Fire-patterned vegetation and the development of organic soils in the lowland vegetation mosaics of south-west Tasmania
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Date
2011-03-28
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CSIRO Publishing
Abstract
Two contrasting ecological models have been proposed for the forest-moorland vegetation mosaics of southwest Tasmania that stress different interactions between fire, soils, vegetation and the physical environment to produce either stable or dynamic vegetation patterns. We investigated aspects of these models by sampling organic soil profiles across vegetation mosaics to determine variation in soil depth, organic carbon (C) content, nutrient capital, stable C isotope composition (delta(13)C) and (14)C radiocarbon age in two contrasting landscape settings. (14)C basal ages of organic soils ranged from recent (<400 calibrated (cal.) years BP) to mid Holocene (similar to 7200 cal. years BP), with a tendency for older soils to be from poorly drained moorlands and younger soils from the forest. The long-term net rate of C accumulation ranged from 2.7 to 19.2 gCm(-2) year(-1), which is low compared with northern hemisphere peatland systems. We found that delta(13)C in organic soil profiles cannot be used to infer Holocene vegetation boundary dynamics in these systems. We found a systematic decrease of phosphorus from rainforest through eucalypt to moorland, but estimated that phosphorus capital in moorland soils was still sufficient for the development of forest vegetation. Our results suggest that the characteristics of organic soils across the landscape are the result of interactions between not only vegetation and fire frequency, but also other factors such as drainage and topography. © 2011, CSIRO Publishing
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Keywords
Fires, Plants, Soils, Isotope ratio, Carbon 14, Wetlands
Citation
Wood, S.W., Hua, Q., Bowman, D.M.J.S. (2011). Fire-patterned vegetation and the development of organic soils in the lowland vegetation mosaics of south-west Tasmania. Australian Journal of Botany, 59(2), 126-136. doi:10.1071/BT10309