Tree Flora Research Articles

Analysis of Forest Vegetal Characteristics of Akure Forest Reserve from Optical Imageries and Unmanned Aerial Vehicle Data

Forest vegetal characteristics monitoring has a long tradition records with a success rate ranging from low to medium or high depends on the application at the hands. Details information about the indication of association of phenomena as forest indicators, such forest gap, estate and forest status, provides high spatial resolution images. The aim of this study focuses on combining unmanned Aerial Vehicles (UAVs) and satellite multispectral imaging along side by side to details forest parameter during the seasons. UAVs image at 0.15m appeared more detailed of having features such as rock, road, bare ground, riparian trees among others than that of Landsat OLI image, though the features such as rock, road, bare ground, and riparian forest were also seen on the image but it was poorly seen due to the coarse spatial resolution of 30 m. The 3-Dimensional of UAVs, relief pattern and contour from Shuttle Radar Topography Mission was also compared and this study further demonstrated on the advantages of Unmanned Aerial Vehicle data over established remotely sensed data which includes flying blow the cloud, high spatial resolution, flexibility, inexpensive of data acquisition, time effective, using video footage to detect human activities such as tree flora, burning and logging.

Analysis of Forest Vegetal Characteristics of Akure Forest Reserve from Optical Imageries and Unmanned Aerial Vehicle Data

Forest vegetal characteristics monitoring has a long tradition records with a success rate ranging from low to medium or high depends on the application at the hands. Details information about the indication of association of phenomena as forest indicators, such forest gap, estate and forest status, provides high spatial resolution images. The aim of this study focuses on combining unmanned Aerial Vehicles (UAVs) and satellite multispectral imaging along side by side to details forest parameter during the seasons. UAVs image at 0.15m appeared more detailed of having features such as rock, road, bare ground, riparian trees among others than that of Landsat OLI image, though the features such as rock, road, bare ground, and riparian forest were also seen on the image but it was poorly seen due to the coarse spatial resolution of 30 m. The 3-Dimensional of UAVs, relief pattern and contour from Shuttle Radar Topography Mission was also compared and this study further demonstrated on the advantages of Unmanned Aerial Vehicle data over established remotely sensed data which includes flying blow the cloud, high spatial resolution, flexibility, inexpensive of data acquisition, time effective, using video footage to detect human activities such as tree flora, burning and logging.

Regional variation in interior Alaskan boreal forests is driven by fire disturbance, topography, and climate

AbstractHigh latitude regions are warming rapidly with important ecological and societal consequences. Utilizing two landscape‐scale data sets from interior Alaska, we compared patterns in forest structure in two regions with differing fire disturbance, topography, and summer climate norms. Our goal was to evaluate a set of hypotheses concerning possible warming‐driven changes in forest structure suggested by recent literature. We found essentially consistent habitat associations for the tree flora across two disparate study areas concomitant with considerable differences in observed patterns of forest structure and composition. Our results confirmed expected increases in broadleaved species occupancy and abundance in the warmer, more fire‐affected study region along with considerably higher tree occupancy and abundance in high elevation areas there. However, contrary to our predictions, we found no evidence of expected reductions in conifer occupancy or increases in non‐fire related tree mortality. Instead, both individual and combined tree species occupancy, density, abundance, and richness were considerably higher in the warmer, more fire‐influenced region, except in the warmest, driest areas (steep and south‐facing slopes at low elevation). Our comparison of two landscape‐scale data sets suggests that changes in tree distribution and forest structure in interior Alaska will proceed unevenly, governed by a mosaic of site‐dependent influences wherein forest community composition and species dominance will shift along different trajectories and at different rates according to variation in underlying landscape attributes. Although there were clear differences in forest structure between the two areas that were likely attributable to differences in growing season warmth and fire disturbance, we found scant support for the concept of an incipient, ongoing biome shift in interior Alaska resulting from impending diminution of boreal forest cover over the short to medium term. Indeed, we suggest that (depending on severity of disturbance dynamics and the rapidity of future warming) cooler areas of interior Alaska's forest may reasonably be expected to sustain marginal increases in forest cover with additional warming, at least in certain topographic positions (such as poorly drained basins and cool treeline sites) and/or geographic regions, prior to any landscape‐scale diminution of forest cover due to warming.

