University of Colorado at Boulder

Other Event

Tuesday April 25, 2017. 04:00 pm. University Memorial Center, Glenn Miller Ballroom

Wildfire regime shifts in Patagonian-Andean forest ecosystems: Feedbacks and consequences in the face of climate and land-use changes

Tom Veblen

Professor of Geography, CU-Boulder

The Distinguished Research Lectureship is among the highest honors bestowed by the faculty upon a faculty member at CU-Boulder. The lectureship honors a tenured faculty member widely recognized for a distinguished body of academic or creative achievement and prominence, as well as contributions to the educational and service missions of CU-Boulder.

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Abstract: In this public lecture I will summarize the development and the impacts of a forty-year research program on the dynamics of the native forests of southern Chile and Argentina. I will highlight some of the outstanding accomplishments of CU graduates in environmental research and education in Chile and Argentina, reflecting CU’s successful contributions to international education. Our research conducted on disturbance ecology in the late 1970s in the rainforests of southern Chile contributed prominently to the shift away from the equilibrium paradigms dominant globally in ecology in the 1960s and towards modern equilibrium frameworks of forest dynamics. The line of research on disturbance ecology which I initiated in 1975 in Chile and continued in 1979-81 in similar temperate forests in New Zealand revealed the roles of coarse scale disturbances by earthquake-triggered landslides, volcanism, extreme weather events, and fire in controlling the dynamics of these forests. This work in southern South America and New Zealand was important in refining older views of these forests as being out of equilibrium with contemporary climate (i.e. “relicts”), revising understanding of the effects of introduced browsing animals on forest structure, and guiding the development of appropriate forest management practices.

In the early 1980s with important start-up support from CU we initiated a long-term research program on the effects of climate change and wildfire on the forests of the Andean-Patagonian region. I describe how we developed the most extensive tree-ring fire history network in the Southern Hemisphere to understand how both people and climate variability have affected wildfire activity over the past four centuries. Recent upsurges in wildfire activity in the temperate forests of South America are driven primarily by climate change but once these forests are burned the post-fire vegetation is inherently more flammable and prone to subsequent fire spread. The effects of introduced plants and animals exacerbate this trend towards a more flammable landscape. Over an extensive north-south distance along the ecotone between Andean forests and the Patagonian steppe, fires driven by exceptional drought are transforming relatively fire-resistant old forests to more fire prone shrub land and grassland ecosystems which are flammable even in the absence of extreme drought—thus “fire begets fire” in these ecosystems.