A δ13C record of late Quaternary climate change from tropical peats in southern India

Sukumar, Raman; Ramesh, R.; Pant, R. K.; Rajagopalan, G.

doi:10.1038/364703a0

Cited by 234 publications

(145 citation statements)

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“…The persistence of a historical rainforest refugium in the southern Western Ghats [50] could have played a significant role in promoting persistence, reducing extinction, and range expansion of these lineages at low and medium elevations. forest-grassland dynamics associated with glacial and interglacial periods within these massifs [14]. However, the older ages of these sister lineages (e.g.…”

Section: (B) Sisters On Adjacent Massifs: Quaternary Glaciations Versmentioning

confidence: 99%

“…According to palaeoclimate-based models or the 'refuge model', the isolation of populations during dry glacial periods in forest refuge areas is hypothesized to have led to vicariance and speciation; for example, it is suggested that the repetition of this process over different periods resulted in high diversity in the Amazon tropics [13]. This model can be applied to the montane islands of the southern Western Ghats, where there is strong evidence for the effects of climatic oscillations corresponding to glacial-inter-glacial cycles on the dynamics and maintenance of forests and grasslands at higher elevations (more than 1800 m) [14], resulting in in situ diversification within these montane islands (figure 1). In a modified version of this model, the dispersal-vicariance hypothesis for montane taxa [15], lineages could have expanded their ranges downwards during cold glacial periods, followed by subsequent retreat and isolation of lineages in adjoining mountains during dry inter-glacial periods [16].…”

Section: Introductionmentioning

confidence: 99%

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Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

et al. 2016

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The historical processes underlying high diversity in tropical biodiversity hotspots like the Western Ghats of Peninsular India remain poorly understood. We sampled bush frogs on 13 massifs across the Western Ghats Escarpment and examined the relative influence of Quaternary glaciations, ecological gradients and geological processes on the spatial patterns of lineage and clade diversification. The results reveal a large in situ radiation (more than 60 lineages), exhibiting geographical structure and clade-level endemism, with two deeply divergent sister clades, North and South, highlighting the biogeographic significance of an ancient valley, the Palghat Gap. A majority of the bush frog sister lineages were isolated on adjacent massifs, and signatures of range stasis provide support for the dominance of geological processes in allopatric speciation. In situ diversification events within the montane zones (more than 1800 m) of the two highest massifs suggest a role for climate-mediated forest-grassland persistence. Independent transitions along elevational gradients among sub-clades during the Miocene point to diversification along the elevational gradient. The study highlights the evolutionary significance of massifs in the Western Ghats with the high elevations acting as centres of lineage diversification and the low-and mid-elevations of the southern regions, with deeply divergent lineages, serving as museums.

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Section: (B) Sisters On Adjacent Massifs: Quaternary Glaciations Versmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

et al. 2016

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“…Unusual droughts and variation in rainfall are recognized more and more as important in tropical forests (Foster 1982a, Hartshorn 1992, Leigh et al 1990, Woods 1989), but we know little about how populations of individual species change as a result. Certainly we know that past climate changes have led to shifts in species' distributions , Hamilton & Taylor 1991, Sukumar et al 1993, and in temperate forests, detailed descriptions of range shifts that accompany past climate changes are so well documented (Davis 1981, Delcourt & Delcourt, 1987) that precise predictions on the impact of future climate scenarios can be made (Botkin & Nisbet 1992, Dale & Franklin 1989, Franklin et al 1992, Overpeck et al 1990, Pastor & Post 1988, Shugart & Smith 1992, Solomon 1986, Urban et al 1993. The species-specific information behind these predictions is not available for most tropical forests.…”

Section: Introductionmentioning

confidence: 99%

Changes in tree species abundance in a Neotropical forest: impact of climate change