Testing the divergent adaptation of two congeneric tree species on a rainfall gradient using eco‐physio‐morphological traits

AbstractIn tropical Africa, evidence of widely distributed genera transcending biomes or habitat boundaries has been reported. The evolutionary processes that allowed these lineages to disperse and adapt into new environments are far from being resolved. To better understand these processes, we propose an integrated approach, based on the eco‐physio‐morphological traits of two sister species with adjacent distributions along a rainfall gradient. We used wood anatomical traits, plant hydraulics (vulnerability to cavitation, wood volumetric water content, and hydraulic capacitance), and growth data from the natural habitat, in a common garden, to compare species with known phylogeny, very similar morphologically, but occupying contrasting habitats: Erythrophleum ivorense (wet forest) and Erythrophleum suaveolens (moist forest and forest gallery). We identified some slight differences in wood anatomical traits between the two species associated with strong differences in hydraulics, growth, and overall species distribution. The moist forest species, E. suaveolens, had narrower vessels and intervessel pits, and higher vessel cell‐wall reinforcement than E. ivorense. These traits allow a high resistance to cavitation and a continuous internal water supply of the xylem during water shortage, allowing a higher fitness during drought periods, but limiting growth. Our results confirm a trade‐off between drought tolerance and growth, controlled by subtle adaptations in wood traits, as a key mechanism leading to the niche partitioning between the two Erythrophleum species. The generality of this trade‐off and its importance in the diversification of the African tree flora remains to be tested. Our integrated eco‐physio‐morpho approach could be the way forward.

Aspectos ecológicos das espécies regenerantes de uma floresta urbana com 150 anos de sucessão florestal: o risco das espécies exóticas

A presença de florestas dentro de centros urbanos tem grande importância, principalmente devido aos serviços ecossistêmicos proporcionados por elas. Fragmentos urbanos são pouco estudados e trabalhos quantitativos focados na flora arbórea na área do presente estudo nunca foram realizados. O objetivo foi avaliar a composição, estrutura e diversidade de espécies regenerantes de uma floresta urbana, oriunda de um projeto paisagístico. Buscou-se responder a seguinte questão: a floresta está conseguindo avançar no processo sucessional após 150 anos de regeneração natural? O estudo foi realizado em uma área com tamanho total de aproximadamente 7,8 ha e de predomínio da Floresta Atlântica. A amostragem foi realizada em 25 parcelas de 5 x 5 m, nas quais todos os indivíduos com diâmetro a altura do peito (DAP) < 5 cm e altura > 1 m foram amostrados. Encontram-se 1297 indivíduos, distribuídos em 84 espécies. Três espécies exóticas com conhecido potencial invasor foram encontradas: Coffea arabica, Artocarpus heterophyllus e Persea americana. A espécie Coffea arabica apresentou o maior Valor de Importância na comunidade. O índice de diversidade de Shannon foi de H’ = 3,10 nats.ind-1, e equabilidade de Pielou de J’ = 0,70. A análise de Cluster (coeficiente de Morisita-Horn) evidenciou uma comunidade com baixa heterogeneidade interna. A análise dos grupos ecológicos revelou uma comunidade com dificuldades em avançar para estágios sucessionais superiores. Este estudo é importante para reforçar o risco das espécies exóticas invasoras em projetos paisagísticos.

Long-term succession of closed boreal forests at their range limit in eastern North America shows resilience to fire and climate disturbances

The distribution of vegetation zones in northeastern North America forms a gradual transition from closed to open forests, and to tundra. Closed forests near the open forest/tundra boundary generally correspond to residual patches of a once larger forest community. Whether these forest patches have survived as untouched, fire-free communities or as resilient communities during the Holocene remains unknown. To answer to this question, we reconstructed the successional history of two black spruce closed-crown forests and one jack pine forest near the northern limit of closed forest ecosystems. Stand-scale postfire succession was analysed based on charcoal macrofossils. Extensive 14C dating and botanical identification of charcoal fragments located at the organic soil surface and buried in the mineral podzolic solum were used to reconstruct the successional pathways of the sites. The forest sites developed in a context of continuous fire disturbance, except for a short interval of several centuries. The fire history of the three sites is similar with a fire frequency of 34–37 fires over the last 5000–5800 years, which corresponds to a mean fire interval of 150–180 years. Based on parametric and non-parametric estimators, the regional fire regime of the Laforge area (combined fire data of two sites located about 7 km from each other) was most likely characterized by 38 fires over the last 5000–5800 years, i.e., at an interval of about 150–160 years. Birch (Betula papyrifera) was present in the spruce sites between 5800 and 3000 cal. years BP. Jack pine arrived at the pine site about 3000 cal. years BP, at the time when birch was extirpated from the spruce forests. The closed-crown forests near the open forest/tundra boundary are resilient postfire ecosystems which regenerated successfully since mid-Holocene. Compositional change of these forests, which led to the decline of birch but maintained the dominance of conifers, appears related to cooler and wetter conditions of late Holocene. Climatic conditions also slowed the eastward migration of jack pine, which explains the late arrival of this species at its northeastern range. Our data suggest that fire disturbance in these sites of the boreal biome has been a continuous and positive regenerative process since mid-Holocene despite the influence of climatic change on the tree flora.

