Thesis
A study of palaeo-landscapes in the Numundo Region of West New Britain, Papua New Guinea, as indicated by fossil phytolith analysis
Southern Cross University, School of Environmental Science and Management
Doctor of Philosophy (PhD), Southern Cross University
2003
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Abstract
This thesis uses fossil phytoliths for the interpretation of the vegetation history of Holocene sediments from the Numundo Palm Oil Plantation, in the Willaumez Peninsula of West New Britain, Papua New Guinea. The aims of this Ph.D. research were to: (1) establish methodologies for identifying and interpreting spatial and temporal changes in the palaeo landscapes at Numundo; (2) describe the prehistoric landscapes represented within the Holocene palaeosols; (3) define the types of changes that occur in vegetation over time; and (4) identify the vectors responsible for such changes - in particular the differentiation of human impact versus volcanic eruptions. The results of this study indicate that the microwave digestion techniques of phytolith extraction and the digital analyses used in this study are successful and highly transferable across research applications and disciplines.
Distinct changes have been identified in the palaeolandscapes at Numundo. For the period dating from between the W-Kl volcanic eruption (c. 5,900 BP) and the W-K2 volcanic (c.3,600 BP), the results suggest that all the sites in the study area were within close proximity to the coast, and all show varying evidence of disturbance. In the lower sediment samples, this disturbance is probably due to the earlier W-Kl volcanic eruption at c. 5,900 BP. In the upper samples, however, the increased presence of artefacts and continued evidence for burning and the presence of open vegetation types are more consistent with human activity. For the period the W-K2 eruption (c. 3,600 BP) and the W-K3 eruption (c. 1,700 BP), the true forest phytolith types representing regrowth from natural disturbance found in early post W-Kl soils are completely absent. However, many of the phytolith types found in the later pre W-K2 landscape that are considered to indicate likely anthropogenic disturbances and more open environments, are persistent throughout the post-W-K2 eruption period. In the absence of an available seed bank, natural revegetation of the Numundo landscape following the W-K2 eruption was probably slow in comparison to that indicated for the post-W-Kl eruption. However, once the post-W-K2 eruption regeneration of vegetation began to take place, it appears that human presence - albeit on a scattered and locale-specific basis – dominated vegetation development. Moreover, it is likely that the strong presence of charred particles commencing in the lower most samples and persisting throughout the W-K2 palaeosol sequences reflects an ongoing human presence from shortly after the W-K2 eruption and continuing throughout the period between W-K2 and W-K3. Throughout this period the landscape was characteristically a mosaic of regenerating, disturbed and managed vegetation.
The nature of landscape and anthropogenic recovery following the two eruptions, WK3 and W-K4, appears to be completely different. For the most part, this difference is interpreted as resulting from the severity of impact and length of hiatus between eruptions. It is clear, from the percentage of volcanic glass present in the W-K3 horizon, that soil development had not been well established before being sealed in the W-K4 eruption tephra some 300 years later. Although there is some evidence for anthropogenic activity across the landscape, as Torrence (2002) suggests, the low incidence of cultural evidence following the W-K3 eruption indicates that its severity may have been close to that of the W-K2 eruption. The current study supports Torrence's (2002) observation of low levels of cultural evidence, in that most of the W-K3 samples are dominated by phytolith types that are more consistent with natural disturbance (in both the lower and upper levels) rather than anthropogenic disturbance. Alternatively the landscapes represented by the lower and upper samples of the post-W-K4 eruption are interpreted as predominantly associated with anthropogenic disturbance. Thinner tephra deposits and low levels of volcanic glass above the tephra-soil-development interface indicate that the impact of the WK4 eruption was not as severe as the previous W-K3 eruption. The low impact and 900 year hiatus before the next volcanic event helped shape the post-W-K4 landscape quite differently to that following the W-K3 eruption. Dark soils, rich in organic matter, are uniform throughout the W-K4 palaeosols and thus testify to a rapid vegetation recovery and, especially, anthropogenic exploitation of the landscape. The W-K4 horizon landscapes have some similarities to the post-W-K2 eruption period in that there is a high level of inter-site variability, and thus the WK4 landscape is characterised as comprised of a mosaic of localised regenerating, disturbed and managed vegetation.
Details
- Title
- A study of palaeo-landscapes in the Numundo Region of West New Britain, Papua New Guinea, as indicated by fossil phytolith analysis
- Creators
- Jeff Parr
- Contributors
- Bill Edgar Boyd (Supervisor) - Southern Cross UniversityRobin Torrence (Supervisor)
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University, School of Environmental Science and Management
- Number of pages
- xvi, 237
- Identifiers
- 991012957299502368
- Copyright
- © Jeff Parr 2003
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis