Tree Flora Research Articles

Can plant DNA barcoding be implemented in species-rich tropical regions? A perspective from São Paulo State, Brazil.

DNA barcoding helps to identify species, especially when identification is based on parts of organisms or life stages such as seeds, pollen, wood, roots or juveniles. However, the implementation of this approach strongly depends on the existence of complete reference libraries of DNA sequences. If such a library is incomplete, DNA-based identification will be inefficient. Here, we assess if DNA barcoding can already be implemented in species-rich tropical regions. We focus on the tree flora of São Paulo state, Brazil, which contains more than 2000 tree species. Using new DNA sequence data and carefully assembled GenBank accessions, we assembled 12,113 sequences from ten different regions. The ITS, rbcL, psbA-trnH, matK and trnL regions were better represented within the available sequences for São Paulo tree flora. Currently, only 58% of the São Paulo tree flora currently have at least one barcoding sequence available. However, these species represent on average 89% of the trees in São Paulo state forests. Therefore, conservation-oriented and ecological studies can already benefit from DNA barcoding to obtain more accurate species identifications. We present which taxa remain underrepresented for the São Paulo tree flora and discuss the implications of this result for other species-rich tropical regions.

Tree and shrub flora in the surroundings of the Parque Nacional do Iguaçu, Paraná State, Brazil: contribution to ecological restoration

ABSTRACT Aiming to expand the regional floristic knowledge and compile species information to subsidize restoration projects, we conducted a floristic survey in native forest fragments of an area located between the Parque Nacionaldo Iguaçu and the Área de Preservação Permanente do Lago de Itaipu, in western Paraná State. We found 204 species and 51 families, being the richest Fabaceae (29 spp.), Myrtaceae (18 spp.), Solanaceae (10 spp.), Euphorbiaceae, Meliaceae and Rutaceae (nine spp. each). The zoochoric syndrome was the most common (69% of the species), followed by anemochoric (17%) and autochoric (14%). The non-pioneer species were the most frequent (64%). In general terms, these results agree qualitatively with those observed in seasonal semideciduous forests. Based on phytosociological data from other studies, we indicated 34 locally abundant species that can be used in greater proportions in restoration projects. We recorded seven species threatened and 15 exotic, of which 12 have invasive potential and require actions for controlling.

Dendroflora parku podworskiego we wsi Wojsławice w powiecie zduńskowolskim

Park w Wojsławicach jest cenną pozostałością dawnego założenia dworskiego, powstałego na przełomie XIX i XX wieku wokół siedziby rodziny Siemiątkowskich. Oryginalny układ przestrzenny założenia został zmieniony w wyniku zmian sposobu zagospodarowania terenu po upaństwowieniu, a następnie sprywatyzowaniu (części) obiektu. Obecnie na dendroflorę parku składają się 73 gatunki drzew i krzewów (20 gatunków iglastych i 53 gatunki liściaste), reprezentujących 23 rodziny. Charakterystycznym komponentem parku są liczne okazałe jesiony wyniosłe Fraxinus excelsior, klony zwyczajne Acer platanoides i topole kanadyjskie Populus canadensis. Walorem parku są wielogatunkowe zgrupowania drzew, najlepiej zachowane w części (centralnej) przypałacowej. Nowsze elementy założenia tworzone są głównie przez barwne odmiany i formy obcych gatunków krzewów iglastych i liściastych. Wśród szczegółowo zinwentaryzowanych 281 drzew i drzewiastych form krzewów dostępnych w części nieleśnej parku i blisko 300 drzew w części leśnej, wyróżnia się 10 okazów o wymiarach pomnikowych.

Does the ‘Marine Signature’ of Driftwood Persist in the Archaeological Record? An Experimental Case Study from Iceland

ABSTRACTThe limited native tree flora of Iceland, combined with the decline in native woodlands following the settlement of the island in the late ninth century AD, led to a very limited availability of timber on the island. However, Icelanders continued to rely on wood for fuel, construction and artefact production. Driftwood, which arrives in great quantities on the shores of Iceland, became an extremely important resource, especially for construction. Driftwood has been identified in archaeological wood assemblages in Iceland through taxonomic categorisation of wood remains as deriving from native, drifted or imported wood. However, many of the species found as driftwood have wide geographical ranges, or are anatomically indistinguishable from taxa which may have been imported to Iceland. Furthermore, the use of modern studies of driftwood as comparisons is problematic due to the influence of changing forest composition, oceanic circulation and logging practices. Driftwood has a marine chemical signature due to its immersion in seawater. This paper uses electrical conductivity testing of ‘fresh’, drifted and archaeological wood to assess the extent to which this marine signature is likely to persist in the archaeological record, and whether this could be used to conclusively identify driftwood in archaeological assemblages.

