364 research outputs found
Tropical montane cloudforest
No full textcover: Inside a tropical montane cloudforest near timberline in the southern Peruvian Andes of Manu National Park (13.12345 S, 71.61721 W, 3600 m.a.s.l.). Picture by Kenneth Feeley.</span
Changes in tree functional composition across topographic gradients and through time in a tropical montane forest
No full textUnderstanding variation in tree functional traits along topographic gradients and through time provides insights into the processes that will shape community composition and determine ecosystem functioning. In montane environments, complex topography is known to affect forest structure and composition, yet its role in determining trait composition, indices on community climatic tolerances, and responses to changing environmental conditions has not been fully explored. This study investigates how functional trait composition (characterized as community-weighted moments) and community climatic indices vary for the tree community as a whole and for its separate demographic components (i.e., dying, surviving, recruiting trees) over eight years in a topographically complex tropical Andean forest in southern Ecuador. We identified a strong influence of topography on functional composition and on species' climatic optima, such that communities at lower topographic positions were dominated by acquisitive species adapted to both warmer and wetter conditions compared to communities at upper topographic positions which were dominated by conservative cold adapted species, possibly due to differences in soil conditions and hydrology. Forest functional and climatic composition remained stable through time; and we found limited evidence for trait-based responses to environmental change among demographic groups. Our findings confirm that fine-scale environmental conditions are a critical factor structuring plant communities in tropical forests, and suggest that slow environmental warming and community-based processes may promote short-term community functional stability. This study highlights the need to explore how diverse aspects of community trait composition vary in tropical montane forests, and to further investigate thresholds of forest response to environmental change
Branch, leaf, and stomatal traits in relation to topography and tree size in the Amacayacu Forest Dynamics Plot
No full textTrait and tree-level data associated with the article:
Zuleta, D., Muller-Landau, H. C., Duque, A., Caro, N., Cardenas, D., Leon-Pelaez, J. D., & Feeley, K. J. (In press). Interspecific and intraspecific variation of tree branch, leaf, and stomatal traits in relation to topography in an aseasonal Amazon forest. Functional Ecology.
Please contact Daniel Zuleta for further details ([email protected])
Widespread but heterogeneous responses of Andean forests to climate change
No full textGlobal warming is forcing many species to shift their distributions upward, causing consequent changes in the compositions of species that occur at specific locations. This prediction remains largely untested for tropical trees. Here we show, using a database of nearly 200 Andean forest plot inventories spread across more than 33.5° latitude (from 26.8° S to 7.1° N) and 3,000-m elevation (from 360 to 3,360 m above sea level), that tropical and subtropical tree communities are experiencing directional shifts in composition towards having greater relative abundances of species from lower, warmer elevations. Although this phenomenon of ‘thermophilization’ is widespread throughout the Andes, the rates of compositional change are not uniform across elevations. The observed heterogeneity in thermophilization rates is probably because of different warming rates and/or the presence of specialized tree communities at ecotones (that is, at the transitions between distinct habitats, such as at the timberline or at the base of the cloud forest). Understanding the factors that determine the directions and rates of compositional changes will enable us to better predict, and potentially mitigate, the effects of climate change on tropical forests.Fil: Fadrique, Belén. University of Miami; Estados UnidosFil: Báez, Selene. Escuela Politécnica Nacional; EcuadorFil: Duque, Álvaro. Universidad Nacional de Colombia; ColombiaFil: Malizia, Agustina. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Blundo, Cecilia Mabel. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Carilla, Julieta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Osinaga Acosta, Oriana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Malizia, Lucio Ricardo. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; ArgentinaFil: Silman, Miles. University Wake Forest; Estados UnidosFil: Farfán Ríos, William. Universidad Nacional San Antonio Abad del Cusco; Perú. University Wake Forest; Estados UnidosFil: Malhi, Yadvinder. University of Oxford; Reino UnidoFil: Young, Kenneth R.. University of Texas at Austin; Estados UnidosFil: Cuesta C., Francisco. University of Amsterdam; Países BajosFil: Homeier, Jurgen. Universität Göttingen; AlemaniaFil: Peralvo, Manuel. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; EcuadorFil: Pinto, Esteban. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; EcuadorFil: Jadan, Oswaldo. Universidad de Cuenca. Facultad de Ciencias Agropecuarias; EcuadorFil: Aguirre, Nikolay. Universidad Nacional de Loja. Programa de Investigación Biodiversidad y Servicios Ecosistémicos; EcuadorFil: Aguirre, Zhofre. Universidad Nacional de Loja. Programa de Investigación Biodiversidad y Servicios Ecosistémicos; EcuadorFil: Feeley, Kenneth J.. University of Miami; Estados Unidos. Fairchild Tropical Botanic Garden; Estados Unido
