Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associate canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is < 2000 mm.yr−1 (water-limited forests) and to radiation otherwise (light-limited forests); on the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. Precipitation first-order control indicates an overall decrease in tropical forest productivity in a drier climate.Peer reviewe

Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is  < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall  < 2000 mm yr⁻¹

Bois-bumbás de Parintins: síntese metafórica da realidade? Bois-bumbás of Parintins: metaphoric synthesis of reality?

Este artigo analisa como os atores sociais internos percebem o evento dos bois-bumbás da cidade de Parintins, tendo em vista o valor que tal fenômeno representa para a comunidade local nos aspectos culturais, econômicos e sociais, e por criar um espaço onde os seus integrantes possam refletir, falar e produzir conhecimento sobre sua realidade. Procurou-se identificar a percepção dos atores sociais internos sobre a influência desse fenômeno cultural nas dimensões sistêmica e cultural do desenvolvimento local sustentável (DLS) da cidade de Parintins. Os pressupostos que orientaram o estudo foram: elementos da cultura brasileira estão presentes na cultura local representada pelo contexto dos bois-bumbás; a cultura indígena amazônica dá significado aos elementos que possibilitam a construção dos bois-bumbás; e o boi-bumbá está se transformando em mercadoria subsumida às necessidades do capital. O referencial de análise baseou-se principalmente nos conceitos de DLS, modo de produção capitalista e cultura. A metodologia utilizada foi de natureza qualitativa. As conclusões sinalizam para a confirmação dos pressupostos.<br>This article investigates on how the inside social actors perceive the boi-bumbá celebrations in the town of Parintins, Brazil, considering the value that such phenomenon represents to the local community in its cultural, economic and social aspects, as well as the opportunity for the participants to reflect on, speak about and produce knowledge on their own reality. The investigation identified how such actors perceive the influence of this social phenomenon in the systemic and cultural dimensions of the town's sustainable local development (SLD). The hypotheses that guided the study were: elements of the Brazilian culture are present in the local culture represented by the boi-bumbá context; the native Amazonian culture gives signification to the elements that allow the construction of the bois-bumbás; the boi-bumbá is becoming a merchandise submitted to the capital's demands. The analytical framework was based mostly in the concepts of SLD, capitalist production system and culture. The investigation adopted a quantitative method. The conclusions confirm the hypotheses

Coping with unbalanced class data sets in oral absorption models

Class imbalance occurs frequently in drug discovery datasets. In oral absorption datasets, in the literature, there are considerably more of highly-absorbed compounds compared with poorly-absorbed compounds. This produces models that are biased towards highly-absorbed compounds which lack generalization to industry settings where more early stage drug candidates are poorly-absorbed. This paper presents two strategies to cope with unbalanced class datasets: Under-sampling the majority high absorption class and misclassification costs using classification decision trees. The published dataset by Hou et al (2007), which contained percentage human intestinal absorption of 645 drug and drug-like compounds, was used for the development and validation of classification trees using C&amp;RT analysis. The results indicate that under-sampling the majority class, highly-absorbed compounds, leads to a balanced distribution (50:50) training set which can achieve better accuracies for poorlyabsorbed compounds, whereas the biased training set achieved higher accuracies for highlyabsorbed compounds. The use of misclassification costs resulted in improved class predictions, when applied to reduce false positives or false negatives. Moreover, it was shown that the classical overall accuracy measure used in many publications is particularly misleading in the case of unbalanced datasets and more appropriate measures presented here may be used for a more realistic assessment of the classification models ’ performance. Thus, these strategies offer improvements to cope with unbalanced class datasets to obtain classification models applicable in industry

WagnerClimateSeasonalityLimits.pdf

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is  < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall  < 2000 mm yr⁻¹