succession

Relationships between composition of secondary vegetation and environment were studied in central North Island, New Zealand. A classification procedure was used to identify broad compositional groups which included forest, broadleaved scrub, shrub-fernland, sclerophyllous scrub and shrubland, and tussock-shrubland. Generalised additive models (GAMs) were used to examine relationships between species' distributions and mean annual temperature and rainfall, stand age, distance from intact forest, slope, topography, and drainage.

The relationship between fleshy-fruited indigenous species and adventive weeds in the diet of 500 mist-netted birds was studied in forest remnants of differing size and degree of modification. Fruit abundance Peaked in March and April, and most fruit was either red/orange or purple/black. The physical parameters of adventive and indigenous fruits were not significantly different. Six of the 15 passerine species netted are frugivores, and of those netted 77% had eaten fruit.

Exclosure plots established in three separate areas of kanuka (Kunzea ericoides var. ericoides) forest on south Kaipara spit in 1983 to assess the impact of introduced fallow deer (Dama dama) were remeasured in 1993. Kanuka shared canopy dominance with mapou (Myrsine australis), houpara (Pseudopanax lessonii) and mahoe (Melicytus ramiflorus ssp. ramiflorus) in relatively old forest in Lookout Bush, Woodhill, and dominated exclusively in two younger stands at South Head; Coprosma rhamnoides dominated understories throughout.

This paper reviews current knowledge of dynamic processes in New Zealand land-water ecotones drawing on published quantitative data wherever possible. Basic ecosystem processes in forested and natural unforested land-water ecotones are compared, and dynamic processes are discussed under the following headings: time scales of change; water movement; sediment trapping and transport; dissolved nutrient dynamics; dissolved oxygen; trophic interactions.

Volcanic activity has damaged or destroyed at least 20,000 has of indigenous vegetation in the North Island in the last 450 years. The primary and secondary successions initiated are discussed and considered in relation to some recently proposed models of succession. Most of the variation relates to the scale and intensity of disturbance, and the type and heterogeneity of the substrate emplaced.

The impact of discharging an oxidation pond effluent into a wetland in the Waitangi Forest (Northland) was assessed by comparing the water, soil, and vegetation of this wetland (the sewage wetland) with that of an adjacent wetland not receiving effluent (the reference wetland). The hydroperiod of the two wetlands differs markedly with the sewage wetland now permanently flooded whereas the reference wetland is subject to summer drawdown. Marked differences were found in gross chemical indicators such as pH and redox potential between the soils of the 2 wetlands.

Seedlings of fifteen species of shrubs and small trees, commonly found in open sites and early stages of secondary succession, were grown in a glasshouse under light intensities of 16% and 66% full daylight, and their growth parameters (height, number of leaves, dry weight, mean relative growth rate) recorded. Three species from open habitats, Coprosma robusta and Dodonaea viscosa, and an adventive shrub, Crataegus monogyna, had the highest mean relative growth rates in 66% daylight and 16% daylight, but their ranking for other parameters (e.g. height) was variable.

Forty years since the cessation of grazing on Tiritiri Matangi, the island has been transformed by a restoration programme. However, a big question remained: What the island would have looked like if restoration had not occurred? This study addresses that question. Some sections of the island were deliberately not restored and allowed to regenerate naturally to provide a reference point for the changes brought about by direct intervention. In one area a transect of plots was available in which species composition and frequency information had been measured in a pre-restoration state.

Restoration of native forest vegetation in urban environments may be limited due to isolation from native seed sources and to the prevalence of exotic plant species. To investigate urban seed availability we recorded the composition of seed rain, soil seed banks and vegetation at native forest restoration plantings up to 36 years old in Hamilton City and compared these with naturally regenerating forest within the city and in a nearby rural native forest remnant.

Invasive mammalian herbivores (e.g. deer, feral goats and brushtail possums; hereafter ‘herbivores’) are widespread throughout New Zealand and their control is important for conservation. In addition to known biodiversity benefits, it has recently been suggested that herbivore control could lead to measureable carbon gains when aggregated across a large area of conservation land. However, a significant amount of uncertainty exists regarding the potential effects of herbivore control on carbon, and the practicalities of successfully implementing such projects.