UMA APLICAÇÃO DE MODELAGEM DO CICLO HIDROLÓGICO E IMPACTOS DO AUMENTO DA CONCENTRAÇÃO DE CO2 ATMOSFÉRICO NA AMAZÔNIA

O presente trabalho busca validar um modelo de balanço hídrico para permitir sua aplicabilidade no bioma Amazônico, em linha com o projeto Amazon-FACE (free-air CO2 enrichment), buscando melhorar o entendimento dos efeitos do aumento de CO2 na dinâmica hídrica desse bioma. O modelo a ser utilizado trata-se do submodelo de balanço hídrico do modelo CPTEC-Potential Vegetation Model 2 (PVM2). A avaliação deste submodelo ocorrerá através dos protocolos desenvolvidos pelo International Land Model Benchmarking Project (I-LAMB). Para avaliar o efeito do aumento de CO2 no bioma amazônico será adicionado ao modelo 200ppmv de CO2 a mais que a concentração atual. As variáveis a serem avaliadas serão água no solo, evapotranspiração e escoamento superficial. O projeto ainda está em andamento, mas apresenta alguns resultados preliminares referentes a atualização do modelo hídrico, sendo a aplicação e validação os próximos passos

Ant-tended hemiptera in Amazonian myrmecophytes: Patterns of abundance and implications for mutualism function (Hymenoptera: Formicidae)

We assessed how the abundance of ant-tended Hemiptera associated with two Amazonian myrmecophytes, Tococa bullifera and Maieta guianensis, varied as a function of resident ant species. We collected five species or morpho-species of adult hemiptera in the domatia of M. guianensis, with four of these species also found in Tococa bullifera. Maieta guianensis plants inhabited by Crematogaster laevis had over four-fold more hemiptera in them than plants inhabited by Pheidole minutula. In contrast, the density of hemiptera in Tococa bullifera domatia was independent of the species of ant resident. For each of the two ant species inhabiting Maieta guianensis, there was a positive and significant relationship between the abundance of hemiptera and workers inhabiting a plant. This relationship was also significant and positive for the Tococa bullifera plants inhabited by C. laevis. However, there was no relationship between Azteca worker and hemipteran density, although there was a trend towards a positive relationship. Our results indicate that hemipteran abundance can vary significantly between different myrmecophyte species, but that the nature of this relationship is mediated by the identity of the ant associate. Because hemipterans are herbivores, the costs and benefits of different ant partners to the host plant may vary in ways that are often overlooked

Amazon Forest Ecosystem Responses to Elevated Atmospheric CO2 and Alterations in Nutrient Availability: Filling the Gaps with Model-Experiment Integration

The impacts of elevated CO2 (eCO2) and alterations in nutrient availability on the carbon (C) storage capacity and resilience of the Amazon forest remain highly uncertain. Carbon dynamics are controlled by multiple eco-physiological processes responding to environmental change, but we lack solid experimental evidence, hampering theory development and thus representation in ecosystem models. Here, we present two ecosystem-scale manipulation experiments, to be carried out in the Amazon, that examine tropical ecosystem responses to eCO2 and nutrient addition and thus will elucidate the representation of crucial ecological processes by ecosystem models. We highlight current gaps in our understanding of tropical ecosystem responses to projected global changes in light of the eco-physiological assumptions considered by current ecosystem models. We conclude that a more detailed process-based representation of the spatial (e.g. soil type; plant functional type) and temporal (seasonal and inter-annual variation) diversity of tropical forests is needed to enhance model predictions of ecosystem responses to projected global environmental change

In situ short-term responses of Amazonian understory plants to elevated CO₂

The response of plants to increasing atmospheric CO2 depends on the ecological context where the plants are found. Several experiments with elevated CO2 (eCO2) have been done worldwide, but the Amazonian forest understory has been neglected. As the central Amazon is limited by light and phosphorus, understanding how understory responds to eCO2 is important for foreseeing how the forest will function in the future. In the understory of a natural forest in the Central Amazon, we installed four open-top chambers as control replicates and another four under eCO2 (+250 ppm above ambient levels). Under eCO2, we observed increases in carbon assimilation rate (67%), maximum electron transport rate (19%), quantum yield (56%), and water use efficiency (78%). We also detected an increase in leaf area (51%) and stem diameter increment (65%). Central Amazon understory responded positively to eCO2 by increasing their ability to capture and use light and the extra primary productivity was allocated to supporting more leaf and conducting tissues. The increment in leaf area while maintaining transpiration rates suggests that the understory will increase its contribution to evapotranspiration. Therefore, this forest might be less resistant in the future to extreme drought, as no reduction in transpiration rates were detected.</p

