Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa

Prentice, I.C.; Jolly, D.; Afanas’eva, N.B.; Ager, T.A.; Anderson, K.; Anderson, P.M.; Andrieu, V.; Andreev, A.A.; Ballouche, A.; Bartlein, P.J.; de_Beaulieu, J.L.; Bengo, M.; Berezina, N.A.; Bezusko, L.G.; Bezusko, T.V.; Bigelow, N.H.; Blyakharchuk, T.A.; Bolikhovskaya, N.S.; Bonnefille, R.; Bottema, S.

Авторы: Prentice I.C., Jolly D., Afanas’eva N.B., Ager T.A., Anderson K., Anderson P.M., Andrieu V., Andreev A.A., Ballouche A., Bartlein P.J., de_Beaulieu J.L., Bengo M., Berezina N.A., Bezusko L.G., Bezusko T.V., Bigelow N.H., Blyakharchuk T.A., Bolikhovskaya N.S., Bonnefille R., Bottema S.
Журнал: Journal of Biogeography
Том: 27
Номер: 3
Год издания: 2000
Издательство: Blackwell Publishing Inc.
Местоположение издательства: United Kingdom
Первая страница: 507
Последняя страница: 519
Аннотация: BIOME 6000 is an international project to map vegetation globally at mid-Holocene (6000 14 C yr BP) and last glacial maximum (LGM, 18,000 14 C yr BP), with a view to evaluating coupled climate-biosphere model results. Primary palaeoecological data are assigned to biomes using an explicit algorithm based on plant functional types. This paper introduces the second Special Feature on BIOME 6000. Site-based global biome maps are shown with data from North America, Eurasia (except South and Southeast Asia) and Africa at both time periods. A map based on surface samples shows the method’s skill in reconstructing present-day biomes. Cold and dry conditions at LGM favoured extensive tundra and steppe. These biomes intergraded in northern Eurasia. Northern hemisphere forest biomes were displaced southward. Boreal evergreen forests (taiga) and temperate deciduous forests were fragmented, while European and East Asian steppes were greatly extended. Tropical moist forests (i.e. tropical rain forest and tropical seasonal forest) in Africa were reduced. In south-western North America, desert and steppe were replaced by open conifer woodland, opposite to the general arid trend but consistent with modelled southward displacement of the jet stream. The Arctic forest limit was shifted slighly north at 6000 14 C yr BP in some sectors, but not in all. Northern temperate forest zones were generally shifted greater distances north. Warmer winters as well as summers in several regions are required to explain these shifts. Temperate deciduous forests in Europe were greatly extended, into the Mediterranean region as well as to the north. Steppe encroached on forest biomes in interior North America, but not in central Asia. Enhanced monsoons extended forest biomes in China inland and Sahelian vegetation into the Sahara while the African tropical rain forest was also reduced, consistent with a modelled northward shift of the ITCZ and a more seasonal climate in the equatorial zone. Palaeobiome maps show the outcome of separate, independent migrations of plant taxa in response to climate change. The average composition of biomes at LGM was often markedly different from today. Refugia for the temperate deciduous and tropical rain forest biomes may have existed offshore at LGM, but their characteristic taxa also persisted as components of other biomes. Examples include temperate deciduous trees that survived in cool mixed forest in eastern Europe, and tropical evergreen trees that survived in tropical seasonal forest in Africa. The sequence of biome shifts during a glacial-interglacial cycle may help account for some disjunct distributions of plant taxa. For example, the now-arid Saharan mountains may have linked Mediterranean and African tropical montane floras during enhanced monsoon regimes.
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