The geography of the Anthropocene in New Zealand: Differential catchment response to human impact (13630)
New Zealand provides globally a unique environment to test the notion that the Anthropocene is a new geological epoch and its value as a concept for environmental management. In NZ there are two well-dated anthropogenic impact ‘events’: Polynesian settlement c.AD 1280, and European colonisation c.1800. Polynesian impacts are recorded by lake charcoal and pollen, European land-use change is historically documented. Little attention has been given to regional catchment response to these, although it has been assumed that both Polynesian and European disturbance significantly increased erosion rates across most of NZ. However, a new study of post-settlement alluvium in North and South Islands indicates a highly variable pattern of human impacts on erosion and sedimentation in river systems. In South Island there appears to be little modification to natural process, even following European arrival, because catchments are dominated by glacial and paraglacial processes. In North Island, catchments draining the central plateau are similarly dominated by natural volcanic legacy. In the southern North Island, response was hydrological, with a change in channel planform linked to European forest clearance. Clearest evidence for human disturbance is found in the East Coast and Coromandel, where late 19th and early 20th century deforestation and mining, respectively, transformed river systems. In Northland, alluviation is recorded from c. AD 1300 linked to early Polynesian settlement. Our study indicates significant geographical variability in the timing of the Anthropocene in NZ, despite two synchronous phases of human settlement, questioning its utility as a guiding concept for environmental sustainability.