Forest fires are powerful agents of ecological change, linked to the amounts and types of fuels as well as to climate patterns such as the El Nino-Southern Oscillation (ENSO) and Pacific Decadal and Atlantic Oscillations. This project is an international collaboration with Mexican scientists Jose Villanueva-Diaz and Eladio Cornejo-Oviedo. A new network of long-term fire and climate chronologies will be developed together with analyses of fuel dynamics in northern Mexico. Unique relict sites that are among the least perturbed by modern human impacts, will be a key part of the chrono-sequences to be established. The study will reconstruct fire regimes for the past about 300 years using fire-scarred trees. Climate variables will be determined through tree-ring analysis and from data collected by field instruments, and forest structure will be directly measured.
The research will benefit both Mexico and the United States. Funding will support graduate and undergraduate students from both countries. In addition to scientific publications, the results will be interpreted and transferred to decision makers, including landowners, managers, and conservation organizations. The findings will increase understanding of the fuel and climate factors that regulate fire regimes and of how fire patterns might change in the future. They will have immediate relevance for conservation strategies in the biologically diverse forests of northern Mexico and the southwestern U.S.
" studied the patterns of forest fires, their ecological effects, and the degree to which climate regulates fire occurrence in one of the most biologically diverse regions of the world. Our research team included several U.S. and Mexican scientists, plus colleagues from South America and Europe. We sampled over 22 sites in five study areas of the Sierra Madre Oriental and Sierra Madre Occidental, in northern Mexico between 2007-2012. Over 1100 fire-scarred samples have been collected and analyzed with tree-ring dating (dendrochronology); numerous permanent field plots were established to measure trees, understory plants, and organic debris. Intellectual merit: this project approximately doubled the number of sites with data on fire, climate, and forest interactions, strategically locating the new sites to facilitate fire-climate analysis over a continental-scale network. Novel research findings published in peer-reviewed scientific journals to date include the first report of a change over time in the association between El Niño/Southern Oscillation (ENSO) events and fires (Ecology 2010), the least-disrupted surface fire regime encountered to date in North America (Ecological Applications 2011), a new plant species, and an innovative test of the relative importance of climatic vs. land management factors in controlling fire regimes across the U.S.-Mexico border (Ecology, in press). Five additional published papers reported fire, tree growth, and climate interactions at many sites across northern Mexico. Soon-to-be-published research presented in two doctoral theses in 2011 includes a comprehensive analysis of the climatic controls on fire across all of subtropical Mexico and documentation of ecological complexity in the form of mixed severity (lethal/non-lethal) fire regimes in Mexican Mountain Pine (Pinus hartwegii). In patches of unlogged forests that provide examples of natural conditions, we found that forest structures maintained by frequent surface fire regimes, including large old trees and snags (dead standing trees), provide key habitat for an endangered species, the Thick-billed Parrot. Our data showed that forests protected in a national park were older and more biologically diverse than nearby logged forests; we suggest that conservation can be enhanced by blending protection and sustainable use of forest resources in a regional context. Data have been contributed to the International Multiproxy Paleofire Database and the Fire And Climate Synthesis (FACS) project. Plant samples from previously unstudied sites have been contributed to 3 research herbaria in the U.S. and 2 in Mexico. Broader impacts: the research contributed to academic education, technology transfer, increased international research cooperation, development of Mexico´s national fire management policy, and public outreach. Two Ph.D. students, one a U.S. and one a Mexican citizen, were supported by this project and graduated in 2011. Another Ph.D. student (U.S.) and an M.S. student (Mexican) were partially supported. Three undergraduate students were supported with supplementary Research Experiences for Undergraduates funds. Two have graduated (B.S.) and the third is completing B.S. studies. Two Mexican students visited Arizona to learn analytical techniques for fire history; one of those former students is now the only scientist in Mexico specifically employed to investigate fire regimes using dendrochronology. The project led to numerous new contacts among U.S. and Mexican scientists, resulting in several new collaborative research proposals. One U.S.-funded proposal led to the first dendrochronological fire-climate study on Mexico´s tallest mountain, Pico de Orizaba. A Mexican-funded proposal is extending fire history research in several regions of the country. Several of us participated in meetings organized by Mexican ecologists and forest management officials to incorporate scientific findings in a revision of Mexico´s national fire management policy. We are also working with the U.S. Peace Corps in Mexico to share research findings with Mexican forest managers. Finally, the outreach effort from this research includes a bilingual website (www.eri.nau.edu/en/northern-mexico/overview). We have engaged resource managers through technical publications in Mexico and have given many oral and poster presentations at professional meetings in the US, Mexico, and Europe.
