Don Falk

Professor
Don Falk portrait

School of Natural Resources

Dr. Falk’s work focuses on three general areas: fire regimes, disturbance interactions and fire-climate relationships, and restoration ecology. Most fieldwork is conducted in western North America, including ongoing programs in New Mexico and Arizona. New initiatives include fire history and fire-climate analysis in the North American Great Basin and the Sierra Madre of Mexico.

One set of questions addressed in Falk’s lab revolves around the mathematical foundations of fire regime reconstruction and the development of analytical tools for fire history. A central case concerns the existence of scaling relationships in fire regimes, a problem not previously studied systematically. We also work on probability models for surface fire regimes and mathematical theory for sample size analysis in fire history.

A second emerging area of interest is fire-climate relationships. Collaborating with Dr. Swetnam, we use multivariate methods to understand persistent cross-scale patterns of synchrony in fire regimes of the western US. Collaborators include Rocky Mountain Tree-Ring Research, the US Forest Service Fire Sciences Laboratory, and Northern Arizona University. A new project funded by the Joint Fire Science Program links fire history, fire behavior, and land management practices in forest-grassland ecotones of the Valles Caldera National Preserve (VCNP), New Mexico. This project will attempt to reconstruct the ecotonal fire regime using remnant tree-ring evidence, and to infer spatial patterns of fire spread and climate regulation. The USGS Jemez Mountains Field Station is a central collaborator. In 2006 we initiated a program of fire history and climate work in the North American Great Basin, the largest area of the western United States lacking a basic network of fire history sites; the region is also located pivotally with respect to the “dipole” of the El Niño Southern Oscillation (ENSO) teleconnection in North America. We are beginning fieldwork in 2007, with collaborators in the Bureau of Land Management and US Forest Service.

The Falk lab collaborates with Dr. Ann Lynch, US Forest Service, Rocky Mountain Research Station (RMRS), to study disturbance interactions in the Pinaleño Mountains, Arizona, one of the highest “sky island” ranges, supporting high-elevation spruce-fir forests as well as extensive areas of mixed-conifer and other forest types. Our work combines reconstruction of historical fires, insect outbreaks, tree demography, and the role of climate variability in regulating short- and long-term forest dynamics.

In restoration ecology, a key project was a book addressing the theoretical basis for the science of restoration ecology. Falk collaborated with Joy Zedler (University of Wisconsin), Margaret Palmer (University of Maryland), and more than 20 colleagues to assemble the first book on this subject. Foundations of Restoration Ecology was published by Island Press in 2006.

In the field, the Falk group has been working on forest and fire regime restoration at Monument Canyon, New Mexico since 2003. We have established a plot-based program of annual monitoring of tree condition, understory diversity, and other variables. 230 ha were thinned in 2005-6 following a “process-centered restoration” model designed collaboratively with the Santa Fe National Forest (SFNF). We are also continuing a longitudinal study of old-tree responses to drought and competition in collaboration with the USGS Jemez Mountains Field Station, and a study of ecophysiological response of old trees to competition and release in collaboration with Los Alamos National Laboratory. A new restoration project linking forest thinning, fire behavior models, ecophysiology, and restoration of the fire regime is beginning in the Sangre de Cristo Mountains, New Mexico. This project, also with the SFNF, will use strategically-placed thinning treatments (“SPLATS”) followed by reintroduction of fire. Our lab’s role includes monitoring of treatment effects on old trees, as well as expanded fire history and post-treatment responses.