Pantropical modelling of canopy functional traits using Sentinel-2 remote sensing data

Tropical forest ecosystems are undergoing rapid transformation as a result of changing environmental conditions and direct human impacts. However, we cannot adequately understand, monitor or simulate tropical ecosystem responses to environmental changes without capturing the high diversity of plant functional characteristics in the species-rich tropics. Failure to do so can oversimplify our understanding of ecosystems responses to environmental disturbances. Innovative methods and data products are needed to track changes in functional trait composition in tropical forest ecosystems through time and space. This study aimed to track key functional traits by coupling Sentinel-2 derived variables with a unique data set of precisely located in-situ measurements of canopy functional traits collected from 2434 individual trees across the tropics using a standardised methodology. The functional traits and vegetation censuses were collected from 47 field plots in the countries of Australia, Brazil, Peru, Gabon, Ghana, and Malaysia, which span the four tropical continents. The spatial positions of individual trees above 10 cm diameter at breast height (DBH) were mapped and their canopy size and shape recorded. Using geo-located tree canopy size and shape data, community-level trait values were estimated at the same spatial resolution as Sentinel-2 imagery (i.e. 10 m pixels). We then used the Geographic Random Forest (GRF) to model and predict functional traits across our plots. We demonstrate that key plant functional traits can be accurately predicted across the tropicsusing the high spatial and spectral resolution of Sentinel-2 imagery in conjunction with climatic and soil information. Image textural parameters were found to be key components of remote sensing information for predicting functional traits across tropical forests and woody savannas. Leaf thickness (R2 = 0.52) obtained the highest prediction accuracy among the morphological and structural traits and leaf carbon content (R2 = 0.70) and maximum rates of photosynthesis (R2 = 0.67) obtained the highest prediction accuracy for leaf chemistry and photosynthesis related traits, respectively. Overall, the highest prediction accuracy was obtained for leaf chemistry and photosynthetic traits in comparison to morphological and structural traits. Our approach offers new opportunities for mapping, monitoring and understanding biodiversity and ecosystem change in the most species-rich ecosystems on Earth

Antiparasitic Macrolides: General Pharmacological Properties and Usage Instructions in the African Veterinary Context

Antiparasitic macrolides (or endectocides) represent the most recent class of antiparasitic drugs. This class is homogeneous because of its unique and specific, glutaminergic, mode of action, and its pharmacological properties. These drugs have a spectrum of action directed against many nematodes, as well as many insects and mites. Their structures and associated galenic formulations also enable them to have a high remanent potential. Unfortunately, endectocides are generally used in African countries without any recording procedure. Moreover, the introduction of generic formulations facilitated massive and repetitive uses that have led to therapeutic failures. These drugs should be given a good set-up to be effective in an African tropical environment, in particular by taking into account the characteristics of local breeds and environmental constraints. The first element to consider is the choice of the most potent route of administration. At the same time, the differences observed between animal species targets as well as physiological peculiarities must lead to a better adapted use

A comparative kinetic study of doramectin and moxidectin in zebu Gobra cattle (Bos indicus)

International audienceThe plasma kinetics of doramectin and moxidectin were evaluated in zebu Gobra under field conditions after subcutaneous administration of 0.2 mg kg−1 of commercially available formulations for cattle. The results indicate that the absorption of moxidectin from the site of injection was significantly faster (absorption half-life [t1/2ab]=0.7 day) than that of doramectin (t1/2ab=3.1 days). Moxidectin peak plasma concentration (Cmax) was reached significantly earlier (tmax=0.4 day) compared with that of doramectin (tmax= 5.3 days). No differences in Cmax values were observed; the area under the concentration–time curve was higher for doramectin (475 ng day ml−1) compared with moxidectin (198 ng day ml−1), while the mean residence time was longer for moxidectin (13.4 days) compared with doramectin (9.4 days). These results obtained give interesting information on doramectin and moxidectin pharmacokinetics in zebu Gobra, which show a similar pharmacokinetic profile as in other cattle

Kinetic and therapeutic properties of macrocyclic lactone endectocides, doramectin and moxidectin, in N’Dama cattle (<em>Bos taurus</em>) in Gabon

The plasma kinetics and efficacy of doramectin and moxidectin were studied in N’Dama taurine cattle after subcutaneous administration at the recommended dose of 0.2 mg/kg. Absorption half-life values showed that the absorption of moxidectin (0.05 day) was significantly faster than that of doramectin (1.7 day). No significant differences were observed in maximum concentrations, but they were reached earlier with moxidectin (0.3 day) than with doramectin (4.8 days). Exposure, measured by the area under the curve, was higher for doramectin (458 ng.day/ml) than for moxidectin (159 ng.day/ml), whereas moxidectin seemed more remanent. Both molecules showed 100% efficacy between days 15 and 30 posttreatment. These results are similar to those observed in other taurine breeds. Doramectin and moxidectin can therefore be recommended to control gastrointestinal parasitoses in N’Dama in humid tropical regions