“Study of Phenology of Woody Flora of Gulmarg and Its Neighbourhood” for Landscape Use

The present investigation entitled “Study of phenology of ornamental flora of Gulmarg and its neighbourhood for landscape use” conducted during the years 2008-2010 in Gulmarg area of Kashmir valley. For this purpose four representative zones including zone A. ferozpur (1880 m.asl) and Tangmarg (2153 m.asl), zone B. Drang. (2218 m.asl) zone C. Doobi ghat (2218 m.asl), Gulmarg (2688 m.asl) and Baba reshi (2703 m.asl) and zone D. khelanmarg (3041 m.asl) were selected and recorded observations on flower emergence by making exploratory trips to these sites. Phonological spectrum of the flora of deciduous trees and shrubs, broad leaf evergreen trees and shrubs, deciduous woody vines, ground covers and evergreen ground cover shrubs revealed maximum availability of flowers during spring followed by summer and autumn.

Pollen and non-pollen palynomorph analyses of Upper Holocene sediments from Dianshan, Yangtze coastal lowlands, China: Hydrology, vegetation history and human activity

The coastal deltaic plain of the Yangtze River between Taihu (Lake Tai) and Shanghai in eastern China has been the scene of human settlement and agriculture since the early Neolithic, becoming increasingly intensive in the Upper Holocene when delta accretion and the establishment of a stable hydrological regime of freshwater lakes and wetlands allowed the development of extensive agriculture and complex society in late prehistoric and dynastic times. During this period the area was significantly affected by changes in sea level, climate and vegetation, resulting in a dynamic and complex environmental history, however little research has concentrated on environmental change and human impacts during the last few millennia. This study focuses on this late period, presenting the results of integrated sedimentary, microfossil and radiocarbon analyses from a core near the eastern margin of Lake Dianshan, to the east of Taihu. After the withdrawal of intertidal conditions and the conversion to freshwater lake at the core site about 2600 cal. yr BP, pollen and algal spore data show that increased sedimentation gradually reduced freshwater depth until a surface peat formed ca. 1500 cal. yr BP. This also dates the start of a switch in woodlands from sub-tropical and warm temperate trees to a mainly cool temperate and coniferous tree flora, under climatic cooling and human impact. After this time water depths at the site increased greatly, partly due to climate change and flooding, but also because of the establishment of deepwater ‘paddy’ agriculture. Microcharcoal and pollen data show that a major episode of human impact using fire, with deforestation and rice cultivation, occurred between ca. 1500 and 1200 cal. yr BP. These dates suggest it is one of the latest examples of ‘flooded-field’ ‘paddy’ cultivation before more intensive agricultural techniques were adopted in the area after ca. 800 cal. yr BP.

Towards a dynamic list of Amazonian tree species

To provide an empirical foundation for estimates of the Amazonian tree diversity, we recently published a checklist of 11,675 tree species recorded to date in the region (ter Steege H, et al. (2016) The discovery of the Amazonian tree flora with an updated checklist of all known tree taxa. Scientific Reports 6:29549). From this total of plant records compiled from public databases and literature, widely used in studies on the Amazonian plant diversity, only 6,727 tree species belong to the first taxonomically-vetted checklist published for the region (Cardoso D, et al. (2017) Amazon plant diversity revealed by a taxonomically verified species list. PNAS 114:10695-10700). The striking difference in these two numbers spurred us to evaluate both lists, in order to release an improved Amazonian tree list; to discuss species inclusion criteria; and to highlight the ecological importance of verifying the occurrence of “non-Amazonian” trees in the region through the localization and identification of specimens. A number of species in the 2016 checklist that are not trees, non-native, synonyms, or misspellings were removed and corresponded to about 23% of the names. Species not included in the taxonomically-vetted checklist but verified by taxonomists to occur in Amazonia as trees were retained. Further, the inclusion of recently recorded/new species (after 2016), and recent taxonomic changes added up to an updated checklist including 10,071 species recorded for the Amazon region and shows the dynamic nature of establishing an authoritative checklist of Amazonian tree species. Completing and improving this list is a long-term, high-value commitment that will require a collaborative approach involving ecologists, taxonomists, and practitioners.

