101 research outputs found

    Mapeamento preditivo da vegeta√ß√£o: uso de SIG para modelar a distribui√ß√£o espacial de esp√©cies arb√≥reas na Amaz√īnia Central

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    A distribui√ß√£o espacial das popula√ß√Ķes vegetais √© abordada na ecologia como uma importante quest√£o devido a sua contribui√ß√£o ao entendimento de padr√Ķes e processos em florestas tropicais. A configura√ß√£o espacial das popula√ß√Ķes vegetais √© afetada pela intera√ß√£o dos fatores bi√≥ticos e abi√≥ticos do ambiente. Desta forma, a compreens√£o dos fatores que estruturam as popula√ß√Ķes vegetais possibilita a elabora√ß√£o de modelos de distribui√ß√£o de esp√©cies. Assim, este trabalho teve como objetivo principal elaborar e validar modelos de capazes de predizer a probabilidade de ocorr√™ncia de Aniba roseaodora, Cariniana micrantha, Caryocar villosum, Dinizia excelsa, Dipteryx odorata, Goupia glabra, Manilkara bidentata e Manilkara huberi, Parida multifuga, Parkia pendula, Peltogyne paniculata, Pseudopiptadenia psilostachya em fun√ß√£o de vari√°veis topogr√°ficas. A probabilidade de ocorr√™ncia dessas 12 esp√©cies arb√≥reas foi estimada a partir de regress√£o log√≠stica m√ļltipla. Os par√Ęmetros estimados foram incorporados a um SIG e com isso foi obtida a representa√ß√£o espacial das probabilidades de ocorr√™ncia estimadas para cada uma das esp√©cies. Os modelos indicaram associa√ß√£o entre a ocorr√™ncia dos indiv√≠duos em rela√ß√£o √† topografia para 10 esp√©cies. Os modelos estimaram de maneira acurada a ocorr√™ncia de 9 esp√©cies. A densidade dos indiv√≠duos variou entre as √°reas do modelo e de valida√ß√£o. Para √°rea onde o modelo foi validado houve sobreposi√ß√£o entre a distribui√ß√£o observada e estimada para as 9 esp√©cies citadas anteriormente. No entanto, houve grande varia√ß√£o entre o acr√©scimo de acerto de ocorr√™ncia para essas esp√©cies. Desta forma, o trabalho aqui apresentado indica que modelos preditivos de distribui√ß√£o de esp√©cies arb√≥reas podem predizer com acur√°cia ocorr√™ncia de esp√©cies em determinada √°rea, mas que a extrapola√ß√£o para outras √°reas deve considerar outros fatores, al√©m da topografia

    Manual de utilização de ferramenta do Centro Comum de Investigação para validação das mudanças da cobertura vegetal e do uso da terra

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    O projeto TREES-3 do CCI tem como objetivo avaliar mudan√ßas da cobertura vegetal na regi√£o tropical que ocorreram entre 1990 e 2000, e entre 2000-(2005)-2010. Para isto, foram processadas e avaliadas mudan√ßas da cobertura vegetal em uma grande quantidade de imagens de sat√©lite multi-temporais de resolu√ß√£o espacial m√©dia (unidades amostrais de 20 km x 20 km de imagens Landsat). Desta forma, o projeto TREES-3 busca avaliar para cada uma das unidades amostrais a cobertura florestal e as mudan√ßas da cobertura vegetal ocorrida num quinqu√©nio ou d√©cada com a mais alta precis√£o poss√≠vel. A an√°lise da mudan√ßa da cobertura vegetal e do uso da terra inclui tamb√©m uma etapa de valida√ß√£o visual da classifica√ß√£o das imagens de sat√©lite para atribuir as classes definitivas. Para esta etapa, o CCI desenvolveu uma ferramenta computacional chamada ‚Äė‚ÄėFerramenta do CCI para valida√ß√£o das mudan√ßas da cobertura vegetal e do uso da terra‚Äô‚Äô. Esta ferramenta √© utilizada por agentes florestais nacionais ou especialistas em sensoriamento remoto provenientes de pa√≠ses tropicais. Nesta ferramenta, a interpreta√ß√£o visual das imagens de sat√©lite √© efetuada de maneira simult√Ęnea utilizando imagens de dois per√≠odos diferentes. Desta forma, √© poss√≠vel verificar e ajustar classes de uso da terra que foram previamente definidas. Neste trabalho, a FAO colabora com o CCI no √Ęmbito do projeto de levantamento por sensoriamento remoto para avalia√ß√£o dos recursos florestais mundiais (FRA). O CCI agregou na ferramenta computacional uma fun√ß√£o que permite atribuir classes de uso da terra que fazem parte da classifica√ß√£o utilizada pela FAO. O presente documento, intitulado ‚Äė‚ÄėManual de utiliza√ß√£o de ferramenta do Centro Comum de Investiga√ß√£o para valida√ß√£o das mudan√ßas da cobertura vegetal e do uso da terra‚ÄĚ, explica o procedimento para instala√ß√£o da ferramenta e descreve as caracter√≠sticas da interface gr√°fica do usu√°rio.JRC.H.3-Forest Resources and Climat

    Metacommunity patterns of Amazonian Odonata: The role of environmental gradients and major rivers

