The spatial variability of P. radiata variables and the soil-landscape, upper Mamaku terrain, Kinleith Forest

Abstract

The Mamaku Plateau has formed from a series of welded ignimbrites, the youngest of which is the Mamaku Ignimbrite (c. 220 ka). The south-western side is characterised by a dissected upper Mamaku terrain, broad interfluves and valleys (mid Mamaku terrain), widening at lower elevation to form rolling hills (lower Mamaku terrain). The study site comprises a complex land system consisting of two simple land systems (Oruanui and Mamaku) on the upper Mamaku terrain. The area covers 7950 ha in the north-eastern part of Kinleith Forest, Tokoroa. Holocene tephras including Taupo Ignimbrite overlying a single stratigraphic feature of composite yellowish-brown weathered rhyolitic tephra beds (yellowish-brown beds) drape flat, hillock, ridge and ravine land components of previously eroded Mamaku Ignimbrite. The forest comprises Pinus radiata of various ages and management history. Forest nutrition and growth are known to vary spatially (Payn et al., 1999). However, the cause and structure of the variability has not been determined. This study aims to spatially partition variability of selected forest variables using a hierarchical landscape stratification and determine whether the spatial variability of forest nutrition and growth on the upper Mamaku terrain exhibits a relationship with regolith thickness and soil morphological properties.