The study of approximately 250 km2 comprises the glaciated Haupiri, Douglas, Anatoki, Devil, Snowden, and Lockett Ranges between the Aorere and Takaka valleys. The climate is cool and moist overall, but precipitation decreases from 5600 mm to 2800 mm in the east. The Cambrian rocks are mainly volcanic and volcanic derived sediments and small areas of limestone. These respond to faulting and weathering in different ways which contributes to the different landforms found on each range. There are between 300 to 350 species on each range but about 200 species are limited to one or a few ranges. Their distribution is discussed in relation to their preferences for sites such as limestone or peat soils and the major biogeographical patterns in northern South Island. Twenty-six vegetation units are described. The main cover is Nothofagus forming the timberline, scrub communities dominated by species of Dracophyllum, species of Hebe, and Brachyglottis bidwillii, tall tussocklands of Chionochloa species, minor amounts of cushion herbfield, sedgeland and rushland, and open lands of bare rock with less than 20% vegetation cover. There are strong vegetation gradients from west to east and from one geological terrain to another. Each range is therefore different and a reserve system which was representative of the whole area would need to include substantial parts of 5 of the ranges.