CharKey: An electronic identification key for wood charcoals of French Guiana

ABSTRACT Tropical tree floras are highly diverse and many genera and species share similar anatomical patterns, making the identification of tropical wood charcoal very difficult. Appropriate tools to characterize charcoal anatomy are thus needed to facilitate and improve identification in such species-rich areas. This paper presents the first computer-aided identification key designed for charcoals from French Guiana, based on the wood anatomy of 507 species belonging to 274 genera and 71 families, which covers respectively 28%, 67% and 86% of the tree species, genera and families currently listed in this part of Amazonia. Species of the same genus are recorded together except those described under a synonym genus in Détienne et al. (1982) that were kept separately. As a result, the key contains 289 ‘items’ and mostly aims to identify charcoals at the genus level. It records 26 anatomical features leading to 112 feature states, almost all of which are illustrated by SEM photographs of charcoal. The descriptions were mostly taken from Détienne et al.’s guidebook on tropical woods of French Guiana (1982) and follow the IAWA list of microscopic features for hardwood identification (Wheeler et al. 1989). Some adjustments were made to a few features and those that are unrelated to charcoal identification were excluded. The whole tool, named CharKey, contains the key itself and the associated database including photographs. It can be downloaded on Figshare at https://figshare.com/s/d7d40060b53d2ad60389 (doi: 10.6084/m9.figshare.6396005). CharKey is accessible using the free software Xper2, specifically conceived for taxonomic description and computer aided-identification.

Analyses of Chloroplast Genomic and Morphological Evolutionomy of Yulania Sprengeri and Two New Confusable Species (Magnoliaceae)

To scientifically solve the taxonomical confusion of Yulania sprengeri (Pamp.) D. L. Fu in the world, the chloroplast genomic sequences of four confusable species were assembled and compared with the other species of Yulania Spach by means of the typical algorithm. The results indicated that the evolutionary system of Yulania Spach includes four natural sections: Y. sect. Yulania, Y. sect. Buergeria (Sieb. & Zucc.) D. L. Fu, Y. sect. Rosula D. L. Fu, sect., nov., and Y. sect. Tulipastrum (Spach) D. L. Fu, which all have the same boundaries: PHS (17bp) = 0.96. The species Y. sprengeri (Pamp.) D. L. Fu belong to sect. Yulania, but several confusable species such as Y. diva (Stapf. ex Dandy) D. L. Fu, sp. transl. nov., Y. urceolata D. L. Fu, B. H. Xiong et X. Chen, sp. segregat. nov., Y. pendula D. L. Fu, sp. nov. and Y. viridula D. L. Fu, T. B. Zhao et G. H. Tian belong to the new section Rosula D. L. Fu. According to International Code of Botanical Nomenclature, Y. sprengeri (Pamp.) D. L. Fu is proposed for conservation and emended with the conserved type (D. L. Fu 2017100803, CAF). The misidentified epitype of Magnolia sprengeri, the illustration in Flora of Trees of China, differing taxonomically, selected as Lectotype, with almost equal specimen, paratype (D. L. Fu 2017093001, CAF) from Weining County, Guizhou province of China, was segregated as a new species, Y. urceolata D. L. Fu, B. H. Xiong et X. Chen. The other new confusable species, Y. pendula D. L. Fu, is described and illustrated based on the holotype (D. L. Fu 2012040201, CAF) from Sichuan province of China, which was once misidentified as Y. biondii (Pamp.) D. L. Fu or Y. sprengeri (Pamp.) D. L. Fu. The typci-evolutionary characters including diagnostic differences and particularity of the new section and two new species, are given respectively. The evolutionary system scientifically overcomes the partiality and subjectivity of past taxonomical systems of Yulania Spach of Magnoliaceae Juss.

