How does climate change Impact island rainforests: first measurements in The Lesser Antilles archipelago

International audienceRainforests in tropical islands are characterized by high endemism and unusual structures. Canopies are lower than in continental areas with a similar climate, but the number of trees per hectare is much higher. It is likely that these structural attributes are due to the frequency of hurricanes but also more generally to some peculiarities of island climates.Recent works show that in areas where plants are subject to seasonal drought, the metabolism of tropical trees negatively responds to rising temperatures and rainfall reduction. Given the particularities of island ecosystems, we wanted to study the behavior of forests growing in climates without true dry season.The results obtained on four 1-hectare plots (4312 trees) show that during the last nine years, tree growth has accelerated and at the same time, tree mortality has increased - although the estimation of mortality is more uncertain. These joint trends reflect a significant acceleration in the turnover of tree stands.The measurements carried out thanks to the "Forest Ecosystems Observatory" put in place since 2010, demonstrate that the Caribbean island rainforests are impacted by the current climate change and that they respond in a singular way. The results obtained do not provide information on changes in biodiversity or loss of endemic species, but they suggest that Lesser-Antilles rainforests are reducing their carbon storage capacity

How does climate change Impact island rainforests: first measurements in The Lesser Antilles archipelago

International audienceRainforests in tropical islands are characterized by high endemism and unusual structures. Canopies are lower than in continental areas with a similar climate, but the number of trees per hectare is much higher. It is likely that these structural attributes are due to the frequency of hurricanes but also more generally to some peculiarities of island climates.Recent works show that in areas where plants are subject to seasonal drought, the metabolism of tropical trees negatively responds to rising temperatures and rainfall reduction. Given the particularities of island ecosystems, we wanted to study the behavior of forests growing in climates without true dry season.The results obtained on four 1-hectare plots (4312 trees) show that during the last nine years, tree growth has accelerated and at the same time, tree mortality has increased - although the estimation of mortality is more uncertain. These joint trends reflect a significant acceleration in the turnover of tree stands.The measurements carried out thanks to the "Forest Ecosystems Observatory" put in place since 2010, demonstrate that the Caribbean island rainforests are impacted by the current climate change and that they respond in a singular way. The results obtained do not provide information on changes in biodiversity or loss of endemic species, but they suggest that Lesser-Antilles rainforests are reducing their carbon storage capacity

Low genetic diversity in a widespread whistling alien: A comparison of Eleutherodactylus johnstonei Barbour, 1914 (Eleutherodactylidae) and congeners in native and introduced ranges

There is no clear empirical evidence to support the general assumption that genetic diversity favours successful invasions. Many invading species disperse and establish successfully despite low genetic diversity, a phenomenon known as the genetic paradox of biological invasion. Model systems that allow comparison of genetic patterns between exotic and native source populations are still scarce. This is particularly true for amphibians. Here we compare genetic patterns of the widely introduced Johnstone’s Whistling Frog, Eleutherodactylus johnstonei, with its successful alien congener E. antillensis and the single island endemic E. portoricensis. Genetic diversity and population differentiation in native and introduced populations of the three taxa were inferred from mitochondrial D-loop sequences (235 bp). Our results reveal that exotic populations of the two alien taxa, E. johnstonei and E. antillensis, are not only genetically impoverished due to founder effects, but that, moreover, their native range source-populations exhibit low genetic diversity and inter-population differentiation in the first place. Populations of the endemic E. portoricensis, on the other hand, are genetically more diverse and show marked inter-population differentiation. These observed genetic patterns are consistent with geological processes and invasion histories. We argue that the establishment success of the alien taxa in our model system is better explained by ecological factors and anthropogenic drivers than by genetic diversity. As these factors provide more parsimonious explanations, they should be given priority in management decisions. However, molecular studies with higher resolution are needed to fully test possible genetic and epigenetic components that could promote the invasion process.</jats:p

Effect of anakinra versus usual care in adults in hospital with COVID-19 and mild-to-moderate pneumonia (CORIMUNO-ANA-1): a randomised controlled trial

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