The Members' Journal

Welcome Ken Burns fans!

Other contributors include Yosemite Ranger Shelton Johnson, who appears in every episode of the film, as well as Kimi Kodani Hill, who describes how Yosemite inspired many of the most famous paintings of her grandfather, Chiura Obata, and Pamela Wright Lloyd, daughter of pioneering biologist George Melendez Wright, whose ideas about conserving wildlife laid the foundations of present park system protections. Both Hill and Lloyd are continuing the Yosemite legacy of their families as Yosemite Association members.

We would like to send you a complimentary copy of this special “America’s Best Idea” edition as an invitation you to join the Yosemite Association. Since 1923, the Yosemite Association has helped the park’s strongest supporters deepen their connection and contribute to the protection of this national treasure. To request a copy, please send an email with your name and address to bestidea@yosemite.org

As a member, you will receive Yosemite, the journal of the Yosemite Association, three-four times each year. It's full of articles about Yosemite's history, natural history and current events. It also includes information about volunteer opportunities and special member events. There is no other journal devoted to Yosemite that combines up-to-date news, with general information for park lovers and visitors.

To download the Spring/Summer 2009 Special Edition Annual Report issue of Yosemite in PDF format, please click here. (The file is 6.5 mb,so it may take some time to transfer.)

Sample articles from earlier issues of Yosemite:

Invasion of the Aliens
By Jeff Lahr

It’s morning in the high country. The sun slowly rises above Mount Dana. High in this alpine environment, the white-tailed ptarmigan searches steadfastly for a morning meal of seeds and leaves among the sparse alpine plants. Nothing could be more natural...

A few hours later, the sun shines brightly in Yosemite Valley—dew-covered meadows shimmer in the light. These pristine valley meadows appear to look pretty much as they have for hundreds of years. Another natural scene…?

Actually, both of these are examples of what is not natural in the park, despite appearances. The ptarmigan among the rocks and some of the meadow grasses are alien to Yosemite’s ecosystem where they now flourish.

They are examples of floral and fauna invaders-—unnatural members of the environment. There is evidence that our national parks are hosts to a rapidly growing assortment of exotic forms of life that can alter, and in some cases, destroy the habitats of native plants and animals.

These intruders go by several aliases: alien, exotic, invasive, introduced, non-native, and noxious. No matter what they are called, they are a threat to native natural environments. Non-native plants can outcompete native plants, shrink available habitat for wildlife, and limit diversity by creating monocultures. Many scientists believe that invasive organisms are one of the greatest threats to biodiversity.

The scope of the problem
It isn’t just the naturalists in the national parks who worry about the impact of these foreign plants and animals. The concern about non-native species is shared through the federal departments of the Interior, Agriculture, and even Commerce. The damage can be seen economically as well as environmentally. Accordingly, President Clinton proposed for the 2000 federal budget a $29 million increase that is earmarked for the reduction and control of non-native plant species. In a statement issued in February of 1999, President Clinton stated, "Some experts estimate the cost [of alien species] to the American economy to be as high as $123 billion per year…I urge Congress to join us in protecting our economy and our natural heritage against the threat of non-native species."

Secretary of the Interior Bruce Babbitt mirrored the President’s sentiments. "The invasion of noxious alien species wreaks havoc on the environment and the economy… These aliens are quiet opportunists, spreading in a slow motion explosion… Weeds infest 100 million acres in the U.S., spread at 14 percent per year, and—on public lands—consume 4,600 acres of wildlife habitat per day."

Is the problem as serious in Yosemite National Park as is suggested by the concern shown nationally? Definitely, says Sue Fritzke, vegetation resource manager, who estimates that there are more than 180 introduced plant species in Yosemite, representing over 10% of the total park flora. The number of identified non-native species has doubled in the last ten years (due in part to more exotics but also to a growing awareness of the problem of non-native plants). Although the numbers aren’t as high, similar problems exist for non-native animals.

Unwelcome guests
All living things have a home in some corner of the world. In their native habitats, plants and animals evolve under certain conditions. Within that environment are factors that limit the species’ growth and population. These natural parameters help maintain a balanced ecosystem and a healthy distribution of that species. When some species are transported into a foreign environment, they have opportunities to grow at an unnaturally fast rate. In other words, these non-native species are often able to outcompete native plants and animals that are subject to the growth-limiting factors of their own environment.