Dendrochronology and climate in the Brazilian Atlantic Forest: Which species, where and how

As dendrochronology noticeably increased in tropical regions during the last three decades, some general patterns could emerge from comprehensive analyses of case studies. Here, we investigated the state of dendrochronology’s contributions to the bioclimatology of wood species in the Brazilian Atlantic Forest (AF). We asked: Which species and sites had cross-datable growth-ring series suitable for bioclimatic inference? What were the sampling and analytical methods applied? What do these studies tell us about plant-growth sensitivity to climate conditions? Which knowledge gaps may be identified? For this, we searched for articles addressing climate-growth relationships by means of cross-dated growth-ring chronologies within the AF. We found 11 articles, covering 16 chronologies from 10 species. The average number of trees in chronologies was 16 individuals. 87% of chronologies suggested a positive precipitation signal, and some positive temperature signal was identified in all chronologies that were compared to monthly or seasonal temperature series. The findings are supported by the specialized literature, which points out the influence of precipitation in the tropics. However, making stronger conclusions about the role of climate on the growth of AF tree species will require greater efforts in surveying the diverse tree flora and developing rigorous cross-dated chronologies. Keywords: climate-growth relationship, dendrochronological parameters, tropical forest, subtropical forest.

MODELOS ARQUITETÔNICOS PARA AS ESPÉCIES ARBÓREAS DE UMA FLORESTA ESTACIONAL SUBTROPICAL NO RIO GRANDE DO SUL

Os modelos arquitetônicos ajudam a descrever o desenvolvimento e a organização das copas das árvores.Este conhecimento é essencial para a compreensão do desenvolvimento das árvores na floresta e podeajudar a entender a relação evolutiva entre táxons. O trabalho teve como objetivo verificar a riqueza demodelos arquitetônicos das espécies arbóreas de uma Floresta Estacional. Os dados foram coletados a partirde observações de campo e literatura especializada. Foram encontradas 53 espécies da flora arbórea de umaFloresta Estacional Subtropical de Santa Maria - RS, distribuídas em 45 gêneros e 28 das famílias. No total,13 diferentes modelos arquitetônicos foram reconhecidos. Os modelos com maior destaque foram Rauh,Troll, Scarrone, Roux e Massart. A complexidade arquitetural, refletida pelo elevado número de modelosdescritos, se deve ao desenvolvimento do dossel no remanescente estudado. O trabalho teve um caráterpioneiro e exploratório e deve fornecer um marco para novos estudos sobre arquitetura de plantas na regiãosubtropical do Brasil.

Environmental and Ecosystem Services, Tree Diversity and Knowledge of Family Farmers

ABSTRACT The objective of this work is to identify environmental and ecosystem services provided by trees from the perception of family farmers in the Serra dos Tapes, southern Rio Grande do Sul, Brazil, addressing the relevance of species for ecosystem sustainability of family farming. Environmental and ecosystem services offered by the tree flora of semi-deciduous submontane forest are presented according to the perception of farmers who use accumulated knowledge for social, cultural and economic reproduction in family farming. Four farmers were selected for their remarkable knowledge related to the agro-ecosystem and the local floristic composition, and they answered semi-structured interviews about 115 native tree species relating them to environmental and ecosystem services. The knowledge of farmers regarding the importance of forest cover for beekeeping, agroforestry system installation, source of biological materials for environmental recovery, conservation of hydric resources and for feeding mammals and birds was evidenced.

Trees description in the main square of São José do Rio Preto, São Paulo State, Brazil

The knowledge of the flora existing in the cities is of great importance from the ecological and sustainable point of view, as well as being a premise for actions that provide greater safety, comfort and well-being for the population. The objective of this work was to perform an analysis of the composition, diversity and quality of the tree flora (trees and palms) existing in Rui Barbosa Square, São José do Rio Preto, São Paulo State. This square is considered the main place for its location, history and use, and is located in the central region, next to the Cathedral. The arboreal individuals present in the square were counted, identified and evaluated the height and circumference of the trunk at the height of the chest; were determined phytosociological descriptors, Shannon-Weaver index and observed qualitative aspects (stem-glass balance, general status of the specimen, phytosanity and presence of association with other organisms: insects, lichens, epiphytes or parasites). The floristic composition of Rui Barbosa Square, consisted of 15 botanical families, composed of 25 genera and 28 species, in a total of 103 individuals, among trees and palm trees. The most representative species was Dypsis lutescens, with a frequency of 20.39%. The Shannon-Weaver index, an indicator of diversity, was 2.77, showing that the square presents great floristic diversity. The majority (72.8%) of individuals is in a regular or poor state; 66.02% had some fungus symptoms; 12.62% present problems due to termite attack; mosses, lichens and epiphytes are present in73.78% of the individuals in the square.

