The soils of the southeastern sector of Egmont National Park

Abstract

The soils of the southeastern slopes of Egmont National Park, Taranaki, are youthful in absolute age and also in soil development. They are classed as recent soils on a parent material basis: andesitic tephras, alluvium, and peat with interbedded tephra. Of these groups the former covers the greatest part of the surveyed area and was studied in the most detail. The recent soils from andesitic tephra have a profile form dominated by buried soil horizons and little weathered tephra layers, the youngest of which was erupted 210 years ago. Characteristic features are the very weak weathering of minerals in the upper soil layers, the variable depth of melanisation, the extremely leached state of the soil profile and lastly the marked similarity of the soil chemical parameters despite appreciably different biotic regimes and a range in slope and altitude. It is concluded that the extremely high rainfall, in excess of 150 inches per annum, so controls soil processes that the variables of site and vegetation are not expressed in the measured soil parameters.