|Writer’s Note: Over the past thirty years, animal species dependent on the ancient forests of the Pacific Northwest and elsewhere have dominated media headlines. The plight of those species dependent upon disturbances that include fire, flood, and windstorms is less well-known to the general public. What follows is an examination of the now-extinct lotis blue butterfly and the need to create and perpetuate—with fire, chainsaws, and heavy equipment—a vegetational mosaic for the benefit of all species.
Some Thoughts on Human/Plant Interactions
(The Lesson of Lotis Blue)
Our home sits in a clearing amid 3 acres of redwoods. Living close to these iconic trees is a mixed blessing. During my three decades in Humboldt County, I’ve seen many people immigrate to our area—as I did—from the San Francisco Bay area. I suppose it makes perfect sense to want to live in the redwoods when one’s experience includes yucca-and sage-dotted hillsides a stone’s throw away, as near Big Sur. However, those of us with a passion for passive solar homes and a need to dry out when the annual winter rainfall approaches 100 inches, have a term for home locations in the redwoods: “Pneumonia Gulch.”
Working as a wildlife technician, I can readily understand why old-growth dependent bird species get the majority of press. Figures vary from region to region, but a scant 1-10% of ancient trees remain. In addition, untouched blocks of habitat—be they willow/cottonwood streamside areas or redwood forests—can cease to function as they once did if the extent of habitat alteration nearby has reduced them to isolated, fragmented stands.
However, in my avocation as a birder and gardener, I occupy a somewhat different vantage point. For I know that the most diverse assemblage of birds and butterflies will be found in areas that have experienced some sort of disturbance, which, in turn, creates a mosaic of habitat types. Natural disturbances include landslides, fire, windstorms, and floods. Human-caused disturbances include activities such as logging, setting fires, and haying and mowing. It may come as a surprise that birders consider a redwood forest impoverished, relative to overall number of bird species.
The goal for our landscaping and gardening activities is to make areas already cleared of trees more suitable for pollinators that include bees, hummingbirds, butterflies, and sphinx moths (aka hawkmoths). The property adjoining ours has a large cleared area that formerly operated as a lumber mill. Bulldozers were used to level the site. Several dozen black cottonwood trees have colonized the disturbed areas near the mill. Few species of trees harbor more kinds of birds than willows and cottonwoods. In addition, the leaves of these two plants are utilized by the larval stage of several species of butterflies. The northcoast of California, dominated by conifers, lacks the flashy fall pyrotechnics of the Rocky Mountains or eastern hardwood forests. Even our dominant hardwood, red alder, fails to produce fall colors. Of our native species, willows and cottonwoods occupy a prominent place on the short list of species admired for their fall colors. Their contribution to soil fertility through annual leaf drop and the cottonwood’s leaf-quaking abilities—albeit muted relative to aspen—make it easy to see why they rank as two of my favorite trees.
Willows also are common in our neighborhood. However, they’re not the wetland-loving lowland trees that most often come to mind. Our local willow, Scouler’s, colonizes dry sites disturbed by logging or fire. For those unfamiliar with redwoods, these towering conifers quickly re-sprout when cut, sending tens, if not hundreds, of hedge-like shoots into the air. When we bought our place, there were a number of these willow trees, weakened and suppressed by redwood stump sprouts. In fact, I was unaware of many of the willows until they turned color during the fall.
Two years ago, I collected cottonwood cuttings from my neighbor’s trees. All but one cutting survived; the tallest is now eight feet. One day, while walking our dog Gypsy, I stopped to admire my neighbor’s cottonwood trees. To me, their presence on this relatively dry ridge is remarkable because I know of no others nearby. The wind-carried seeds must have traveled a long distance. Next to the cottonwoods, along the road, were a number of 3 foot-tall willows. As I continued exercising Gypsy, I reflected on our primary local disturbance mechanisms – turning each one over in my mind, as if they were layers of compost. Hmmm… massive windstorms are rare. Landslides and floods are nonexistent on our flat ridgetop. And substantial fires in the foggy coastal belt occur far less than one per century. Suddenly, it struck me: we humans were the only disturbance factor remaining; cottonwoods and willows would cease to exist in our neighborhood if we weren’t here.
Passionate debates over the fate of old growth-dependent wildlife species in the Pacific Northwest began in the 1970s. In the 1980s, concern mounted over the decline of neotropical migrant birds, chiefly in the eastern United States. In 1993, we learned of the rapid decline of grassland bird species when, at the Cooper Ornithological meeting, biologist Fritz Knopf presented the results of his analysis of 25 years of breeding bird surveys. He found that 16 of the 25 species most associated with grasslands were on a decline steeper than any other group of North American species, including neotropical migrants. Habitat loss—estimated at 60% in the shortgrass and 99% in the tallgrass prairie—was cited as one factor.
