Nature Notes

Volume XXV - 1994

Taking Inventory at Oregon Caves
By John Roth

Effective monitoring, mitigation, and restoration of important resources can be done only if good inventories exist. Few caves, however, have good inventories. This is because many of them are very diverse, often difficult to access, and represent an alien environment to most people.

To close this data gap, volunteers from EARTHWATCH helped National Park Service staff et Oregon Caves complete the first comprehensive inventory of any large federal cave in the United States. One of the difficulties in conducting inventories is that definitions sometimes set arbitrary limits, but this one is flexible enough for use in other caves. As a result, inventory items for Oregon Caves were developed from a standardized 400 word glossary which caters to site-specific needs, yet allows for comparisons of those features that many caves have in common.

Several important correlations became apparent during the inventory. One of them involved finding the largest passages correspond with fault directions and the direction water flows the fastest, or steepest hydraulic gradient. This helps explain why Oregon Caves is so big in comparison to nearby caves.

Inventory teams also found marked breaks between the dimensions of some cave features which allow more sophisticated comparisons to be made. Similar features, such as parallel ridges among microgours in flowstone and those occurring in rimstone dams, can be separated by breaks in averaged measurements or by different distributions. For example, microgours usually range up to one quarter of an inch in size while the low end measurements of rimstone dams are about one inch. Consequently, flowstone and rimstone can be better indicators of localized differences in the cave's hydrology. This is possible because flowstone is formed by water slowly seeping between rock layers in contrast to rimstone dams following stream flow.

More information is now at hand concerning the magnitude of direct human impacts on cave formations. "Cave slime" are actinomycetes bacteria, which appear as small white spots on walls. This bacteria is less evident along the tour route, leading to the supposition that bacteria feeding on lint from clothing may be outcompeting cave slime. There are also fewer white formations on the tour route than elsewhere in the cave. Skin oils and smoke from torches decades ago have certainly contributed to this situation.

Now that the inventory has provided some insight on human impacts at Oregon Caves, cleaning and repair of formations has begun. Tons of rubble from previous trail building efforts have already been removed. These measures are part of a restoration effort and will enhance future visits to the cave.

An Overlooked Legacy at Oregon Caves
By Steve Mark

Virtually all of the structures at Oregon Caves National Monument are sheathed in bark of the Port Orford-cedar, Chamaecyparis lawsoniana. This detail is part of a site design aimed at blending buildings with their surroundings. Port Orford-cedar (the name is hyphenated because it is not a member of the genus Cedrus, or true cedar) occurs from the eastern Siskiyou Mountains to the coast. Although its relative abundance at one time has been greatly reduced by disease, fire, and logging, a number of stream drainages in the vicinity of Oregon Caves contain enough cedar to draw tree lovers.

Oregon Caves Chateau
All buildings at Oregon Caves Natonal Monument are sheathed in cedar bark, including the Chateau, seen here in this 1937 photo by Francis Lange.

Below the cave entrance area, Port Orford-cedar can be seen on Cave Creek as you leave the monument and follow the trail toward Cave Creek Campground. The remaining trees are along the fringe of several clearcuts, but there are enough of them to make a worthwhile walk. In this part of the Siskiyou National Forest, Port Orford-cedar is found in riparian areas or places where seepage is a foot or less below the surface. The tree can be identified by elegantly sweeping boughs and lacy foliage, as well as by a red brown fluted bark that can weather to a slight silver tinge with age. In this setting, Port Orford-cedar is often associated with an attractive understory of Pacific rhododendron, Rhododendron macrophyllum, or western azalea, R. occidentale.

Many visitors to Oregon Caves are unaware that they can see Port Orford-cedar on the trail to Big Tree. The "cedar" occurs throughout this part of the monument's mixed conifer forest, though many visitors focus on the large Douglas-fir, Pseudotsuga menziesii, such as Big Tree or sugar pine, Pinus lambertiana. A young stand of cedar can be seen amid the Douglas-fir and Bigleaf maple, Acer macrophyllum, in Panther Creek downslope of Big Tree with some off-trailhiking. More impressive stands can be seen by taking the longer segment of the loop trail to Big Tree. Although sometimes steep, this route also provides access to Mount Elijah or a return to the cave entrance area.