Greater tree species richness in eastern North America compared to Europe is coupled to denser, more clustered functional trait space filling, not to trait space expansion

AbstractAimDetermine if differences in species richness between currently climatically similar regions correlate to dissimilarities in functional diversity.LocationEurope and eastern North America.Time periodNeogene and Quaternary.Major taxa studiedTemperate trees of Europe and eastern North America.MethodsUsing classic functional traits defining distinct ecological strategies, we described the trait spaces of European and eastern North American tree floras. The trait space of each region was described based on the occupied area, species accumulation pattern, and the trait‐space size, dispersion and clustering. We then evaluated if the species richness differences between these two climatically similar regions correlate to dissimilarities in both occupied areas and species accumulation patterns; as well as differences in the trait‐space size, dispersion and clustering.ResultsDifferences in species richness between climatically similar regions do not necessarily result in functional dissimilarities. Regardless of eastern North American species having a larger trait‐space, occupied areas and species accumulation patterns converged. Although in both regions species clumped towards the trait‐space centroid, we observed statistically significant differences between Europe and eastern North America in the dispersion and clustering but not in size of the trait space. Moreover, traits from species in genera still present in eastern North America but lost from Europe during the Neogene and Quaternary were fully contained within the currently occupied European trait space.Main conclusionsPositional convergence between European and eastern North American trait spaces suggests that this species richness anomaly does fully translate to the functional space. Our results suggest that species accumulation within a region occurs within a climatically restricted trait space, and not via trait‐space expansion. Moreover, the consistent aggregation of species towards the trait‐space centre aligns with the idea of a directional section towards a generalized morphology, which might provide the best way to interact with a broad array of environmental conditions.

Epiphytic strangler trees colonizing extreme habitats of building envelopes in Hong Kong

Trees growing spontaneously on building envelopes, as wall vegetation, denote unique urban ecology. This study investigates the tree flora, substrate, and colonization-development factors on poorly-maintained buildings in Hong Kong. Field surveys gleaned data on species composition, microhabitat, shoot-root dimensions, and biomass structure. The survey sampled 567 trees. They belonged to ten species, distinguished as strong stranglers, moderate stranglers and non-stranglers. Strong stranglers, such as the native Ficus microcarpa and F. virens, were dominant, with diaspores dispersed mainly by frugivorous birds tapping cultivated and ruderal trees. Most trees had limited crown spread and height, and the larger ones were strong stranglers. The compact tree form, reflecting growth constraints, limited their landscape-scenic contributions. Most surface roots displayed restricted lateral growth contrasted by more vertical extension. Five microhabitats were identified. Two mainly vertical ones accommodated 42.3% of the trees, including wall vertical surface holding the most, and pipe surface. Three mainly horizontal microhabitats, more conducive to seed lodging and tree establishment, held 57.7%, including awning & ledge, roof top & edge taking the second largest share, and window sill & canopy. The stranglers scaled more vertical sites, whereas non-stranglers more horizontal. Root-shoot and root-biomass ratios reflected microhabitat controls. The findings were discussed vis-a-vis pre-adaptation of stranglers to vertical-habitat existence, enabling and restrictive microhabitat traits, plaster degradation as critical pre-condition, leap-frog succession and species paucity, analogy with rocky cliff habitat, and application to building-tree management.

The tree species pool of Amazonian wetland forests: Which species can assemble in periodically waterlogged habitats?

