Introduction – New Zealand’s dryland environments
Dryland tussock country, Mesopotamia Station. Image - Andrea Byrom.
New Zealand’s dryland zone is located in the rain shadow east of the main mountain ranges and includes parts of the East Coast, Hawke’s Bay, Wellington, Nelson-Marlborough, Canterbury, Otago, and Southland (Fig.). Drylands cover 19% of New Zealand’s land area and contain some of the least protected and most threatened native ecosystems and species. They have undergone tremendous modification and change in land use in the past century with a historical emphasis on pastoralism, but more recently on cropping, viticulture, horticulture, dairying, forestry, and lifestyle blocks. Dryland environments contain about half of New Zealand’s most threatened plant species, with more than 70% of such habitat lost and only 3% legally protected.
However, significant barriers exist to achieving conservation gains in many dryland areas due to low public awareness and appreciation of the indigenous fauna and flora there, the threats they face, their generally poor ecological condition, and their potential for recovery. New Zealanders are more familiar with conservation issues centred on large birds in forest ecosystems than those in dry non-forest ecosystems. Hence, there are relatively few community-led conservation initiatives in drylands where the focus is on less ‘charismatic’ species (e.g. lizards and invertebrates) and communities (e.g. mixed indigenous–exotic shrublands commonly regarded as a nuisance by pastoralists). As a consequence, little indigenous biodiversity remains, restoration examples are few, and advocacy and protection activities have instead been focused on more intact, usually wetter and higher elevation ecosystems.
In recent years, public and agency awareness of the values of drylands has been raised by Crown Land reform, and resulted in the return of some leasehold high-country land to public ownership and management by the Department of Conservation. These values include those of amenity, biodiversity, and potential for carbon sequestration and soil and water conservation. With this growing awareness has come a raft of opinions about how DOC should manage this newly acquired land. Now more than ever, evidence-based science has a role to play in informing policy and management in dryland environments.
Landcare Research, together with a number of agencies, has been investigating how dryland ecosystems function and how they can be restored. This issue of Kararehe Kino highlights some of the recent vertebrate pest research in drylands, from gaining a greater understanding of exotic grazers on recently retired Crown land, modelling interactions among invasive mammal species, understanding the processes of germination and survival of threatened native plants, quantifying invasive mammal impacts on native biota, and predicting the outcomes of shrub succession for both native and introduced species. The common theme is a systems-based approach to the management of one of New Zealand’s most precious ecosystems.
