In 250 2 0 m X 20 m permanent plots in the Craigieburn Range, Canterbury, New Zealand, 1970 stem density was 2,19l/ha, basal area was 52.4 m2/ha, and stem biomass was 178.1 P. A. Harcombe is Professor in the
SUMMARYIn primeval times the Aorangi Range supported an almost continuous forest cover broken only by occasional slips and young stream terraces. Forest still forlT15 the mo.,t extensive cover in the area. It can be broadly classified into four main types: mahoe-hinau-rewarcwa forest en the more stable slopes and flats up to an altitude of 1,700-1,900 ft; black b(;ech forest on the drier, more exposed spur sites up to 1,600 ft; red beech forcst on the mid slopes between 1,400 ft and 1,900 ft; and silver beech forc.~t along the ridges between 2,000 ft and the highest points of the range.In recent times the vegetation of the area has been modified by fire, browsing, and erosion. Erosion has favoured the extension of seral plant communities such as are found on slips, in gully heads, and on aggrading river terraces. Burning has given rise to tall kanuka scrub at lower altitudes and to subalpine scrub and tussock grassland at higher altitudes. Browsillg mammals have considerably altered the composition of cach forest type and have modified Succc.~sion on bared areas.The first section of this paper hriefly describes the physical nature of the range; the second deals with the distribution, structure, and composition of the main forest types, and the third descrihes how erosion. fire. and hrowsing have altered these to produce the present seral and suhclimax communities. I NTRODII('TIONThe greater part of the Aorangi Range (commonly referred to as the "Haurangis") lies within permanent State forest. The total area of State forest is approximately 34.000 acres. divided into a northern and a southern section by a strip of hilly grazing country lying to the true left of Turanganui River (Fig. I).The range is comparatively low. the two highest peaks being Mt Ross 0.226 ft) in the southern section. and Mt Te Munga (3.211 ft) in the northern section. It constitutes a major block moving between two transcurrent fault zones which trend in a NE-SW direction. The present sharp ridges of the range resulted from extensive southward movement of the block during the Tertiary period (Wellman. 1956;Kingma. 1959) 1967]North ISland N Z. [MARCH movement caused the development of a series of minor faults and consequent large-scale internal deformation. Many of these minor faults are still active (Fig. 2). The drainage pattern of the range is largely influenced by the pattern of fault lines and shatter zones. and is of a somewhat trellised nature. As a result downcutting by the streams is rapid and the valleys are typically V -shaped and steep walled. with numerous gorges. The parent rock is predominantly grey wacke. dating from the Aptian and Neocomian stages of the Cretaceous (Grindley. Harrington. and Wood, 1959). Minor volcanics. probably of Jurassic age (Wellman, (956), border the south-western margin. and towards the north-east there are pockets of limestone resulting from movement during the Kaikoura diastrophism (Kingma. 1959). The Aorangi Range. and the mountain ranges to the north-east. are a continuation of the ranges of the ...
The forests and shrublands of the Seaward Kaikoura Range are classified into eight associations: coastal scrub-hardwood forest. mixed podocarp forest. Hall's totara forest. sub-alpine scrub, beech forest. mixed scrub-hardwood forest, LeplOspermum forest and scrub, and bluff scrub. The composition, structure, and habitat of each are described, and an indication is given of how each is being modified by the introduced mammals (red deer, goats, chamois, and opossums).Distribution of the first four of these associations is related mainly to changes in altitude. Coastal scrub-hardwood forest occurs below 1,000 ft altitude. Mixed podoearp forest forms a belt above it, and in tum gives way to Hall's totara forest. Hall's totara forms a fire-modified timberline between 3,000 and 3,400 ft. The sub-alpine scrub above timberline has been severely modified by fire and discontinuous patches of it occur up to 4,500 ft.Beech forest is most important at the northern and southern ends of the range. It occupies a wide altitudinal range from 200 to 3,000 ft and may be dominated by mountain beech, red beech, or black beech. The mixed scrubhardwood and Leptospcrmllm associations are usually seral. The scrub-hardwood occurs on eroded sites and the Leptospcrmum on old fire scars and terraces. The bluff association occnpies only very steep slopes but at a wide range of altitude. Several of the physiognomic species in it are endemic to the vicinity of the Seaward Kaikoura Range.The two scrub-hardwood associations arc undergoing major changcs in composition as a result of browsing by introduced mammals. The physiognomic species in each arc favoured fodder and very susceptible to damage by browsing. The mixed scrub-hardwood forest is unlikely to regenerate if animal pressure is maintained at the present level.
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