We determined the filtered tree species pool of Amazonian wetland forests, based on confirmed occurrence records, to better understand how tree diversity in wetland environments compares to tree diversity in the entire Amazon region. The tree species pool was determined using data from two main sources: 1) a compilation of published tree species lists plus one unpublished list of our own, derived from tree plot inventories and floristic surveys; 2) queries on botanical collections that include Amazonian flora, curated by herbaria and available through the SpeciesLink digital biodiversity database. We applied taxonomic name resolution and determined sample-based species accumulation curves for both datasets, to estimate sampling effort and predict the expected species richness using Chao’s analytical estimators. We report a total of 3 615 valid tree species occurring in Amazonian wetland forests. After surveying almost 70 years of research efforts to inventory the diversity of Amazonian wetland trees, we found that 74% these records were registered in published species lists (2 688 tree species). Tree species richness estimates predicted from either single dataset underestimated the total pooled species richness recorded as occurring in Amazonian wetlands, with only 41% of the species shared by both datasets. The filtered tree species pool of Amazonian wetland forests comprises 53% of the 6 727 tree species taxonomically confirmed for the Amazonian tree flora to date. This large proportion is likely to be the result of significant species interchange among forest habitats within the Amazon region, as well as in situ speciation processes due to strong ecological filtering. The provided tree species pool raises the number of tree species previously reported as occurring in Amazonian wetlands by a factor of 3.2.

The ecology of Central European tree species: Trait spectra, functional trade-offs, and ecological classification of adult trees

Plant functional traits offer insights into the plant-environment relationship and may help to understand how plants influence ecosystem functions. Applying trait-based models on climate and land-use change to forests is often hindered by poor data quality, as many data are estimates and traits are often parameterized for juvenile and not adult trees. For advancing theory building and improving the quality of trait data with relevance for adult trees, we compiled a unique trait database for the complete tree flora of Central Europe (42 species from 11 families), covering 38 morphological and physiological traits mostly parameterized with sun and shade crown and root data from adult trees. Despite only small variation in climate, several traits vary largely in this tree species sample, likely reflecting regional edaphic variation, while the influence of phylogenetic diversity is low and restricted to the angiosperm-gymnosperm divergence. The well-established shade tolerance-drought tolerance and wood density-drought sensitivity trade-offs are not supported by our data set, possibly due to the explicit consideration of adult trees and the absence of extended climatic gradients. For the 11 major tree species with high information density, a principal components analysis (PCA) identified three key functional traits, (i) minimum light demand of the adult trees’ shade leaves, (ii) stand leaf area index (LAI), and (iii) maximum tree height, which allows distinguishing five tree functional groups, among them a mid-successional tree group. Only a small minority of traits changes significantly along the early-to-late successional axis, contradicting a main paradigm in forest succession research. The functional contrast between early- and late-successional trees is smaller in the sun canopy of adults than in seedlings or saplings, suggesting that trait data from juveniles cannot simply be extrapolated to adults. Focusing on adult trees and on traits with a more direct link to the underlying processes may significantly improve tree functional classification and trait-based models in forest ecology and biogeochemistry.

Plant responses to fertilization experiments in lowland, species-rich, tropical forests.

We present a meta-analysis of plant responses to fertilization experiments conducted in lowland, species-rich, tropical forests. We also update a key result and present the first species-level analyses of tree growth rates for a 15-yr factorial nitrogen (N), phosphorus (P), and potassium (K) experiment conducted in central Panama. The update concerns community-level tree growth rates, which responded significantly to the addition of N and K together after 10yr of fertilization but not after 15yr. Our experimental soils are infertile for the region, and species whose regional distributions are strongly associated with low soil P availability dominate the local tree flora. Under these circumstances, we expect muted responses to fertilization, and we predicted species associated with low-P soils would respond most slowly. The data did not support this prediction, species-level tree growth responses to P addition were unrelated to species-level soil P associations. The meta-analysis demonstrated that nutrient limitation is widespread in lowland tropical forests and evaluated two directional hypotheses concerning plant responses to N addition and to P addition. The meta-analysis supported the hypothesis that tree (or biomass) growth rate responses to fertilization are weaker in old growth forests and stronger in secondary forests, where rapid biomass accumulation provides a nutrient sink. The meta-analysis found no support for the long-standing hypothesis that plant responses are stronger for P addition and weaker for N addition. We do not advocate discarding the latter hypothesis. There are only 14 fertilization experiments from lowland, species-rich, tropical forests, 13 of the 14 experiments added nutrients for five or fewer years, and responses vary widely among experiments. Potential fertilization responses should be muted when the species present are well adapted to nutrient-poor soils, as is the case in our experiment, and when pest pressure increases with fertilization, as it does in our experiment. The statistical power and especially the duration of fertilization experiments conducted in old growth, tropical forests might be insufficient to detect the slow, modest growth responses that are to be expected.