Lecture illuminates 400 years of fire

Nature Conservancy presents Harwood Museum talk by Dr. Ellis Margolis


The Nature Conservancy presents a free lecture by Dr. Ellis Margolis, a research ecologist with the United States Geological Survey’s New Mexico Landscapes Field Station based in Santa Fe. Margolis recently led a research team in a study of the history of fire patterns in the Taos mountains.

The team examined tree rings, historical photographs and the age of aspen stands to reconstruct fire patterns in the area going back 400 years. The research was funded by The Nature Conservancy with a grant from the Taos Ski Valley Foundation.

Margolis’ lecture will be given today (Jan. 18), 6:30 p.m., at the Harwood Museum of Art, 238 Ledoux St. Laura McCarthy, associate director of The Nature Conservancy in New Mexico will provide an introduction to Margolis and briefly discusses Taos area conservation projects.

Margolis and his team began their study of fire in the Taos mountains in 2016 and finished it in 2017. The study spanned about a year-and-a-half. It is the most recent, and the most comprehensive study of its kind to be done on fire patterns in the Taos mountains.

The research study collected samples from a relatively large area of three watersheds: the Río Hondo, the Río Pueblo de Taos, and the Río Fernando. Samples were collected from two types of sites: lower, drier ponderosa and dry, mixed conifer forest-types; and high alpine and sub-alpine forest types which are wetter, cooler and dominated by spruce, fir and aspen. Margolis said the study did not sample from the “big chunk of forest in the middle” of these two forest types.

In the lower, drier forest, evidence indicates that fire moved through the landscape with historically low-severity and relative frequency, said Margolis. Up at higher elevations, fires were less frequent but much more intense, he noted. These findings have important implications for forest management.

In the lower, drier ponderosa forest, Margolis said a good management strategy is to “thin out younger trees that grew in after fires stopped 100 years ago, and open up stands so crowns aren’t touching.” He recommended following thinning with controlled burns or prescribed lightning starts.

“Fire was this ubiquitous process that was part of the ecosystem for centuries or millennia,” said Margolis. “There are a lot of benefits for having fire in the system.”

One benefit is reducing the forest’s fuel load. “Having fire as part of treatment is one of the most effective ways to reduce subsequent fire intensity,” said Margolis. In addition, he said fire has other benefits, which ecologists are only beginning to understand. For example, “fire takes dead biomass and puts it in soil,” said Margolis. He added that certain grasses will flower once they have burned and smoke from fire can help to germinate some seeds.

“The challenging part is in upper elevation forests where historically those sub-alpine forests burn in big hot patches and burn to the ground. Whatever’s in the way could be in trouble. What do you do? Let people know you’re living in a place where there is this potential,” said Margolis. He stressed the importance of evacuation plans for alpine communities such as Taos Ski Valley.

The final progress report for the study, titled “Tree-ring fire history of the Taos Valley Watersheds, Sangre de Cristo Mountains, New Mexico” was released Oct. 25, 2017. The report indicated some of the patterns associated with fire in the Taos mountains. Seasonally, the study found that the vast majority of fires (90 percent) broke out in the spring and early summer. They usually took place in a drought year. Often the drought year or years had been preceded by wet conditions in prior years, which likely promoted the growth of surface fuels which helped the fire to spread across the landscape.

From 1600 to 1899 CE, the report stated, “mean fire intervals among sites ranged from 11 to 43 years but fires also re-burned sites as frequently as every two years, or as infrequently as 74 years.”

“Historic fire regimes collapsed across the study area in the late 1800s, leaving all sites without recorded fire for over 115 years,” the report stated.

Margolis received his doctorate in Watershed Management from the Laboratory of Tree-Ring Research at the University of Arizona, in Tucson. He joined the U.S. Geological Survey in 2015 and opened the only tree-ring lab in New Mexico, the New Mexico Dendroecology Lab. His research is focused on the interactions between fire, forests and climate and is used to guide fire regime and forest restoration for watershed management in the southwestern U.S. For more information about Dr. Ellis Margolis, visit usgs.gov/staff-profiles/ellis-margolis.

The New Mexico Dendroecology Lab uses tree-ring analysis to conduct landscape-scale research on the effects of climate variability on forest ecology, fire ecology and ecohydrology. The lab works closely with Bandelier National Monument and Emeritus Regents’ Professor Dr. Thomas Swetnam. The Lab was not the first dendrochronology lab in New Mexico, but it is the only one currently operating. For more information, visit usgs.gov/centers/fort/science/new-mexico-dendroecology-lab.