5 Climate change and fire ecology
Wildfires are integral in shaping the structure and distribution of fauna and flora in many habitats, giving rise to self-regulating ecosystems. Native species and their interaction have evolved along with fire and are dependent on the conditions created by fire. However, it is becoming increasingly evident, that human activity and the impact of human-induced changes in fire regimes, have caused a shift in this stable state.
Over the last few years there have been an increasing number of devastating wildfires reported in the media. Research is now showing that one of the main causes of these bigger, more frequent fires is global warming. Higher temperatures result in drier forests, longer periods of dry weather, more intense winds, more intense storms and higher incidents of lightning strikes. Added to these more obvious effects of a warming climate, other, less obvious factors, are also playing a role. In the Western United States and Canada, longer periods of warmer temperatures have resulted in large increases in the numbers of bark beetles. Although the beetles are native to the region the hot dry weather has water-stressed trees and beetle numbers have exploded, killing the trees and increasing the amount of fuel available to sustain wildfires. Similarly, insect outbreaks in California resulted in the death of more than 300 million trees between 2010 and 2017, turning them into kindling for catastrophic forest fires.
Possibly of greatest concern is the feedback process generated by a warming climate. Warming causes more fires which release more greenhouse gases which causes more warming.
Although it is difficult to predict the full effects of climate change, it is becoming evident that the fire regimes of many ecosystems are changing with respect to both intensity and frequency - such changes in turn will have significant effects on the type and distribution of fauna and flora that inhabit them. For example, in Africa, drier conditions due to global warming will result in less biomass to fuel savannah fires. This, together with increasing CO2 levels which favours the spread of less flammable C4 grasses, could result in a reduction in fire frequency in these ecosystems and the expansion of forest into savannahs.