Fire as a key driver of Earth's biodiversity

Abstract

Many terrestrial ecosystems are fire prone, such that their composition and structure are largely due to their fire regime. Regions subject to regular fire have exceptionally high levels of species richness and endemism, and fire has been proposed as a major driver of their diversity, within the context of climate, resource availability and environmental heterogeneity. However, current fire-management practices rarely take into account the ecological and evolutionary roles of fire in maintaining biodiversity. Here, we focus on the mechanisms that enable fire to act as a major ecological and evolutionary force that promotes and maintains biodiversity over numerous spatiotemporal scales. From an ecological perspective, the vegetation, topography and local weather conditions during a fire generate a landscape with spatial and temporal variation in fire-related patches (pyrodiversity), and these produce the biotic and environmental heterogeneity that drives biodiversity across local and regional scales. There have been few empirical tests of the proposition that 'pyrodiversity begets biodiversity' but we show that biodiversity should peak at moderately high levels of pyrodiversity. Overall species richness is greatest immediately after fire and declines monotonically over time, with postfire successional pathways dictated by animal habitat preferences and varying lifespans among resident plants. Theory and data support the 'intermediate disturbance hypothesis' when mean patch species diversity is correlated with mean fire intervals. Postfire persistence, recruitment and immigration allow species with different life histories to coexist. From an evolutionary perspective, fire drives population turnover and diversification by promoting a wide range of adaptive responses to particular fire regimes. Among 39 comparisons, the number of species in 26 fire-prone lineages is much higher than that in their non-fire-prone sister lineages. Fire and its byproducts may have direct mutagenic effects, producing novel genotypes that can lead to trait innovation and even speciation. A paradigm shift aimed at restoring biodiversity-maintaining fire regimes across broad landscapes is required among the fire research and management communities. This will require ecologists and other professionals to spread the burgeoning fire-science knowledge beyond scientific publications to the broader public, politicians and media.

Predator responses to fire: A global systematic review and meta‐analysis

“…For example, Leahy et al (2016) found an initial increase in dingo detections 2 weeks after a high severity fire, but because we calculated pooled mean abundances in burnt and unburnt areas across the whole sampling period, the short-term response was not clearly captured in the effect size calculation. The lack of predator responses to fire was unexpected given the broad potential effects of fire on ecosystems (Bond & Keeley, 2005;He et al, 2019). Many predators, especially mammals and birds, use a wide variety of habitats due to their large home ranges and generalist diets (Santos et al, 2014).…”

“…Fire has shaped Earth's ecosystems for millennia through the combustion of vegetation (Bond & Keeley, 2005), influencing how animals such as predators behave and are distributed in fire-prone landscapes (He, Lamont, & Pausas, 2019;Hradsky, Mildwaters, Ritchie, Christie, & Stefano, 2017). In their native ranges, apex predators can have positive effects on ecosystems and biodiversity by limiting the activity or abundance of herbivores and smaller 'mesopredators', either through killing (Pasanen-Mortensen, Pyykönen, & Elmhagen, 2013) and/or by instilling fear (Swanson et al, 2014).…”

Fire as a fundamental ecological process: Research advances and frontiers

“…Fire ecologists have constructed an increasingly nuanced, sophisticated and mechanistic understanding of the variable nature of fire as part of the ecological system. Fire is now recognized as a recurrent process, resulting in fire regimes that have direct ecological effects and act as selective forces by shaping species traits throughout the histories of entire lineages (He, Lamont, & Pausas, 2019; Simon et al., 2009). Moreover, fire regimes are important at multiple levels of biological organization, influencing populations, communities and ecosystems.…”

Indigenous Knowledge and Seasonal Calendar Inform Adaptive Savanna Burning in Northern Australia

“…Wildfire management is an escalating issue globally, with economic, environmental, social and cultural consequences [1][2][3][4]. In fire-prone regions such as the Americas, Australia and parts of Asia and Africa, wildfire management presents a formidable ongoing challenge that must be urgently addressed.…”