What is the fine-grained topic of the following text: Results from a 2016 study by Coppoletta and others suggests that in areas where fire regimes and forest structure have been dramatically altered, contemporary fires have the potential to set forests on a positive feedback trajectory with successive reburns, one in which extensive stand-replacing fire could promote more stand-replacing fire. Only return the topic.
The impact of successive reburns on forest structure and fire regimes.