Floristic distributional patterns in a diverse ecotonal area in South America

The Paraguayan territory and region, in the centre of South America, is a huge transition area with a succession of various vegetation types. However, this area has received little attention from researchers, with few works published on its flora and its delimitations. We aimed to identify the most important environmental driving forces and delimit floristic patterns in this region, since understanding the forces that drive floristic variations in this ecotonal region could help comprehend the distribution of vegetation not only in this region but throughout South America. We obtained 1234 tree species occurrence records, 205 geographic coordinates and 23 environmental variables and altitude from the ‘NeoTropTree’ database and verified the influence and contribution of environmental factors through variance partition. We tested the floristic consistency of the different vegetation types using dendrogram, indicator species and ordination analyses. We also constructed multiple linear models to check the correlation between species distribution and environmental variables. We found eight consistent vegetation types. The spatial variables coupled with environmental variables were more important than individual environmental or spatial variables. Among the environmental variables, the aridity index was the most important. Despite the importance of spatial factors, due to environmental heterogeneity, we found a gradient related to climate and edaphic variables related to tree flora. The results confirm that the Paraguayan territory and region can be considered to be a diversified and important ecotone area in South America with respect to tree flora.

Karst tiankengs as refugia for indigenous tree flora amidst a degraded landscape in southwestern China

We conducted floristic and community analyses to compare the floristic composition, forest structure, taxonomic richness, and species diversity between two tiankeng (large doline, or sinkhole) habitats and two outside-tiankeng habitats of forest fragments in a degraded karst area in southwestern China. We found remarkably higher taxonomic richness in the tiankeng habitats than in the outside-tiankeng habitats at the species, generic, and familial levels. The inside-tiankeng habitats had higher floristic diversity but lower dominance. The remarkably higher uniqueness at all taxonomic levels and the much larger tree size in the two tiankeng habitats than in the outside-tiankeng habitats demonstrated the old-growth and isolated nature of the tiankeng flora. Plot-scale species richness, Shannon-Wiener index, Pielou’s evenness, and Berger-Parker dominance significantly differed across habitats. Heterogeneity in floristic composition at the species, generic, and familial levels was extremely significant across habitats. In pairwise comparisons, except for the Chuandong Tiankeng-Shenmu Tiankeng pair, all the pairs showed significant between-habitat heterogeneity in floristic composition. Our results suggest that as oases amidst the degraded karst landscape, tiankengs serve as modern refugia that preserve old-growth forest communities with their rich floristic diversity, and can provide a model for habitat conservation and forest restoration in that area.

Diversity, endemism, and composition of tropical mountain forest communities in Sulawesi, Indonesia, in relation to elevation and soil properties

Explaining the diversity and distribution of tree taxa in the isolated tropical mountain forests (TMF) of the Malesian archipelago remains one of the great challenges of tropical biogeographical research. We investigated tree diversity, endemism and community composition in 13 plots of 0.24ha between 700 and 2400m in the TMF of Central Sulawesi’s (Indonesia) highlands and related the patterns to gradients in elevation, climate and soil properties. Special attention was paid to understorey trees with stem diameters as low as 2cm, not exceeding 2/3 of stand canopy height. Based on extensive taxonomic work on the plots, we found that Sulawesi’s TMF flora is with 27–78 species per 0.24ha not species-poorer than that of other Malesian islands, and vascular plant endemism is higher (22% of the species endemic to Sulawesi) than previously thought. Alpha diversity was mainly dependent on elevation and not soil factors (7 parameters tested). The alpha diversity of tree species, genera and families declined linearly with elevation, as did the number of species and genera per family, revealing higher phylogenetic clustering at lower elevations. Indicator Species Analysis and cluster analysis identified three main forest belts (sub-montane at c. 700–1400m, lower montane at c. 1400–2000m, upper montane at >c. 2000m), deviating from earlier zonation concepts by separating sub-montane (rich in taxa related to the lowlands) and lower montane communities (rich in Fagaceae and Myrtaceae). With 27–51% of all tree species in a plot never found in the upper canopy, our data suggest that the guild of true understorey tree species is species-rich (estimated at c. 130 species in our region), contradicting the hypothesis that Southeast Asian tropical forests with mass-flowering trees (here: Fagaceae) are particularly poor in understorey tree species. We conclude that the mountains of Sulawesi harbour remarkably species-rich, but still understudied, TMF with a unique tree flora rich in understorey trees, which are of high conservation priority.

