A study of human impact on an urban forest remnant: Redwood Bush, Tawa, near Wellington, New Zealand

Abstract

The impact of recent human activity on a 9.3 ha stand of mature lowland kohekohe (Dysoxylum spectabile}-tawa (Beilschmiedia tawa) dicotylous forest was studied, with particular attention to damage resulting from recreational use. Urban development that created new forest margins was found to initiate further receding of the margins and subsequently the growth of a protective lateral canopy. This marginal adjustment appeared to be leading to almost complete loss of the canopy trees in small outlier stands which were left in the midst of residential areas. The main stand was found to be critically small for the maintenance of species diversity, recent and proposed marginal development of the forest being associated with the extinction of several species. Damage to the stand from trampling was recorded, but most significant was that caused by children playing in the forest—cutting, felling, and otherwise injuring trees. This destructive activity was concluded to be altering rapidly the stand structure and the population densities of its dominant species—leading to the replacement of tawa by kohekohe and to a rejuvenation of the forest canopy. The stumps of many felled tawa and kohekohe trees survived, with the development of coppice shoots, but a greater proportion of tawa than kohekohe died as a result of felling. Coppicing apparently was not associated with either the stump height or the species-specific number of stems per plant. The implications of these results to the management of this and similar stands are discussed.