BURNING IN A NEW ZEALAND SNOW-TUSSOCK GRASSLAND: EFFECTS ON VEGETATION AND SOIL FAUNA

摘要: Although New Zealand has a fire history extending back at least 20 million years, natural fires were rare in the Pleistocene and Holocene contemporary vegetation shows few adaptations to burning. A dramatic rise charcoal occurrence about 1000 years ago, coincident with Polynesian colonization, presaged widespread phase of deforestation that reduced area forest by 40%. With European settlement mid-19th century further 20-30% primary forest, much regenerating lands, cleared, burned converted into farmland (Basher et al., 1990; Wardle, 1991). Many areas Zealand, especially eastern South Island high country, previously supported Nothofagus which was displaced during later burning tall tussock grassland (Tate, 1992; Fire continues be used as cheap effective but controversial management tool scrublands. is widely suppress shrub development. Tall also burnt improve stock access induce nutritious regrowth. Studies post-fire recovery grasslands demonstrate after an initial change species dominance, floristics structure return approach pre-burn condition within two decades Allen Partridge, 1988; Gitay Payton 1986). Physical sustainablity agro-ecosystems hill country elsewhere world, dependent on maintenance soil resource medium for supplying water nutrients plant growth. Objectives managing are maintain or enhance physical chemical characteristics soil. Depth soil, texture, organic matter structural stability control ability supply growth, resist erosive forces wind water. Maintenance fertility adequate levels, diverse population organisms, efficient nutrient cycling. Burning without replacement fertiliser, inputs from atmosphere weathering, will ultimately result degradation limit growth 1990); combination loss cover erosion intense rainfall events could important context possible global climate (Meyer 1992). G.W. YEATES WILLIAM G. LEE Manaaki Whenua Landcare Research, Private Bag 11052, Palmerston North, Zealand; 1930, Dunedin, Zealand.