Exploring the floristic diversity of tropical Africa

BackgroundUnderstanding the patterns of biodiversity distribution and what influences them is a fundamental pre-requisite for effective conservation and sustainable utilisation of biodiversity. Such knowledge is increasingly urgent as biodiversity responds to the ongoing effects of global climate change. Nowhere is this more acute than in species-rich tropical Africa, where so little is known about plant diversity and its distribution. In this paper, we use RAINBIO – one of the largest mega-databases of tropical African vascular plant species distributions ever compiled – to address questions about plant and growth form diversity across tropical Africa.ResultsThe filtered RAINBIO dataset contains 609,776 georeferenced records representing 22,577 species. Growth form data are recorded for 97% of all species. Records are well distributed, but heterogeneous across the continent. Overall, tropical Africa remains poorly sampled. When using sampling units (SU) of 0.5°, just 21 reach appropriate collection density and sampling completeness, and the average number of records per species per SU is only 1.84. Species richness (observed and estimated) and endemism figures per country are provided. Benin, Cameroon, Gabon, Ivory Coast and Liberia appear as the botanically best-explored countries, but none are optimally explored. Forests in the region contain 15,387 vascular plant species, of which 3013 are trees, representing 5–7% of the estimated world’s tropical tree flora. The central African forests have the highest endemism rate across Africa, with approximately 30% of species being endemic.ConclusionsThe botanical exploration of tropical Africa is far from complete, underlining the need for intensified inventories and digitization. We propose priority target areas for future sampling efforts, mainly focused on Tanzania, Atlantic Central Africa and West Africa. The observed number of tree species for African forests is smaller than those estimated from global tree data, suggesting that a significant number of species are yet to be discovered. Our data provide a solid basis for a more sustainable management and improved conservation of tropical Africa’s unique flora, and is important for achieving Objective 1 of the Global Strategy for Plant Conservation 2011–2020.

Estructura y composición arbórea de tres estadios sucesionales de selva mediana subperennifolia del municipio de Huautla, Hidalgo, México

Information on the taxonomic composition and conservation status of the semi-evergreen tropical forest in the state of Hidalgo is limited and descriptive, and disturbances caused by human activities are drastically affecting its structure and original physiognomy. For these reasons, the objectives of this study were: 1) to conduct an inventory of the tree flora, and 2) to provide quantitative data on the structure of the different semi-evergreen tropical forest successional stages. The floristic inventory and structural characterization were conducted in 9 localities of Huautla municipality, in the “Huasteca hidalguense”. In each locality, the basal area, frequency, density of individuals (normal diameter > 10cm) and relative importance value of each species were calculated. A total of 92 species, 76 genera and 31 families of trees were identified. The families Fabaceae, Malvaceae and Moraceae were the most representative for their species richness. The species with highest relative importance value were Adelia barbinervis and Cedrela odorata in early stages of succession, Bursera simaruba and Guazuma ulmifolia in intermediate stages and Brosimum alicastrum in mature stages. In few localities, mature vegetation was observed, and total tree species richness was comparable with that recorded in the same type of vegetation in other entities of Mexico.

Annotated checklist of the tree flora of Bangladesh

Not available.This book is authored by Shukla Rani Basak and M. Khairul Alam.Bangladesh J. Plant Taxon. 23(2): 261-262, 2016 (December)

Angiosperm species of “Cerrado” sensu stricto in Terra Ronca State Park, Brazil: floristics, phytogeography and conservation

