Turberas en Valle del Alto Mayo, Perú: importancia, amenazas y perspectivas de conservación.

Los palmares de Mauritia flexuosa (aguajales) son considerados las principales turberas tropicales amazónicas que contribuyen al man¬tenimiento de la biodiversidad y del ciclo hidrológico, además de su aporte en el secuestro y almacenamiento de carbono. Mediante una revisión bibliográfica y observaciones de campo, se identifica la importancia, factores de amenaza y oportunidad para estos ecosistemas. Las turberas almacenan más del doble de carbono que todos los bosques del mundo en conjunto y conforman un grupo objetivo para el estudio del cambio climático. El acceso a sistemas de extracción no destructiva para la cosecha de los frutos debe estar articulado con planes socioeconómicos de desarrollo. Es imprescindible la aplicación de políticas participativas de educación ambiental e incentivos económicos a las comunidades que protegen estos territorios

Most species are not limited by an Amazonian river postulated to be a border between endemism areas

At broad scales in the Amazon, it is often hypothesized that species distributions are limited by geographical barriers, such as large rivers (river-barrier hypothesis). This hypothesis has been used to explain the spatial-distribution limits of species and to indicate endemism areas for several phylogenetic lineages. We tested the ability of the river-barrier hypothesis to explain patterns of species diversity and spatial-distribution limits for 1952 easily-detected species in 14 taxonomic groups that occur around the Madeira River, and our results indicate that the hypothesis that the Madeira River is the border between endemism areas and explains much of the diversity found in the region is inappropriate for >99% of species. This indicates that alternative hypotheses should be proposed to explain the limits of distributions of species around the Madeira River, as well as a revision of the criteria that are used to determine species-endemism areas. © 2018 The Author(s)

Different environmental gradients affect different measures of snake β-diversity in the Amazon rainforests

Mechanisms generating and maintaining biodiversity at regional scales may be evaluated by quantifying β-diversity along environmental gradients. Differences in assemblages result in biotic complementarities and redundancies among sites, which may be quantified through multi-dimensional approaches incorporating taxonomic β-diversity (TBD), functional β-diversity (FBD) and phylogenetic β-diversity (PBD). Here we test the hypothesis that snake TBD, FBD and PBD are influenced by environmental gradients, independently of geographic distance. The gradients tested are expected to affect snake assemblages indirectly, such as clay content in the soil determining primary production and height above the nearest drainage determining prey availability, or directly, such as percentage of tree cover determining availability of resting and nesting sites, and climate (temperature and precipitation) causing physiological filtering. We sampled snakes in 21 sampling plots, each covering five km2, distributed over 880 km in the central-southern Amazon Basin. We used dissimilarities between sampling sites to quantify TBD, FBD and PBD, which were response variables in multiple-linear-regression and redundancy analysis models. We show that patterns of snake community composition based on TBD, FBD and PBD are associated with environmental heterogeneity in the Amazon. Despite positive correlations between all β-diversity measures, TBD responded to different environmental gradients compared to FBD and PBD. Our findings suggest that multi-dimensional approaches are more informative for ecological studies and conservation actions compared to a single diversity measure

The global abundance of tree palms

Aim Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location Tropical and subtropical moist forests. Time period Current. Major taxa studied Palms (Arecaceae). Methods We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work. Conclusions Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests

Palms and trees resist extreme drought in Amazon forests with shallow water tables

1. The intensity and frequency of severe droughts in the Amazon region has increase in recent decades. These extreme events are associated with changes in forest dynamics, biomass and floristic composition. However, most studies of drought response have focused on upland forests with deep water tables, which may be especially sensitive to drought. Palms, which tend to dominate the less well‐drained soils, have also been neglected. The relative neglect of shallow water tables and palms is a significant concern for our understanding of tropical drought impacts, especially as one third of Amazon forests grow on shallow water tables (<5m deep). 2. We evaluated the drought response of palms and trees in forests distributed over a 600 km transect in central‐southern Amazonia, where the landscape is dominated by shallow water table forests. We compared vegetation dynamics before and following the 2015–16 El Nino drought, the hottest and driest on record for the region (−214 mm of cumulative water deficit). 3. We observed no change in stand mortality rates and no biomass loss in response to drought in these forests. Instead, we observed an increase in recruitment rates, which doubled to 6.78% y‐1 ± 4.40 (mean ± SD) during 2015–16 for palms and increased by half for trees (to 2.92% y‐1 ± 1.21), compared to rates in the pre‐El‐Nino interval. Within these shallow water table forests, mortality and recruitment rates varied as a function of climatic drought intensity and water table depth for both palms and trees, with mortality being greatest in climatically and hydrologically wetter environments and recruitment greatest in drier environments. Across our transect there was a significant increase over time in tree biomass. 4. Synthesis: Our results indicate that forests growing over shallow water tables – relatively under‐studied vegetation that nonetheless occupies one‐third of Amazon forests ‐ are remarkably resistant to drought. These findings are consistent with the hypothesis that local hydrology and its interactions with climate strongly constrain forest drought effects, and has implications for climate change feedbacks. This work enhances our understanding of integrated drought effects on tropical forest dynamics and highlights the importance of incorporating neglected forest types into both the modeling of forest climate responses and into public decisions about priorities for conservation

