We’ve all noticed; trails throughout the region have been closed due to fires and flooding for more than a year now. But what does this really mean, the fire’s out and the flooding has dissipated, so why all the continued closures? Each land management agency has their own specific reasons for the closures impacting our region and they should be contacted directly if you have specific questions. However, there are a multitude of ecological reasons trails and open areas should remain closed following disturbances, especially after a wildfire. Read below to learn more!

Ecological Concerns:

Fire has many ecological consequences that can be exacerbated by the premature re-introduction of visitors to an area.

A hydrophobic layer will often form in soils that are exposed to fire in this region. Hydrophobic soils occur when a water-repellent layer is created within soil layers. This layer prevents water from percolating into the soil, decreasing water infiltration and increasing overland water flow. Increased overland water flow can displace sediment on hillslopes, creating gullies upstream and sediment deposition in downstream reaches.  This layer can also make it more difficult for seeds to germinate by preventing rooting and access to moist soils. Additional disturbance, such as people walking on hydrophobic soils, can cause an even larger increase in displaced soils and unnecessary damage to hillslopes and downstream reaches. 

The absence of vegetation on fire-scarred slopes causes serious negative impacts to soils. Without foliage to intercept them, raindrops directly hit soils, causing displacement. The combination of hydrophobic soils and a lack of vegetation to absorb some moisture can cause extreme increases in the quantity of water moving through a watershed. The water must go somewhere and without the ability to absorb into soil or vegetation, it tends to move downstream very quickly, in fact, post-fire flooding can be anywhere from 10-100x worse than in undisturbed areas.

Sensitive soils are slow to recover and newly germinated vegetation can be easily re-disturbed with just a few footprints.  The more time we can leave soils undisturbed, the faster vegetation will re-establish. The quicker vegetation re-establishes, the safer downstream areas will be!

Fire-scarred landscapes are at an early successional stage and are often more susceptible to non-native species invasions. Since fire typically damages or destroys much of the above ground vegetation, the opportunity for new species to invade is high. If non-native species invade the site native species may have a tougher time reclaiming the area. Unfortunately, visitors to the area and their pets can unintentionally transport non-native seeds via cars, shoes, clothing, and fur.

Of course, don't forget that fire is a completely natural process in our ecosystems and can make a forest more resilient to stressors by removing unhealthy trees, increasing and recycling nutrient availability, creating breaks in the canopy to allow light to reach the forest floor, and increasing the diversity and abundance of native understory plant species.

Here is a list of native species (good plants!) that tend to benefit when exposed to a fire or smoke:

• Wild geranium
• Aspen
• Golden Smoke
• Front Range Beardtongue
• Fendler’s ragwort
• Spreading Dogbane
• Fireweed (pictured)