title: Local and global pyrogeographic evidence that indigenous fire management creates pyrodiversity.
abstract: Despite the challenges wildland fire poses to contemporary resource management, many fire-prone ecosystems have adapted over centuries to millennia to intentional landscape burning by people to maintain resources. We combine fieldwork, modeling, and a literature survey to examine the extent and mechanism by which anthropogenic burning alters the spatial grain of habitat mosaics in fire-prone ecosystems. We survey the distribution of Callitris intratropica, a conifer requiring long fire-free intervals for establishment, as an indicator of long-unburned habitat availability under Aboriginal burning in the savannas of Arnhem Land. We then use cellular automata to simulate the effects of burning identical proportions of the landscape under different fire sizes on the emergent patterns of habitat heterogeneity. Finally, we examine the global extent of intentional burning and diversity of objectives using the scientific literature. The current distribution of Callitris across multiple field sites suggested long-unburnt patches are common and occur at fine scales (<0.5 ha), while modeling revealed smaller, patchy disturbances maximize patch age diversity, creating a favorable habitat matrix for Callitris. The literature search provided evidence for intentional landscape burning across multiple ecosystems on six continents, with the number of identified objectives ranging from two to thirteen per study. The fieldwork and modeling results imply that the occurrence of long-unburnt habitat in fire-prone ecosystems may be an emergent property of patch scaling under fire regimes dominated by smaller fires. These findings provide a model for understanding how anthropogenic burning alters spatial and temporal aspects of habitat heterogeneity, which, as the literature survey strongly suggests, warrant consideration across a diversity of geographies and cultures. Our results clarify how traditional fire management shapes fire-prone ecosystems, which despite diverse objectives, has allowed human societies to cope with fire as a recurrent disturbance.
authors.affiliation: Department of Natural Resources and Environmental Management, College of Tropical Agriculture and Human Resources, University of Hawai'i at Mānoa Honolulu, Hawai'i, 96822 ; School of Plant Science, University of Tasmania Hobart, Tasmania, 7001, Australia.
authors.forename: Clay
authors.initials: C
authors.lastname: Trauernicht
authors.affiliation: Environment Institute and School of Earth and Environmental Sciences, University of Adelaide Adelaide, South Australia, 5005, Australia.
authors.forename: Barry W
authors.initials: BW
authors.lastname: Brook
authors.affiliation: NERP Environmental Decisions Hub, School of Botany, The University of Melbourne Melbourne, Victoria, 3010, Australia.
authors.forename: Brett P
authors.initials: BP
authors.lastname: Murphy
authors.affiliation: School of Plant Science, University of Tasmania Hobart, Tasmania, 7001, Australia.
authors.forename: Grant J
authors.initials: GJ
authors.lastname: Williamson
authors.affiliation: School of Plant Science, University of Tasmania Hobart, Tasmania, 7001, Australia.
authors.forename: David M J S
authors.initials: DM
authors.lastname: Bowman
keywords: Coupled human and natural systems; fire ecology; heterogeneity; indigenous burning; landscape burning; patch mosaic burning; pyrodiversity