Author Correction: Mature Andean forests as globally important carbon sinks and future carbon refuges
No full textAuthor Correction: Widespread but heterogeneous responses of Andean forests to climate change
No full textResearch Priorities for the Conservation and Sustainable Governance of Andean Forest Landscapes
No full textThe long-term survival of Andean forest landscapes (AFL) and of their capacity to contribute to sustainable development in a context of global change requires integrated adaptation and mitigation responses informed by a thorough understanding of the dynamic and complex interactions between their ecological and social components. This article proposes a research agenda that can help guide AFL research efforts for the next 15 years. The agenda was developed between July 2015 and June 2016 through a series of workshops in Ecuador, Peru, and Switzerland and involved 48 researchers and development experts working on AFL from different disciplinary perspectives. Based on our review of current research and identification of pressing challenges for the conservation and sustainable governance of AFL, we propose a conceptual framework that draws on sustainability sciences and social–ecological systems research, and we identify a set of high-priority research goals and objectives organized into 3 broad categories: systems knowledge, target knowledge, and transformation knowledge. This paper is intended to be a reference for a broad array of actors engaged in policy, research, and implementation in the Andean region. We hope it will trigger collaborative research initiatives for the continued conservation and sustainable governance of AFL
Mature Andean forests as globally important carbon sinks and future carbon refuges
No full textAbstract It is largely unknown how South America’s Andean forests affect the global carbon cycle, and thus regulate climate change. Here, we measure aboveground carbon dynamics over the past two decades in 119 monitoring plots spanning a range of >3000 m elevation across the subtropical and tropical Andes. Our results show that Andean forests act as strong sinks for aboveground carbon (0.67 ± 0.08 Mg C ha −1 y −1 ) and have a high potential to serve as future carbon refuges. Aboveground carbon dynamics of Andean forests are driven by abiotic and biotic factors, such as climate and size-dependent mortality of trees. The increasing aboveground carbon stocks offset the estimated C emissions due to deforestation between 2003 and 2014, resulting in a net total uptake of 0.027 Pg C y −1 . Reducing deforestation will increase Andean aboveground carbon stocks, facilitate upward species migrations, and allow for recovery of biomass losses due to climate change.Abstract It is largely unknown how South America’s Andean forests affect the global carbon cycle, and thus regulate climate change. Here, we measure aboveground carbon dynamics over the past two decades in 119 monitoring plots spanning a range of >3000 m elevation across the subtropical and tropical Andes. Our results show that Andean forests act as strong sinks for aboveground carbon (0.67 ± 0.08 Mg C ha −1 y −1 ) and have a high potential to serve as future carbon refuges. Aboveground carbon dynamics of Andean forests are driven by abiotic and biotic factors, such as climate and size-dependent mortality of trees. The increasing aboveground carbon stocks offset the estimated C emissions due to deforestation between 2003 and 2014, resulting in a net total uptake of 0.027 Pg C y −1 . Reducing deforestation will increase Andean aboveground carbon stocks, facilitate upward species migrations, and allow for recovery of biomass losses due to climate change
Commentary: Estimating the global conservation status of more than 15,000 Amazonian tree species
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The Ecophysiology of Photosynthetic Heat Tolerances in Tropical Plants
No full textTemperature governs several biological processes from molecular to macroecological scales. Underlying many ecological processes is the assumption that fitness is constrained by the physiological limits of species’ metabolic function. The thermal limits of metabolic function, termed thermal tolerances, are often assumed to directly translate into the environmental conditions that define species’ abiotic thermal niches. When species exceed their physiological thermal tolerances, it is expected to negatively impact fitness, and may therefore provide a basis for understanding the environmental constraints on species distributions. Given the rising temperatures caused by climate change, heat tolerances are of particular interest for understanding these constraints. Heat damage in plants has the potential to influence growth rates, which are tied to fitness and contribute to ecosystems services like carbon sequestration that modulate climate change. Photosynthesis is a temperature-sensitive metabolic process, and photosynthetic heat tolerances can be readily assessed, but provide only incomplete information for understanding whole-plant fitness. Understanding the effect of thermal damage on plant growth is necessary if heat tolerances are to predict species thermal niches, their