Functional susceptibility of tropical forests to climate change

Tropical forests are some of the most biodiverse ecosystems in the world, yet their functioning is threatened by anthropogenic disturbances and climate change. Global actions to conserve tropical forests could be enhanced by having local knowledge on the forestsʼ functional diversity and functional redundancy as proxies for their capacity to respond to global environmental change. Here we create estimates of plant functional diversity and redundancy across the tropics by combining a dataset of 16 morphological, chemical and photosynthetic plant traits sampled from 2,461 individual trees from 74 sites distributed across four continents together with local climate data for the past half century. Our findings suggest a strong link between climate and functional diversity and redundancy with the three trait groups responding similarly across the tropics and climate gradient. We show that drier tropical forests are overall less functionally diverse than wetter forests and that functional redundancy declines with increasing soil water and vapour pressure deficits. Areas with high functional diversity and high functional redundancy tend to better maintain ecosystem functioning, such as aboveground biomass, after extreme weather events. Our predictions suggest that the lower functional diversity and lower functional redundancy of drier tropical forests, in comparison with wetter forests, may leave them more at risk of shifting towards alternative states in face of further declines in water availability across tropical regions

Functional susceptibility of tropical forests to climate change

Tropical forests are some of the most biodiverse ecosystems in the world, yet their functioning is threatened by anthropogenic disturbances and climate change. Global actions to conserve tropical forests could be enhanced by having local knowledge on the forestsʼ functional diversity and functional redundancy as proxies for their capacity to respond to global environmental change. Here we create estimates of plant functional diversity and redundancy across the tropics by combining a dataset of 16 morphological, chemical and photosynthetic plant traits sampled from 2,461 individual trees from 74 sites distributed across four continents together with local climate data for the past half century. Our findings suggest a strong link between climate and functional diversity and redundancy with the three trait groups responding similarly across the tropics and climate gradient. We show that drier tropical forests are overall less functionally diverse than wetter forests and that functional redundancy declines with increasing soil water and vapour pressure deficits. Areas with high functional diversity and high functional redundancy tend to better maintain ecosystem functioning, such as aboveground biomass, after extreme weather events. Our predictions suggest that the lower functional diversity and lower functional redundancy of drier tropical forests, in comparison with wetter forests, may leave them more at risk of shifting towards alternative states in face of further declines in water availability across tropical regions

Functional susceptibility of tropical forests to climate change

Tropical forests are some of the most biodiverse ecosystems in the world, yet their functioning is threatened by anthropogenic disturbances and climate change. Global actions to conserve tropical forests could be enhanced by having local knowledge on the forestsʼ functional diversity and functional redundancy as proxies for their capacity to respond to global environmental change. Here we create estimates of plant functional diversity and redundancy across the tropics by combining a dataset of 16 morphological, chemical and photosynthetic plant traits sampled from 2,461 individual trees from 74 sites distributed across four continents together with local climate data for the past half century. Our findings suggest a strong link between climate and functional diversity and redundancy with the three trait groups responding similarly across the tropics and climate gradient. We show that drier tropical forests are overall less functionally diverse than wetter forests and that functional redundancy declines with increasing soil water and vapour pressure deficits. Areas with high functional diversity and high functional redundancy tend to better maintain ecosystem functioning, such as aboveground biomass, after extreme weather events. Our predictions suggest that the lower functional diversity and lower functional redundancy of drier tropical forests, in comparison with wetter forests, may leave them more at risk of shifting towards alternative states in face of further declines in water availability across tropical regions

Functional susceptibility of tropical forests to climate change

Tropical forests are some of the most biodiverse ecosystems in the world, yet their functioning is threatened by anthropogenic disturbances and climate change. Global actions to conserve tropical forests could be enhanced by having local knowledge on the forestsʼ functional diversity and functional redundancy as proxies for their capacity to respond to global environmental change. Here we create estimates of plant functional diversity and redundancy across the tropics by combining a dataset of 16 morphological, chemical and photosynthetic plant traits sampled from 2,461 individual trees from 74 sites distributed across four continents together with local climate data for the past half century. Our findings suggest a strong link between climate and functional diversity and redundancy with the three trait groups responding similarly across the tropics and climate gradient. We show that drier tropical forests are overall less functionally diverse than wetter forests and that functional redundancy declines with increasing soil water and vapour pressure deficits. Areas with high functional diversity and high functional redundancy tend to better maintain ecosystem functioning, such as aboveground biomass, after extreme weather events. Our predictions suggest that the lower functional diversity and lower functional redundancy of drier tropical forests, in comparison with wetter forests, may leave them more at risk of shifting towards alternative states in face of further declines in water availability across tropical regions