Cattle grazing and the regeneration of totara (Podocarpus totara var. waihoensis) on river terraces, south Westland, New Zealand

Totara-matai forests are an under-represented forest type in Westland, relative to their original extent, and require protection and enhancement where possible. This study examined the regeneration of totara on gorse-covered river terraces of the Whataroa and Waiho Rivers, on a site grazed by cattle at Whataroa, and ungrazed sites at both locations. Totara is regenerating prolifically at all sites. Tall-seedling densities were significantly higher at the grazed Whataroa site than at the ungrazed Whataroa site. Conversely densities of small seedlings were significantly higher at the ungrazed Waiho site, with the majority of seedlings occurring on raised surfaces created by rafted logs or occasional silt patches, than at either of the Whataroa sites where seedlings established on the ground. Sapling and tree densities were similar at both Whataroa sites, but significantly greater than at the Waiho site. There was a significant relationship between the density of saplings and trees with terrace age at the Whataroa sites. Gorse cover and seedling density were significantly related at both ungrazed sites, but not at the grazed site. Grazing and gorse cover both appear to have roles in totara regeneration on river terraces. The implications of current management for future forest development are discussed, and it is considered that these areas warrant designation as areas of significant indigenous vegetation because of their conservation potential.