Edward A. Johnson Kiyoko Miyanishi Jon E. Keeley Matthew Dickinson Simon R. J. Bridge Sheri L. Gutsell 2001 <p><span>Covington states in his Commentary</span>^{<a href="http://www.nature.com/nature/journal/v409/n6823/full/409977b0.html#B1" data-mce-href="http://www.nature.com/nature/journal/v409/n6823/full/409977b0.html#B1">1</a>}<span> that the open ponderosa pine forests of the western United States are "in widespread collapse" because fire suppression by humans has eliminated the low-intensity surface fire regime that maintained the open, park-like structure of these forests. He fears this will lead to an "unprecedented" crown fire regime that will eliminate forests.</span></p> application/pdf 10.1038/35059312 en Nature Varied ecosystems need different fire protection article