Managing That Wild Natural Look

English: This picture if of a Golden Trout fro...

A  golden trout from French Creek in the French Canyon. Located within the John Muir Wilderness in California. (Photo credit: Wikipedia)

In 1978, I was just beginning my career with the California Department of Forestry and Fire Protection (Cal Fire). I worked in the southern Sierra Nevada range as the Assistant Forest Manager at Mountain Home State Forest. The federally managed 1.2 million acre Sequoia National Forest surrounded the 4800-acre state forest. On most of the state forest’s eastern boundary Mountain Home abutted the newly designated Golden Trout Wilderness.

Our neighbor, the United States Forest Service, was struggling to transform the Golden Trout Wilderness Area from primitive to pristine.

The Wilderness Act of 1964 required that the GTWA would be “an area where the earth and its community of life are untrammelled by man.” Well, many thought that man had pretty well trammeled the area. Quite a few high country lakes and streams had been “coffee can stocked” with rainbow, brook, and brown trout. The native golden trout had crossed with many of the rainbow (golden trout is a sub-species of rainbow) to produce a hybrid trout that looked just like a golden until you drilled down to the chromosomal level.

The question was, then, how to make the wilderness into wilderness, to resemble a time before man changed it. Drumroll please…

The answer was to destroy the fish population, using the poisonous insecticide rotenone, to “save” it.

The strategy was and is to “chemically treat the headwaters of drainages with rotenone above fish barriers to remove non-native trout species that compete or hybridize with native trout,” a U.S. Fish and Wildlife Service brochure [PDF here] notes, “After that, native trout are reintroduced to the reclaimed habitats.” Many of the high country lakes were left sterile since the agency experts decided that was their natural state before European or Indian contact.

Some of the Forest Service’s people thought that was a crazy idea, saying, “If it looks like a golden trout, why not call it a golden trout?” After all, golden trout (Oncorhynchus mykiss aguabonita) is a sub-species of rainbow trout (O. mykiss).

But, why destroy a vibrant fish population? In her book, Rambunctious Garden, Emma Marris explains, “For many conservationists, restoration to a pre-human or a pre-European baseline is seen as healing a wounded or sick nature. For others, it is an ethical duty. We broke it; therefore we must fix it.” The pre-human or pre-European state thus becomes “the one correct state.”

The irony, of course, is that pristine areas are illusions; people have to work hard to make them to look how people think “pristine” ought to look. Peter Kareiva, the chief scientist of the Nature Conservancy, along with his two co-authors, argues that the great lengths we go to “removing unwanted species while supporting more desirable species,” such as drilling wells to provide wildlife with water and manipulating the land through “fire management that mixes control with prescribed burns,” we “create parks that are no less human constructions than Disneyland.”

So, oddly, the more natural we want a place to look, the more human management it needs.


Further Reading:


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Trees ain’t thermometers

I used to work on Mountain Home State Forest in the southern Sierra. MHSF has about 3000 specimen-sized sequoia within its boundaries. Dendrochronolgists often visited to see the stumps from logging in the mid to late 1800s. These were often over 2000 years old when they had been cut.

The Dendrochronolgists were interested in the tree-ring patterns. Trees grow fast or slow in response to many factors and these seasonal factors (light, water, nutrients) created ring signatures or patterns. Certain years might have been favorable for growth with plentiful water, light and nutrients (each favorable year would be marked a large, wide ring) and certain years might have had poor conditions for growth–drought, late spring conditions, early winter–marked by thin (in some cases–microscopic) rings. In general, the wider the ring the more favorable the growing season, the narrower the ring the poor the growing conditions. These ring patterns can be distinctive and can be used to date archeological sites (where wood is present).

