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.

Native American depopulation, reforestation, and fire regimes in the Southwest United States, 1492–1900 CE

“…3 and 4 B and C). Such a complex mosaic of fire regimes is consistent with existing models of anthropogenic pyrodiversity, with likely consequences for biodiversity and carbon budgets (67). The assumption that more (indigenous) people equates to more fire activity (68) fails to accurately characterize these complex conditions.…”

Community owned solutions for fire management in tropical ecosystems: case studies from Indigenous communities of South America

“…Most importantly, the institutionalization of Indigenous fire management, and its scientific and technocratic discourse strongly privileges one particular aspect of Indigenous fire management: early dryseason burning to protect against late dry-season burning [62]. This fails to recognize that Indigenous fire management is characterized by regular and sometimes opportunistic burning throughout the dry season linked to various social, ecological and spiritual purposes (as shown in table 1), which can buffer the impacts of climate variability [37] and produce habitat mosaics that support landscape biodiversity [66,67] We can see from this that Indigenous fire management is being incorporated into policies through already established and clearly defined government schemes; disincentivizing, command-and-control methods of firefighting through the creation of Indigenous fire brigades, and incentivising approaches focused on prescribed early dry-season burning. Our contention is that although firefighting and early prescribed burning are necessary as part of an overall fire management strategy, there needs to be enabling policies that focus on legitimizing and strengthening Indigenous fire management as a community owned solution.…”

Living on a flammable planet: interdisciplinary, cross-scalar and varied cultural lessons, prospects and challenges

“…They may reduce the frequency or spread of unintended lightning fires, and may increase landscape diversity by creating smaller-scale vegetation mosaics through pyric succession [12,29,[57][58][59][60][61]. Anthropogenic fire regimes also may buffer against unpredictable climate-driven changes in fire behaviour and create ecological stability in the face of non-equilibrium vegetation dynamics [38,60].…”