DO NON-NATIVE PLANTS INVADE BURNED PONDEROSA PINE FORESTS MORE INTENSELY AFTER PRESCRIBED OR

forests more intensely after prescribed or wild fires? CEE protocol 10-012. Collaboration for Environmental Evidence: www.environmentalevidence.org/SR10012.html. 1. Background Fire plays an integral role in ponderosa pine (Pinus ponderosa)-dominated forests by maintaining low tree densities, a diverse understory, sparse litter accumulation, and regulating many ecosystem processes (Weaver, 1951; Cooper, 1960; Hart et al., 2005; Laughlin and Fulé, 2008). Native ponderosa pine forests, which range from southern British Columbia south to northern Mexico, historically supported frequent, low-intensity fires that burned unevenly across the landscape. Starting in the late 1800s, land managers actively disrupted the historical fire regime in forests dominated by ponderosa pine. Ponderosa pine forests were heavily grazed by livestock, reducing the fine fuels generated by perennial grasses that carried surface fires through the system. The removal of perennial grasses by grazing also created germination sites for woody species, especially ponderosa pine seedlings, resulting in a denser canopy. The reduction in fine fuels and increases in woody species shifted the fire regime away from frequent surface fires to less-frequent crow