Human settlement and landscape change on Rarotonga, southern Cook Islands

Abstract

This thesis seeks to examine certain aspects of those changes which occurred in the land scape of Rarotonga during the period it has been occupied by humans. Because the exact date of human arrival is as yet uncertain, part of the problem has been to try to establish this b y attempting to detect initial human interference with the landscape, in particular the vegetation. A number of different approaches have been used in the investigation of these problems: swamp deposits were analysed by stratigraphic and palynological studies. Modern vegetation surveys and modern pollen rain studies provided a statement of the present landscape and comparisons for the fossil data and ethnographic and historical sources contributed information about the last two hundred years , and generated ideas and models for earlier periods and helped establish control over any changes to the landscape that were of more recent origin. Finally, archaeological evidence and oral tradition, where available , establish as far as possible what changes may have occurred in landscape usage and manipulation from first settlement to European contact. In addition, from late 1992, a series of techniques were brought to bear on the swamp sediments, in order to clarify questions raised by the pollen evidence. These include X-ray analysis , chemical analysis and particle-size analysis. The early Holocene rising sea-level could have caused lake formation at Karekare before 8137 BP. Accruing sediment and local hydrology reduced the depth of the lake, consequently forming a marsh , though other factors may also have been in volved . Falling sea-level could have been a vital factor too . With the formation of a marsh from 4 ,500 BP , there followed what is interpreted as a hydrosere beginning with swamp ferns , then some swamp forest, finally being replaced by drier elements after 3000 BP . Factors such as truncation, shrinkage and compaction due to cultivation and drainage by colonizing people between 2700 and 800 BP brought the sequence to an end. A four phase model based on biogeographic theories is proposed for landscape change on Rarotonga, starting with the island before humans arrived, then with the first Polynesian settlement and later developments therefrom (up to European contact), then the arrival of Europeans and finally the late twentieth century . Wider implications for Pacific Islands emerging from this thesis are discussed under the following headings : extinction, problems with other sites , plant distribution history , sea-level change and climatic change, dating of human arrival and the influence of the environment on settlement history. It could well be that whilst some extinctions are related to initial colonization of islands and later expansion therefrom, others may be associated with the economic, religious and social changes brought about by missionaries, merchants and colonial authorities . It is suggested here that whilst early Polynesian settlers no doubt altered their landscapes, it is not necessary to invoke quite as much alteration by them as is sometimes inferred . It is proposed that early Polynesian colonists adapted their economy to the landscape and did not attempt to impose a totally alien system on the local ecology of newly settled islands. Some plant were discovered to have existed on Rarotonga before humans arrived , others formerly had different distributions than today. Living memory, oral tradition (see Chapter 6) and missionary records show that breadfruit trees and plantains were grown in the lower-lying areas because they are better adapted to the warmer , drier conditions, whilst the taro and mountain plantains were grown further up the valleys, where reliable all-the-year-around supplies of freshwater were available...