New Zealand Journal of Ecology (1978) 1: 27- 50

Alpine phytomass and primary productivity in central Otago, New Zealand

Research Article
Colin D. Meurk  
  1. Botany Department, University of Otago, P.O. Box 56, Dunedin, New Zealand

Phytomass was measured and net potential productivity estimated for normal climatic conditions on the Otago rainshadow mountains. 7 tall snow tussock grasslands were compared with lower-statured cushion, herbfield and short grassland communities. The main grass spp. were Chionochloa macra, C. rigida and Poa colensoi. Total phytomass ranged from 5 to 9 kg/m² (22 000-40 000 kcal/m²) in tall tussock and from 2 to 4 kg/m² (8100-16 500 kcal/m²) in cushion, herbfield or short grassland vegetation. Root:shoot ratios of <1, in all communities, probably reflected the oceanic nature of the climate. Total annual potential net production ranged from 0.7 to 1.0 kg/m² (3200-4600 kcal/m²) in tall tussock, and was 1.0 kg/m² (4200 kcal/m²) in an induced mid-alt. Poa colensoi turf grassland. Growing season efficiency ratings (0.5-1.2%) tended to increase with alt., suggesting an adaptation to the short and climatically erratic summers. The 150- to 200-day growing seasons were considerab!