Fire Part I: Introduction and History

Abstract

Evidence of fire is found first in the Carboniferous age 400 Mya forming fusain or fossilized charcoal in coal deposits, but it was not until the Devonian sufficient fuel may have accumulated for widespread fires, the first trees evolving in the mid-Devonian, and it is not until the late Devonian that there were extensive coastal forests and more charcoal appears in the fossil record. The macrofossil record suggests wild fires in the northern hemisphere then became a regular part of the ecosystem being widespread and frequent (Scott 2000). Some consider the evolution of grasses and their capacity to sprout from leaf bases protected by old leaf sheaths heralded one of the most profound changes of life on earth, enabling them to survive fire this led to the adaptive radiation of large herbivores and their ability to exist at high population densities. The C₄ grassland ecosystems appeared first between 6 and 8 million years ago, one suggestion being that this was due to decreasing atmospheric carbon dioxide (CO₂). But the assumption of the existence of low levels of carbon dioxide in the Miocene has been disputed and it is hard to see how by consuming grass herbivores would promote the spread of grasslands at the expense of forests.