Pinus contorta invasions increase wildfire fuel loads and may create a positive feedback with fire

• Autores: Taylor, Kimberley; Maxwell, Bruce; McWethy, David; Pauchard, Aníbal; Nuñez, Martin Andres; Whitlock, Cathy
• Año de publicación: 2017
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: BIOLOGICAL INVASION; FIRE; FUEL LOAD; INVASION IMPACT; INVASION THRESHOLD; PINE INVASION; PINUS CONTORTA; POSITIVE FEEDBACK
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Invasive plant species that have the potential to alter fire regimes have significant impacts on native ecosystems. Concern that pine invasions in the Southern Hemisphere will increase fire activity and severity and subsequently promote further pine invasion prompted us to examine the potential for feedbacks between Pinus contorta invasions and fire in Patagonia and New Zealand. We determined how fuel loads and fire effects were altered by P. contorta invasion. We also examined post-fire plant communities across invasion gradients at a subset of sites to assess how invasion alters the post-fire vegetation trajectory. We found that fuel loads and soil heating during simulated fire increase with increasing P. contorta invasion age or density at all sites. However, P. contorta density did not always increase post-fire. In the largest fire, P. contorta density only increased significantly post-fire where the pre-fire P. contorta density was above an invasion threshold. Below this threshold, P. contorta did not dominate after fire and plant communities responded to fire in a similar manner as uninvaded communities. The positive feedback observed at high densities is caused by the accumulation of fuel that in turn results in greater soil heating during fires and high P. contorta density post-fire. Therefore, a positive feedback may form between P. contorta invasions and fire, but only above an invasion density threshold. These results suggest that management of pine invasions before they reach the invasion density threshold is important for reducing fire risk and preventing a transition to an alternate ecosystem state dominated by pines and novel understory plant communities.
Fil: Taylor, Kimberley. State University of Montana; Estados Unidos
Fil: Maxwell, Bruce. State University of Montana; Estados Unidos
Fil: McWethy, David. State University of Montana; Estados Unidos
Fil: Pauchard, Aníbal. Universidad de Concepción; Chile. Universidad de Chile; Chile
Fil: Nuñez, Martin Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina
Fil: Whitlock, Cathy. State University of Montana; Estados Unidos