Altitudinal patterns of vegetation, flora, life forms, and environments in the alpine zone of the Fiord Ecological Region, New Zealand

Abstract

The altitudinal zonation patterns of vegetation structure, vascular flora, and life/growth forms were comprehensively assessed in relation to temperature and soil factors from treeline (1040 m) to the high‐alpine summit of Mt Burns (1645 m) in southeastern Fiord Ecological Region. We tested Körner's hypothesis which stipulates that the physiognomic zonation pattern: treeline, shrub line, tussockline, and beyond, is driven mainly by increased decoupling between the ambient temperature and that experienced directly by plants in relation to proximity of their canopy to the ground. This hypothesis is generally supported, particularly with replacement of the tussock life form by dwarfed, mostly cushion species, at the low‐ to high‐alpine zone transition. The soil pattern appears to be more of a response to, rather than a driver of, the alpine vegetation pattern, including a localised area of frost‐active solifluc‐tion terraces. The Nothofagus menziesii treeline conformed to the “warmest month” model and also with a worldwide growing season mean (7.15°C) of 5.5–7.5°C. We stress the closer analogy in the overall alpine zonation pattern in this region of oceanic New Zealand to that of the tropical high mountains and other oceanic regions, than with the temperate Northern Hemisphere continental mountains.