Biotic influences on landslide occurrence in the kaimai range

Abstract

Explanations are sought for the recent increased erosion in the Kaimai Range. Vegetation mortality adjacent to the landslide scars is thought to be the most important factor predisposing the area to erosion. No evidence was found to suggest that the mortality was due to browsing animals, but mortality was linked with a severe drought in 1946. Prevalent fog, by maintaining high soil moisture contents, may enhance vegetation susceptibility to drought and increase the landslide risk in the fog zone. Severe storms in 1954, 1960, 1966, and 1972 followed a period of below-average storm intensity and triggered the current erosion episode. An earthquake in 1972 postdated the main erosion increase and intensified the erosion episode. The same factors have produced increased erosion elsewhere in New Zealand. Consequently greater attention must be given to natural forest devastation of long return period acting indirectly on the regolith. © 1983 Taylor & Francis Group, LLC.