Oxford’s Tree-ring Laboratory put it this way:

The way dendrochronology works is relatively simple. As a tree grows, it puts on a new growth or tree-ring every year, just under the bark. Trees grow, and put on tree-rings, at different rates according to the weather in any given year: a wider ring in a favourable year and a narrower ring in an unfavourable year. Thus, over a long period of time (say 60 years or more) there will be a corresponding sequence of tree-rings giving a pattern of wider and narrower rings which reflect droughts, cold summers, etc. In effect, the span of years during which a tree has lived will be represented by a unique fingerprint, which can be detected in other geographically-similar tree-ring chronologies.

Using tree rings as a proxy for temperature however is fraught with caveats and pitfalls.

Mike D.‘s of the Western Institute for Study of the Environment comment (on William M. Briggs’ blog) about using tree ring data as proxies for temperature is an excellent explanation of the problems of using tree ring growth for temperature. He starts with how tree rings are laid down:

Diameter growth on any tree is theoretically a sigmoid growth function. No tree puts on constant radial growth year after year. Trees grow by adding a layer of new wood at the cambium, under the bark. Each year a larger surface area is added. If growth is constant, the rings get narrower. But growth is never constant. There is significant deviation from ideal (model) sigmoid diameter growth in individual trees regardless of the weather. Even when sigmoid growth models are used, the natural variation adds statistical error.

Two sigmoid curves. The taller is the period annual increment for cubic feet; the lower smoother S curve is for mean annual increment of cubic feet.

So as the diameter expands, the amount of material put on would need to be more if the ring’s width was to stay the same as the previous season. Think of a clay disk that you add the same amount of clay to in successive rings. The volume of clay would be the same but the thickness of each new ring would decrease. The ring growth is S-shaped (sigmoid) because initially the tree has little foliage for photosynthesis and often puts its initial years into root development for survival. Then once roots are deep enough the tree puts its growth into height and width.

He then points out that tree-to-tree competition for light, water, and nutrients also affects the ring growth:

Dense stands exhibit narrow rings on individual trees, sparser stands may have wider ring growth, yet both stands may have equivalent gross growth. That’s why only open-grown trees are supposed to be selected for ring studies. But nobody knows what the tree density surrounding an individual tree was 100, 200, 500 years ago. Competitors could have arisen and died without leaving evidence of their presence so long ago. More error.

Besides competition, disease and injury can affect growth.

Trees can sustain injuries that affect growth, such as top and branch damage, that are difficult to detect 200 years later, especially a few feet off the ground where the rings are sampled. There are very few pristine, undamaged trees. I know, having searched for such across broad acreages. Open grown trees at high elevations are always damaged. A heavy winter snow can snap off branches and the tree will exhibit reduced diameter growth for a few years, even if growing season conditions are ideal.

This makes using tree ring data as stand-ins for temperature problematic.

Ring width has all but been abandoned as a temperature proxy. Instead, the latest technique is sampling rings for O18 ratios, under the assumption that O18 varies with temperature. Regardless of the ring width, the O18 ratio is supposed to have recorded growing season temperature. But that theory is fuzzy and mushy, and O18 ratios in living trees correlate very poorly with known growing season temperatures. In other words, it calibrates with much error at best.

Trees are not thermometers, but even thermometers have some serious measurement error problems.

Tree ring studies are a fad akin to phrenology and other discredited pseudosciences that has not dissipated as it should have decades ago.

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Weekend Postcard from Mountain Home State Forest

I was the Assistant Forest Manager at Mountain Home State Forest in the early 1980’s.

Mountain Home Demonstration State Forest is a 4,800 acre tract of forest land in Tulare County managed by the California Department of Forestry and Fire Protection. The State Forest lies within the Tule River watershed some 22 air miles northeast of Porterville. Elevations range from 4,500 feet to 7,500 feet. Vegetation on the forest is dominated by a mixed-conifer forest with over 5,000 individual old-growth giant sequoia trees.

For more information on MHSF read Management of Giant Sequoia on Mountain Home Demonstration State Forest written by forest manager, David Dulitz.

Here’s a picture of a kid standing in one of the area’s so-called “Indian Bathtubs.”

For more on these rock basins read Rock Basins in Mt. Home State Forest and Immediate Vicinity.

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