rarity

We describe spatial patterns in the geographic ranges of all New Zealand ferns and lycophytes, test if range sizes are correlated with phylogeny, and identify ecological characteristics related to their range sizes. Herbarium records for all species of fern and lycophyte in New Zealand were used to generate distribution maps and estimate range sizes by summing the area of occupied ecological districts. Trait, habitat, biostatus, and distribution data were compiled from the literature and DNA sequence data were obtained for each species.

The Kean–Barlow model predicts how the equilibrium distribution and abundance of a population may be affected by local rates of increase, dispersal, colonisation, and extinction. Here, the model is parameterised for three insects: the Glanville fritillary Melitaea cinxia in Åland, Finland, the ribbonwood aphid Paradoxaphis plagianthi in Christchurch, New Zealand, and the coxella weevil Hadramphus spinipennis in the Chatham Islands, New Zealand. The model was modified for the weevil to accommodate its unusual habit of overexploiting local resources.

We examined the threat status of the low tree Pittosporum patulum throughout its range in eastern South Island, based on plot-based sampling of habitat, defoliation by mammalian herbivores, demographic and dieback characteristics. Using environmental modelling (Land Environments of New Zealand), we found no explanation for the ‘gap’ in its disjunct distribution from Nelson–Marlborough–north Canterbury to south Canterbury as a component of upper montane Nothofagus forest and non-Nothofagus subalpine scrub.

The rapid decline in bumblebee populations within Europe has been linked to habitat loss through agricultural intensification, and a consequential reduction in the availability of preferred forage plants. The successful introduction of four European Bombus species to the South Island of New Zealand from England (in 1885 and 1906) provides an opportunity to determine how important different forage plants (also introduced from the U.K.) are to two severely threatened European bumblebee species (Bombus ruderatus and B. subterraneus).

In the first quantitative study of an endemic New Zealand aphid, the only known field populations of the rare Paradoxaphis plagianthiwere monitored for two years from 1999 to 2001. The species appears to be anholocyclic, persisting viviparously throughout the year on its deciduous host tree, the lowland ribbonwood (Plagianthus regius). Local aphid abundance increased rapidly in spring as new leaves appeared, but collapsed abruptly in November, probably due to dispersal and a decline in resource quality.

Terrestrial ecosystems that were rare before human colonisation of New Zealand often have highly specialised and diverse flora and fauna characterised by endemic and nationally rare species. Although many of these ecosystems are under threat from anthropogenic modification and their biodiversity values are declining, they still are not adequately identified by current land classifications. We compiled a list of 72 rare ecosystems from the literature and by canvassing New Zealand ecologists and land managers. Rare ecosystems are defined as those having a total extent less than 0.5% (i.e.