The different ways an exotic plant species can effect a natural area are numerous. They can:
* displace the native plant species;
* degrade the biological diversity of a natural area;
* alter the soils’ chemical make-up, moisture-holding capabilities, and erodibility;
* hybridize with native plants to change their genetic make up, leading to changes in the species’ ability to cope with natural stresses such as drought or insect infestation;
* harbor toxins poisonous to native animals.

Although many of these invaders are hazardous hitchhikers from other countries, this is not always the case. A plant may be labeled non-native, even if it is from our own country, if it is foreign to the environment in which it now grows. Whether foreign or domestic, exotic species have been called "biological pollution" by environmental experts.

Ptarmigans and Cowbirds
The white-tailed ptarmigan is a bird found naturally in arctic and alpine regions of North America, but not in Yosemite. Originally released as a game bird on the eastern side of the Sierra Nevada, the ptarmigan has established itself in the subalpine regions of the park.

Annual plants growing at high elevations have only a few weeks to mature, flower and produce new seeds for the following season. The ptarmigan’s appetite is suspected of reducing the number of seeds available for the following year’s flower crop and altering the intricate balance of the ecosystem above treeline. High elevation plant communities can take years to recover from this kind of effect.

Another non-native bird is a threat in the lower elevations. The cowbird is an innocuous looking species, sometimes confused with a blackbird. Like blackbirds, they are attracted to areas near horses and stables where they dine on the undigested seeds found in horse manure. Cowbirds are considered nest parasites. Instead of hatching their own young, they lay their eggs in the nests of other species and let those foster-parent birds raise the young. The cowbird hatchling is typically bigger than those of the host species, so the parent birds work overtime satisfying the young cowbird’s large appetite while their own offspring starve to death. A cowbird can lay up to forty eggs a year. The impact is felt especially by smaller species of birds, such as the yellow warbler, solitary vireo and warbling vireo.

Early Warning
The impact of exotic plants and animals has been in the headlines for several years, but early warnings were sounded nearly seventy-five years ago. Dr. Joseph Grinnell, the first Director of the Museum of Vertebrate Zoology at Berkeley, was an early advocate for eliminating exotic species of animals from the national parks. In 1928, Grinnell addressed a conference of national park superintendents. In his remarks criticizing decisions to introduce non-native animals into national parks, specifically the introduction of elk in Yosemite, he stated, "According to well-known biological law, the introduction of any non-native species is bound to be followed by the disappearance of some native species with which the alien competes."

But the arrival of the first non-native plants occurred long before Dr. Grinnell’s outspoken advocacy of maintaining pristine ecosystems. Non-native plants were introduced into Yosemite Valley with the arrival of the first pioneers. As non-Indians settled in the valley, they quickly planted hay and other fodder for livestock in the valley’s meadows. Since that time the problem has grown more complex. Today, seeds from non-native plants can enter the park through a variety of ways such as in the tread of a car’s tires, in the bottom of backpacks and other gear, or in the fill dirt used during roadway building and other construction work.

Attempting to control these out-of-control aliens require the efforts of a small legion of volunteers as well as park resource management employees. Currently about fifteen species of exotic plants are being managed. The top five troublesome species in Yosemite are spotted knapweed, yellow star thistle, Himalayan blackberry, bull thistle, and common mullein. Those plants have been identified as most invasive, but there are many more: tumble mustard, puncture vine, black locust, tree of heaven, oxe-eye daisy, foxglove, scotch broom, to name a few.

Yellow Star Thistle
Yellow star thistle is a very aggressive non-native that has spread across California in the last several decades. According to a 1998 study by the California Department of Food and Agriculture, yellow star thistle now covers more than 22% of California, over 20 million acres. Not surprisingly, the thistle has worked its way up into the Sierra, and it now ranks as one of Yosemite’s "big five" plant menaces. This obnoxious weed quickly dominates any area it invades and has become prolific in the El Portal area.
Yellow star thistle is an annual plant varying from 6 inches to 3 feet in height and is easily recognized by the star-shaped cluster of spines surrounding a yellow flower. Each plant can have a few flowers up to hundreds. It is a prodigious seed producer, pumping out as many as 29,000 seeds per square meter. Yellow star thistle kills off competitors in part by sending a tap root as deep as eight feet into the ground and sucking the moisture out of the soil. Some scientists believe that the plant may also emit a substance called an allelochemical that stunts the growth of nearby plants. Star thistle not only displaces native plants but also native animals that depend on those plants such as deer, quail, rabbits, skunks and raccoons.

