10 research outputs found

    Sensitivity of South American tropical forests to an extreme climate anomaly.

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    Sensitivity of South American tropical forests to an extreme climate anomaly

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    This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: Publicly available climate data used in this paper are available from ERA5 (ref. 64), CRU ts.4.03 (ref. 65), WorldClim v2 (ref. 66), TRMM product 3B43 V7 (ref. 67) and GPCC, Version 7 (ref. 68). The input data are available on ForestPlots42.Code availability R code for graphics and analyses is available on ForestPlots42.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

    Sensitivity of South American tropical forests to an extreme climate anomaly

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    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

    Inhibitory properties of snake venoms by phytocomplex

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    FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOVegetal extracts usually have a large diversity of bioactive compounds showingseveral pharmacological activities, including antiophidian properties. In this study, bothcoumarin and tannic acid (100 ÎŒg/mL) showed no changes in the basal response oftwitches in mouse nerve phrenic diaphragm preparations. In opposite, Crotalus durissusterrificus (Cdt 15 ÎŒg/mL) or Bothrops jararacussu (Bjssu 40 ÎŒg/mL) venoms causedirreversible neuromuscular blockade. Tannic acid (preincubated with the venoms), butnot coumarin, was able to significantly inhibit (p<0.05) the impairment of the musclestrength induced by Cdt (88 ± 8%) and Bjssu (79 ± 7.5%), respectively. A remarkableprecipitation was observed when the venoms were preincubated with tannic acid, but notwith coumarin. Plathymenia reticulata is a good source of tannins and flavonoidswhereas Mikania laevigata contain high amounts of coumarin. P. reticulata (PrHE, 0.06mg/mL) and M. laevigata (MlHE, 1 mg/mL) hydroalcoholic extracts were assayed withor without Bjssu or Cdt venoms. Both PrHE and MlHE showed protection against Bjssu(79.3 ± 9.5% and 65 ± 8%, respectively) and Cdt (73.2 ± 6.7% and 95 ± 7%,respectively) neuromuscular blockade. In order to observe if the protective mechanismcould be induced by protein precipitation, tannins were eliminated from both extracts andthe assay was repeated. MlHE protected against the blockade induced by Bjssu (57.2 ±6.7%), but not against Cdt. We concluded that plants containing tannins could induce theprecipitation of venoms' proteins and plants containing coumarin showed activity againstBothrops venoms, but not against Crotalus venoms. We also concluded that the use ofisolated bioactive compounds could not represent the better strategy against ophidianvenoms, since the purification may exclude some bioactive components resulting in aloss of antivenom activity. In addition, M. laevigata showed better antiophidian activitythan P. reticulata. © 2009 Nova Science Publishers, Inc. All rights reserved.Vegetal extracts usually have a large diversity of bioactive compounds showingseveral pharmacological activities, including antiophidian properties. In this study, bothcoumarin and tannic acid (100 ÎŒg/mL) showed no changes in the basal response oftwitches in mouse nerve phrenic diaphragm preparations. In opposite, Crotalus durissusterrificus (Cdt 15 ÎŒg/mL) or Bothrops jararacussu (Bjssu 40 ÎŒg/mL) venoms causedirreversible neuromuscular blockade. Tannic acid (preincubated with the venoms), butnot coumarin, was able to significantly inhibit (p<0.05) the impairment of the musclestrength induced by Cdt (88 ± 8%) and Bjssu (79 ± 7.5%), respectively. A remarkableprecipitation was observed when the venoms were preincubated with tannic acid, but notwith coumarin. Plathymenia reticulata is a good source of tannins and flavonoidswhereas Mikania laevigata contain high amounts of coumarin. P. reticulata (PrHE, 0.06mg/mL) and M. laevigata (MlHE, 1 mg/mL) hydroalcoholic extracts were assayed withor without Bjssu or Cdt venoms. Both PrHE and MlHE showed protection against Bjssu(79.3 ± 9.5% and 65 ± 8%, respectively) and Cdt (73.2 ± 6.7% and 95 ± 7%,respectively) neuromuscular blockade. In order to observe if the protective mechanismcould be induced by protein precipitation, tannins were eliminated from both extracts andthe assay was repeated. MlHE protected against the blockade induced by Bjssu (57.2 ±6.7%), but not against Cdt. We concluded that plants containing tannins could induce theprecipitation of venoms' proteins and plants containing coumarin showed activity againstBothrops venoms, but not against Crotalus venoms. We also concluded that the use ofisolated bioactive compounds could not represent the better strategy against ophidianvenoms, since the purification may exclude some bioactive components resulting in aloss of antivenom activity. In addition, M. laevigata showed better antiophidian activitythan P. reticulata249262249262FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOsem informaçã

    Sensitivity of South American tropical forests to an extreme climate anomaly

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    NERC Knowledge Exchange Fellowship (NE/V018760/1) to E.N.H.C.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.Publisher PDFPeer reviewe
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