Ecological interaction between introduced and indigenous plant species in the Manawatu District

[First paragraph...]
As a result of the invasion of New Zealand by people of European origin, and by the plants and animals that they introduced, much of the plant covering of the country now consists of mixtures of native and exotic species. Smith (1957) has stated that the study of this mixed vegetation, while most of the steps in the amalgamation processes are still discernible and interpretable, is one of the most fascinating and most urgent tasks of New Zealand botanists. However, only a few workers appear to have given special attention to the subject, although the contributions of those few, notably Levy (1923), Guthrie-Smith (1926), Cockayne et al.(1932), and Allan (1936), are of the greatest importance. In the hope of supplementing the existing contributions, the writer has made an ecological survey of the vegetation of the Manawatu district, with emphasis on the interaction of introduced and indigenous species. The results are embodied in an unpublished thesis (Carnahan 1957), on which the present paper is based.