Fire Ecology and Insect Ecology

Abstract

Fire is not a recent phenomenon in the world’s history, and its influences by far pre-date human interests or involvement in its extent and impacts. The incidence of wildfires in North American grasslands, for example, has been stated to have been consistent over their roughly five million year history, perhaps markedly influencing their condition and evolution. However, such generalities can be questioned – it has also been conjectured that decreased fire frequency over North American prairies has resulted in the woody plant environments that have transformed these formerly far more extensive grasslands into other biotopes that have contributed to massive habitat alienation for grassland specialist insects and other biota. Likewise, long incidence of fires in savannas of northern Australia has moulded their current condition, and the features of resident biota. More generally, the influences of fires on Mediterranean ecosystems have been profound, as discussed by Faivre et al. (2011), and have left a complex biotic legacy. Some Western Australian mygalomorph spiders were regarded by Main (1998) as Gondwanan faunal relicts, evolving before fire was believed to have become widespread in the region: she believed that such taxa may be under increasing threat as fires, of whatever origin, become more pervasive. Many parallels occur amongst insects, and uncertainties and debate continue over how fires may have influenced the world’s ecosystems and their inhabitants. Indeed, the succinct summary of global impacts of fire over the ages led Pausas and Keeley (2009) to comment ‘We cannot understand our biota, in terms of adaptations and ecosystem distribution, without including fire as a process in the natural history of our planet’. Those influences also continue, with the frequency and intensity of fires affected strongly by climate, and by the nature and amount of fuel available – together with impacts of human activity. Implications of recent climate change link with likelihood of increased fire frequency and intensity in many places, with many of the possible outcomes very poorly understood. Fire has long been, and will continue to be, a major transformative agent in many terrestrial biomes. It can reasonably be considered among the ‘profound disturbances’ that can disrupt ecosystems, drawing on an early but now classic definition of ‘disturbance’ as ‘any relatively discrete event in time that disrupts ecosystem, community or population structure and changes resources, substrate availability, or the physical environment’ (Pickett and White 1985). ‘Every fire leaves an imprint in the landscape’ (Catchpole 2002), and the numerous variables that influence fire behaviour (Keith 2012; Sullivan et al. 2012) can render the consequences of any individual imprint highly unpredictable.