Yellow star thistle is the focus of the infamous June Work trip called the "Weed Warriors." Each year, a small but dedicated group of YA members braves the summer heat to attack the plant by pulling it out by hand in various parts of the El Portal and Foresta communities.

"We don’t have the resources to deal with all the exotics," said Sue Fritzke. "Some plants, such as the meadow grasses are more benign than, say, bull thistle. Grasses still provide meadow habitat, whereas bull thistle quickly forms monocultures lacking wildlife habitat and biodiversity. We will expend our resources on those plants that threaten the natural diversity found in the park’s most sensitive ecosystems. Wetlands and meadows are most susceptible to foreign take-overs. These ecosystems also are the natural homes to some rare species that show a greater sensitivity to encroachment of foreign competitors."

The Vegetation Management staff works diligently to keep new plants from being introduced into the park, but removal of existing non-natives can be time consuming and expensive. Many require removal by hand. In 1999, approximately 2400 volunteer hours were dedicated to the removal of unwanted plants. Volunteers from the Yosemite Association and Yosemite Fund work crews, students and teachers with the Yosemite Institute, Yosemite Concession employees and other service organizations all participated in the effort. Without the help of volunteers, efforts to control non-native plants would be seriously hampered.

The "Weed Warriors" trip that attacks star thistle yearly is part of a unique program of cooperative workweeks that occur each summer. These trips involve four of the park partners: YA arranges for members to serve as volunteers and coordinates planning, Yosemite Institute provides staff who direct campground activities for each group and also handle food preparation, Yosemite Concession Services underwrites some of the expenses, and the National Park Service plans the projects and leads the work in the field. This successful program which combines hard work with great camaraderie is in its thirteenth year. Its participants point with pride to many areas throughout the park that reflect their industrious efforts from previous years.

Life member Georgia Stigall began working as a volunteer in 1989 and participated in numerous YA work trips. Now she volunteers for the NPS Vegetation Management program and coordinates an independent workforce of weed whackers and thistle snippers who average 1,000 hours of volunteer time each year. Many hot summer days are spent in the effort to rid the park of exotic species.

"Volunteers return year after year because they want to give something back to a place that is so special to all of us," said Stigall. "This work can be physically demanding, but we always have a good time!"

If the parks are to be successful in restoring the integrity of the native environment, there must be adequate funding so that the issue of non-native plants and animals can be addressed.

"I’d love to have enough funding to support a full-time crew of five. We are getting money through the fee demonstration program for a three-person seasonal crew starting next year for four years, but I’d like to augment the crew with additional staff and extend seasons to nearly year-round," says Fritzke. "This would be another $35,000-$50,000 per year—pretty steep, but if we want to manage those species that are best controlled during the spring and fall shoulder seasons, that’s what we would need."

With sufficient funding, the task of eradicating non-native species could be met head-on by resources managers, their staff, and concerned volunteers. These unsung heroes play a crucial role in preserving the natural environment that makes Yosemite a national treasure.

Lessons Learned
It’s clear that our national parks are important not only for their recreational value, but also for their role in preserving regional ecosystems. As Dr. Grinnell remarked decades ago in his book, Animal Life in Yosemite,
The longer we study the problem, the clearer it becomes that in the natural forests, which happily are being preserved in our National Parks, a finely adjusted interrelation exists, amounting to a mutual interdependence, by which all the animal and plant species are within them able to pursue their careers… Each [native] species carries on its existence in perfect harmony on the whole with the larger scheme of living nature.

Jeff Lahr is a ranger naturalist in Wawona each summer and teaches social studies at the junior high level in Santa Maria.

Editor’s note: For information on worktrip locations and dates for 2001, click here, or call the YA office at (209) 379-2317. People interested in working with Georgia Stigall can contact her by email, by phone at (650) 941-1068, or by mail at 17287 Skyline Blvd. #102, Woodside, CA 94062