Vegetation at Ajax Hill, south-east Otago, New Zealand

Abstract
Ajax Hill, part of an undulating plateau at c. 700 m in the Catlins region of south-east Otago, comprises a mosaic of cushion bog, flush, and scrub-woodland communities. Cushion bog covers several small plateaux, overlies up to 5.5 m of peat, and is dominated by Calorophus minor, Donatio novae-zelandiae, lichens, and heaths, with scattered bushes of Leptospermum scoparium and Dracophyllum longifolium. Dracophyllum also dominates scrub-woodland on better-drained slopes, with Dacrydium biforme and emergent flag-form small trees of Libocedrus bidwillii. The blanket peat has been eroded locally by streams which contain flush vegetation, predominantly Sphagnum spp. and Chionochloa rubra, overlying 0.5–1 m of peat, and characterised by a permanently high water table. Quantitative data are given for cushion bog and scrub-woodland, and a profile presented to show the gradation from flush through scrub-woodland to bog. Increment corings from 10 Libocedrus trees indicate relatively fast diameter growth rates compared with other areas. Growth on the lee side of flag-form trees tends to be greater than on the windward side. The floristic list contains a total of 117 vascular plants (including 13 adventives) and 24 cryptogams. Comparison with other southern bog areas shows that each has floristic peculiarities. Astelia subulata is the most notable rarity at Ajax Hill and Phyllachne colensoi, Dracophyllum prostratum, Dacrydium bidwillii, and Schoenus pauciflorus the principal absences.

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