Variação espacial e temporal da biomassa vegetal direcionada por preditores ambientais em floresta de terra-firme na ESEC Cuniã – interflúvio madeira-purus, Rondônia, Brasil

Tese de Doutorado apresentada junto ao Programa de Pós-Graduação em Desenvolvimento Regional e Meio Ambiente, Área de Concentração em Desenvolvimento Sustentável & Diagnóstico Ambiental, para obtenção do Título de Doutor em Desenvolvimento Regional e Meio Ambiente. Porto Velho (RO) 2017Estudos referentes à composição de espécies e estimativas de biomassa vegetal na Amazônia são essenciais para ampliar o conhecimento de sua biodiversidade e subsidiar estimativas confiáveis para modelos de fluxo de carbono e predição da função das florestas tropicais no clima global. Além dos fatores climáticos e estocásticos, as variáveis edáficas, topográficas e hidrológicas também determinam os padrões estruturais e de distribuição de espécies e biomassa vegetal, atuando como preditores ambientais de grande influência. Neste estudo, são avaliados os efeitos destes preditores e das taxas de recrutamento e mortalidade sobre as variáveis: abundância e riqueza de espécies; variação espacial e temporal de biomassa viva acima do solo e variação espacial de necromassa. O estudo foi realizado em 30 parcelas permanentes de terra firme na Estação Ecológica do Cuniã – ESEC Cuniã, conforme a metodologia de Pesquisa Ecológica de Longa Duração – PELD e as diretrizes do Programa de Pesquisa em Biodiversidade – PPBio. A área de estudo, compreendida no interflúvio Madeira-Purus, possui fatores edáficos, topográficos e hidrológicos bastante específicos dentro do bioma, pertencendo a uma região de paleovárzea de solos oligotróficos, com alto percentual de palmeiras e estoque de biomassa vegetal relativamente baixo quando comparado a demais áreas na Amazônia. Por meio de análises fitossociológicas e emprego de modelagem de equações estruturais (SEM), em síntese, os resultados encontrados foram que: por estar inserida em uma região recente do ponto de vista geológico de características ecológicas peculiares, a área estudada reflete grande heterogeneidade ambiental com ausência de correlação entre as variáveis topográficas, edáficas e hidrológicas; ocorre alta variabilidade da composição de espécies, porém, os valores médios de riqueza, diversidade, área basal, percentual de espécies localmente raras e estoques de biomassa são baixos quando comparados à Amazônia; a integração das variáveis ambientais com os atributos fitossociológicos e estruturais vegetacionais possibilitou alto poder preditivo da variação espacial da composição florística, biomassa vegetal e necromassa, em que a riqueza foi direcionada principalmente pelo teor de silte no solo e a diversidade e variação espacial e temporal de biomassa foram principalmente determinadas pela distância horizontal da rede de drenagem, indicando maior produtividade e acúmulo de carbono em áreas próximas a rios e igarapés; e os estoques de necromassa de árvores grossas foram principalmente determinados por anoxia causada pela retenção de água no solo. Por fim, os resultados encontrados podem subsidiar políticas públicas de conservação e desenvolvimento regional para a região. Palavras-chave: Biomassa; Preditores ambientais; Amazônia Sul-Ocidental

Estrutura funcional de uma comunidade de palmeiras (Arecaceae) ao longo de gradientes ambientais em uma floresta da Amazônia Central

