Fire, climate and the origins of agriculture: micro-charcoal records of biomass burning during the Last Glacial Interglacial Transition in Southwest Asia.

Abstract

This study investigates changes in climate, vegetation, wildfire and human activity in Southwest Asia during the transition to Neolithic agriculture between ca. 16 and ca. 9 ka. In order to trace the fire history of this region, we use microscopic charcoal from lake sediment sequences, and present two new records: one from south central Turkey (Akgo¨ l) and the other from the southern Levant (Hula). These are interpreted primarily as the result of regional-scale fire events, with the exception of a single large event ca. 13 ka at Akgo¨ l, which phytolith analysis shows was the result of burning of the local marsh vegetation. Comparison between these and other regional micro-charcoal, stable isotope and pollen records shows that wildfires were least frequent when the climate was cold and dry (glacial, Lateglacial Stadial) and the vegetation dominated by chenopod–Artemisia steppe, and that they became more frequent and/or bigger at times of warmer, wetter but seasonally dry climate (Lateglacial Interstadial, early Holocene). Warmer and wetter climates caused an increase in biomass availability, with woody matter appearing to provide the main fuel source in sites from the Levant, while grass fires predominated in the interior uplands of Anatolia. Southwest Asia’s grasslands reached their greatest extent during the early Holocene, and they were maintained by dry-season burning that helped to delay the spread of woodland by up to 3 ka, at the same time as Neolithic settlement became established across this grass parkland landscape. Although climatic changes appear to have acted as the principal ‘pacemaker’ for fire activity through the last glacial–interglacial climatic transition (LGIT), human actions may have amplified shifts in biomass burning. Fire regimes therefore changed markedly during this time period, and both influenced, and were influenced by, the cultural-economic transition from hunter-foraging to agriculture and village life