178 
Floristik, Geographie, Systematik etc. 
and ice a small lake which is frequently hot and emits steam. Other 
lakes occur within the Park, as well as several active volcanoes and 
“blowholes”. Some of the lava-flows are recent, and the area is 
covered with volcanic ash and scoria into which rain and melting 
snow rapidly sinks to emerge at lower levels. The nature of the 
soil, the strong isolation in summer, and the frequency of high 
winds favour desert and steppe Vegetation on the summits. The cli- 
mate is comparatively dry on the eastern plateau, the rainfall being 
about 150 c.m. on 112 days p. ann. at Taupo, whereas on the Western 
side 250 c.m. on 230 days has been recorded. Snow lies only a few 
days at elevations of 1000 m., but above this it continues in places 
tili March. These snow-patches along with the snowfields of Rua- 
pehu afford a constant supply of water which emerges to the sur- 
face in places and gives rise to tracts of semi-bog on the steppes 
and in the forests. 
The Geology of the area is described in detail by Mr. R. 
Speight. The volcanoes appear to have become active in late Plio- 
cene times, and, from the presence of charred tree-remains in 
pumice, it is probable that the volcanic material destroyed forest 
which existed on the now treeless region. 
The Plant Formations. The Vegetation is mainly subalpine 
in character, the lowest altitude of the park-reserve being about 
1000 m. It presents two main types „forest” and „steppe” connected 
by a subalpine scrub, but the earlier stages are desert. The substrata 
result from the weathering of molten lavas, hot ashes and scoria. 
“The general sequence would be — lava and ash-fields; disintegra- 
tion of lava, and colonisation of ash-fields first and lava at a later 
date; hollowing-out or reconstructing river-valleys; building up of 
flood-plains; cutting of ravines and gullies into these; gradual 
weathering through water-action, wind, etc.; while finally would 
come the changes occasioned by introduced animals”. Stated gene- 
rally, “there would be a procession of Vegetation such as this:Rock- 
plants, desert, steppe, shrubby steppe, scrub, and finally forest.” 
“A spring of water would at once offer special conditions, and pools 
or bogs varying in their water-content would be formed.” 
Forest Formations. The climate of the volcanic plateau is 
that of the New Zealand rain-forest, but actual forest can only 
occur where the grass and shrub formations have prepared a soil,. 
or where topographical conditions provide shelter. Little forest lies 
within the park-reserve itself which is limited almost entirely to 
the volcanic plateau, but the formation is well represented in the 
valleys at lower elevations. The abundant rainfall of the Western 
side of Ruapehu permits forest growth to a considerable altitude, 
but on the drier eastern side there are only patches in places spe- 
cially favourable. The upper forest is dominated mainly by Notho- 
fagus , of which N. fusca distinguishes the lower zone, N. Mensiesit 
the middle, and N. cliffovtioides the uppermost zone. The author 
describes the life-forms of these and other physiognomic plants, and 
in a review of their ecological features points out that while many 
have coriaceous leaves, a divaricating habit and other xerophytic 
characters, yet several of the commonest plants (e. g. Coprosma 
foetidissima and C. tennifolia ) are not xerophytic. “The composition 
of the forests depends far more upon the history of trie Vegeta¬ 
tion — i. e., upon the plants which came to settle down on the new 
ground — :than upon any special adaptations these may have pos- 
sessed.” The main requisite is frost-endurance, but xerophytic cha- 
