The west is ablaze

Much of the western United States has been on fire this summer. Affected landscapes range from California chaparral to temperate rainforest in the Pacific Northwest. Fire danger appears to be elevated this year because of the convergence of a few important factors. First, much of the western US (but particularly California) has been experiencing severe drought over the last few years. Second, climate change continues to steadily result in higher land temperatures year over year. And finally, western forests have been subject to a long history of fire suppression by management agencies that have left more fuel than would otherwise be present.

Fire is a natural part of some ecosystems. In fact, certain plant species are dependent on fire for establishment of juveniles or completion of their life cycle. Examples include many species of pines and the giant sequoia of the Sierra Nevada. The latter species requires high light and fires help clear out competitors that might shade young sequoias.

Stebbins Cold Canyon Reserve in spring 2014 with
pine, oak and chaparral habitat.

Unfortunately, fire management policies have exacerbated the threat of large intense fires in the west. During the early decades of the 1900s, fire was suppressed at all costs. In some cases this may have led to the excessive buildup of fuels in dense forests. Once the importance of fire to some native ecosystems began to be better understood, land management agencies such as the US Forest Service recognized the importance of allowing some fires to run their course. Despite this change in attitude about fires in western ecosystems, fires are still managed in many cases. Continued encroachment of human development deeper into forests or other wildlands increases the likelihood that a fire will need to be suppressed to protect human infrastructure instead of letting it runs its natural course.

The Wragg fire was a moderate sized fire that ignited earlier this summer and burned through chaparral and pine forest habitat along state route 128 in the coast range hills of northern California near Lake Berryessa. The fire consumed the whole area of the Stebbins Cold Canyon Reserve, a small University of California research reserve where I have been hiking several times over the last decade.

Stebbins Cold Canyon Reserve protects a north-south oriented canyon in the hills of the northern California coast range. It is an example of relatively dry coast range habitat, with a mixture of chaparral and oak and pine woodland. The valley floor has a small creek with riparian habitat and the valley slopes are spotted with oaks and pines and manzanitas.

My most recent hike at the reserve was during April 2014. Monkeyflowers, Brodiaea, Castilleja and Dichelostemma were in bloom at the time. The most striking plant I observed was the heartleaf milkweed, Asclepias cordifolia. Emerging stoutly a half meter or so from the short groundcover of grasses, it had slate green fleshy opposite leaves and bright purple flowers. The magenta petals were slightly reflexed (bent backwards) and contrasted vividly with white hoods that form little loops around the center of the flower.

Habit and flowers of Asclepias cordifolia, heartleaf milkweed, spring 2014.

Cold Canyon in late August 2015, after the Wragg fire.

The Wragg fire however, transformed the landscape dramatically this summer. Although the Reserve is currently closed to visitors, from the highway it is possible to see the scorched hillsides. The ground was blackened and trees stood like ruins on the hillside. Looking closely, I could see that not all vegetation was equally affected; many trees had at least some green in their canopies, suggesting tree damage, but not complete mortality. Of course, the soil retains a seed bank and perhaps individuals of some species escaped mortality if the fire moved quickly through an area. It will be very fascinating over the next few years to hike the trails again and observe how the ecosystem recovers.

References

- Eckenwalder JE. 2009. Conifers of the World. Timber Press, Portland.

- Forest History Society. U.S.Forest Service Fire Suppression.

- Harvey HT. 1978. The sequoias of Yosemite National Park. Yosemite Association, Yosemite National Park, CA, 36 pp.