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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

Fossil spores of the dung fungus Sporormiella spp. in sediment cores from throughout Madagascar provide new information concerning megafaunal extinction and the introduction of livestock. Sporormiella percentages are very high in prehuman southwest Madagascar, but at the site with best stratigraphic resolution the spore declines sharply by Ϸ1,720 yr B.P. (radiocarbon years ago). Within a few centuries there is a concomitant rise in microscopic charcoal that probably represents human transformation of the local environment. Reduced megaherbivore biomass in wooded savannas may have resulted in increased plant biomass and more severe fires. Some now-extinct taxa persisted locally for a millennium or more after the inferred megafaunal decline. Sites in closed humid forests of northwest Madagascar and a montane ericoid formation of the central highlands show only low to moderate Sporormiella percentages before humans. A subsequent rise in spore concentrations, thought to be evidence for livestock proliferation, occurs earliest at Amparihibe in the northwest at Ϸ1,130 yr B.P. F ossil spores of the dung fungus Sporormiella spp. have been shown in western North America to serve as a reliable proxy for megafaunal biomass in late Pleistocene sediments. These spores decline rapidly at the end of the Pleistocene at the approximate time of megafaunal extinctions and increase again in sediments of recent centuries after livestock introduction (1, 2). We present here application of the technique described in refs. 1 and 2 to the study of late Holocene extinctions on the island of Madagascar. Sediment cores from throughout the island contain these spores, and stratigraphic trends offer a way to produce a chronology for megafaunal decline and livestock introductions.Research over the last two decades has clarified many aspects of this remarkable ecological catastrophe (3-5), which eliminated virtually the entire endemic megafauna including the giant lemurs, elephant birds, pygmy hippopotami, and giant tortoises. Four independent lines of stratigraphic evidence are consistent with the beginning of a human presence on the island at least by Ϸ2,000 radiocarbon years before present (yr B.P.): (i) dates on humanmodified bones of extinct animals (6); (ii) pollen of prehistorically introduced plants (7); (iii) a large spike of charcoal particles in lake and bog sediments (5); and (iv) pollen evidence for a decline in forest and increase in grasses and ruderal herbs (8). Studies of the Malagasy language also show a separation from its closest surviving linguistic relatives in the highlands of Borneo approximately two millennia ago, although divergence could have begun before protoMalagasy speakers departed from Indonesia (9). Integrated multidisciplinary analyses of rich late Holocene fossil sites with accelerator mass spectrometry dating and close stratigraphic control show that, whereas some megafaunal taxa seem to decline rapidly after human arrival, others persisted at some sites for a millennium or more after first evidence for hum...

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Humans now play a major role in altering Earth and its biota. Finding ways to ameliorate human impacts on biodiversity and to sustain and restore the ecosystem services on which we depend is a grand scientific and societal challenge. Conservation paleobiology is an emerging discipline that uses geohistorical data to meet these challenges by developing and testing models of how biota respond to environmental stressors. Here we (a) describe how the discipline has already provided insights about biotic responses to key environmental stressors, (b) outline research aimed at disentangling the effects of multiple stressors, (c) provide examples of deliverables for managers and policy makers, and (d ) identify methodological advances in geohistorical analysis that will foster the next major breakthroughs in conservation outcomes. We highlight cases for which exclusive reliance on observations of living biota may lead researchers to erroneous conclusions about the nature and magnitude of biotic change, vulnerability, and resilience. 79 Annu. Rev. Earth Planet. Sci. 2015.43:79-103. Downloaded from www.annualreviews.org Access provided by University of California -San Diego on 06/01/15. For personal use only.