Wildfire and SageSTEP Research: an inevitable collision
By Jim McIver
In a matter of just hours, the Martin Fire swept down from the Goat Corral Mountains on July 6, 2018 near Winnemucca, Nevada – ballooning by nearly 88,000 acres overnight (figs. 1,2). Over the course of four days, it worked its way, sizzling and smoking, through 700 square miles of land in northern Nevada and was the largest fire in the U.S. at the time. At a staggering 54 miles across from east to west, the fire emitted a column of smoke that could be seen from space.
Although no lives or structures were lost in the massive wildfire, it had scientific implications, especially for SageSTEP. The fire burned completely through all treatment plots of the SageSTEP Owyhee site (fig. 3) one of six remaining treeless sagebrush steppe sites in the study. A satellite image of the burned area shows the Owyhee site well within the burn perimeter (fig. 1). This isn’t the first such event for SageSTEP sites. During the summer of 2007, the Castlehead site burned in the Murphy Complex Wildfire, just months before SageSTEP treatments could be applied. Of the sites with fully implemented treatments, Owyhee was the third site burned in wildfire since treatments were applied in 2006, 2007, and 2008 – joining Stansbury (2009 Big Pole Fire) and Roberts (2010 Jefferson Fire) as the next casualty of the seeming inevitable risk facing sagebrush steppe land in much of the Great Basin.
Over the years, other wildfires have burned close to or slightly into other SageSTEP sites. Last year, half of the mechanical plot of the Blue Mountain site also burned in the Steele Fire (46,000 acres burned in total). Over the years, wildfires have burned up to the edge of our Saddle Mountain site (2018 Wahluke Slope and Saddle Mountain Fires), Rock Creek site (2010 Poker Jim Fire), and the Onaqui site (2017 Onaqui Complex Fire). All told, of 20 original SageSTEP sites, 8 of them, or 40%, have experienced wildfire, either within or adjacent to their plots in the 12 years since the project began. This certainly demonstrates the primacy of fire in sagebrush steppe country of the interior west, especially in recent years – but what does it mean for the research?
Of the four fully implemented sites that have now experienced wildfire within plot perimeters, one site (Blue Mountain), will remain in the study. This is because only half of one plot (mechanical) at Blue Mt burned, and thus we can continue with our monitoring in the other half of that plot. However, Stansbury, Roberts, and now Owyhee must now be dropped from the original study, because wildfire has erased the initial experimental design, and replaced it with a more severe disturbance. But despite losing these sites as part of the SageSTEP experiment, all is not lost, because much can be still learned from the sites that burned. For example, the Stansbury site burned in the Big Pole wildfire in 2009, just weeks after sampling. The site was treated in the late summer and fall of 2007, and so before the wildfire we had one year of pre-treatment data (2007), and two years of post-treatment data — year 1 (2008), and year 2 (2009). Furthermore, the prescribed fire treatment was the most effective among all woodland sites, with 95% of juniper trees killed, and nearly all of the down woody material consumed. The mechanical treatments, both clearcut and mastication, were similarly well implemented. Thus, we had a great opportunity to evaluate the effects of a severe wildfire burning through areas treated with ‘fuel-reduction’ methods. We’ve written about the results at Stansbury in a previous newsletter, but generally speaking, we discovered that only the prescribed fire treatment significantly reduced wildfire severity: not only did data loggers survive in that treatment compared to the three others, but perennial bunchgrass survival was higher one year after wildfire in the prescribed fire plot. More likely than not, it is the removal of fuel on the ground that explains the significantly lower fire severity in the prescribed fire plot. Other interesting results have been discovered at the Roberts site as well, emphasizing that these burned sites have substantial value in understanding wildfire effects.
SageSTEP scientists have made the decision to continue monitoring all burned sites – even though they can longer be included in the mainline experiment – because of their value in assessing wildfire effects on treated and untreated plots. After all, we’ve got very robust pre-fire data, and it makes sense to take advantage of that when sites burn.
Researchers taking a soil core sample.
Soil core sample.
Dpt. Fisheries & Wildlife
Oregon State University
Corvallis, OR 97330
GB Rangelands Research
USDA Ag. Res. Service
Reno, NV 89512
(775) 784-6057 ext. 233