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Peat Accumulation (peat + accumulation)
Selected AbstractsSphagnum under pressure: towards an ecohydrological approach to examining Sphagnum productivityECOHYDROLOGY, Issue 4 2008D. K. Thompson Abstract The genus Sphagnum is the key peat-forming bryophyte in boreal ecosystems. Relying entirely on passive capillary action for water transport, soil moisture is often the limiting factor in Sphagnum production, and hence peat accumulation. While several hydrological models of peat physics and peatland water movement exist, these models do not readily interface with observations and models of peatland carbon accumulation. A conflict of approaches exists, where hydrological studies primarily utilize variables such as hydraulic head, while ecological models of Sphagnum growth adopt the coarse hydrological variables of water table (WT), volumetric water content (VWC) or gravimetric water content (WC). This review examines the potential of soil pressure head as a measurement to link the hydrological and ecological functioning of Sphagnum in peatlands. The non-vascular structure of Sphagnum mosses and the reliance on external capillary transport of water in the mosses make them an ideal candidate for this approach. The main advantage of pressure head is the ability to mechanistically link plot-scale hydrology to cellular-scale water requirements and carbon exchange. Measurement of pressure head may improve photosynthetic process representation in the next generation of peatland models. Copyright © 2008 John Wiley & Sons, Ltd. [source] Evaluating interactions between soil drainage and seedling performance in a restoration of Pinus sylvestris woodland, ScotlandGLOBAL ECOLOGY, Issue 2 2001M. D. Crowell Abstract 1,This paper evaluates the role of soil drainage in tree seedling performance at a site being restored from Calluna vulgaris moorland to Pinus sylvestris woodland, in Glen Affric, Scotland. The investigation focuses on the relationships between height of planted seedlings, type of ground vegetation and drainage conditions. 2,Slope, aspect, and soil depth were assessed as potential surrogates for direct measures of soil drainage, all of which were derived from digital terrain data. 3,Six variables related to drainage were recorded at 58 seedling locations and used in a factor analysis to understand links between soil moisture conditions, topographic variables and soil depth characteristics. 4,Factor analysis generated two factors that accounted for 70.5% of the variance in the correlation matrix of these variables: Factor 1 correlated strongly with variables that controlled peat accumulation and Factor 2 correlated strongly with topographic controls upon drainage patterns. 5,These two factors explained a significant amount of the variance in height of the Pinus seedlings planted at these locations. Significant differences were found between the factor scores associated with different types of ground vegetation, as well as between the seedling heights observed at locations with different vegetation types. 6,Multiple regressions were developed that indicated that slope, aspect, and soil depth were significant as independent variables in models where soil moisture content and aerobic soil depth were the dependent variables. [source] Modelling two-dimensional steady-state groundwater flow and flow sensitivity to boundary conditions in blanket peat complexesHYDROLOGICAL PROCESSES, Issue 2 2005D. R. Lapen Abstract This study used a two-dimensional steady-state finite-element groundwater flow model to simulate groundwater flow in two Newfoundland blanket peat complexes and to examine flow system sensitivity to changes in water table recharge and aquifer properties. The modelling results were examined within the context of peat-forming processes in the two complexes. Modelled flow compared favourably with observed flow. The sensitivity analyses suggested that more highly decomposed bog peat along bog margins probably has/had a positive impact on net peat accumulation within bog interiors. Peat with lower hydraulic conductivity along bog margins effectively impedes lateral drainage, localizes water table drawdown to extreme bog margins, and elevates water tables along bog interiors. Peat formation and elevated water tables in adjacent poor fens/laggs currently rely on placic and ortstein horizons impeding vertical drainage and water flow inputs from adjacent bogs. Modest reductions in atmospheric recharge were found to govern bog-flow-system geometries in a way that would adversely affect paludification processes in adjacent fens/laggs. Copyright © 2004 John Wiley & Sons, Ltd. [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] Formation Mechanism of Maceral and Mineral Compositions of the "Barkinite" Liptobiolith from the Jinshan Mine, Anhui Province, ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2010Yuzhuang SUN Abstract: In order to study the accumulation mechanism of "barkinite", eight Late Permian channel benches (approximately 15-cm across and 10-cm deep) were taken from the Jinshan Mine, Anhui Province, China. The samples were analyzed by microscopical and geochemical methods. The microscopical observations indicate that the occurrence modes of "barkinite" in this area are different from those in other areas of China. The ratios of structureless "barkinite" are much higher in the Jinshan Mine, probably due to the flow-water and marine influenced environments. Furthermore, vitrinite macerals also show a strong fluorescence. The vitrinite fluorescence characteristics have not been observed in the Permian "barkinite" coals from northern China. The composition and variation of minerals in the column section also showed that the swamps in the study area were seriously influenced by seawater in the early and late stage during the peat accumulation. [source] Holocene peat growth and decay dynamics in sub-arctic peat plateaus, west-central CanadaBOREAS, Issue 1 2009A. BRITTA K. SANNEL Peat and net carbon accumulation rates in two sub-arctic peat plateaus of west-central Canada have been studied through geochemical analyses and accelerator mass spectrometry (AMS) radiocarbon dating. The peatland sites started to develop around 6600,5900 cal. yr BP and the peat plateau stages are characterized by Sphagnum fuscum peat alternating with rootlet layers. The long-term peat and net carbon accumulation rates for both profiles are 0.30,0.31 mm/yr and 12.5,12.7 gC/m2yr, respectively. These values reflect very slow peat accumulation (0.04,0.09 mm/yr) and net carbon accumulation (3.7,5.2 gC/m2yr) in the top rootlet layers. Extensive AMS radiocarbon dating of one profile shows that accumulation rates are variable depending on peat plateau stage. Peat accumulation rates are up to six times higher and net carbon accumulation rates up to four times higher in S. fuscum than in rootlet stages. Local fires represented by charcoal remains in some of the rootlet layers result in very low accumulation rates. High C/N ratios throughout most of the peat profiles suggest low degrees of decomposition due to stable permafrost conditions. Hence, original peat accretion has remained largely unaltered, except in the initial stages of peatland development when permafrost was not yet present. [source] | ||||||||||