Tropical Forests under the Climates of the Last 30,000 Years

Flenley, J. R.

doi:10.1007/978-94-017-2730-3_2

Cited by 81 publications

(86 citation statements)

References 57 publications

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“…Furthermore, in the subsoil horizons 2Bt (H) and 3Bt (G) there is evidence for downward movement and accumulation of clay in the form of clay skins (argillans) on aggregate surfaces, which was not encountered elsewhere in the stratigraphic section. The intense weathering regime of 2Bt (H) and 3Bt (G) might be a result of a very long period of weathering or it could be related to a shift in climate from a drier and cooler period in the Late Pleistocene to a wanner, wetter period in the early Holocene, as has been suggested by Flenley (1998) for other tropical lowland rain forest regions.…”

Section: Environmental Implications For Human Occupationmentioning

confidence: 82%

Pleistocene colonisation of the Bismarck Archipelago: new evidence from West New Britain

Torrence

Neall

Doelman

et al. 2004

Archaeology in Oceania

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The geological and archaeological signatures al the site of Kupona na Dari on the Willaumez Peninsula, West New Britain provide important new data about human colonisation of the Bismarck Archipelago. Analyses of the stratigraphy and weathering of paleosols and manuporls. when combined with fission track. radiocarbon, and luminescence dating, indicate that the site was first occupied at about 35-45.000 years ago. During the whole peri(Kl of occupation, people were exposed to a series of volcanic events which varied in terms of tbeir potential impacts on the local environment. A PIXE-PIGME characterisation study of the obsidian artefacts at tbe site demonstrates that from the earliest period stone resources were acquired from outcrops located across a relatively large region. When compared with Early-Middle Holocene assemblages from nearby localities, the Pleistocene stone tool technology differs in only a few minor respects. From this analysis we infer tbat groups were mobile in both periods, but slightly different strategies for tbe procurement and maintenance of tbe stone tools were required for tbe more extensive ranges exploited during the Pleistocene. The inter-disciplinary study of Kupona na Dari concludes that colonisation comprised a long term process of settling into this volcanically active environment. Due to variability in the environments tbat people encountered, the pattern of colonisation may not have been similar across the entire Bismarck Archipelago, RT: Anthropology. Tbe Australian Museum,

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Section: Environmental Implications For Human Occupationmentioning

confidence: 82%

Pleistocene colonisation of the Bismarck Archipelago: new evidence from West New Britain

Torrence

Neall

Doelman

et al. 2004

Archaeology in Oceania

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“…We chose to limit our analysis to lowland and upland areas as defined here to focus on distinct vegetation zones. To incorporate the response of vegetation zones to local temperature change, we calculated vegetation lapse rate using 4 values (83, 124, 166, and 207 m/⌬C°), based upon a review for the region (10). Because this vegetation response rate was estimated for forests at 1,000 m asl, the response of lowland forest was adjusted by 40%.…”

Section: Methodsmentioning

confidence: 99%

“…The product of an ongoing collision between 2 ancient continents separated by an island archipelago (4,5), several distinct centers of biological diversity can be identified within a small geographic range (Indochina, Sundaland, Wallacea, and Papuasia), demarcated by the Isthmus of Kra (6) and Wallace's Line (7). During the Quaternary Period, cyclical climate changes have affected the region in 2 ways: sea level change (8) modified total land area (9) while climate change affected the geographic distribution and elevational zonation of forest types (10). These land area dynamics may have had an impact on global climate as well, potentially affecting the ENSO cycle (11).…”

mentioning

confidence: 99%

“…Using conservative estimates for the distinction between evergreen and seasonal forest, we present maximum, median, and minimum scenarios of lowland evergreen rainforest (LERF) at the LGM. These scenarios represent the interactions among precipitation levels in the paleoclimate simulation, equatorial temperature change (15), and assumptions about the vegetation lapse rate (10). These scenarios compare 3 distinct vegetation zones: coastal-swamp (0-10 m elev.…”

mentioning

confidence: 99%

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The current refugial rainforests of Sundaland are unrepresentative of their biogeographic past and highly vulnerable to disturbance

Cannon

Morley²,

Bush³

2009

Proc. Natl. Acad. Sci. U.S.A.

