Holocene fire regimes reconstructed from peat core charcoal analysis, in the South Island, New Zealand.
Thesis DisciplineEnvironmental Sciences
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
This study investigates the role that climate and human intervention, have on local and regional fire regimes on the East Coast of the South Island, New Zealand during the second half of the Holocene. Continuous sampling of peat cores, from Travis Swamp, Halls Bush, Glendhu and Pomahaka, at one centimetre intervals allowed the detection of temporal and spatial differences in charcoal abundance. A set of nested sieves, with a mesh sizes of 250 μm, 125 μm and 63 μm, a digital camera, and image analysis software were successfully used to indicate charcoal abundance. Fire regimes prior to human arrival were controlled by fuel moisture levels and restricted by climatic influences on the lack of a suitable ignition source, resulting in significantly higher levels of fire activity in the Otago region compared with Canterbury. Regional fire activities changed over time due to changes in precipitation or evaporative rates. Polynesian exploration of the South island on arrival was rapid, resulting in a sudden increase in the frequency of fire simultaneously throughout the East Coast, approximately 700 years b.p. Deforestation in the Otago region was rapid and complete, due to low moisture levels, compared with a slower more gradual process of forest loss at the Canterbury sites. European settlement resulted in intensive burning associated with to farming practices, throughout the East coast. This change in fire regime resulted in the further deforestation of forest in the Canterbury region. After deforestation had occurred, fire became restricted due to lack of sufficient fuel continuity in the drier areas. Critique of the methodology indicates the most suitable of sieves to utilise in future studies is the one with the 250 μm mesh size. As there is superior accuracy and there is significantly shorter time needed for analysis.