Rapid landscape transformation in South Island, New Zealand, following initial Polynesian settlement

Abstract

Humans have altered natural patterns of fire for millennia, but the impact of human-set fires is thought to have been slight in wet closed-canopy forests. In the South Island of New Zealand, Polynesians (Māori), who arrived 700–800 calibrated years (cal y) ago, and then Europeans, who settled ∼150 cal y ago, used fire as a tool for forest clearance, but the structure and environmental consequences of these fires are poorly understood. High-resolution charcoal and pollen records from 16 lakes were analyzed to reconstruct the fire and vegetation history of the last 1,000 y. Diatom, chironomid, and element concentration data were examined to identify disturbance-related limnobiotic and biogeochemical changes within burned watersheds. At most sites, several high-severity fire events occurred within the first two centuries of Māori arrival and were often accompanied by a transformation in vegetation, slope stability, and lake chemistry. Proxies of past climate suggest that human activity alone, rather than unusually dry or warm conditions, was responsible for this increased fire activity. The transformation of scrub to grassland by Europeans in the mid-19th century triggered further, sometimes severe, watershed change, through additional fires, erosion, and the introduction of nonnative plant species. Alteration of natural disturbance regimes had lasting impacts, primarily because native forests had little or no previous history of fire and little resilience to the severity of burning. Anthropogenic burning in New Zealand highlights the vulnerability of closed-canopy forests to novel disturbance regimes and suggests that similar settings may be less resilient to climate-induced changes in the future.

Fire responses to postglacial climate change and human impact in northern Patagonia (41–43°S)

“…In other parts of the world, hunter-gatherers have used fire to facilitate travel, hunting, and sometimes warfare, as well as to gather and maintain important plant resources (49,50). Although it is possible that fire was required for the same purposes in northern Patagonia, there is no evidence that anthropogenic burning altered the broad patterns of fire (inferred from the generalized CHAR trends) inasmuch as shifts in biomass burning seem well explained by changes in fuel availability and climate (Fig.…”

Fire history on the California Channel Islands spanning human arrival in the Americas

“…For example, in New Zealand (which was colonized approx. 1280 AD), anthropogenic fire detected in terrestrial archives comes as asynchronous increases in charcoal contemporaneous with a wave of human arrival across the country [28,29]. Detecting the clear arrival of people and the associated shift in fire regime in this region was helped by (i) New Zealand's low background of natural wildfire and (ii) the relatively stable climate during this period.…”

Youngest reported radiocarbon age of a moa (Aves: Dinornithiformes) dated from a natural site in New Zealand

“…The results of this study also have serious implications for hypotheses suggesting that introduced diseases (Gemmell et al 2004) and human-mediated habitat loss (Didham et al 2005) were the main drivers of moa extinction in contrast to overhunting or multi-causal extinc-tion scenarios (Anderson 1989a;Wilmshurst & Higham 2004;Wilmshurst et al 2008;McWethy et al 2010). Introduced avian diseases have been documented to have little impact on alpine bird communities.…”

“…There is overwhelming archaeological and palaeoenvironmental evidence that overhunting and habitat destruction by early Māori were the dominant causes of the extinction of moa (Anderson 1989a;Wilmshurst & Higham 2004;Wilmshurst et al 2008;McWethy et al 2010). Though no verifiable crested moa remains have been found in Māori middens (Worthy 1997b;Anderson 2002;Tennyson & Martinson 2007), the new radiocarbon dates (Table 1) suggest that it is highly probable that crested moa were hunted to extinction.…”