Wildfires and Sierran Ecosystems (IMAGE) American Society of Agronomy Caption Wildfires used to be a natural part of Sierran ecosystems, with minor fires sweeping through at intervals of 10 to 25 years Credit Photo courtesy of Dale Johnson and Soil Horizons/Soil Science Society of America Usage Restrictions Credit photo License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.