Kauri are officially 'threatened'
Over a five yearly cycle the Department of Conservation hosts a panel of experts representing a range of skills and interest groups to undertake threat listings of New Zealand’s biota. Two week's ago the eighth conservation assessment of the New Zealand Vascular Flora was published as part of the New Zealand Threat Classification Series (Vol. 22). The new listing replaces the previous listing prepared in 2012 and published in 2013.
The situation for the New Zealand indigenous Flora is not good; 2502 taxa at the rank of species, and 283 taxonomically indeterminate and/or informally recognized ‘tag-named’ taxa were assessed. These figures represent the most accurate statement of the New Zealand Indigenous Vascular Flora currently available. Seven taxa are listed as ‘Extinct’ (one less than the 2012 listing), and 403 taxa are listed as ‘Threatened’ (114 more than in the previous listing). Sixty-one taxa have experienced severe documented declines since the last listing, 59 taxa now have worse conservation assessments, and another 77 have a worsening conservation status. These declines can be directly mapped to deteriorating water quality, the impact of dairy farming in the intermontane basins of the Eastern South Island, ongoing loss of habitat, and direct pressure from browsing animals and diseases.
In some cases, the cause of decline remains unclear. For example, the poroporo (Solanum aviculare var. aviculare) once abundant 30-40 years ago in the North Island is now in serious decline, such that it is either absent from or in sharp decline over large parts of its former range. Oddly, whilst it is in decline its close relative Solanum laciniatum is not, in some places actively spreading into habitat S. aviculare var. aviculare once occupied. Even stranger is that the offshore island race of S. aviculare, var. latifolium is also spreading in places where it has been planted on the mainland. Research as to why this happening is urgently needed.
In the case of kauri (Agathis australis) the cause of decline is now well known, and for the first time this iconic conifer has been listed as ‘Nationally Vulnerable’ reflecting the impact of the killer disease (Phytophthora agathidicida), a listing made possible because a predicted decline rate and a national population estimate for kauri now exists. Less certain has been the call to list all of New Zealand’s indigenous myrtles (Myrtaceae) as ‘Declining’ or ‘Threatened’ – a precautionary decision taken by the panel on the basis of the arrival of myrtle rust (Austropuccinia psidii), and concern over impact this rust may have / is already having on our Myrtaceae. Advice from Australian myrtle rust experts was used to arrive at this conclusion, and though myrtle rust is still in the early stages of establishment in New Zealand, already – as predicted – we are seeing an impact on the endemic myrtle genus Lophomyrtus and the maire tawake (Syzygium maire), though so far mostly on cultivated plants or those growing in forest remnants in urban areas.
The panel acknowledges that the high listing for the Myrtaceae may be inaccurate – and they are only too happy to be proved wrong. The decision to take this step however, accords with the precautionary principle advocated by the New Zealand Threat Classification System, and the stance already being taken by Ministry of Primary Industries and Department of Conservation. Both agencies have been trying to obtain seed and germ-plasm of New Zealand myrtles in the full expectation that some of these iconic trees and shrubs are going to go extinct whilst the rest are probably going to get very sick. With no cure in sight this is a potential disaster for New Zealand’s coast to montane vegetated ecosystems.
A copy of the list is available free here