441 research outputs found

    Threats to environmentally sensitive areas from peri-urban expansion in Mauritius

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    Rapid population growth and economic change on the tropical islands of Mauritius have led to one of the highest rates of urban build-out in the world. Pressure on many of the island's natural features and resources increasingly risks further degradation to the environmental services that they provide to the country. Fourteen types of marine and terrestrial environmentally sensitive areas (ESAs) are critical to the nation's sustainable development. Twelve of these ESA types are currently at risk of degradation, owing to their spatial proximity to built-up areas (BUAs) and current use designation. There was a bimodal distribution in proximity; eight of the 12 ESA types analysed had an area-weighted modal peak < 500 m from the nearest BUA, and four ESAs had a modal peak 2–3 km from the nearest BUA. Six coastal and marine ESAs had limited protection from urban expansion and over-use. The Mauritian experience reflects trends that are emerging across many tropical developing countries, where the bulk of future global growth in urban area is expected to occur. The approach detailed in this case study is replicable and may be useful in assessing degradation risk as a result of urban expansion in other island countries. (Résumé d'auteur

    Regional scale rain-forest height mapping using regression-kriging of spaceborne and airborne lidar data : application on French Guiana

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    LiDAR data has been successfully used to estimate forest parameters such as canopy heights and biomass. Major limitation of LiDAR systems (airborne and spaceborne) arises from their limited spatial coverage. In this study, we present a technique for canopy height mapping using airborne and spaceborne LiDAR data (from the Geoscience Laser Altimeter System (GLAS)). First, canopy heights extracted from both airborne and spaceborne LiDAR were extrapolated from available environmental data. The estimated canopy height maps using Random Forest (RF) regression from airborne or GLAS calibration datasets showed similar precisions (~6 m). To improve the precision of canopy height estimates, regression-kriging was used. Results indicated an improvement in terms of root mean square error (RMSE, from 6.5 to 4.2 m) using the GLAS dataset, and from 5.8 to 1.8 m using the airborne LiDAR dataset. Finally, in order to investigate the impact of the spatial sampling of future LiDAR missions on canopy height estimates precision, six subsets were derived from the initial airborne LiDAR dataset. Results indicated that using the regression-kriging approach a precision of 1.8 m on the canopy height map was achievable with a flight line spacing of 5 km. This precision decreased to 4.8 m for flight line spacing of 50 km

    Pharmacognostic and Phytochemical Investigation of Ficus carica Linn.

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    Ficus carica Linn. (Syn: Ficus sycomorous; family: Moraceae) is grows in tropical and subtropical regions of India, used for varity of purpose in traditional medicine. The usefulness of this plant is scientifically evidenced, and different biologically active phytoconstituents were isolated form plant. But no reports are available on morphoanatomy, and phytochemical studies, hence present attempt was undertaken to investigate the microscopical and preliminary phytochemical studies. The study revels the midrib is biconvex and lamina is dorsiventral, shows presence of nonglandular trichome, anomocytic stomata, prismatic calcium oxalate crystals. It shows presence of steroids, triterpenoids, cumarines, flavanoids and glycoside
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