Leaf surface water, not plant water stress, drives diurnal variation in tropical forest canopy water content.

Variation in canopy water content (CWC) that can be detected from microwave remote sensing of vegetation optical depth (VOD) has been proposed as an important measure of vegetation water stress. However, the contribution of leaf surface water (LWs ), arising from dew formation and rainfall interception, to CWC is largely unknown, particularly in tropical forests and other high-humidity ecosystems. We compared VOD data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and CWC predicted by a plant hydrodynamics model at four tropical sites in Brazil spanning a rainfall gradient. We assessed how LWs influenced the relationship between VOD and CWC. The analysis indicates that while CWC is strongly correlated with VOD (R2  = 0.62 across all sites), LWs accounts for 61-76% of the diurnal variation in CWC despite being < 10% of CWC. Ignoring LWs weakens the near-linear relationship between CWC and VOD and reduces the consistency in diurnal variation. The contribution of LWs to CWC variation, however, decreases at longer, seasonal to inter-annual, time scales. Our results demonstrate that diurnal patterns of dew formation and rainfall interception can be an important driver of diurnal variation in CWC and VOD over tropical ecosystems and therefore should be accounted for when inferring plant diurnal water stress from VOD measurements.

Modeling of fish seizures after the implementation of the closed fishing season law in the Amazon Basin / Modelagem das apreensões de pescado após a implementação da lei do defeso na Bacia Amazônica

The organization of fisheries in the Amazon region is an important theme, since the current management model is based mainly on the closed fishing season policy. This strategy suspends the catching of specific fish stocks and provides subsidies to professional fishers. Thus, the present study analyzed, through mathematical modeling, the behavioral interfaces of illegal fisheries that occurred between 1992 to 2017 in the Amazon basin, considering the hydrological seasonality and the effect of the presence or absence of the Closed Fishing Season law (CFSL). The data were tabulated and used for the construction of two illegal fishing scenarios. The first showed negative impacts with the absence of the CFSL, indicated by the high number of seizures of illegal catches that occurred during the period in which river water level is rising and showed continued growth over time. However, the second scenario showed apprehension apexes occurring at the beginning of the high-water level and at beginning of the low water level, with a continuous decrease in the seizures of illegal catches due to the new law. Thus, the ecosystem model constructed is a promising instrument for testing hypotheses and for formulating and monitoring management scenarios for fisheries in the region.

O ordenamento pesqueiro na região amazônica é um tema importante, uma vez que o atual modelo de gestão se baseia principalmente na política do defeso. Essa estratégia suspende a captura de estoques específicos de peixes e fornece subsídios aos pescadores profissionais. Assim, o presente estudo analisou, por meio da modelagem matemática, as interfaces comportamentais da pesca ilegal que ocorreram entre 1992 e 2017 na bacia Amazônica, considerando a sazonalidade hidrológica e o efeito da presença ou ausência da Lei do Defeso (LD). Os dados foram tabulados e utilizados para a construção de dois cenários de pesca ilegal. O primeiro apresentou impactos negativos com a ausência da LD, apontado pelo elevado número de apreensões de pescado ilegais que ocorreram durante o período da enchente, momento em que o nível da água do rio está subindo, e apresentou crescimento contínuo ao longo do tempo. No entanto, o segundo cenário mostrou ápices de apreensões ocorridas no início da cheia e no início da seca, com redução contínua das apreensões de capturas ilegais devido a lei LD. Assim, o modelo ecossistêmico construído é um instrumento promissor para testar hipóteses e para formular e monitorar cenários de gestão para a pesca na região.

Modeling of fish seizures after the implementation of the closed fishing season law in the Amazon Basin / Modelagem das apreensões de pescado após a implementação da lei do defeso na Bacia Amazônica

The organization of fisheries in the Amazon region is an important theme, since the current management model is based mainly on the closed fishing season policy. This strategy suspends the catching of specific fish stocks and provides subsidies to professional fishers. Thus, the present study analyzed, through mathematical modeling, the behavioral interfaces of illegal fisheries that occurred between 1992 to 2017 in the Amazon basin, considering the hydrological seasonality and the effect of the presence or absence of the Closed Fishing Season law (CFSL). The data were tabulated and used for the construction of two illegal fishing scenarios. The first showed negative impacts with the absence of the CFSL, indicated by the high number of seizures of illegal catches that occurred during the period in which river water level is rising and showed continued growth over time. However, the second scenario showed apprehension apexes occurring at the beginning of the high-water level and at beginning of the low water level, with a continuous decrease in the seizures of illegal catches due to the new law. Thus, the ecosystem model constructed is a promising instrument for testing hypotheses and for formulating and monitoring management scenarios for fisheries in the region.(AU)

