California White Fir

Abies concolor lowiana

The white fir is widely found across the mountains of the West, from the Colorado Rockies to the Coast Ranges of Oregon and south to the Baja peninsula. It has a number of geographically distinct varieties, one being the California white fir. A few pockets of the California white fir exist in southern California in the Tehachapis and Transverse and Peninsular ranges. In the Los Padres National Forest they are found primarily at high altitudes on the Mt. Pinos Ranger District in northern Ventura County.

The white fir is commonly found with other conifers, including ponderosa pine, Jeffrey pine, sugar pine, and incense-cedar. In contrast to other white fir varieties, the California white fir is more spire-like and narrow at the crown and has a darker, greener foliage (though it appears grayish and frosted when viewed from below.) They are also much larger, growing more than 240 feet tall.

All white fir have bark that changes with age, from light gray and smooth to dark brown and thickly furrowed. Their needles are strongly aromatic with citrus-like essential oils present, and cones are found only in the treetops and are tightly barrel-shaped, upright, and green in the summer turning brown when mature. Because cones are borne almost exclusively in the uppermost part of the crown, any top damage caused by insects, diseases, wind, or snow will reduce cone production. Large old trees are especially prone to such damage. Seeds are released as the cones disintegrate on the tree.

Wildfire suppression has allowed these shade-tolerant trees to mature in greater numbers. As taller conifer species grow old and begin to succumb to disease or bark beetles, white firs grow up to replace them and effectively shade out any new pines attempting the establish themselves under the canopy. White firs also act as a “fire ladder” because of their resinous foliage and retention of their lower limbs. They become a sort of incendiary device, allowing flames to reach up to the canopy, thinning out large pine stands that might otherwise escape smaller forest fires.

White fir is one of twelve Management Indicator Species (“MIS”) on the Los Padres National Forest. MIS are plants and animals that are monitored by the U.S. Forest Service because they indicate the effects of land use activities. There are 3 MIS to evaluate the health of montane conifer forests on the forest and white fir is one of them.

 

Threats

Strangely, it is the white fir’s association with all things merry (i.e. the Christmas holiday) that contributes to some of the threats it faces. These trees, often sold in the commercial Christmas tree business due to their neatly pyramidal shape and soft needles, face poaching threats each December as people illegally harvest them from Forest Service land. Forest Service officers report catching a couple tree rustlers a year, though they note many more trees illegally removed from the roadside. The penalty for taking one tree can be as much as $5,000.

Another link the white fir shares with the holidays is its display of mistletoe, though it is certainly not the tree’s idea of “decorating.” A parasitic plant, the mistletoe will grow as an infestation upon the tree, creating weak spots in trunk and limbs that can lead to breakage and often death. A study in 1990 found that as much as 1/3 of white fir stands are infected with mistletoe. It’s all part of the forest life cycle, with downed trees contributing soil nutrients and habitat for wildlife.

Dwarf mistletoe on a white fir. Photo John Guyon, USDA Forest Service

Other general threats facing the California white fir include wildfire, drought, beetle infestation, and various diseases like root rot and yellow cap fungus. Thin-barked, resin blistered, drooping lower branches makes young white firs highly susceptible to fire, and those trees damaged by fire are more susceptible to attack by insects and disease as fire scars serve as a point entry for a variety of diseases and organisms. Recent wildfires such as the Butler 2, Cedar, Day, and Slide have burned large areas in higher elevations of the four National Forests in southern California where white fir is abundant, leading to population decrease. Also the drought of 2003 likely decreased the overall tree density of white fir; for example on the San Bernardino National Forest, thousands of large and small-diameter firs died in the drought, especially those at lower elevations where the white fir had expanded owing to successful fire suppression.

ForestWatch will continue to work with the Forest Service in monitoring the twelve Management Indicator Species of the Los Padres, which the white for is one of, to gauge the health of our local forests.