We conducted a floristic survey of “Cerrado” sensu stricto on Quartzipsamment soils in the northeastern state of Goias, Brazil, in Terra Ronca State Park (PETeR). In addition, we analysed phytogeographical aspects to investigate the floristic relationships between “Cerrado” and the Amazon, Atlantic Forest and “Caatinga” biomes. Furthermore, we assessed the shrub–tree flora similarity with other sites having the same type of physiognomy and soil class. We collected species along three 5 km × 60 m (90 ha) transects and recorded 278 species. Erythroxylum loefgrenii Diogo, Eugenia blanchetiana O.Berg and Martianthus stachydifolius (Epling) Harley & J.F.B.Pastore were listed as new records for the “Cerrado” (Brazilian savanna), and thirteen species were newly recorded for the state of Goias. Approximately, 28% of the species are endemic to the “Cerrado”, and 72% are shared with other Brazilian biomes. The shrub–tree layer of the “Cerrado” shares more species with the “Caatinga”, which shows the transitional aspects and affinities of the local flora with this biome. The high similarity between the woody flora of PETeR and “Cerrado” sensu stricto on Quartzipsamment soil sites in Bahia and northern Minas Gerais state associated with the occurrence of floristic elements that considered typical of the north–northeast portion of the “Cerrado” phytogeographical province reinforces the inclusion of the northeast region of Goias in this floristic province. The protected area in the Vao do Parana region represents only 3.3% of the total area of the region and 6% of the remaining natural vegetation in the area. Considering that the studied region holds an important flora and at the same time presents strong anthropogenic pressure from the occupation of agribusiness, it would be extremely important to prioritize conservation strategies to maintain the remaining natural vegetation in the northeastern portion of the “Cerrado”.

Evolutionary heritage influences Amazon tree ecology.

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.

The discovery of the Amazonian tree flora with an updated checklist of all known tree taxa.

Amazonia is the most biodiverse rainforest on Earth, and the debate over how many tree species grow there remains contentious. Here we provide a checklist of all tree species collected to date, and describe spatial and temporal trends in data accumulation. We report 530,025 unique collections of trees in Amazonia, dating between 1707 and 2015, for a total of 11,676 species in 1225 genera and 140 families. These figures support recent estimates of 16,000 total Amazonian tree species based on ecological plot data from the Amazonian Tree Diversity Network. Botanical collection in Amazonia is characterized by three major peaks, centred around 1840, 1920, and 1980, which are associated with flora projects and the establishment of inventory plots. Most collections were made in the 20th century. The number of collections has increased exponentially, but shows a slowdown in the last two decades. We find that a species’ range size is a better predictor of the number of times it has been collected than the species’ estimated basin-wide population size. Finding, describing, and documenting the distribution of the remaining species will require coordinated efforts at under-collected sites.

Is DNA barcoding child's play? Science education and the utility of DNA barcoding for the discrimination of UK tree species

We present the findings of a DNA barcoding study of the UK tree flora, implemented as part of an innovative, research-based science education programme called ‘Tree School’. The UK tree flora comprises native and introduced species, and is a taxonomically diverse study group for the exploration of the potential and limitations of DNA barcoding. The children participating in the project collected voucher specimens and generated DNA barcode sequences from trees and shrubs found in the grounds and surrounding woodlands of a residential field centre in Dorset, UK. We assessed the potential of rbcL and matK markers for amplification and DNA sequencing success and for species discrimination among the 67 tree and shrub species included in this study. Although we achieved 100% PCR amplification and sequencing success for rbcL and matK, mononucleotide repeats affected sequence quality in matK for some taxonomic groups (e.g. Rosaceae). Species discrimination success ranged from 65% to 71% using tree-based methods to 86% using BLASTN. The occurrence of known hybrids (diploid and polyploid) and their progenitors on the study site reduced the overall species discrimination success for both loci. This study demonstrates that, even in a floristic context, rbcL and matK alone are insufficient for the discrimination of UK tree species, especially where taxonomically complex groups are present. From a science education perspective, DNA barcoding represents a compelling and accessible platform for the engagement of non-experts in ongoing research, providing an opportunity for them to contribute authentic scientific data to an international research campaign.

Twenty years of woodland establishment through natural succession on a sandy landfill site in Berlin, Germany

