Cold Temperate Belt: Scrub.

Scrub formation is extensive in the Northern Tararua Area and on the windward slopes of the Western Tararua Area, but only occurs elsewhere in very restricted extent. Where well-developed it is extremely difficult to penetrate owing to its denseness and the extreme rigidity of the terminal branchlets. Very often the only practicable method of progress is to worm one's way along the ground or even to walk upon the top of the shrubs, except where tracks cut open by tramping clubs or broken open by deer are available and at its worst even deer refuse to face it.

There are a number of distinct associations in the scrub formation, but the one dominated by Olearia Colensoi is by far the most common. Other species of significance are Senecio elaeagnifolius, Coprosma pseudocuneata, C. foetidissima, Nothopanax Colensoi, Pittosporum rigidum and Dracophyllum Urvilleanum, any one of which may become dominant in isolated places. Where scrub occurs in the lower portion of the belt Weinmannia racemosa is an important constituent and in the Northern Tararua Area Phyllocladus alpinus. Olearia arborescens, O. lacunosa, Pimelea longifolia, Hebe buxifolia, Gaultheria rupestris are very common and among these Gahnia pauciflora, Danthonia flavescens and Phormium Colensoi occur in many places. Under the scrub Astelia Cockaynei is generally plentiful and where light penetrates freely the following are found:—Euphrasia cuneata var. tricolor, Gentiana bellidifolia, G. Grisebachii, Thelymitra uniflora, Danthonia nigricans, Agrostis Dyeri, Lycopodium fastigiatum, Gaultheria depressa, Nertera depressa, N. setulosa, N. dichondraefolia, Cyathodes empetrifolia, Blechnum procerum, Polystichum vestitum, Hymenophyllum sanguinolentum, H. multifidum.

In several localities in the Northern Area, in particular at its boundary with the Western Area along the ridge between the Mangahao and Otaki rivers leading to Pukematawai, the entire upper part of the belt is under scrub which merges imperceptibly with the Subpolar Belt. Immediately above the timber line, which is here in the vicinity of 900 m., the scrub association is of the usual type, but with increase in altitude this becomes more and more intermingled with tussocks, at first of Gahnia pauciflora and later of Danthonia flavescens, which grow among the shrubs to a height of 2 m. or more. Higher up the slope shrub species decrease in stature and in numbers to give place to subpolar tussock.

A noteworthy case of scrub formation at a low elevation occurs on the eastern side of the range along the boundary of the Northern and Eastern Areas where it traverses the foothills east of Ruapai. Forest, with Weinmannia racemosa dominant and Podocarpus Hallii,