300

313

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Understanding the historical dynamics of forest communities is a critical element for accurate prediction of their response to future change. Here, we examine evergreen rainforest distribution in the Sunda Shelf region at the last glacial maximum (LGM), using a spatially explicit model incorporating geographic, paleoclimatic, and geologic evidence. Results indicate that at the LGM, Sundaland rainforests covered a substantially larger area than currently present. Extrapolation of the model over the past million years demonstrates that the current ''island archipelago'' setting in Sundaland is extremely unusual given the majority of its history and the dramatic biogeographic transitions caused by global deglaciation were rapid and brief. Compared with dominant glacial conditions, lowland forests were probably reduced from approximately 1.3 to 0.8 ؋ 10 6 km 2 while upland forests were probably reduced by half, from approximately 2.0 to 1.0 ؋ 10 5 km 2 . Coastal mangrove and swamp forests experienced the most dramatic change during deglaciations, going through a complete and major biogeographic relocation. The Sundaland forest dynamics of fragmentation and contraction and subsequent expansion, driven by glacial cycles, occur in the opposite phase as those in the northern hemisphere and equatorial Africa, indicating that Sundaland evergreen rainforest communities are currently in a refugial stage. Widespread human-mediated reduction and conversion of these forests in their refugial stage, when most species are passing through significant population bottlenecks, strongly emphasizes the urgency of conservation and management efforts. Further research into the natural process of fragmentation and contraction during deglaciation is necessary to understand the long-term effect of human activity on forest species. lowland evergreen rainforest ͉ paleoclimate simulation ͉ upland evergreen rainforest T he Southeast Asian continent has one of the most complex geological histories in the world (1-3). The product of an ongoing collision between 2 ancient continents separated by an island archipelago (4, 5), several distinct centers of biological diversity can be identified within a small geographic range (Indochina, Sundaland, Wallacea, and Papuasia), demarcated by the Isthmus of Kra (6) and Wallace's Line (7). During the Quaternary Period, cyclical climate changes have affected the region in 2 ways: sea level change (8) modified total land area (9) while climate change affected the geographic distribution and elevational zonation of forest types (10). These land area dynamics may have had an impact on global climate as well, potentially affecting the ENSO cycle (11). Understanding the historical spatial dynamics of forest distribution plays a crucial role in the ability to predict community response to future change (12, 13).Here, we have generated a distribution model of Sundaland rainforest at the Last Glacial Maximum (LGM) by combining paleontological constraints (5) with the results of a numerical simulation of paleoclimate...

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“…During these episodes, the climate in tropical Africa was drier and cooler, causing an expansion of savannah and a contraction of lowland tropical rainforests into regions still presenting sufficient humidity, as demonstrated by pollen records in lake sediments (Maley, 1996). Hence, fragmentation-expansion cycles of the lowland rain forest habitats likely occurred during the Pleistocene, causing population fragmentation of their constituent species (Flenley, 1998). More recently (around 2500 cal years BP), the rainforest in Africa has also been disturbed by a southwards shift of the intertropical convergence zone, as attested by a high-resolution pollen profile obtained from South West Cameroon (Ngomanda et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Population history and gene dispersal inferred from spatial genetic structure of a Central African timber tree, Distemonanthus benthamianus (Caesalpinioideae)

2010

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African rainforests have undergone major distribution range shifts during the Quaternary, but few studies have investigated their impact on the genetic diversity of plant species and we lack knowledge on the extent of gene flow to predict how plant species can cope with such environmental changes. Analysis of the spatial genetic structure (SGS) of a species is an effective method to determine major directions of the demographic history of its populations and to estimate the extent of gene dispersal. This study characterises the SGS of an African tropical timber tree species, Distemonanthus benthamianus, at various spatial scales in Cameroon and Gabon. Displaying a large continuous distribution in the Lower Guinea domain, this is a model species to detect signs of past population fragmentation and recolonization, and to estimate the extent of gene dispersal. Ten microsatellite loci were used to genotype 295 adult trees sampled from eight populations. Three clearly differentiated gene pools were resolved at this regional scale and could be linked to the biogeographical history of the region, rather than to physical barriers to gene flow. A comparison with the distribution of gene pools observed for two other tree species living in the same region invalidates the basic assumption that all species share the same Quaternary refuges and recolonization pathways. In four populations, significant and similar patterns of SGS were detected. Indirect estimates of gene dispersal distances (sigma) obtained for three populations ranged from 400 to 1200 m, whereas neighbourhood size estimates ranged from 50 to 110.

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Tropical Forests under the Climates of the Last 30,000 Years

Cited by 81 publications

References 57 publications

Pleistocene colonisation of the Bismarck Archipelago: new evidence from West New Britain

Pleistocene colonisation of the Bismarck Archipelago: new evidence from West New Britain

The current refugial rainforests of Sundaland are unrepresentative of their biogeographic past and highly vulnerable to disturbance

Population history and gene dispersal inferred from spatial genetic structure of a Central African timber tree, Distemonanthus benthamianus (Caesalpinioideae)

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