Abstract:
This thesis provides the first look at the late Holocene plant assemblages and fire regimes on D’Urville Island. D’Urville has a rich human history in large part because its abundance of metamorphosed indurated mudstone, provided an excellent lithic resource for tool building and subsequent trade for Polynesian settlers. The island would have also offered abundant food resources and easy access to sheltered bays for fishing. I analysed pollen, charcoal and magnetic susceptibility from three different locations. The result was a 2200 year record that begins c. 1550 years before human arrival, and spans around 650 years of human settlement. The prehuman vegetation was a heterogeneous mosaic of beech-podocarp forest with a broadleaf sub-canopy and diverse shrub and small tree layer; a ground layer of ferns was also common. Coastal locations and those surrounding lakes and wetlands would have been abundant in Rhopalostylis and Dysoxylum forest. Previous work places human settlement of D’Urville Island at 1500 AD (albeit with a substantial potential error range). This research offers a more refined and earlier date of around c. 1300 AD. The first wave of Polynesian settlement brought with it transformations to the vegetation assemblages synonymous with previous paleoecological studies throughout New Zealand, namely the substantial loss of forest cover and increases in bracken and grass abundance. Fire would have been a major contributor to this transformation and charcoal is common in the record during both Polynesian and European settlement waves. With European settlement a decline in charcoal accumulation occurs, but there is no recovery of native forest. During this European period exotic plant species appear and subsequently spread across the landscape. Of primary concern is the invasion of Pinus into sensitive ultramafic communities. Opportunities for restoration are plentiful given the possum-free status of the island and community engagement in conservation. D’Urville Island has retained patches of remnant forest, and these provide excellent opportunities for both conservation, and as seed sources to aid in the recovery of degraded areas. The paleo records developed and evaluated here will help to better inform future restoration decisions and provide important prehuman vegetation baselines for D’Urville Island.