A garden at the edge of the world; the diversity and conservation status of the New Zealand flora

Abstract

Summary After drifting away from Gondawana, the land that we presently know as New Zealand went through several geological events such as the Oligocene drowning, the upheaval of the Southern Alps and several glacial–interglacial periods. These events have dramatically shaped New Zealand’s flora and fauna, causing the extinction of some lineages but also promoting speciation and ecological diversification in others. Nowadays, the New Zealand vascular flora includes over 2230 species; most of them endemic ( c . 80%). Despite being one of the last places on the world to be reached by people, damage to its native flora and fauna has been significant. Currently, over 38% of the native vascular flora is of conservation concern and six species became extinct. The main threats to New Zealand plants are habitat destruction, herbivory, competition from weeds and the disruption of ecological interactions. Birds are important pollinators and seed dispersers in New Zealand so a decline in their number, caused by the introduction of mammalian predators, has severely damaged plant–bird interactions and the effects of reproduction and dispersal failure are already being noticed. The spread of introduced plant pathogens is also a threat to native plants and their effect on native trees, in particular, is a matter of current concern. Preservation of New Zealand’s flora is a matter of national and international relevance and many initiatives are working towards this goal. Examples include: habitat protection and restoration, conservation by cultivation, and establishment of seed banks. Future research, however, should focus on the autoecology of threatened plants, particularly in those species that depend on mutualistic interactions. This research will help to maximise resources allocated to their conservation and secure their survival and functioning in the long term. Origin of New Zealand flora