Stakeholders' perspectives on the operationalisation of the ecosystem service concept : Results from 27 case studies

The ecosystem service (ES) concept is becoming mainstream in policy and planning, but operational influence on practice is seldom reported. Here, we report the practitioners' perspectives on the practical implementation of the ES concept in 27 case studies. A standardised anonymous survey (n = 246), was used, focusing on the science-practice interaction process, perceived impact and expected use of the case study assessments. Operationalisation of the concept was shown to achieve a gradual change in practices: 13% of the case studies reported a change in action (e.g. management or policy change), and a further 40% anticipated that a change would result from the work. To a large extent the impact was attributed to a well conducted science-practice interaction process (>70%). The main reported advantages of the concept included: increased concept awareness and communication; enhanced participation and collaboration; production of comprehensive science-based knowledge; and production of spatially referenced knowledge for input to planning (91% indicated they had acquired new knowledge). The limitations were mostly case-specific and centred on methodology, data, and challenges with result implementation. The survey highlighted the crucial role of communication, participation and collaboration across different stakeholders, to implement the ES concept and enhance the democratisation of nature and landscape planning. (C) 2017 Published by Elsevier B.V.Peer reviewe

Modeling the interplay between land use, bioenergy production and climate change

International Max Planck Research School on Earth System Modelling, Hamburg, German

Arquitetura de ninhos da formiga neotropical Ectatomma brunneum F. Smith, 1858 (Formicidae, Ponerinae) em ambientes alterados

In this paper we relate the excavation of seven E. brunneum nests in sites altered by human action in Rio Claro SP, southeastern Brazil. This ant nests are poor elaborated, just like in other species of this genus and subfamily. The depths and dispositions of the chambers did not show a defined pattern, nor any complex structure or architecture. We argue that it is due to the fact of this ant has migratory habits, occupying the nest for limited time in relation to their colony life cycle

Interspecific variation in the defensive responses of obligate plant-ants: Experimental tests and consequences for herbivory

The aggressive behavior of ants that protect plants from herbivores in exchange for rewards such as shelter or food is thought to be an important form of biotic defense against herbivory, particularly in tropical systems. To date, however, no one has compared the defensive responses of different ant taxa associated with the same plant species, and attempted to relate these differences to longer-term efficacy of ant defense. We used experimental cues associated with herbivory - physical damage and extracts of chemical volatiles from leaf tissue - to compare the aggressive responses of two ant species obligately associated with the Amazonian myrmecophyte Tococa bullifera (Melastomataceae). We also conducted a colony removal experiment to quantify the level of resistance from herbivores provided to plants by each ant species. Our experiments demonstrate that some cues eliciting a strong response from one ant species elicited no response by the other. For cues that do elicit responses, the magnitude of these responses can vary interspecifically. These patterns were consistent with the level of resistance provided from herbivores to plants. The colony removal experiment showed that both ant species defend plants from herbivores: however, herbivory was higher on plants colonized by the less aggressive ant species. Our results add to the growing body of literature indicating defensive ant responses are stimulated by cues associated with herbivory. However, they also suggest the local and regional variation in the composition of potential partner taxa could influence the ecology and evolution of defensive mutualisms in ways that have previously remained unexplored

Impacts of climate change and the end of deforestation on land use in the Brazilian legal amazon

Climate change scenarios vary considerably over the Amazon region, with an extreme scenario projecting a dangerous (from the human perspective) increase of 3.8°C in temperature and 30% reduction in precipitation by 2050. The impacts of such climate change on Amazonian land-use dynamics, agricultural production, and deforestation rates are still to be determined. In this study, the authors make a first attempt to assess these impacts through a systemic approach, using a spatially explicit modeling framework to project crop yield and land-use/land-cover changes in the Brazilian Amazon by 2050. The results show that, without any adaptation, climate change may exert a critical impact on the yields of crops commonly cultivated in the Amazon (e.g., soybean yields are reduced by 44% in the worst-case scenario). Therefore, following baseline projections on crop and livestock production, a scenario of severe regional climate change would causePRIFPRI3; ISIEPT