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Changes in physico‐chemical properties of superficial soil layers following the substitution of broad leaf trees by conifers have been studied in four Pyrenean sites. Parameter values may change significantly from native to reforested plots, but sometimes in opposite directions. Initial conditions (historical, pedological, and climatic) were not the same in each plot and the present A soil horizon is highly dependent on these. A lessening of organic matter degradation and humification conditions can be, however, inferred from direct humus observations, but differences between physico‐chemical properties in native and reforested plots are, nevertheless, quantitatively low, particularly in the pH range usually appropriate for conifer plantations. [ABSTRACT FROM PUBLISHER]

Despite their environmental and economic significance the exact status and geographical extent of mangrove ecosystems are unknown in Madagascar. For the first time, the deltaic complex of Mahajamba bay has been surveyed, using SPOT 1 and SPOT 2 imagery. An intensive field survey together with complete aerial coverage at a scale of 1 :40 000 were used for the validation of the digital classification. The accuracy of cartographic products and of vegetation changes is closely related both to the adopted image processing methods and to the season of satellite data acquisition. The main input of the present contribution is to provide precise descriptions and mapping of the mangroves in Madagascar using high resolution remote sensing technology to assess conspicuous changes. Some conspicuous limitations of satellite data have also been noted. Nevertheless the results can be used for conservation and management purposes. [ABSTRACT FROM AUTHOR]