International audienceBiome reconstruction from pollen and plant macrofossil data provides an objective method to reconstruct past vegetation. Biomes for Africa and the Arabian peninsula have been mapped for 6000 years sp and provide a new standard for the evaluation of simulated palaeovegetation distributions. A test using modern pollen data shows the robustness of the biomization method, which is able to predict the major vegetation types with a high confidence level. The application of the procedure to the 6000 years data set (pollen and plant macrofossil analyses) shows systematic differences from the present that are consistent with the numerous previous regional and continental interpretations, while providing a more extensive and more objective basis for such interpretations. Madagascar, eastern, southern and central Africa show only minor changes in terms of biomes, compared to present. Major changes in biome distributions occur north of 15 degrees N, with steppe in many low-elevation sites that are now desert, and temperate xerophytic woods/scrub and warm mixed forest in the Saharan mountains. These shifts in biome distributions, imply significant changes in climate, especially precipitation, between 6000 years and present, reflecting a change in monsoon extent combined with a southward expansion of Mediterranean influence

Pollen data from 18,000 14 C yr bp were compiled in order to reconstruct biome distributions at the last glacial maximum in southern Europe and Africa. Biome reconstructions were made using the objective biomization method applied to pollen counts using a complete list of dryland taxa wherever possible. Consistent and major differences from present-day biomes are shown.Forest and xerophytic woods/scrub were replaced by steppe, both in the Mediterranean region and in southern Africa, except in south-western Cape Province where fynbos (xerophytic scrub) persisted.Sites in the tropical highlands, characterized today by evergreen forest, were dominated by steppe and/or xerophytic vegetation (cf. today's Ericaceous belt and Afroalpine grassland) at the last glacial maximum.Available data from the tropical lowlands are sparse but suggest that the modern tropical rain forest was largely replaced by tropical seasonal forest while the modern seasonal or dry forests were encroached on by savanna or steppe. Montane forest elements descended to lower elevations than today.

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(Rutales'> etude taxonornique, palynologique et systematique ['Tht. Cneomc i. ., a taxonomic, palynological and systematic study].-Gram 17: 125-139, 1978. Uppsala 30 November 1978. hlorphological, caryological, anatomical, embryological, phytochemical, serological and palynological characters suggest a separation of the two genera Cneoriirn and Neochnninelen (Cneoraceae) from each other. The family is best placed in the Rutales. The ultn'structure of the exine is similar in the two genera while the exine Ornamentation differs. The pollen morphology resembles that of the Rutaceae and the Simaroubaceae and gives further support to the idea of including the family in the order Rutales. Aprks avoir revu I'ensemble des caractkres rnorphologiqucs, anatomiques, caryologiques, embryologiques, phytochimiques, serdogiques et palynologiques les auteurs concluent ii la necessite de separer les deux genres Cneoriim et Neochnriiuelea et de rattacher la famille aux Rutales. Par I'itude detaillie des caractkres du pollen, ils montrent Cgalernent que I'ultrastructure de I'exine est identique dans les deux genres, bien que I'ornementation et le nornbre des apertures soient diffirents. Le type pollinique des Cneoraceae est comparable ii celui des Rutaceae, Simaroubaceae et vient etayer I'opinion friquemrnent admise que la farnille appartient 5 I'ordre des Rutales.

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