Simulated effects of a seasonal precipitation change on the vegetation in tropical Africa

• DOI: 10.5194/cp-6-169-2010
• Publication Date: 2010-04-29T14:46:57Z
• Authors: E. S. Gritti; C. Cassignat; O. Flores; R. Bonnefille; F. Chalié; J. Guiot; D. Jolly
• Keywords: Biome; Seasonality

Abstract. Pollen data collected in Africa at high (Kuruyange, valley swamp, Burundi) and low altitude (Victoria, lake, Uganda; Ngamakala, pond, Congo) showed that after 6 ky before present (BP), pollen of deciduous trees increase their relative percentage, suggesting thus the reduction annual amount precipitation and/or an length dry season. Until now, pollen-climate transfer functions only investigated mean precipitation, due to absence modern pollen-assemblage analogs under diversified regimes. Hence these omit potential effect a change seasonality modifying In study, we use equilibrium biosphere model (i.e. BIOME3.5) estimate sensitivity equatorial African vegetation, specific sites, such changes. Climatic scenarios, differing monthly distribution current are examined above three locations Africa. Soil characteristics, temperatures cloudiness kept constant present-day values. Good agreement is shown between simulations biomes assemblages, as inferred from data. To date, forest component palaeodata around BP has been interpreted beginning drier climate period. However, our results demonstrate seasonal could also induce observed changes vegetation types. This study confirms importance taking into account hydrological balance. Palaeoecologists can greatly benefit dynamic process based models acccount for modification season when they wish reconstruct composition or infer quantitative parameters, temperature proxy.