jérôme Chave; David Galbraith; Gabriela López‐González; Abel Monteagudo Mendoza; R. Toby Pennington; Lourens Poorter
Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change.
Expanding tropical forest monitoring into Dry Forests: The DRYFLOR protocol for permanent plots
(Wiley, 2020) Peter W. Moonlight; Karina Banda; Oliver L. Phillips; Kyle G. Dexter; R. Toby Pennington; Timothy R. Baker; Haroldo Cavalcante de Lima; Laurie Fajardo; Roy González‐M.; Reynaldo Linares‐Palomino
Societal Impact Statement Understanding of tropical forests has been revolutionized by monitoring in permanent plots. Data from global plot networks have transformed our knowledge of forests’ diversity, function, contribution to global biogeochemical cycles, and sensitivity to climate change. Monitoring has thus far been concentrated in rain forests. Despite increasing appreciation of their threatened status, biodiversity, and importance to the global carbon cycle, monitoring in tropical dry forests is still in its infancy. We provide a protocol for permanent monitoring plots in tropical dry forests. Expanding monitoring into dry biomes is critical for overcoming the linked challenges of climate change, land use change, and the biodiversity crisis.
Fast demographic traits promote high diversification rates of Amazonian trees
(Wiley, 2014) Timothy R. Baker; R. Toby Pennington; Susana Magallón; Emanuel Gloor; Susan G. W. Laurance; Miguel N. Alexiades; Esteban Álvarez‐Dávila; Alejandro Araújo; E.J.M.M. Arets; Gerardo A. Aymard C.
The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show that fast demographic traits--short turnover times--are associated with high diversification rates across 51 clades of canopy trees. This relationship is robust to assuming that diversification rates are either constant or decline over time, and occurs in a wide range of Neotropical tree lineages. This finding reveals the crucial role of intrinsic, ecological variation among clades for understanding the origin of the remarkable diversity of Amazonian trees and forests.
Multi-scale comparisons of tree composition in Amazonian terra firme forests
(Copernicus Publications, 2009) Eurídice N. Honorio Coronado; Timothy R. Baker; Oliver L. Phillips; Nigel C. A. Pitman; R. Toby Pennington; Rodolfo Vásquez; Abel Monteagudo; Hugo F. Mogollón; Nállarett Dávila; Marcos Ríos
Abstract. We explored the floristic composition of terra firme forests across Amazonia using 55 plots. Firstly, we examined the floristic patterns using both genus- and species-level data and found that the species-level analysis more clearly distinguishes among forests. Next, we compared the variation in plot floristic composition at regional- and continental-scales, and found that average among-pair floristic similarity and its decay with distance behave similarly at regional- and continental-scales. Nevertheless, geographical distance had different effects on floristic similarity within regions at distances <100 km, where north-western and south-western Amazonian regions showed greater floristic variation than plots of central and eastern Amazonia. Finally, we quantified the role of environmental factors and geographical distance for determining variation in floristic composition. A partial Mantel test indicated that while geographical distance appeared to be more important at continental scales, soil fertility was crucial at regional scales within western Amazonia, where areas with similar soil conditions were more likely to share a high number of species. Overall, these results suggest that regional-scale variation in floristic composition can rival continental-scale differences within Amazonian terra firme forests, and that variation in floristic composition at both scales is influenced by geographical distance and environmental factors, such as climate and soil fertility. To fully account for regional-scale variation in continental studies of floristic composition, future floristic studies should focus on forest types poorly represented at regional scales in current datasets, such as terra firme forests with high soil fertility in north-western Amazonia.
