Wildfire is a natural and necessary part of many ecosystems.
On an ecosystem timescale, the disturbance caused by fire can increase available nutrients, spur regeneration, and promote diversity. On a human timescale, fire can threaten our homes, destroy places we love, fill skies with smoke, and blacken rivers. For the majority of the 20th century, we prioritized the human timescale by striving to put out every wildfire. But this option has proven to be unsustainable. For forests historically adapted to frequent fire, the increase in fuels from a policy of fire suppression means fires burn hotter with more severe effects to vegetation, soils, watersheds, and wildlife. In addition to impacts from suppression, climate change is making fire more common and less predictable across forest types.
More than anything else, wildfires are driven by weather and climate. During extremely hot and dry periods, aggressive forest thinning or large-scale fire breaks may be futile in stopping a fire driven by high winds. Climate change is making hot and dry conditions more common. Conditions that might have only happened once every 25-50 years are now occurring every ten years1. Higher temperatures also mean less spring snow and earlier snowmelt, increasing the risk and duration of wildfires.
In Colorado, most wildfires occur between spring meltout and the start of summer monsoons. All ten of Colorado’s largest wildfires occurred during this time period. In many years, snow on the ground keeps water in the soil until the monsoons come. In years with low snowpack or early snowmelt , there is a dry period between when the snow melts and monsoons begin. During 2018, low snowpack and late monsoons created the perfect recipe for higher fire danger.
The conditions in the late spring and summer of 2018 led to the largest wildfire season in Colorado since 2002. Fires of varying size and intensity burned in all areas of the State. The largest was the Spring Creek Fire which burned 108,000 acres, making it the third largest recorded wildfire in Colorado history and the most destructive of 2018. The Spring Creek Fire burned more than 140 homes and damaged numerous others.
Lake Christine Fire
This year the Roaring Fork Valley witnessed its most significant wildfire since the Coal Seam Fire in 2002. The Lake Christine Fire which was ignited on July 3rd by tracer rounds fired at the Basalt Shooting Range has burned over 12,000 acres of forests and shrubland and three homes. The fire burned primarily through Pinyon-Juniper forest and while the flames have mostly subsided it’s impact will be felt for years to come.
Different forest have evolved to very different fire regimes, or frequency and severity of fires. Some forests such as lodgepole pine have adapted to relatively frequent fire and are able to quickly recover quickly. Pinyon-juniper forests on the other hand have evolved to long periods of time between fires (as much as 400-500 years) and are typically slow to recover to their previous condition.
Pinyon and juniper are some of the hardiest trees in the southwest. Many of us at one time or another have been amazed to find a pinyon or juniper in what seems like an otherwise barren desert. Because of this they often lack the fine fuels like grasses often necessary to carry flames after an ignition. When pinyon-juniper do burn it’s often high severity, and without frequent fires their seeds haven’t evolved to survive fires.
Without nearby seed sources areas that burn can take decades to recover to their previous state. In areas where human aided restoration doesn’t occur we can expect several years of grasses and forbs followed mountain shrubs like Gambel oak, sagebrush, and mountain mahogany. Slowly pinyon and juniper, with the aid of wildlife carrying seeds, will make their way back, but this could take 50 years or more. Throughout this process we’ll likely witness an influx of wildlife to the area, throughout the valley shrublands provide important fall and winter range for deer, elk, black bears, and numerous birds.