The Geography of the Anthropocene in New Zealand: Differential River Catchment Response to Human Impact

New Zealand provides a useful environment to test the notion that the Anthropocene is a new geological epoch. There are two well-dated anthropogenic impact ‘events’: Polynesian settlement c. AD 1280, and European colonisation c. AD 1800. Little attention, however, has been given to regional catchment response to these, although it has been assumed that both Polynesian and European farming and land use management practices significantly increased erosion rates across most of New Zealand. This paper addresses the nature and timing of human impacts on river systems using meta-analysis of a recently compiled nationwide database of radiocarbon-dated fluvial deposits. This shows highly variable human impacts on erosion and sedimentation in river systems, which are often difficult to separate from naturally driven river activity. Catchment-scale data with high resolution dating control record clearer evidence of human disturbance. In Northland, anthropogenic alluviation is recorded from c. AD 1300 linked to early Polynesian settlement, enhanced further in the late 19th and 20th centuries by European land clearance, when sedimentation rates exceeded 25 mm year−1. This study demonstrates significant geographical variability in the timing of human impact on river dynamics in New Zealand, despite two synchronous phases of human settlement, and highlights the difficulty of formally designating a simple and single ‘Anthropocene Epoch/Age’.