O ordenamento pesqueiro na região amazônica é um tema importante, uma vez que o atual modelo de gestão se baseia principalmente na política do defeso. Essa estratégia suspende a captura de estoques específicos de peixes e fornece subsídios aos pescadores profissionais. Assim, o presente estudo analisou, por meio da modelagem matemática, as interfaces comportamentais da pesca ilegal que ocorreram entre 1992 e 2017 na bacia Amazônica, considerando a sazonalidade hidrológica e o efeito da presença ou ausência da Lei do Defeso (LD). Os dados foram tabulados e utilizados para a construção de dois cenários de pesca ilegal. O primeiro apresentou impactos negativos com a ausência da LD, apontado pelo elevado número de apreensões de pescado ilegais que ocorreram durante o período da enchente, momento em que o nível da água do rio está subindo, e apresentou crescimento contínuo ao longo do tempo. No entanto, o segundo cenário mostrou ápices de apreensões ocorridas no início da cheia e no início da seca, com redução contínua das apreensões de capturas ilegais devido a lei LD. Assim, o modelo ecossistêmico construído é um instrumento promissor para testar hipóteses e para formular e monitorar cenários de gestão para a pesca na região.(AU)

Simulação dos impactos climáticos da desertificação do Nordeste brasileiro / Simulation of climatic impacts of desertification in Northeast Brazil

RESUMO O comportamento climático do Nordeste brasileiro (NEB) foi simulado considerando um cenário onde toda a sua área de Caatinga foi substituída por Deserto. A precipitação sofreu uma redução na região em quase todos os meses do ano, principalmente sobre o setor da Caatinga. A evapotranspiração apresentou decréscimos de grande magnitude ao longo de todo o ano, principalmente durante a estação chuvosa. O escoamento superficial apresentou acréscimos de forma geral, indicando uma diminuição da água extraída pelas raízes das plantas. A temperatura do ar foi a variável mais afetada, com elevações de até 6°C em algumas regiões e um aumento médio de aproximadamente 3°C para a área da Caatinga. Além disso, verificou-se a existência de um mecanismo restaurador associado à convergência de umidade que atuou no favorecimento da precipitação, embora insuficiente para evitar sua redução no NEB.

ABSTRACT The climatic behavior of the Brazilian Northeast (BNE) was simulated considering a scenario where all its caatinga area was replaced by desert. Precipitation decreased in the region in almost every month of the year, mainly on the caatinga sector. Evapotranspiration showed decreases of great magnitude throughout the year, especially during the rainy season. Runoff presented overall increases, indicating a decrease of the water extracted by plant roots. Air temperature was the most affected variable, with increases of up to 6°C in some regions and an average increase of approximately 3°C in the caatinga area. In addition, there was a restorative mechanism associated with convergence of humidity that worked favoring precipitation although insufficient to prevent its reduction in the BNE.

Toward an integrated monitoring framework to assess the effects of tropical forest degradation and recovery on carbon stocks and biodiversity.

Tropical forests harbor a significant portion of global biodiversity and are a critical component of the climate system. Reducing deforestation and forest degradation contributes to global climate-change mitigation efforts, yet emissions and removals from forest dynamics are still poorly quantified. We reviewed the main challenges to estimate changes in carbon stocks and biodiversity due to degradation and recovery of tropical forests, focusing on three main areas: (1) the combination of field surveys and remote sensing; (2) evaluation of biodiversity and carbon values under a unified strategy; and (3) research efforts needed to understand and quantify forest degradation and recovery. The improvement of models and estimates of changes of forest carbon can foster process-oriented monitoring of forest dynamics, including different variables and using spatially explicit algorithms that account for regional and local differences, such as variation in climate, soil, nutrient content, topography, biodiversity, disturbance history, recovery pathways, and socioeconomic factors. Generating the data for these models requires affordable large-scale remote-sensing tools associated with a robust network of field plots that can generate spatially explicit information on a range of variables through time. By combining ecosystem models, multiscale remote sensing, and networks of field plots, we will be able to evaluate forest degradation and recovery and their interactions with biodiversity and carbon cycling. Improving monitoring strategies will allow a better understanding of the role of forest dynamics in climate-change mitigation, adaptation, and carbon cycle feedbacks, thereby reducing uncertainties in models of the key processes in the carbon cycle, including their impacts on biodiversity, which are fundamental to support forest governance policies, such as Reducing Emissions from Deforestation and Forest Degradation.