Aim: Water availability is the major driver of tropical forest structure and dynamics. Most research has focused on the impacts of climatic water availability, whereas remarkably little is known about the influence of water table depth and excess soil water on forest processes. Nevertheless, given that plants take up water from the soil, the impacts of climatic water supply on plants are likely to be modulated by soil water conditions.Location: Lowland Amazonian forests.
Fauset et al. Climate, Traits, and Forest Processes Climate, species composition, and soils are thought to control carbon cycling and forest structure in Amazonian forests. Here, we add a demographics scheme (tree recruitment, growth, and mortality) to a recently developed non-demographic model-the Trait-based Forest Simulator (TFS)-to explore the roles of climate and plant traits in controlling forest productivity and structure. We compared two sites with differing climates (seasonal vs. aseasonal precipitation) and plant traits. Through an initial validation simulation, we assessed whether the model converges on observed forest properties (productivity, demographic and structural variables) using datasets of functional traits, structure, and climate to model the carbon cycle at the two sites. In a second set of simulations, we tested the relative importance of climate and plant traits for forest properties within the TFS framework using the climate from the two sites with hypothetical trait distributions representing two axes of functional variation ("fast" vs. "slow" leaf traits, and high vs. low wood density). The adapted model with demographics reproduced observed variation in gross (GPP) and net (NPP) primary production, and respiration. However, NPP and respiration at the level of plant organs (leaf, stem, and root) were poorly simulated. Mortality and recruitment rates were underestimated. The equilibrium forest structure differed from observations of stem numbers suggesting either that the forests are not currently at equilibrium or that mechanisms are missing from the model. Findings from the second set of simulations demonstrated that differences in productivity were driven by climate, rather than plant traits. Contrary to expectation, varying leaf traits had no influence on GPP. Drivers of simulated forest structure were complex, with a key role for wood density mediated by its link to tree mortality. Modeled mortality and recruitment rates were linked to plant traits alone, drought-related mortality was not accounted for. In future, model development should focus on improving allocation, mortality, organ respiration, simulation of understory trees and adding hydraulic traits. This type of model that incorporates diverse tree strategies, detailed forest structure and realistic physiology is necessary if we are to be able to simulate tropical forest responses to global change scenarios.
The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha−1 per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected.
El COVID-19 golpeó las comunidades indígenas amazónicas del Perú durante dos años, fomentando la recuperación de conocimientos, prácticas y estrategias tradicionales para combatir sus síntomas. Presentamos las especies de plantas y animales usadas por dos comunidades ticuna del bajo Amazonas peruano durante la pandemia del COVID-19, describiendo la forma de preparación y administración de los preparados. La información se obtuvo a partir de entrevistas semiestructuradas a hombres y mujeres de las comunidades durante las dos primeras olas de la pandemia, de mayo del 2020 a junio del 2021. Las entrevistas fueron presenciales, en los trabajos de campo realizados en las comunidades, y virtuales, usando la vía telefónica y aplicaciones de mensajería disponibles en las comunidades o en los centros poblados mayores cercanos. Durante los trabajos de campo en Nueva Galilea se realizaron visitas a los puntos de colecta de las especies vegetales. Se identificaron catorce especies de plantas y tres especies de animales usados en la pandemia. Las partes más usadas de las especies vegetales, en orden de importancia fueron las hojas, las raíces, los bulbos y los frutos, realizándose preparados en forma de infusiones, al fresco, en baños y en inhalaciones de vapor. Se evidencia cómo el conocimiento tradicional en el uso de las plantas y animales que curan, de manera integrada con la apropiación de conocimientos externos, sigue vigente en las comunidades ticuna. El conocimiento sobre las propiedades curativas de catorce especies de plantas y tres especies animales identificadas ha permitido combatir los síntomas de una enfermedad muy agresiva.
Resumo O presente trabalho tem como objetivo contribuir para o conhecimento das espécies de Metteniusaceae ocorrentes na Reserva Ducke. O estudo tem por base a análise morfológica de materiais depositados em herbários e revisão de literatura. Cinco espécies foram registradas: Dendrobangia boliviana, Emmotum acuminatum, E. amazonicum, Poraqueiba guianensis e P. sericea. Chave para identificação, descrições, ilustrações, dados sobre habitat, fenologia e distribuição geográfica das espécies são apresentados.
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