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Fire ecology of ponderosa pine and the rebuilding of fire-resilient ponderosa pine ecosystems

The ponderosa pine ecosystems of the West have change dramatically since Euro-American settlement 140 years ago due to past land uses and the curtailment of natural fire. Today, ponderosa pine forests contain over abundance of fuel, and stand densities have increased from a range of 49-124 trees ha -1 (20-50 trees acre -1 ) to a range of 1235-2470 trees ha -1 (500 to 1000 stems acre -1 ). As a result, long-term tree, stand, and landscape health has been compromised and stand and landscape conditions now promote large, uncharacteristic wildfires. Reversing this trend is paramount. Improving the fire-resiliency of ponderosa pine forests requires understanding the connection between fire behavior and severity and forest structure and fuels. Restoration treatments (thinning, prescribed fire, mowing and other mechanical treatments) that reduce surface, ladder, and crown fuels can reduce fire severity and the potential for high-intensity crown fires. Understanding the historical role of fire in shaping ponderosa pine ecosystems is important for designing restoration treatments. Without intelligent, ecosystem-based restoration treatments in the near term, forest health and wildfire conditions will continue to deteriorate in the long term and the situation is not likely to rectify itself.