The most serious threat to Port Orford-cedar's survival throughout its range is the pathogen Phytophthora lateralis, a root rot fungus. It has infected several stands just three miles from Oregon Caves, killing a number of trees. The cedar is particularly susceptible to Phytophthora's waterborne spores because its roots intermingle with those of other trees in drainages downslope of where infection has occurred. U.S. Forest Service researchers hope that Port Orford-cedar's genetic variability may allow for some resistance to the disease even in heavily infected areas.

Other than small numbers occurring in Redwood National Park, no unit of the National Park System perpetuates Port Orford-cedar apart from Oregon Caves National Monument. The cedar population in the 480 acre monument is so close to infected areas that measures are needed to prevent the root rot's spread to the park. One preventative measure is to keep hikers and vehicles out of places where the fungus spores can be transported into uninfected areas. This is especially important in the spring, when wet boots and tires can become agents for transmitting the fungus.

Phytophthora has considerably less chance of infecting Port Orford-cedar in summer, but another threat - wildfire- increases as fuel moisture levels d op. Catastrophic fires can occur throughout the cedar's range wherever the explosive combination of low fuel moisture, high winds, fuel loads, and an ignition source occurs. Although mature Port Orford-cedar can survive low intensity fire with its thick bark, it was only prompt action by fire crews that stopped the Caves Fire of 1989 from engulfing the monument.

If the Caves Fire had not been contained, more then the commercial and aesthetic qualities of a forest with some Port Orford-cedar component would have been lost. Oregon Caves National Monument has some of the finest rustic architecture in the national park system. One structure, the Oregon Caves Chateau, is a national historic landmark. It and four others comprise a district listed on the National Register of Historic Places. The bark on these and other structures has proven to be exceptionally durable, requiring only occasional replacement after 50 or more years. Port Orford-cedar's durability and past availability are factors in the survival of some pioneer cabins in the Illinois Valley. With age, the wood bleaches white and is why the tree is sometimes called "white cedar." Several examples of cabins that utilized white cedar are on display at the Kerbyville Museum.

Interestingly enough, the landscape architect who proposed that the monument's buildings make use of cedar bark also was concerned about the rapid cutting of Port Orford-cedar on the Oregon Coast as early as 1925. He and other proponents of a state park thought it to be as distinctive as coast redwood, Sequoia sempervirens, and knew that the Port Orford-cedar shares some similar attributes with redwood. Efforts to establish a state park stalled, so the U.S. Forest Service set aside two areas on the Coquille River in Coos County as research natural areas in 1938.

Feasibility studies for a Port Orford-cedar national monument by the National Park Service were the impetus for attempts to expand Oregon Caves National Monument in the 1940s. A fine sample of Port Orford- cedar existed along the ridgeline from the national monument to Grayback Campground, but logging during the 1960s and 1970s dealt a severe blow to hopes for a larger park. Nevertheless, part of Grayback Creek is still lined with Port Orford-cedar, as any adventurous motorist will discover if they take the road toward Low Divide and Williams.

Port Orford-cedar branch and cone
Port Orford-cedar branch and cone
Cedar branch: George Seedworth,
Forest trees of the Pacific Slope, Washington, DC: U.S. Government Printing Office, 1909, p. 173; Cone: Hickman, p. 113.

Stands that Elijah Davidson would have seen on his way from Williams to discover Oregon Caves in 1874 persist, but in dwindling numbers. The cumulative impacts of disease, fire, and logging are compounded by the practice of replacing Port Orford-cedar in managed forest with other conifers. Consequently, the perpetuation of the tree in its native habitat will be difficult because its standing volume has been reduced to 15 percent of what it was estimated to be in 1850.

Although timber cruisers are quick to recognize Port Orford-cedar's value because it has commanded the highest stumpage price of any commercial softwood for the past 40 years, it remains relatively unknown by the public. Unlike the coast redwood, Port Orford-cedar does not dwarf its surrounding conifers and rarely occurs in pure stands. In addition, Port Orford-cedar and Incense-cedar, Calocedrus decurrens are often confused with each other. Indeed, the Port Orford-cedar is so highly imitative in adapting to a wide range of environments that many tree lovers do not suspect that it occurs among the coast redwood of Jedediah Smith Redwoods State Park. As a result, Port Orford-cedar's significance has been largely overlooked. It can only be hoped, however, that the tree does not become a lost legacy.

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