This case study investigates natural colonization and woodland establishment over twenty years after beginning on bare ground on a sandy landfill site at Berlin–Malchow. The landfill, 6ha in extent, was capped with an N-poor, but Ca-rich, mineral soil from a construction site nearby. This deposited soil originated from deep horizons and therefore contained no seed bank. The focus of the paper concentrates on woody species, due to their dominant role during succession. A total of 35 tree species colonized the landfill within twenty years which represent more than 60% of the native and introduced naturalized tree flora of the region. The first colonizers and the dominant tree species were willows and poplars, especially Salix x rubens Schrank. Most tree species arrived within the first 6 years and built a tree layer >5m in height within the first decade. After 20 years of succession, mean species density from three 10m×20m sample plots was 58±10.6 species/200m2. Nearly half of the species were woody species (20±3.6 tree species and 6±1.0 shrub species). Mean total cover of the tree layer was 78.3±2.9%, and mean height was 13.3±1.5m. Mean basal area of trees >7cm DBH (in total 2500±391stems/ha) was 28.25±3.9m2/ha. The herb layer was dominated by perennial grasses, especially Calamagrostis epigejos (L.) Roth. The processes of colonization and succession on the landfill site show that effects of contingency, such as surrounding vegetation, year effects and priority effects act as drivers of vegetation dynamics. The N-poor substrate and the lack of a soil seed bank were no obstacles to the establishment of a woody vegetation cover in a relatively short time.

Tree flora and their environmental services to man: a case study of University of Benin

University campuses may be characterized by their plant species which add value to the environment. Tree species in the Ugbowo campus of University of Benin, Benin City, Nigeria were identified in this study. Using field surveys and structured questionnaires, trees species were inventoried based on their names, habit, environmental roles, and economic values. The study area was divided into 3 sites to enable accurate sampling of tree species. Number of individual species, total count of tree flora, relative density and relative abundance were assessed using appropriate ecological models. A total number of 268 trees comprising 24 species of trees from 14 families were encountered. Tectona grandis had the highest relative density and abundance of 27.99 and 0.28 respectively. About 181 trees (67.54 %) were dicots, and 87 (32.46 %) were monocots. More so, 202 (75.37 %) of the trees were exotic and 66 (24.63 %) were native. Margalef species richness was 2.339, 1.717 and 2.463 for sites A, B, and C respectively. Furthermore, Shannon-Wiener diversity index were 4.926, 57.555 and 227.654 for sites A, B, and C respectively. The different diversity values are supported by Sorenson’s similarity index, which suggest the sites are not similar. Some of the environmental services of the campus tree flora include; nutrient sink, add to the overall campus aesthetic, serve as shield from UV rays, contribute to student education, environmental monitoring, reduce air pollution, erosion control and bio resource conservation. Therefore, majority of the respondents (72 %) strongly disagreed with continuous felling of trees. This study suggests an increase in the cultivation of native tree species as an avenue to improve the diversity of trees in the campus.   

Evolutionary history shapes the susceptibility of an island tree flora to an exotic pathogen

With globalisation, the world’s native biotas are increasingly exposed to disease, parasitism, herbivory and competition from exotic organisms. The vulnerability of native biota to these exotic invasions is exacerbated by human disturbance and global climate change. Rust pathogens are some of the most important plant pathogens, including Puccinia psidii (myrtle rust or guava rust) that is now spreading worldwide at an alarming rate. P. psidii is native to South America and affects species in the family Myrtaceae, including the economically and ecologically important eucalypts. The Australian continent has a rich myrtaceous flora and is the centre of origin of most eucalypt species. P. psidii was first detected in Australia in 2010 and has since rapidly spread along its east coast. We assess the risk this exotic pathogen poses to the eucalypt flora of the southern Australian island of Tasmania, where the first incursion of P. psidii was detected in early 2015. Specifically, we tested the relative importance of phylogenetic history, habitat, endemism, and range size in predicting host susceptibility.Rust screening of seedlings from one to four populations of each of the 30 eucalypt species which are native to Tasmania, revealed significant genetic-based variation in response among host species and populations within the species. Significant population differences in susceptibility were detected in threatened, rare and endemic eucalypt species, as well as Australia’s main plantation eucalypt (Eucalyptus globulus) and the world’s tallest angiosperm species (Eucalyptus regnans). A significant proportion of the variation in host species susceptibility to this exotic pathogen was explained by phylogenetic history, while factors such as habitat, endemism and range size had no detectable effect. Species from subgenus Eucalyptus (13 species) were more susceptible than those from subgenus Symphyomyrtus (17 species) due to differences between the subgenera in the proportion of plants showing a symptomless response. These subgenera are here shown to differ in their leaf oil and wax chemistry. The potential contribution of these differences and other possible mechanisms causing these subgeneric differences in susceptibility are discussed. This study demonstrates the power of a phylogenetic approach to risk assessment for biosecurity and highlights the need for broader resistance screening within and between populations of species of high conservation or economic value.