The functional approach allows us to understand how the environment selects the characteristics of the species that form the communities, and therefore how communities can be modified according to new conditions, such as those induced by climate change. Two forces can functionally structure a community: convergence, which promotes similarity of functional characteristics, and divergence, which promotes variability. Theoretically, it is expected that the environmental filters cause convergence, since they select characteristics suitable for the occupation of each environment. Contrarily, it is expected that biotic interactions and disturbances promote functional divergence by increasing environmental heterogeneity, selecting species with multiple functional strategies. Using palm trees (Arecaceae), an abundant and diverse way of life in the Amazon, as model group we analyze which environmental factors are responsible for generating convergence and functional divergence in local communities. This study was developed in the Adolpho Ducke Forest Reserve, where seven functional characteristics were observed that affect photosynthetic performance, balance and hydraulic safety and leaf economy (stomatal density, stomata size, venation density, dry matter content, leaf thickness, area specific leaf and estimated leaf area) of the 14 most abundant species of the reserve. We tested models including hydrological conditions and soil fertility as resource gradients and the mortality rate of trees as a proxy for the intensity of disturbance. Our results show that: 1) there is a functional differentiation between the hydrological environments, and in the plateaus conservative strategies are selected while in the bottomlands acquisitive strategies are favoured, 2) hydrological environments are the main filter of the functional composition 3) in the bottomlands there is a greater functional divergence of all the characteristics, while in the lowlands functional convergence and 4) the intensity of disturbance can generate both convergence and functional divergence. This means that the functional characteristics are selected mainly by the hydrological conditions of the soil, the disturbances can lead to convergence when its intensity is low and the divergence, when it increases the spatial and temporal heterogeneity of resources. Also, the variability of all the characteristics is greater in the lowlands, since the environmental heterogeneity existing in these places and the plateaus tend to have greater internal convergence due to the low dynamism and the spatial and temporal availability of resources. Thus, convergence is associated with responses to abiotic filters as the ecological theory of communities addresses, but contrary to what is predicted for processes that generate divergence, abiotic disturbances can also generate functional divergence.A abordagem funcional nos permite entender como o ambiente seleciona as características das espécies que formam as comunidades e, portanto, como as comunidades poderão ser modificadas em função de novas condições, como as induzidas por mudanças climáticas. Duas forças podem estruturar funcionalmente uma comunidade: a convergência, que promove similaridade das características funcionais, e a divergência, que leva à variabilidade. Teoricamente, espera-se que os filtros ambientais causem convergência, por selecionarem características adequadas para a ocupação de cada ambiente. Por outro lado, espera-se que interações bióticas e distúrbios promovam divergência funcional, por aumentarem a heterogeneidade ambiental, selecionando espécies com múltiplas estratégias funcionais. Tendo como modelo as palmeiras (Arecaceae), uma forma de vida abundante e diversa na Amazônia, analisamos quais fatores ambientais são responsáveis por gerar convergência e divergência funcional nas comunidades locais. Esse estudo foi desenvolvido na Reserva Florestal Adolpho Ducke, onde foram medidas sete características funcionais que afetam o desempenho fotossintético, balanço e segurança hidráulica e economia foliar (densidade estomática, tamanho dos estômatos, densidade de venação, conteúdo da matéria seca, espessura das folhas, área foliar específica e área estimada da lâmina) das 14 espécies mais abundantes da reserva. Foram testados modelos incluindo as condições hidrológicas e fertilidade do solo como gradientes de recurso e a taxa de mortalidade de árvores como um indicativo para a intensidade de distúrbio. Nossos resultados mostram que: 1) há diferenciação funcional entre os ambientes hidrológicos, sendo que nos platôs são selecionadas estratégias conservativas e nos baixios aquisitivas, 2) os ambientes hidrológicos são o principal filtro da composição funcional 3) nos baixios existe maior divergência funcional de todas as características, enquanto que nos platôs convergência funcional e 4) a intensidade de distúrbio pode gerar tanto convergência quanto divergência funcional. Isso significa que, as características funcionais são selecionadas principalmente pelas condições hidrológicas do solo, sendo os distúrbios podem levar à convergência quando a sua intensidade for baixa e à divergência, quando aumenta a heterogeneidade espacial e temporal de recursos,. Ainda, a variabilidade de todas as características é maior nos baixios, pois a heterogeneidade ambiental existente nesses locais e os platôs tendem a ter maior convergência interna devido ao baixo dinamismo e disponibilidade espacial e temporal de recursos. Sendo assim, a convergência está associada com respostas aos filtros abióticos conforme a teoria ecológica de comunidades aborda, mas contrário do que prediz quanto aos processos que geram divergência, os distúrbios abióticos também podem gerar divergência funcional

The global abundance of tree palms

Aim: Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location: Tropical and subtropical moist forests. Time period: Current. Major taxa studied: Palms (Arecaceae). Methods: We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results: On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work. Conclusions: Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests

The global abundance of tree palms

Aim: Palms are an iconic, diverse and often abundant component of tropical ecosys-tems that provide many ecosystem services. Being monocots, tree palms are evo-lutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon se-questration and storage) and in terms of responses to climate change. We quanti-fied global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change.Location: Tropical and subtropical moist forests.Time period: Current.Major taxa studied: Palms (Arecaceae).Methods: We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co-occurring non-palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure.Results: On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly asso-ciated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long-term climate stability. Life-form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non-tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above-ground biomass, but the mag-nitude and direction of the effect require additional work.Conclusions: Tree palms are not only quintessentially tropical, but they are also over-whelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests