School of Geography - Theses
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ItemThe geomorphology of pool and channel features in mires Mt Field National Park, Tasmania( 2016)This thesis explores the spatial distribution of peatlands (mires) at Mt Field, Tasmania, and the origins of surface water features contained within those mires. Whilst there are numerous studies of fine-scale biological, hydrological and chemical processes in mires, there have been few studies of the large-scale geomorphological processes affecting the spatial distribution of mires. Peatlands within the study area were traced based on aerial photography, and the entire study area was divided into a series of 50 x 50 m cells designated as mire or non-mire. The spatial distribution of mires was examined by comparing the slope and catchment area of mire and non-mire cells. Mires at Mt Field are generally topogenous, occurring on low slope areas where moisture is retained for longer periods, and in larger catchments which have an abundant and more continuous supply of moisture. These findings are consistent with previous studies internationally regarding the conditions favourable for the accumulation of peat, but this is only the second study to rigorously relate the distribution of mires to the landscape-scale, allogenic driving processes. At Mt Field, mires also occur on steeper slopes and at drainage divides, which indicates that unfavourable conditions in one respect (e.g. slope, catchment area) do not preclude the accumulation of peat in a local area. This supports previous studies which have proposed that no single factor determines the distribution of mires, but rather, it is determined by a complex interaction between topography and hydrology. However, slope is generally the dominant control, as mire and non-mire areas are usually separated on the basis of slope. The relationships between pool size, vascular vegetation, and algae were assessed in a pool complex at Lone Pine Moor, Mt Field. There is strong evidence that the pools have been formed by a set of interactions between hydrological, biological and chemical factors, which are known in concert as flark processes. These are responsible for similar pool morphologies in mires on other continents. This study is the first to establish that these processes are operating in Tasmania, or Australia in general. The processes which have contributed to the development of a chain of pools at Lone Pine Moor were assessed by exploring morphological, sedimentological and biological characteristics of the pools and intervening strips of dry land. It is likely that the chain of pools at Mt Field have been formed by a similar set of processes to those previously proposed to have formed string fens and pool-streams in upland Tasmania, whereby vegetation invades small streams over rocky substrates. The chain of pools is likely to be partly inherited from a periglacial landform composed of openwork block debris with a stepped surface, which has become filled with fine sediment and peat, and invaded by vegetation along transverse ridges. Only one other similar morphology has been studied in mires internationally (Otago, NZ), and the chain of pools at Mt Field is the only set of pools found in mires whose linearity is not maintained by valley confinement. Based on analysis of pool complexes and chains of pools at Mt Field, as well as surface water features in mires studied in Tasmania and internationally, it appears that the significant geodiversity of these features is attributed to interaction between a number of different of biotic and abiotic processes acting over long periods of time, some intermittently. Mt Field region of Tasmania offers abundant opportunities to investigate interactions between plants and geomorphology.