Nothofagus Gradient on Mt. Robert
As you follow the trail up Mt. Robert in St. Arnaud, you will notice that the dominant Nothofagus (beech tree) canopy type changes with altitude. At the top of the tree line (around 1300m), the dominant canopy is comprised primarily of a monoculture of N. solandri (black/mountain beech). As you descend, you will see increasing N. menziesii (silver beech), eventually forming a monoculture (around 1200m), and at lower altitudes (1100m and below), N. fusca (Red Beech) will dominate the canopy. Prominent in the vegetation throughout the history of New Zealand, Nothofagus prosper in cool, wet weather, and are therefore very common throughout the south. These trees were widespread on low-relief landscapes by the Eocene period, 55 million years ago.
Gibbs, George W. Ghosts of Gondwana: The History of Life in New Zealand. Nelson, N.Z.: Craig Potton Pub., 2006.