SIHC: Vegetation Pattern

SIHC: Vegetation Pattern

1. Southern Alps

   • Reason for pattern
     • Climate too cold (0'C) for any plant growth. Also no soils. Hardy alpine plants occur in sheltered pockets, where they have adapted to high winds by being low lying.
   • Vegetation Pattern
     • Most of the region is bare rock and covered by snow much of the year. At lower altitudes, some hardy alpine plants, e.g. mountain daisies in spring and summer. Below this, tussock and hebes.

2. Western High Country

   • Reason for pattern
     • Climate, relief and soils suitable to support trees. Type of forest depends on the rainfall and soils, e.g. younger more fertile alluvial soils allow more growth than older glacial moraines. Wetter areas allow matai and totara forests.
   • Vegetation pattern
     • Below 1000m of dense podocarp forest. Canopy of beech trees with understory of ferns and shrubs. Above this , bush and then tussock grasses.

3. Fiordlands

   • Vegetation Pattern
     • Typical zonation pattern occurs. From base up to 1000m, very dense forests with thick undergrowth. Above this subalpine scrub and mosses.
   • Reason for Pattern
     • Very wet conditions (Milford Sound receives 6000mm of rain) allow thick tree growth. Competition for light results in stratification here.

4. Eastern High Country

   • Vegetation Pattern
     • Most of area covered in tussock, except for rocky bluffs.
   • Reason for pattern
     • Area in rainshadow due to orographic rainfall, so rainfall is reduced (1300mm compared to 4000mm on the other side). This, combined with strong fohn (Nor'wester) winds and lack of soils, means only very hardy plants like tussock can survive. Because soils are thin, plants have shallow roots. Drought increasing over time- this was area of beech until recent geological past.