Book of then-and-now photographs show how region's forests are overgrown.
In the aftermath of the devastation caused by the Angora fire in South Lake Tahoe, many declared as fact that the problems for the Sierra Nevada mountains began with logging in the 19th century.
Logging, their theory goes, destroyed abundant forests that never returned.
Those 19th century loggers might make a convenient scapegoat -- they can't do much to defend themselves, after all. But people from the 19th century did leave behind lots of evidence -- evidence that largely contradicts the theory and provides a real view of the historic forests of the Sierra Nevada.
In the 1990s, I embarked on a nine-year project to examine how the landscape of the Sierra Nevada changed over time and what likely happened since the mid 1800s. More than 100 19th and 20th century photographs of the Sierra Nevada were secured from various archives. I then went into the field, relocated the original camera points and re-photographed many of these scenes.
With little exception, the modern-day landscapes are far denser with trees and brush than those that existed more than 100 years ago. And those 19th century forests with fewer trees were much more resistant to catastrophic wildfire.
Landscapes were far less dense because of low-intensity fires caused by lightening strikes or deliberately set by Native Americans as part of their own land management.
As a result, the land was more open, with more meadows and far fewer trees than we see today.
Through fire suppression and restrictions on removing trees, we have created a Tahoe Basin and Sierra Nevada range that is anything but natural and is out of line with the historic forest.
Our land is packed with more trees than ever, often bounded by brush that is far denser than it was historically.
People who live in the area instinctively know this to be the case. They recognized the extreme fire danger and simply hoped that a fire like the Angora one wouldn't occur.
Why did some resist efforts to thin the forests surrounding Lake Tahoe? Very simply, they like to be surrounded and immersed in trees. It is a nice feeling.
But feelings and facts are two different things.
Our forests today in the Tahoe area are unhealthy and badly in danger of falling to yet another catastrophic wildfire. Sadly, wildfire destroys forests and is devastating to those who lose their homes and personal effects.
And today's forests do not provide wildlife the kind of habitat they have historically enjoyed. Closure of tree canopies has virtually eliminated understory shrubs and herbs that are critical to the sustenance of nearly all species of wildlife.
History can help provide a more accurate view of the natural composition of Northern California landscapes and a more realistic benchmark for understanding the relative condition of wildlife habitat.
As people assess what is needed next for Lake Tahoe, we should first take a look back and gain an historic perspective and create a forest that is less prone to catastrophic wildfire and offers more biological diversity.
Source: http://www.times-standard.com/opinion/ci_6468427
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The Real Picture of Sierra Nevada Forests
In April, activists once again criticized efforts to thin forests in the Sierra Nevada, this time because of the inappropriate use of a 1909 Montana photo by the U.S. Forest Service in its brochure, "Forests With a Future."
The photo was used to make a point: historically, California's forests were less dense and more resistant to catastrophic fire. Regrettably, an incorrect photo was used. But that does not change the fact that California's forests were far more fire resistant 100 years ago than they are today.
I have published scores of historic photos side-by-side with modern retakes from the same locations that show how much less dense Sierra Nevada forests were about a hundred years ago.
Our current forest conditions differ greatly with the historic norm - as detailed in my book "Fire in Sierra Nevada Forests: A Photographic Interpretation of Ecological Change Since 1849." California's forests have experienced massive increases in tree cover resulting from human activities, particularly the suppression of natural fires. Similar changes are evident in vegetation throughout the West.
As a wildlife biologist, I know evidence strongly suggests that increasingly dense forests are detrimental to wildlife, including numerous songbirds, rabbits, squirrels, and deer. Historically, wildlife populations adapted to ecosystems that were subjected to frequent low-intensity fires. Today, thicker forests burn in high-intensity crown fires.
Yet, despite this disparity, current conditions often are the primary reference point for biologists making wildlife habitat assessments. We have a tendency, therefore, to essentially preserve wildlife habitat in its present state of decay and high risk of catastrophic wildfire. That must change.
The Forest Service plan for the Sierra Nevada emphasizes retention of forest canopy. To meet the presumed habitat requirements of featured species, Forest Service biologists recommend 50 to 60 percent retention of crown cover. But are high levels of crown closure best? Tree crowns are often so dense that sunlight does not reach the ground and small plants are shaded out.
There is an inverse relationship between the amount of tree cover and the abundance of shrubs, grasses and flowering plants on the forest floor. As trees increase, other green plants decline, primarily from shading and competition for water and nutrients. Wildlife populations also decline because most forest species are dependent not on trees but on low-growing vegetation.
High tree densities and closed canopies pose another threat to wildlife populations: too many trees mean more fuel for catastrophic wildfire.
Scientists from Cal Poly State University and elsewhere have noted that high-intensity wildfire has a far greater impact on the environment than any forest management activities could under California's forestry laws. Catastrophic fires lead to increased erosion, devastate watersheds, pollute the air, and destroy even protected habitat.
The Forest Service has proposed fuel reduction in the Sierra Nevada because it believes that continuing to severely suppress tree harvesting on public lands will increase dramatically the incidence of catastrophic wildfire. With its proposed thinning, the Forest Service expects to reduce the acres lost to catastrophic fire by 30 percent over 50 years and increase the number of old-growth stands.
Yet activists oppose cutting even a miniscule number of trees. The plan they are objecting to calls for harvesting only two tenths of 1 percent of the medium-sized (20-30 inches) trees standing each year. That thinning could save lives and precious habitat.
History can help provide a more accurate view of the natural composition of Northern California landscapes and a more realistic benchmark for understanding the relative condition of wildlife habitat. A historic perspective would also foster a cry to thin forests not just for fire safety, but also for biological diversity.
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Wildlife biologist George E. Gruell is author of Fire in Sierra Nevada Forests: A Photographic Interpretation of Ecological Change Since 1849, (Mountain Press, 2001). The book includes 160 California photos taken from the same spots about one hundred years apart displayed side by side.
