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Seeing the Forest For the Trees

While Studying Heavenly's Controversial Old Growth, Scientists Strive to Look Beyond Individual Old Trees
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On April 25, the Governing Board of the Tahoe Regional Planning Agency will reconsider Heavenly Ski Resort’s 2005 Master Plan Amendment. With the amendment Heavenly proposes to construct a new high-speed quad and two gladed ski runs in the resort’s North Bowl region. The amendment has been opposed by concerned citizens and by members of the League to Save Lake Tahoe, the Sierra Nevada Alliance, and the Tahoe Area Sierra Club, who argue that the proposed lift will degrade a stand of Red Fir old growth. But the ecological value of the North Bowl forest has been the subject of debate. What exactly is old growth and do the North Bowl trees make the cut?

Old Growth, Not Just Big Ol’ Trees: The oldest trees in the North Bowl forest range from 200 to more than 400 years of age, and more than 40 inches in diameter at breast height. However, when defining a forest as old growth, researchers attempt to look beyond the individual trees in order to examine the broader structure of the stand and the ecological functions it performs. 'If you look at a single tree then you’re not on the argument because there’s no way one tree will be considered old growth,' said Dave Fournier, Vegetation Planner for the Lake Tahoe Basin Management Unit.

Old Growth As Structure: According to the Sierra Nevada Ecosystem Project (SNEP), an extensive study of old growth in the Sierra Nevada completed in 1996, 'key structural features' of old growth forests include large diameter trees, decadent trees with flattened tops and patches of rot, standing snags, and large logs. Other important indicators of old growth structure include the density of the forest canopy and the number of large diameter trees in a given area. Researchers focus upon these features of a forest’s structure because they provide habitat and foraging ground for certain animals.

In order to identify old growth in the North Bowl area, Heavenly’s environmental consultants used a rating system designed to take some of these old growth forest structures into account. Under this rating system, stands of trees with average diameters greater than 24 inches, and a certain amount of canopy coverage, qualified as old growth. By these criteria, 283 acres of old growth were identified within Heavenly’s operational footprint. 'Some of the area (in Heavenly’s operational footprint) was indeed meeting the TRPA’s definition of old growth in some small areas, not the whole area,' Fournier said.

However, the classification system used to identify old growth at Heavenly does not always accurately identify all types of old growth forest. According to the 2001 draft of the Sierra Nevada Forest Plan Amendment (SNFPA), the standards used to identify old growth in Heavenly are typically used to define dense patches of 'highly suitable nesting habitat for the California spotted owl or denning habitat for the Pacific Fisher or American marten.' Because the classification system was designed to focus on dense patches, policy decisions based upon it can overlook old forests that are more open in structure. According to SNFPA, in subalpine forest such as the one in the North Bowl, 'a sparse representation of large and old trees for the species and site may be considered old forest.'

John Hoefer, a retired Forest Service Forester who worked in the Bristlecone Pine forest near Bishop, is familiar with this sort of gap in old growth classification systems. He referenced the Bristlecone Forest while describing the potential inadequacies of any old growth classification system. 'Bristlecone Pine Forest is low on (one) ranking system,' Hoefer said, 'but it’s definitely old growth.'

According to the Inyo National Forest web site, the Bristlecone Pine forest is composed of the oldest living trees in the world.

Old Growth as Function: Researchers also define old growth by how it functions. As the Sierra Nevada Forest Plan Amendment puts it, 'function refers to things that ecosystems do.'

Old growth forests function by providing habitat for wildlife, insects, plants, fungi, and other microorganisms, by storing and cycling nutrients, by regulating and cycling water, and by storing carbon.

However, as with the structural side of old growth, scientists tend to analyze the function of an old growth forest by looking at the habitat it provides. Not only are processes such as carbon storage and nutrient cycling difficult to directly observe, but, according to SNFPA, 'Overall, little is known about the function of old forests in the Sierra Nevada. … Most of the information is on wildlife habitat.'

Environmental consultants at Heavenly determined that the North Bowl forest does not provide habitat for certain species that are known to rely on old growth. 'There is no use in the area by spotted owl, eagle, goshawk… any of those,' Fournier said.

Because the forest does not function as old growth habitat, it does not fulfill the criteria the Forest Service uses to identify old growth. 'The stand does not possess old forest characteristics for function or habitat,' said Rex Norman, Public Affairs Officer for the Forest Service’s Lake Tahoe Basin Management Unit. 'The ecological function in the North Bowl has already been impaired, Norman said, 'It’s a ski area.'

