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Charcoal Record (charcoal + record)
Selected AbstractsLate-glacial and Holocene vegetation, climate and fire dynamics in the Serra dos Órgãos, Rio de Janeiro State, southeastern BrazilGLOBAL CHANGE BIOLOGY, Issue 6 2010HERMANN BEHLING Abstract We present a high-resolution pollen and charcoal record of a 218 cm long sediment core from the Serra dos Órgãos, a subrange of the coastal Serra do Mar, located at 2130 m altitude in campos de altitude (high elevation grass- and shrubland) vegetation near Rio de Janeiro in southeastern Brazil to reconstruct past vegetation, climate and fire dynamics. Based on seven AMS 14C ages, the record represents at least the last 10 450 14C yr bp (12 380 cal years bp), The uppermost region was naturally covered by campos de altitude throughout the recorded period. Diverse montane Atlantic rain forest (ARF) occurred close to the studied peat bog at the end of the Late-glacial period. There is evidence of small Araucaria angustifolia populations in the study area as late as the early Holocene, after which point the species apparently became locally extinct. Between 10 380 and 10 170 14C yr bp (12 310,11 810 cal yr bp), the extent of campos de altitude was markedly reduced as montane ARF shifted rapidly upward to higher elevations, reflecting a very wet and warm period (temperatures similar to or warmer than present day) at the end of the Younger Dryas (YD) chronozone. This is in opposition to the broadly documented YD cooling in the northern Hemisphere. Reduced cross-equatorial heat transport and movement of the Intertropical Convergence Zone over northeastern Brazil may explain the YD warming. Markedly extended campos de altitude vegetation indicates dry climatic conditions until about 4910 14C yr bp (5640 cal yr bp). Later, wetter conditions are indicated by reduced high elevation grassland and the extension of ARF into higher elevation. Fire frequency was high during the early Holocene but decreased markedly after about 7020 14C yr bp (7850 cal yr bp). [source] A fine-resolution Pliocene pollen and charcoal record from Yallalie, south-western AustraliaJOURNAL OF BIOGEOGRAPHY, Issue 2 2004Pia Atahan Abstract Aim, This paper aims to reconstruct a high-resolution fire and vegetation history from a period when humans were absent in Australia. This is then used to comment on the frequency of natural fire in high biodiversity heathland, and to compare this with historical fire regime in the same region. Methods, A section of varved sediment covering a period of c. 84 years was taken from Palaeolake Yallalie in south-western Australia. The sediments were separated into approximately single to small multiples of years and then analysed for charcoal, pollen and sediment analysis to reconstruct the environmental conditions at the time. Results, The charcoal record indicates fire recurrence to have been roughly between 5 and 13 years, a little longer than those of the historical period. The pollen record was dominated by Casuarinaceae, Myrtaceae and a large number of Proteaceae species; these are intermixed with Araucariaceae, Nothofagus and Podocarpus. This suggests there was a mix of sclerophyll woodland and a mosaic of rain forest elements, thus conditions must have been wetter, particularly in the summers, compared with today. Conclusions, We assume that fire was most likely confined to the sclerophyll vegetation, and that fire has been a significant feature of the environment long before humans entered Australia. The slightly longer fire recurrence times compared with the present result from the intermittent nature of lightning and wetter summers at the time. [source] Glacial refugia for summer-green trees in Europe and south-west Asia as proposed by ECHAM3 time-slice atmospheric model simulationsJOURNAL OF BIOGEOGRAPHY, Issue 12 2007Suzanne A. G. Leroy Abstract Aim, To generate maps of potential refugia for summer-green trees during the Last Glacial Maximum (LGM). Locations, Southern Europe and south-western Asia. Methods, Time-slice simulations of the atmospheric climate with the ECHAM3 model are used for the LGM. Limiting factors beyond which cool and warm groups of deciduous trees cannot grow (such as temperature in growing degree days, minimum monthly temperature and precipitation in summer) are chosen. A limited validation by fossil pollen and charcoal records from LGM sites was done. Results, Two sets of maps extending from Europe to the Caspian region for cool and warm summer-green trees are presented. Three criteria are combined using contour lines to indicate confidence levels. Small areas within the three southern peninsulas of Europe (Spain, Italy and Greece) are highlighted as possible refugia for summer-green trees. Further, areas that have remained poorly known are now proposed as refugia, including the Sakarya,Kerempe region in northern Turkey, the east coast of the Black Sea and the area south of the Caspian Sea. Main conclusions, The maps produced in this study could be used to facilitate better long-term management for the protection of European and south-western Asian biodiversity. [source] Environmental change and peatland forest dynamics in the Lake Sentarum area, West Kalimantan, IndonesiaJOURNAL OF QUATERNARY SCIENCE, Issue 7 2004Gusti Anshari Abstract Four short pollen and charcoal records from sites within and around Lake Pemerak on the margins of the Danau (Lake) Sentarum National Park in inland West Kalimantan, supported by modern surface samples from the Reserve, provide a partial picture of lowland equatorial vegetation and environments over at least the last 40,000 years. They demonstrate general stability in the distribution of wetland and ombrotrophic (or raised) peatlands through the recorded period with dominance throughout of peatland and swamp forest. However, there was marked variation in sediment accumulation rates and in the floristic composition of the vegetation. The period prior to the last glacial maximum appears to have been the time of most active peatland growth and contrasts with the perception, from previous studies on largely coastal and subcoastal peatlands in Indonesia, that the Holocene was the time of major tropical peat accumulation. A general increase in charcoal, just prior to about 30,000 years ago, suggests that burning became more frequent, and is attributed to initial human impact rather than climate change. The subsequent latest Pleistocene period, embracing the Last Glacial Maximum, is marked by a peak in montane,submontane rainforest taxa, strongly indicating a substantial lowering of temperature. It appears that much of the Holocene is not recorded but recommencement of peat accumulation is evident within the last few thousand years. At the time of fieldwork access to the central part of the Lake Sentarum system was inhibited by strong El Niño drought conditions, but this area has the potential to provide a longer and more continuous history of environmental change for the region. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||