disturbance

Recruitment failure of native plants is common in dryland ecosystems in New Zealand. We investigated whether herbicide control of invasive grasses or restoration of either shrub cover or the natural disturbance regime (river gravel deposition after flooding) can promote seedling establishment of the critically endangered shrub Olearia adenocarpa and two common species also found in river floodplain ecosystems (Carmichaelia australis and Sophora microphylla).

The area of indigenous vegetation and habitat remaining on New Zealand’s primary agricultural lands continues to decrease, but it has been difficult to obtain reliable estimates of the extent and causes of loss. We assess change and identify predictors of vegetation clearance in 856 recommended areas for protection (RAPs) from 35 ecological districts in the North and South Islands, New Zealand, for the period 1989 to 2015. Over 27 years, 7152 ha of these RAPs were cleared (2.3% by area), with rates varying over space and time. Native

Fire, pastoral farming and exotic species have been major drivers of vegetation change in the eastern South Island high country since human arrival. More recently, fire frequency and grazing intensity have declined allowing regeneration of previously suppressed woody elements in some areas, such as our 1775 ha Cass study site. We collected vegetation and abiotic data from 117 Recce plots (10 × 10 m) using an objective grid-based network to classify the vegetation, determine factors influencing vegetation pattern, discuss long-term vegetation changes and assess the role of exotic species.

The role of backcountry huts as focal points for weed establishment and spread into New Zealand’s national parks has received little attention. In this study we describe the pattern of weed spread around Takahe Valley Hut, Murchison Mountains, Fiordland National Park. Established in 1948, the hut is located at 900 m a.s.l. at the ecotone between Nothofagus forest and valley floor shrubland/grassland. We recorded the distribution of vascular plants in quadrats (110) placed by restricted randomisation around the hut, and measured relative irradiance and distance from the hut.

We describe the colonisation of artificially created gaps in an alpine grassland dominated by Chionochloa pallens. Twelve years after their creation, the 50 cm _ 50 cm gaps supported a distinctive vegetation composed of a mixture of perennial forbs, grasses and mosses. Three species (Bryum sp., Epilobium alsinoides and Plantago novae-zelandiae) were recorded only in the gaps.

This paper is a reflection on J.B. Wilson's (1990) publication which presents an attempt to understand the development of terrestrial plant communities of New Zealand against twelve different explanations of Hutchinson's Paradox. I make a rough comparison between terrestrial and planktonic communities; then I briefly review Hutchinson's Paradox and some of the later relevant phytoplankton results.