Vegetative Production and Performance of Calluna vulgaris in New Zealand, with Particular Reference to Tongariro National- Park

Aspects of the production and vegetative performance of Calluna vulgaris (heather) were examined in four areas of New Zealand between 1981 and 1983; Tongariro National Park in the North Island, together with Mount Cook National Park, the Wilderness Scientific Reserve, and Ben Callum peat bog in the South Island. The height and height/width quotient of Calluna bushes, the diameter increment of woody stems and the amount of flowers/stem all decreased with altitude. Other age-adjusted components of stem biomass were positively related to soil depth, soil moisture, soil organic content and soil pH. Biomass by direct harvest gave values between 300 g per m and 2200 g per m for plant communities with Calluna. These are similar Values to recorded from British and European heaths, although the contribution of Calluna to the total biomass was often less in New Zealand. Calluna from New Zealand has a higher proportion of wood relative to total biomass than is normally found in Britain and Europe and this is probably related to the management of British and European heaths by burning. Multiple regressions indicated that increased woodiness is associated with lower altitudes and deeper, moister soils. Woodiness tended to decrease on more organic and more acidic soils, with a corresponding increase in the proportion of green shoots. Flowering declined with increased altitude, while the proportion of green shoots relative to total biomass increased. It is suggested that the upward extension of Calluna within Tongariro National Park is limited mainly by constraints on flowering and sexual reproduction.