Cyathea medullaris (Cyatheaceae) is a frequent pioneer of disturbed areas (e.g. landslides) or edge environments, sometimes forming near continuous canopies. We test the hypothesis that colonisation by this species as a pioneer alters the seedling assemblage to favour more shade-tolerant broadleaved trees than that beneath another common native pioneer (Kunzea robusta, Myrtaceae) in the same landscapes. We compared vegetation and abiotic characteristics of 166 sites across the Auckland region where C. medullaris or K.
Mid to late 20th century expansion of Dracophyllum scrub into tussock grassland on subantarctic Campbell Island has been attributed to the collective effects of global warming, cessation of farming in 1931, and continued grazing by feral sheep. To determine the importance of these, we dated the timing of scrub expansion by aging 241 Dracophyllum plants in 17 plots chosen to sample the range of environments this shrub/ small tree occupies on Campbell Island.
New Zealand bracken (Pteridium esculentum) belongs to a group of closely related fern species of near global extent. Pteridium species worldwide are aggressive, highly productive, seral plants, functionally more akin to shrubs than ferns. Their deeply buried starch-rich rhizomes allow them to survive repeated fire and their efficient nutrient uptake permits exploitation of a wide range of soils. They are limited by cool annual temperatures, frost, wind, and shallow, poorly drained and acidic soils.
Fire occurs relatively frequently in beech (Nothofagus) forest in drought prone eastern areas of the South Island, New Zealand. Because beech is poorly adapted to fire, and is slow to regenerate, forest is normally replaced by scrub or grassland. Seeding was investigated as a means of restoring mountain beech (N. solandri var. cliffortioides) forest after fire destroyed 300 ha of forest at Mt. Thomas, Canterbury, in 1980.
Immediately before human settlement, dense tall podocarp- angiosperm forest dominated the moist Southland and southern coastal Otago districts. Open, discontinuous podocarp-angiosperm forest bordered the central Otago dry interior, extending along the north Otago coast. Grassland was mostly patchy within these woody ecosystems, occurring on limited areas of droughty or low-nutrient soils and wetlands, or temporarily after infrequent fire or other disturbance.
The intermediate disturbance hypothesis has been the focus of considerable analysis in terrestrial and aquatic systems. This model predicts that species diversity will be highest at intermediate frequencies of disturbance. Despite numerous theoretical and empirical analyses, the utility of the model is still the subject of intense debate.
Soil conditions, vegetation features and soil fauna were recorded in montane tall tussock grassland dominated by narrow- leaved snow tussock Chionochloa rigida ssp. rigida up to 30 months after a spring fire. Burning reduced the stature of tussocks and the size and density of tillers in the first growing season. After two growing seasons, tussock canopy development and tiller size remained below those found in the unburnt grassland nearby. New tillers and tussocks established following the prolific fire-induced flowering one year after burning.
Fire has been an important management tool in the pastoral use of New Zealand tussock grasslands. The effects of a farm-scale pastoral fire and subsequent grazing by sheep on soil biochemical properties in tussock grasslands dominated by the narrow-leaved snow tussock (Chionochloa rigida ssp. rigida) were investigated, 1.5 and 2.5 years after the fire event, in 0-2 cm depth mineral soil at a site at 975 m altitude in Central Otago, New Zealand. The nitrogen (N) and phosphorus (P) concentrations of C. rigida leaves were also measured.
Pollen analysis of a high altitude bog (Winterton Bog) and an alluvial soil sequence in the upper Awatere catchment on the western flanks of the Inland Kaikoura Range, and radiocarbon dates on wood and charcoal from the Marlborough region, have established a Holocene, (post 10 000 years B.P.) vegetation history for this area.
Polynesian settlement of New Zealand (c. 1000 yr B.P.) led directly to the extinction or reduction of much of the vertebrate fauna, destruction of half of the lowland and montane forests, and widespread soil erosion. The climate and natural vegetation changed over the same time but had negligible effects on the fauna compared with the impact of settlement. The most severe modification occurred between 750 and 500 years ago, when a rapidly increasing human population, over-exploited animal populations and used fire to clear the land.