If you drive Interstate 25 near Glorieta, you may have noticed something different along the median. In areas previously clogged with trees, you can now see through to the traffic on the other side. Hard-working crews have been thinning trees to prepare the area in case a wildfire moves through. New Mexico State Forestry Division’s Returning Heroes Wildland Firefighter and Inmate Work Camp Programs worked diligently over the summer to leave the healthiest trees, while removing many smaller, unhealthy trees and brush.
Why cut trees in the middle of an interstate? To improve the overall health of the forest and watershed by increasing water availability, improving ecological conditions, and reducing the risk of damaging events that kill trees.
Historically, these areas had fewer, larger trees with wide-open grassy areas and ample room to ride a horse through the forest. Far fewer trees competed for available water and nutrients, wildlife moved easily among the trees, and grassy ground cover protected the soils and conserved water.
In contrast, the small, crowded trees in today’s overstocked forests are more susceptible to insects, disease and wildfires like those that devastated parts of California and the Northwest this past summer.
Open forests with larger trees are more able to resist wildfire. Moreover, when fires do ignite in thinned areas, they tend to stay on the ground and spread slowly, burning grasses and smaller trees. They are not as hot, dangerous, or destructive as crown fires.
Wildfires can be ignited by lightning strikes, a dragging chain, cigarette butts, or equipment. Instead of creeping along the ground as in the past, fires in altered ecosystems, such as those around Glorieta and Santa Fe, can easily climb “ladder fuels” into the tree crowns and spread quickly, consuming all fuel and producing embers that can jump as much as a mile ahead to ignite surrounding forests.
Projects like the one on I-25 reduce the risk of wildland fire. This corridor is identified in the San Miguel County Community Wildfire Protection Plan as an evacuation route in the event of a wildfire. Restoring the median will make it more likely to remain open in such an emergency.
Thinning the median along I-25 also enables firefighters to use it as a firebreak. If a fire does start, it’s less likely to cross the interstate and spread through adjacent forests. This reduces the risk for everyone living along the I-25 corridor or who drives on the interstate.
The I-25 Median Project covers 100 acres of ponderosa pine and piñon-juniper forests. Funding comes from Gov. Susana Martinez’s Watershed Restoration Initiative. Since 2014, the state Legislature has allocated $12.2 million for 51 major watershed restoration and rehabilitation projects on 19 high priority public watersheds across the state.
New Mexico State Forestry coordinates thinning projects like this on state, tribal and public lands. The division assists private forest landowners with technical and financial assistance, and collaborates with other state, federal and tribal agencies, non-governmental organizations, soil and water conservation districts, and the private sector in collaborative groups such as the Greater Santa Fe Fireshed Coalition to restore healthy conditions to New Mexico’s forests.
Donald Griego is the New Mexico state forester. Alan Barton is collaboration program manager with the New Mexico Forest & Watershed Restoration Institute.