Condit¹,

1996

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. ABSTRACT. The abundance of all tree and shrub species has been monitored for eight years in a 50 ha census plot in tropical moist forest in central Panama. Here we examine population trends of the 219 most numerous species in the plot, assessing the impact of a long-term drying trend. Population change was calculated as the mean rate of increase (or decrease) over eight years, considering either all stems :10 mm diameter at breast height (dbh) or just stems :100 mm dbh. For stems B 10 mm, 40% of the species had mean growth rates <1 % per year (either increasing or decreasing) and 12%l had changes B5/5% per year. For stems 100 mm, the figures were 38% anid 8%. Cambridge University PressSpecies that specialize on the slopes of the plot, a moist microhabitat relative to the plateau, suffered significanitly more declines in abundance than species that did not prefer slopes (stems 10 mm dbh). This pattern was due entirely to species of small stature: 91 % of treelets and shrubs that were slope-specialists declined in abundance, but just 19% of non-slope treelets and shrubs declined. Among larger trees, slope and non-slope species fared equally. For stems I100 mm dbh, the slope effect vanished because there were few shrubs and treelets with stems I100 mm dbh. Another edaphic guild of species, those occurring preferentially in a small swamp in the centre of the plot, were no mor-e likely to decline in abundance than non-swamp species, regardless of growth form. Species that preferentially colonize canopy gaps in the plot were slightly more likely to decrease in abundance than non-colonizing species (only for stems B10 mm dbh, not B100 mm). Despite this overall trend, however, several colonizing species had the most rapidly increasing populations in the plot.The impact of a 25-year drying trend and an associated increase in the severity of the 4-month dry season is having an obvious impact on the BCI forest. At least 16 species of shrubs and treelets with affinities for moist microhabitats are headed for extinctioin in the plot. Presumably, these species invaded the forest during a wetter period prior to 1966. A severe drought of 1983 that caused ulnusually high tr-ee mortality contributed to this trend, anid may also have been responsible for sharp increases in abundance of a few gap-colonizers because it temporarily opened the forest canopy. The BCI forest is remarkably sensitive to a subtle climatic shift, yet we do not know whether this is typical for tropical folrests because no other lalge-scale censuses exist fol comparisonl.

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“…There is a successful history of this approach in the temperate zone (Delcourt and Delcourt, 1987;Overpeck et al, 1990;Shugart and Smith, 1992;Urban et al, 1993), but the data needed for tropical forest models are not available. Few records of quaternary forest distributions exist (Bush et al, 1990;Hamilton and Taylor, 1991;Sukumar, et al, 1993), and climatic effects on the demography and distribution of individual species are seldom known. The Center for Tropical Forest Science is attempting to remedy this data shortage with its network of large, permanent plots distributed throughout the major tropical forest blocks of the world (Manokaran et al, 1992;Sukumar et al, 1992;Condit, 1995).…”

Section: Introductionmentioning

confidence: 99%

Ecological Implications of Changes in Drought Patterns: Shifts in Forest Composition in Panama

Condit

1998

Potential Impacts of Climate Change on Tropical Forest Ecosystems

105

152

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Abstract. CO2 concentration is increasing, temperature is likely to rise, and precipitation patterns might change. Of these potential climatic shifts, it is precipitation that will have the most impact on tropical forests, and seasonal patterns of rainfall and drought will probably be more important than the total quantity of precipitation. Many tree species are limited in distribution by their inability to survive drought. In a 50 ha forest plot at Barro Colorado Island in Panama (BCI), nearly all tree and shrub species associated with moist microhabitats are declining in abundance due to a decline in rainfall and lengthening dry seasons. This information forms the basis for a simple, general prediction: drying trends can rapidly remove drought-sensitive species from a forest. If the drying trend continues at BCI, the invasion of drought-tolerant species would be anticipated, but computer models predict that it could take 500 or more years for tree species to invade and become established.Predicting climate-induced changes in tropical forest also requires geographic information on tree distribution relative to precipitation patterns. In central Panama, species with the most restricted ranges are those from areas with a short dry season (10-14 weeks): 26-39% of the tree species in these wet regions do not occur where it is drier. In comparison, just 11-19% of species from the drier side of Panama (18 week dry season) are restricted to the dry region. From this information, I predict that a four-week extension of the dry season could eliminate 25% of the species locally; a nine-week extension in very wet regions could cause 40% extinction. Since drier forests are more deciduous than wetter forests, satellite images that monitor deciduousness might provide a way to assess long-term forest changes caused by changes in drought patterns.I predict that increasing rainfall and shorter dry seasons would not cause major extinction in tropical forest, but that drying trends are a much greater concern. Longer dry seasons may cause considerable local extinction of tree species and rapid forest change, and they will also tend to exacerbate direct human damage, which tends to favor drought-adapted and invasive tree species in favor of moisture-demanding ones.

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A δ13C record of late Quaternary climate change from tropical peats in southern India

Cited by 234 publications

References 24 publications

Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

Changes in tree species abundance in a Neotropical forest: impact of climate change

Ecological Implications of Changes in Drought Patterns: Shifts in Forest Composition in Panama

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