In recent decades a boom in cashew (Anacardium occidentale) cultivation has taken place in Guinea-Bissau, leading to the replacement of traditional slash-and-burn agriculture by a cash crop. As a result, the country is currently one of the world's largest producers of raw cashew nuts and the cashew sector has acquired enormous importance in Guinea-Bissau's economy. Changes induced by the cashew boom at social and environmental levels are yet to be analyzed and understood. The present study provides an account of the process of cashew expansion in Guinea-Bissau, reviews the current situation and discusses its future prospects. The cashew tree was introduced into the country by the Portuguese in the XIXth century, but only effectively expanded in the mid-1980s. It is largely cultivated by small farmers around villages and also plays a role in land ownership, since land tenure practices are linked to the planting of trees.The effects of this cashew boom on habitat fragmentation, fire regimes and biodiversity are still to be assessed. On the other hand, the spread of pests and diseases is becoming a problem.Strong dependence on a single cash crop also renders the country vulnerable to market fluctuations, entailing risks to local producers and the national economy. In the medium term, losses of export earnings can occur, which may impact the living standards and food security of BissauGuineans both in urban and rural areas.

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In this work residues and extracts resulting from high-pressure extractions of Eucalyptus globulus Labill. by 1,4-dioxane and l,4-dioxane-CO2 mixtures, in the temperature range 160°C-180°C at 170 bar and 250 bar pressures were characterised by spectroscopic and Chromatographie techniques. Spectral data of extraction residues showed that thermal degradation starts to occur at 180°C. At lower temperatures cellulose is neither degraded nor extracted and changes in intensity of FTIR absorption bands indicate lignin and hemicellulose extraction. Hemicellulose removal is an essentially degradative process. The FTIR spectra of lignins recovered from extraction liquors show absorption bands with very well defined peaks. They are very similar to literature data obtained for hardwood lignins extracted in mild conditions. Namely, all the absorption bands observed in milled wood lignins of GS3-GS4 types are visible. Acid soluble residual lignins appear to be rich in guaiacyl units, while UV and FTIR spectra show that extracted lignins are rich in syringyl units.

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