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    Background. We identified and classified damselfly (Zygoptera) and dragonfly (Anisoptera) metacommunities in Brazilian Amazonia, relating species distribution patterns to known biological gradients and biogeographical history. We expected a random distribution of both Zygoptera and Anisoptera within interfluves. At the Amazonian scale, we expected Anisoptera metacommunities to be randomly distributed due to their higher dispersal ability and large environmental tolerance. In contrast, we expected Zygoptera communities to exhibit a Clementsian pattern, limited by the large Amazonia rivers due to their low dispersal ability. Methods. We used a dataset of 58 first-to-third order well-sampled streamlets in four Amazonian interfluves and applied an extension of the Elements of Metacommunity Structure (EMS) framework, in which we order Zygoptera and Anisoptera metacommunities by known spatial and biogeographic predictors. Results. At the Amazonian scale, both Zygoptera and Anisoptera presented a Clementsian pattern, driven by the same environmental and biogeographical predictors, namely biogeographic region (interfluve), annual mean temperature, habitat integrity and annual precipitation. At the interfluve scale, results were less consistent and only partially support our hypothesis. Zygoptera metacommunities at Guiana and Anisoptera metacommunities at Tapaj√≥s were classified as random, suggesting that neutral processes gain importance at smaller spatial scales. Discussion. Our findings were consistent with previous studies showing that environmental gradients and major rivers limit the distribution of Odonata communities, supporting that larger Amazonian rivers act as barriers for the dispersal of this group. In addition, the importance of habitat integrity indicates that intactness of riparian vegetation is an important filter shaping metacommunity structure of Amazonian stream Odonata.This work was supported by the Coordination for the Improvement of Higher Education Personnel‚ÄĒCAPES (120147/2016-01), Brazil National Council for Scientific and Technological Development‚ÄĒCNPq (303252/2013-8, 574008/2008-0, 305542/2010-9,478884/2008-7, 314523/2014-6), Brazilian Agriculture Research Corporation EMBRAPA (SEG 02.08.06.005.00), the UK Darwin Initiative (17023), The Nature Conservancy and the Natural Environment Research Council‚ÄĒNERC (NE/F01614X/1 and NE/G000816/1)

    Metacommunity patterns of Amazonian Odonata: the role of environmental gradients and major rivers

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    Background We identified and classified damselfly (Zygoptera) and dragonfly (Anisoptera) metacommunities in Brazilian Amazonia, relating species distribution patterns to known biological gradients and biogeographical history. We expected a random distribution of both Zygoptera and Anisoptera within interfluves. At the Amazonian scale, we expected Anisoptera metacommunities to be randomly distributed due to their higher dispersal ability and large environmental tolerance. In contrast, we expected Zygoptera communities to exhibit a Clementsian pattern, limited by the large Amazonia rivers due to their low dispersal ability. Methods We used a dataset of 58 first-to-third order well-sampled streamlets in four Amazonian interfluves and applied an extension of the Elements of Metacommunity Structure (EMS) framework, in which we order Zygoptera and Anisoptera metacommunities by known spatial and biogeographic predictors. Results At the Amazonian scale, both Zygoptera and Anisoptera presented a Clementsian pattern, driven by the same environmental and biogeographical predictors, namely biogeographic region (interfluve), annual mean temperature, habitat integrity and annual precipitation. At the interfluve scale, results were less consistent and only partially support our hypothesis. Zygoptera metacommunities at Guiana and Anisoptera metacommunities at Tapajós were classified as random, suggesting that neutral processes gain importance at smaller spatial scales. Discussion Our findings were consistent with previous studies showing that environmental gradients and major rivers limit the distribution of Odonata communities, supporting that larger Amazonian rivers act as barriers for the dispersal of this group. In addition, the importance of habitat integrity indicates that intactness of riparian vegetation is an important filter shaping metacommunity structure of Amazonian stream Odonata

    Macroecological links between the Linnean, Wallacean, and Darwinian shortfalls

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    Species are the currency of most biodiversity studies. However, many shortfalls and biases remain in our biodiversity estimates, preventing a comprehensive understanding of the eco-evolutionary processes that have shaped the biodiversity currently available on Earth. Biased biodiversity estimates also jeopardize the effective implementation of data-driven conservation strategies, ultimately leading to biodiversity loss. Here, we delve into the concept of the Latitudinal Taxonomy Gradient (LTG) and show how this new idea provides an interesting conceptual link between the Linnean (i.e., our ignorance of how many species there are on Earth), Darwinian (i.e., our ignorance of species evolutionary relationships), and Wallacean (i.e., our ignorance on species distribution) shortfalls. More specifically, we contribute to an improved understanding of LTGs and establish the basis for the development of new methods that allow us to: (i) better account for the integration between different shortfalls and, (ii) estimate how these interactions may affect our understanding about the evolutionary components of richness gradients at macroecological scales.This manuscript is partially derived from a working group on ‚ÄúBiodiversity Shortfalls‚ÄĚ held in November 2019 and sponsored by the National Institutes for Science and Technology (INCT) in Ecology, Evolution, and Biodiversity Conservation (CNPq proc. 465610/2014-5 and FAPEG proc. 201810267000023). JJMG and LEF are supported by Ph.D. and M.Sc. scholarships from CAPES, while LM and RBP are supported by postdoctoral fellowships from CAPES (PNPD). JS was funded by the funded by the European Union‚Äôs Horizon 2020 research and innovation programme under the Marie SkŇāodowska-Curie Action (grant agreement #843234; project: TAXON-TIME) and by the Spanish Council for Scientific Research (IF_ERC). GT and LJ are supported by a DTI fellowships from CNPq, while JAFD-F, LGL, and CJBC are supported by Productivity Grants from CNPq.Peer reviewe

    Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models

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    Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influences AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs

    Evolutionary Heritage Influences Amazon Tree Ecology

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    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

    Evolutionary Heritage Influences Amazon Tree Ecology

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    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

    Hyperdominance in Amazonian Forest Carbon Cycling

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    While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few ‚Äėhyperdominant‚Äô species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only ‚Čą1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region
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