Abstract Detail

From High Islands to the Ocean Floor: Pacific Island Plants at the Extreme

Weeds at the extreme: infestations in early Māori cultivation systems of Southern Polynesia.

Polynesian cultivation systems prior to European colonisation in the late 18^th century are widely assumed to have endured little economic loss from weed infestations. Early but limited observations of cultivations such as those from the James Cook led expeditions between 1769-1777 led some scholars to maintain that Polynesians either had to contend with few weeds, or kept their cultivations cleared of weeds. Yet, many of the plant collections made during those initial expeditions were of species with weedy characteristics. There has been a long-standing debate on whether this was due to the lack of weeds in indigenous Pacific Island floras prior to European colonization. Alternatively, if indigenous weeds were present they did not markedly reduce production of target crops, or, Polynesians fastidiously tended cultivations, keeping them weed-free. However, the likelihood that many of these species were indigenous and instead flourished through soil tillage, regular burning or other disturbances such as soil erosion from heavy rains or floods. It has also been widely assumed that there is a lack of herbaceous plants with weedy characters in the indigenous floras of the remote Pacific Islands colonized by Polynesians, and that this may have limited the extent of weed infestations prior to the introduction of highly invasive weeds following European colonization in the early 19^th century. In Aotearoa, there are numerous indigenous herbaceous taxa that possess weedy traits, and some of these have become naturalised or invasive outside of their indigenous distribution (e.g. Cardamine corymbosa Hook.f., Geranium retrorsum group and Oxalis exilis A. Cunn.). Multiple lines of evidence accumulated from palaeobotanical and archaeobotanical studies, as well as herbarium specimens from 18^th and 19^th century botanical collections, coupled with phylogeographic and molecular data, now allow for the biostatus and probable economic impact of alien or native weedy plants to be more accurately determined. Here I examine the above sources to assess the biostatus of a group of mostly herbaceous plants that have been identified from archaeobotanical and other fossil contexts from the remote subtropical, temperate and sub-antarctic Pacific Islands, focusing on Aotearoa

1 - University of Canterbury, School of Earth and Environment, Beatrice Tinsley Building, University of Canterbury, Christchurch, New Zealand

Keywords:
weeds
Polynesia
Pacific islands
cultivation.

Presentation Type: Symposium Presentation
Number: S6007
Abstract ID:369
Candidate for Awards:None