Master of Tropical Environmental
Management
Research Projects
SBI550-551
Previous Project Proposals – a reference collection for intending students
This booklet contains a collection of project proposals prepared by previous candidates in the Master of Tropical Environmental Management.
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The distribution of fine and coarse roots in a semi-arid savanna of northern Australia.
by Michelle Allnutt
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4
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Temporal changes in Mimosa pigra seed bank following integrated control
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8
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Laboratory and field analysis of factors affecting larval settlementof the Topshell, Trochus niloticus
by Jamie Colquhoun
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11
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A critique of environmental management systems and their relevance in the north Australian pastoral industry
By Siobhan Denniss
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18
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Survival modelling of the northern brown bandicoot, Isoodon macrourus (Gould) from mark-recapture data using an information-theoretic approach
by Guy Pardon
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21
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Harvesting of Bombax ceiba for wood carvings in the Maningrida region: working towards a sustainable carving industry
by Annie Philips
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28
| by Kristen Skertchly
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33
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Territoriality and mating systems of the frillneck lizard Chlamydosaurus kingii (Agamidae).
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35
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CONTENTS (continued)
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Accounting for Indigenous Cultural Values in the Northern Territory Water Act
By Erin Leigh Aucoin-Wenkoff
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42
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Subsistence and potential for commerce: Indigenous harvest of mangrove clams in a remote community
By Johanna Karam
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45
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Survival of populations of the Arnhemland Cycad (Cycas arnhemica) under Experimental Harvest Regimes
By Julia Schult
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50
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MTEM Project Proposal
Student Name: Michelle Allnutt
Student Number: 110601
Supervisor: Dr L Hutley (NTU)
External Supervisor: Dr RJ Williams (CSIRO)
Project Title
The distribution of fine and coarse roots in a semi-arid savanna of northern Australia.
Aims and Objectives
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To determine the distribution patterns of roots in relation to soil depth and distance from trees of varying sizes.
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To determine the root to shoot ratio of sampled trees.
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To determine tree density of the savanna sampled.
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To use the root to shoot ratio, tree density and root distribution information to predict root biomass per hectare in the sampled savanna.
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To compare the above method of root density estimation (which considers tree density constant) with a more comprehensive method using scaling or zoning of root patterns with distance from tree stem.
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To produce a model on which underground biomass can be predicted using measurements (eg diameter at breast height and distance from tree) from the above-ground biomass.
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To compare the results of this study with those of studies conducted in other savannas in Australia and internationally.
Introduction
Tropical savannas cover 25% of Australia and have had many changes in land practices in recent years. All tropical savannas in Australia have a long dry season and the vegetation located there has various strategies that enables survival through the drought period (Brock 2001). It has been noted by several studies (Canadell et al. 1996; Vogt et al. 1996) that some trees (eg eucalypt species) have both shallow roots and deep tap roots which enables them to survive through the long dry seasons. Root distribution can therefore reflect patterns of water availability, and could help to show the health of the savanna as root systems affect the health of the tree and the soil structure. Understanding the distribution of roots in savannas will increase our understanding of the structure of savanna vegetation, and enable us to calculate root carbon stocks.
Roots are also a significant component of the subterranean carbon store, and root production contributes approximately half of the carbon being cycled annually in many forests (Vogt et al. 1996) and 25% of global NPP (Jackson et al. 1997). Therefore any assessment of carbon density, tree biomass and primary production require detailed information about below-ground biomass. This will enable us to discover how land-use may affect carbon pools.
It would be useful to produce a protocol for predicting root biomass. One potential way is to predict root biomass from tree stem density and tree stem size. If such a protocol for estimating root biomass can be developed from this study it will allow calculations of above-ground carbon stocks to be made with non-destructive methods that are less costly and less labour intensive than ones involving the removal of root samples from the area.
In the NT, savannas occur across a large rainfall gradient ranging from more than 200mm – 2000mm per yr (O’Grady et al. 2000). Recently a study of root distribution conducted in the wetter savannas of the Top End near Darwin has been completed (Eamus et al. 2002; O'Grady et al. 2000), but there has been no similar research on root distribution in semi-arid savannas, such as those around Katherine. It was assumed that root density is constant throughout the study site (ie there were no large gaps between trees where there would be no roots) in as the tree density was fairly high. However in the study site near Katherine, the tree density is likely to be less with longer distances between tree stems. It may not be correct to assume root biomass is constant throughout the area. A better method may be to calculate the relationship between root biomass and the distance from tree stem, and produce a more comprehensive zoning equation or model. The two root biomass estimation methods shall be examined in this study.
Implications for this research include developing a framework and capacity that enables site-level data to be scaled-up to provide regional estimates of biomass and biomass change (eg woody thickening) for subterranean components of woody vegetation. In addition, the research will be relevant to producing methods to understand how changes in land management practices such as clearing and fire management for tropical savannas might affect stocks of carbon. This study contributes towards bringing Australia up to the standard set by the Kyoto protocol, which requires an inventory of carbon stocks for major ecosystems.
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