Floristic Diversity of Forests of the Northwest Republic of the Congo

The study of structural and tree flora biodiversity of the forest of the Mbomo-Kellé UFA was done on an area of 88.5 ha (0.014% of the total UFA area). The inventory was carried out in plots of 200 m × 25 m (0.5 ha), arranged in a contiguous way along the opened trails in the forest with an equidistance interval of 2 km. 11,012 trees of DBH ≥20 cm were counted, divided into 107 genera, 31 families and 133 species including 121 completely identified and 12 defined only in terms of genus. Data analysis consisted of calculating relative and weighted frequencies, the Shannon and Weaver diversity indexes, Pielou’s evenness index, and the Jaccard and Sorensen similarity indices. Relative frequencies showed that the most representative family in terms of species is the Fabaceae-Caesal piniodeae with 18.05% of species and the most representative in terms of individuals is the Burseraceae with 19.17% of inventoried trees. The principal components analysis allowed to show inter- and intra-block heterogeneities.

Growth-climate relationships at yew and wild service trees on the eastern edge of their range in Europe

Aim of study: The aim of the study was the construction of regional chronologies for South-Western Poland for yew (Taxus baccata L.) and wild service tree (Sorbus torminalis L.), two of the rarest native tree species on the edge of their range in Europe. The relationships growth-climate and incremental dynamics at both these species were investigated as well.Area of study: The eastern borders of the ranges of yew and wild service trees run across Poland. The majority of the yew occurrence sites are situated in South Poland, within the area of uplands and mountains, whereas the wild service tree grows in the western part of the country. The study plots (5 for yew trees, 4 for wild service trees) were located in nature reserves in SW Poland.Material and Methods: The research materials were cores from 200 trees (115 yew trees and 85 wild service trees). The annual growth widths were measured, then, local chronologies were constructed using classic methods of dating. Regional chronologies were based on yew trees with the Student’test t > 6.0, and wild service trees with t > 5.9. The chronologies were subjected to the indexation and used for dendroclimatological analyses: pointer years, correlation and response function.Main results: The yew chronology, spanning 219 years (1790-2008), was established on the basis of 51 samples, the average width of annual growths amounted to 0.61 mm. The wild service tree chronology, representing the period 1841-2013 (173 years), was produced from 37 samples, the average width of annual growth amounted to 0.60 mm (from 0.27 up to 0.58 mm). Dendroclimatological analyses of the yew indicated thermal conditions of the winter months and beginning of spring (straight correlations) as the predominating factor affecting the annual growth widths. Summer drought was an additional factor limiting growth. For the wild service trees cool and humid summer months in the growing season favour the formation of wide growths.Research highlights: On account of strong dispersion and limited small populations of these two tree species, there are few dendrochronological studies available. Therefore, every piece of information on the ecology of the yew and wild service tree allows us to broaden our knowledge of these rare species enriching the biodiversity of the native tree flora.Keywords: tree-ring width; Taxus baccata L.; Sorbus torminalis L.; dendroclimatology; Poland.

Revisiting Patterns of Tree Species Composition and their Driving Forces in the Atlantic Forests of Southeastern Brazil

AbstractThe elucidation of phytogeographic patterns and their drivers in biodiversity hotspots is essential to the study of ecology and the conservation of these areas. In 2000, an important study by Oliveira‐Filho and Fontes led to changes in the paradigms that define our understanding of the Atlantic Forest (Brazil). Here, our aim was to revisit this study using a more comprehensive set of environmental predictors, an updated and much larger tree species dataset and checklist, and more refined data analyses. We performed exploratory and confirmatory analyses, including the modeling of the spatial components with Moran's Eigenvector Maps, using data from 483 sites in southeastern Brazil, which encompass a total of 3546 species and 33 geo‐climatic variables. We observed strong floristic similarities between rain‐ and seasonal forests and a species distribution continuum across the main gradients. The environmental and spatial variables were significantly correlated with floristic patterns, and we demonstrated that the tree flora of the seasonal forests should no longer be considered a simple subset of the rain forest flora. The findings of the original paper were not only confirmed but we also unveiled additional, important phytogeographic patterns. We also reinforced the main conclusion of the paper that the Atlantic Forest concept must encompass all of the forest types east of the dry corridor in South America, a designation of utmost importance for the conservation of this biodiversity hotspot.