Flowering Records of Some Subalpine Trees and Shrubs at Arthur's Pass, New Zealand

The flowering periodicity and intensity of some subalpine trees and shrubs at Pegleg Flat, Arthur's Pass National Park, was recorded from 1981/82 to 1984/85. Moderate to heavy flowering of most species in 1981/82 was followed by two years of little or no flowering in 1982/83 and 1983/84; almost all species observed flowered heavily in 1984/85. No clear correlation was found between flowering intensity and mean summer temperatures of the previous growing season, when flower buds were initiated. It is suggested that the extent of flower bud initiation may also depend on current carbohydrate and mineral nutrient levels in the plants, which are temporarily depleted after mass-flowering years. The observed 3-year cycle of heavy flowering coincides with previous records for many other New Zealand trees and shrubs.