But in the absence of the resort, North Bowl would be suitable nesting ground for at least one of those species. 'Goshawks would normally be nesting this time of year, but they won’t in the North Bowl area,' Hoefer said, 'They would be disturbedby skiers and the ski equipment.'

Old Growth, Longer-Lived Than Us: In large part, local environmental groups take issue with the time-frame considered in TRPA’s decision. David Kean of the Tahoe Area Sierra Club argued that a longer time scale needs to be taken into account. ' ‘(Goshawks and Pacific Fishers) aren’t in North Bowl now’ is not a valid argument,' Kean said, 'They should be. If the future goal is to allow them to ever live here again we need to restore and connect habitat.'

Kean also explained that 'specialist' species such as the Pacific Fisher and the American marten do not interact well with humans. Whereas, 'generalist' species such as the Western Spotted Skunk, Ringtail, Grey Fox, and Raccoon thrive in the presence of humans. 'We’re replacing specialist species with generalist species,' Kean said, 'Habitat loss, fragmentation, and the introduction of invasives are the three main reasons for ‘specialist’ species decline.'

According to Heavenly’s Environmental Impact Report, the American Marten is present in the North Bowl area.

John Hoefer explained that the criteria the TRPA used to define old growth are intended to define the way a forest functions over time. 'Twenty-four inches really isn’t that great of a measure of old growth,' Hoefer said, 'It’s more an indicator of which trees will have the potential to become old growth in the future. We have a goal to increase old growth, but if we disturb old growth we’re not approaching that goal.'

But when forests that change over centuries meet the here-and-now of planning policies, a few years tend to slip from the accounting. 'From a policy perspective (defining old growth) becomes so literal, but in reality it can’t be literal,' Fournier said.

Rex Norman approached the issue from a different angle. 'The stand in North Bowl does not (function),' Norman said, 'What would change that? I’d like to see someone propose this: Close the resort, and wait a couple hundred years. That of course would not be supported.'


What’s in a Word? Or For That Matter, a Woods?
(Some handy info and definitions)

Old Forests of Tahoe’s Past: The Tahoe Basin was never entirely covered in old forest. As rough scientific consensus has it, Tahoe forests were between 30 and 55 percent old forest before Europeans showed up. Ninety-five percent of Tahoe forest was indeed logged during the Comstock mining period; but before that the forest was regularly thinned and renewed by fire. So, as Rex Norman stressed, 'It’s misleading to say that because 95 percent of the Tahoe Basin was logged, only 5 percent of the original old growth remains.'

Fire: You know what it is, but what does it do for the forest? These days, when scientists search for pristine forest in the Tahoe Basin, they actually look for areas that have been scorched by fire.

When a fire burns through a forest it creates open areas where new vegetation can put down roots. In fact, Tahoe forests might be more in need of new trees than old. According to Dave Fournier, Tahoe forests contain a large amount of middle-aged growth, about a normal portion of old trees, but relatively few young trees.

So again, when researchers go poking around for old forest they’re not really looking for old trees. Instead they’re searching for forest stands that have been shaped by centuries of disturbances, and are made up of trees of a variety of ages.

Seral: Lots of the recent Heavenly press has contained the phrase, 'late-seral;' but what does seral mean?

A 'sere' is one stage in a succession. Plant communities progress through a number of such seres from pioneer growth to old growth. Each transitory stage is a seral stage. So 'late-seral' is a slightly more descriptive way of getting at old growth. It’s also a way to avoid that politically- and emotionally-loaded term, 'old growth.'


TRPA to Reconsider Heavenly North Bowl Lift
On March 28, the Governing Board of the Tahoe Regional Planning Agency voted to conduct a full rehearing of the 2005 Master Plan Amendment.

The Governing Board originally approved the amendment during a Feb. 28 meeting, but voted to reconsider the issue because a severe storm prevented several governing board members from physically attending.

The rehearing will take place on April 25 at the TRPA offices in Stateline, Nevada, or at a larger meeting area in South Tahoe if necessary. The issue will be reconsidered in full, without reference to the Board’s previous deliberations. For information contact TRPA, 775-588-4527, or

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Reader comments so far...

Jacqui Zink (not verified)
Outstanding article on an important issue. I agree with the Sierra Club's David Kean; its more important to restore and connect important habitats for specialist species (ski area or not) that are having a difficult time surviving the human onslaught than to expand a ski area. When are we going to start putting the health of our planet before profit? Happy Earth Day!

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March 14, 2019