Starting around 1870, with the advent of homesteaders and cattle barons, those forces of disturbance—fire, bison, and prairie dogs—that had previously molded the Great Plains were subsumed. Some 60 million bison once reduced localized areas to dust, their dung fertilizing seedbeds soon to be colonized by a panoply of annual plants and grasses. Immense prairie dog towns and fires, both lightning and human-caused, were greatly diminished. These forces no longer contribute to the degree they did to create a mosaic of bareness and greenery. A scant 2% of prairie dogs remain and the vast herds of bison are but a dream.
Which brings us to a tale I term “The lesson of lotis blue.” The lotis blue, now thought extinct, was one of the rarest North American butterflies. Prior to European contact, the lotis blue was found in association with coastal peat bogs in two or three California counties: Sonoma, Mendocino, and possibly Marin. Since 1930, this species has been recorded at only one site, a sphagnum bog located under the Elk-Fort Bragg power transmission line operated and maintained by Pacific Gas & Electric Company (PG&E). The lotis blue butterfly was listed as threatened under the Endangered Species Act in 1976.
Within the former range of the lotis blue butterfly, natural openings had been maintained by fire, windstorms, and Roosevelt elk. More recently, openings have been created by timber harvest, bulldozing, and controlled burns. PG&E removed shrubby and woody vegetation along the power line right-of-way (r-o-w) from the late 1950s until 1976. In 1976, however, when the lotis blue was listed as endangered, PG&E ceased vegetation removal from the r-o-w. The company did so because the U.S. Fish and Wildlife Service was concerned that the company’s maintenance would further endanger the butterfly. Also, PG&E was mindful of complying with Section 9 of the Endangered Species Act, which prohibits “take” of an endangered species.
The lack of power line maintenance hastened the conversion of the site from open meadow to trees and brush. PG&E conducted a study along the power line r-o-w in 1990 to determine the butterfly's status. Intensive field surveys failed to locate the butterfly in any life stages. The sparsely vegetated patches and bare ground surrounding the bog had provided habitat for coast trefoil (Lotus formosissimus), the presumed principal host plant for larvae of the lotis blue. The coast trefoil is an early successional plant, disappearing once trees and brush become established. The literature is clear that plants such as Lotus, require sunny, open conditions, not dense forest. So, in part owing to the reluctance of a regulatory agency to allow the use of chainsaws, the lotis blue butterfly no longer flies.
Clearly, the “do-nothing” option for disturbance-dependent ecosystems is a death sentence, especially when they have been subjected to the synergistic effects of dams, a century of fire supression, overgrazing, the removal of top-end predators, and the introduction of exotic plants and animals. The preservation of biodiversity is an incredibly complex process. Decisions must be made on a case-by-case basis. The lesson of lotis blue teaches us that land managers must consider the full range of alternatives, which include prescribed fire, select harvest of trees, and carefully controlled grazing, if we are to steward a mosaic of vegetational patterns that benefit all plant and wildlife species.
Epilog: My “home range” in northern California has its own set of vegetation management problems. Our coastal grasslands once supported vast herds of Roosevelt elk. Although still present, the elk now are confined to several small state parks. Lightning rarely occurs but native peoples had an aggressive “controlled-burn policy” designed to favor grass over brushfields. Add some invasive exotic plants to the mix (cotoneaster, heather, gorse, scotch and french broom) and it’s clear to see why our area is losing grassy coastal areas, especially in areas where no grazing occurs.
One of my favorite places to hike is a state park that contains a coastal bluff known as Elk Head. Since there’s no camping permitted there, I often encounter no one during my early morning stroll in search of birds. Quite early one Saturday, I came upon two people in the parking lot and several more along the trail. “What gives?” I thought.” Pausing to scan for birds where the forest surrenders to a grassy, brushy headland, my binoculars framed several more people plus a generator and two huge speakers. “What the …?” I thought. I was so intent on inspecting the trampled, grassy meadow that I nearly stumbled over several people in sleeping bags.
A couple hand-in-hand walked toward me. “What’s up?” I said, with a sweep of my arm. “Oh, we had a rave here last night. Danced until the sun came up. We heard about it on the internet.” “Oh, OK,” I mumbled before continuing on my way. At first, I got a bit hot under the collar, as I recalled the trampled grass. But, where I live, with all its rain, grass is pretty resilient. By next spring, you wouldn’t even know they had been here. Anyway, the elk are gone and the residents of expensive oceanfront homes take a pretty dim view of setting fires. I smiled broadly, as the realization hit me. Unbeknownst to the dancers, they were carrying on a long tradition of keeping brush down in coastal grasslands.
Biological Diversity and Seral Stages: A Case Study of the Lotis Blue Butterfly (Lycaeides Idas [=Argyrognomon] Lotis. Sally de Becker, Mary Boland, and Richard A. Arnold. Published in Proceedings of the Symposium on Biodiversity of Northwestern California, October 28-30, 1991, Santa Rosa, CA
U.S. Fish and Wildlife Service. 1985. Lotis Blue Butterfly Recovery Plan [Lycaeides argyrognomon lotis (Lintner)]. Portland, OR. 46 pp.