Is Anthropogenic Pyrodiversity Invisible in Paleofire Records? (original) (raw)
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Archaeological and paleoecological studies demonstrate that human-caused fires have long-term influences on terrestrial and atmospheric systems, including the transformation of " wild " landscapes into managed, agricultural landscapes. Sedimentary charcoal accumulations alone provide only limited information about the influence of human-caused fires on long-term fire regimes. Computational modeling offers a new approach to anthropogenic fire that links social and biophysical processes in a " virtual laboratory " where long-term scenarios can be simulated and compared with empirical charcoal data. This paper presents CharRec, a computational model of landscape fire, charcoal dispersion, and deposition that simulates charcoal records formed by multiple natural and anthropogenic fire regimes. CharRec is applied to a case study in the Canal de Navarrés region in eastern Spain to reveal the role of human-driven fire regimes during the early and middle Holocene. A statistical comparison of simulated charcoal records and empirical charcoal data from the Canal de Navarrés indicates that anthropogenic burning, following the Neolithic transition to agro-pastoral subsistence, was a primary driver of fire activity during the middle Holocene.
Bimodal fire regimes unveil a global-scale anthropogenic fingerprint
Aim: While fire is recognized as an integral part of the Earth system, the ability of humans to shape fire regimes both spatially and temporally remains poorly understood. Our goals were to identify the extent of fire regimes exhibiting two annual fire seasons and to investigate the environmental correlates of such regimes at the global scale. Location: All areas of the globe exhibiting relevant fire activity, at 0.5 spatial resolution. Time period: 2002-2012. Major taxa studied: (not applicable). Methods: The modality of fire seasonality at the global scale was classified using a 10-year record of satellite-derived fire activity and model fitting of circular statistical distributions. The main environmental correlates controlling global fire regimes were then analysed over bimodal and unimodal areas using the Kolmogorov–Smirnov test. Results: About 25% of the global land surface with relevant fire activity has two significantly distinct fire seasons per year, with at least one of these seasons occurring under sub-optimal fire weather conditions. In these bimodal areas, population density and the fraction of fires occurring in actively managed land, especially in croplands and pastures, are significantly higher than in neighbouring unimodal areas. Results reveal that through these land-use and management practices humans have a strong influence on global patterns of fire seasonality. Main conclusions: We identified a bimodal seasonality pattern, previously unreported at the global scale, and show that it reveals an anthropogenic fingerprint on fire regimes. Insights into where and when fire is actively employed as a land management tool enhance our understanding of the role of fire in the Earth system, and highlight the need to better understand how fire practices may change in the future.