geographic distributions, or their responses to climate change. This dissertation investigates the ecophysiology of heat tolerances in order to advance their use in linking ecological patterns to physiological processes. In the first chapter we provide an introduction to heat tolerances and a review of existing heat tolerance literature. In this review, we call attention to the different sources of methodological variation likely to bias estimates of plant heat tolerances. Using the newly assembled database of heat tolerances, we illustrate current the methodological biases that may prevent heat tolerances from being integrate into ecological contexts. We also discuss how environmental conditions like a) growth temperature, b) drought, c) light, d) salinity, and e) ontogenetic stage can cause variation in estimates of heat tolerance. Finally, we propose a standardized terminology to facilitate interpretation of heat tolerance data among studies. One issue limiting the use of heat tolerances to understand species distributions is mixed support for the hypothesis that hotter climates select for higher heat tolerances. Furthermore, the limited heat tolerance data that exist indicate some taxonomic groups have distinct ranges of heat tolerances. In the second chapter we hypothesized that phylogenetic structure may help to explain variation in heat tolerances, resolve the conflicting effects that climate has been observed to have on heat tolerances, and advance the use of heat tolerances in broader ecological contexts. To address our hypothesis, we measured the heat tolerances for 123 species of ferns, gymnosperms, magnoliids, monocots, and eudicots grown in a common climate at Fairchild Tropical Botanic Garden and the John C. Gifford Arboretum in Miami, FL USA. Phylogenetic analysis using Blomberg’s K indicated that species’ heat tolerances are not phylogenetically conserved, but data from the five groups we studied suggest there may be some evolutionary constraints on plant heat tolerances at coarse phylogenetic resolutions that are potentially related to leaf thermoregulation. Phylogenetic independent contrasts of heat tolerance and climatic data for 102 species revealed limited support for the hypothesis that climate can predict species heat tolerances. We also re-analyzed the effect of climate on heat tolerances using a subset of our study species that were most unlikely to experience heat tolerance down-regulation, which confirmed the inability of climate to predict species heat tolerances. We conclude that there are weak phylogenetic and climatic constraints on the heat tolerances of plants. In the third chapter, we attempt to develop a mechanistic explanation for the variation in heat tolerance among species. Given that plants exhibit unique thermoregulatory traits that influence leaf temperatures, and that leaf temperatures can be decoupled from ambient air temperatures, we hypothesized that photosynthetic heat tolerances are adapted to extreme leaf temperature as opposed to coarse climatic variables. We measured thermoregulatory traits, maximum leaf temperatures and two different metrics of photosynthetic heat tolerances for 19 plant species growing at Fairchild Tropical Botanic Garden (Coral Gables, FL, USA). The first metric of heat tolerance is termed Tcrit and is defined as the temperature that causes an initial decrease in the quantum yield of photosynthesis. The second metric of heat is termed T50 and is defined as the temperature that cause as a 50% reduction in the quantum yield of photosynthesis. The thermoregulatory traits measured at the Garden were used to parameterize a leaf energy balance model and predict maximum in situ leaf temperatures across the geographic distributions of 13 species. The maximum observed leaf temperatures and maximum predicted in situ leaf temperatures were positively correlated with only heat tolerances. The breadth of species’ thermal safety margins (the difference between heat tolerance and leaf temperature for T50) was negatively correlated with T50. Our results provide observational and theoretical support for the hypothesis that photosynthetic heat tolerances are adapted to extreme leaf temperatures, but refute the assumption that species with higher PHTs are less susceptible to thermal damage. Tree growth is an important predictor of tree survival and component of the global carbon sink that is potentially negatively influenced by thermal damage. In the fourth chapter, we investigate the ability of heat tolerances to predict annual growth for eight tropical tree species. More specifically, we test the hypotheses that 1) species with higher heat tolerances are more likely to experience decelerating growth rates across multiple years; and 2) thermal safety margins are capable of predicting species’ annual growth rates. Our results suggest that only species with a combination of high leaf temperatures and low heat tolerances are expected to experience thermal damage, but that thermal damage is unlikely drive changes in species’ growth. Instead of heat tolerances, our results point to optimal temperatures for photosynthesis, not respiration, as a promising physiological mechanism explaining species growth rates. Nevertheless, Tcrit may provide a limited ability to explain growth deceleration when photosynthesis ceases, while and T50 may act as a thermal constraint on leaf size.</p
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