Management strategies for the riparian zones of the Manganuioteao River

Abstract

The Manganuioteao River is the last unmodified river in the central North Island, and is protected against development by a National Water Conservation Order. As a result of the Department of Conservation's concern for the apparent deterioration of Manganuioteao River riparian zone vegetation, this thesis presents a basis for riparian zone management.

The research is composed of two studies; a riparian zone grazing exclusion study and an examination of the meanings managers ascribe to the Manganuioteao River. The grazing exclusion study has two objectives. The first objective is to illustrate the change to native vegetation once stock is excluded. The second objective is to predict a 10 year scenario for indigenous riparian zone vegetation once stock is excluded. Results illustrate that after 11 months of stock exclusion many new tree seedlings appear in the groundcover, and many existing species increase in number. It is predicted that a longer period of stock exclusion from riparian zones will benefit both mature and re-establishing native riparian zone vegetation.

The second study uses a naturalistic research to focus on the managers themselves, exploring the meanings they ascribe to the Manganuioteao River. Meanings are determined by the ways in which managers interact with the river. Results indicate that conservation is a common management theme for both the formal managers (Department of Conservation, Ruapehu District Council) and the informal managers (e.g. adjacent landowners, Rotary Club). Interaction between management groups is also important for the continuing conservation of the Manganuioteao River.

The management strategies presented focus on determining a suitable agricultural and recreational carrying capacity for riparian zone vegetation. The grazing exclusion experiment illustrates that agriculture has caused considerable damage to indigenous riparian vegetation. Agricultural activity on riparian zones, therefore, needs to be curtailed, particularly on riparian zones clothed in native forest, unmodified except for the changes caused through domestic stock grazing. It is possible, however, to continue grazing on the more heavily modified riparian zones.

More information will be required on the user needs and wants to successfully determine recreational carrying capacity. To allow for an increase in the number of visitors to the river, while at the same time providing a "wilderness experience", management should increase the river's physical carrying capacity. This can be expanded by providing more interpretation and by guiding the visitor to areas where carrying capacity is greater. Visitors' perceptions of crowding should also be evaluated by the managers as an aid to maintaining the wilderness environment.