Phylogenetic diversity of Amazonian tree communities
(Wiley, 2015) Eurídice N. Honorio Coronado; Kyle G. Dexter; R. Toby Pennington; Jérôme Chave; Simon L. Lewis; Miguel N. Alexiades; Esteban Álvarez‐Dávila; Atila Alves de Oliveira; Iêda Leão do Amaral; Alejandro Araujo‐Murakami
Abstract Aim To examine variation in the phylogenetic diversity ( PD ) of tree communities across geographical and environmental gradients in Amazonia. Location Two hundred and eighty‐three c . 1 ha forest inventory plots from across Amazonia. Methods We evaluated PD as the total phylogenetic branch length across species in each plot ( PD ss), the mean pairwise phylogenetic distance between species ( MPD ), the mean nearest taxon distance ( MNTD ) and their equivalents standardized for species richness (ses. PD ss, ses. MPD , ses. MNTD ). We compared PD of tree communities growing (1) on substrates of varying geological age; and (2) in environments with varying ecophysiological barriers to growth and survival. Results PD ss is strongly positively correlated with species richness ( SR ), whereas MNTD has a negative correlation. Communities on geologically young‐ and intermediate‐aged substrates (western and central Amazonia respectively) have the highest SR , and therefore the highest PD ss and the lowest MNTD . We find that the youngest and oldest substrates (the latter on the Brazilian and Guiana Shields) have the highest ses. PD ss and ses. MNTD . MPD and ses. MPD are strongly correlated with how evenly taxa are distributed among the three principal angiosperm clades and are both highest in western Amazonia. Meanwhile, seasonally dry tropical forest (SDTF) and forests on white sands have low PD , as evaluated by any metric. Main conclusions High ses. PD ss and ses. MNTD reflect greater lineage diversity in communities. We suggest that high ses. PD ss and ses. MNTD in western Amazonia results from its favourable, easy‐to‐colonize environment, whereas high values in the Brazilian and Guianan Shields may be due to accumulation of lineages over a longer period of time. White‐sand forests and SDTF are dominated by close relatives from fewer lineages, perhaps reflecting ecophysiological barriers that are difficult to surmount evolutionarily. Because MPD and ses. MPD do not reflect lineage diversity per se , we suggest that PD ss, ses. PD ss and ses. MNTD may be the most useful diversity metrics for setting large‐scale conservation priorities.
Plant biogeography of rock outcrops in South American tropical lowlands
(International Biogeography Society, 2025) Rosie Clegg; Luísa Azevedo; Maira T. Martinez-Ugarteche; Danilo M. Neves; Catherine Kidner; D. J. N. Hind; Alexandre Antonelli; Lucy Rowland; R. Toby Pennington
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. 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.
Sensitivity of Bolivian seasonally-dry tropical forest to precipitation and temperature changes over glacial–interglacial timescales
(Springer Science+Business Media, 2013) Bronwen S. Whitney; Francis E. Mayle; Michael J. Burn; René Guillén; Ezequiel Chavez; R. Toby Pennington
The history of Seasonally Dry Tropical Forests in eastern South America: inferences from the genetic structure of the tree <i>Astronium urundeuva</i> (Anacardiaceae)
(Wiley, 2008) S. Caetano; Darién E. Prado; R. Toby Pennington; Stephan Beck; Ary Teixeira de Oliveira‐Filho; Rodolphe Spichiger; Yamama Naciri
Today, the Seasonally Dry Tropical Forests (SDTF) of eastern South America occur as large, well-defined nuclei (e.g. Caatinga in the northeast) and as smaller enclaves within other vegetations (e.g. Cerrado and Chaco). In order to infer the way the present SDTF distribution was attained, the genetic structure of Astronium urundeuva, a tree confined to SDTF, was assessed using two chloroplast spacers and nine microsatellite loci. Five haplotypes were identified, whose distribution was spatially structured. The distribution of the two most common and divergent haplotypes suggested former vicariance and progressive divergence due to isolation. More recent range expansions of these two lineages subsequently occurred, leading to a secondary contact at the southern limit of the Caatinga SDTF nucleus. The multilocus-Bayesian approach using microsatellites consistently identified three groups of populations (Northeast, Central and Southwest). Isolation by distance was found in Northeast and Southwest groups whereas admixture was detected in the Central group, located at the transition between Caatinga and Cerrado domains. All together, the results support the existence of range expansions and secondary contact in the Central group. This study provides arguments that favour the existence of a previously more continuous formation of SDTF in eastern South America.