Fire Ecology

Fire is Natural to Tahoe’s Environment

Low intensity fire

Fire has been a natural part of Tahoe’s environment for thousands of years. These historic fires were frequent, of low intensity, and a major influence on the appearance of Tahoe’s forests. Beginning in the 1870s, Tahoe’s forests and the occurrence of fire experienced some dramatic changes.

Much of the Lake Tahoe Basin is considered a “fire environment.” It contains flammable vegetation and a climate to support fire. Fire is a natural process in the Lake Tahoe Basin and many of the plants growing here evolved in the presence of frequent fires. In fact, it is unnatural for fire to be absent for very long in many areas of the Lake Tahoe Basin.

 

Tahoe’s Historic Fire Occurrence Source: Lake Tahoe Watershed Assessment
Click on image to enlarge.

The map presented to the left shows the occurrence of fire in the Tahoe Basin prior to European-American settlement. During this period much of the Lake Tahoe Basin burned, on average, every five to 18 years. These areas are shown as pale yellow on the map. Because these areas burned so often, large amounts of wildfire fuels could not build up. Consequently, these fires were usually of low intensity.

The frequency and intensity of fire influences the type and health of Tahoe’s forests. The frequent, low-intensity fires prior to European-American settlement created an open, park-like forest. The photo at the bottom left corner is of Emerald Bay, taken in the 1890s. Experts feel this is a good example of what Tahoe’s original (prior to European-American settlement) forest looked like.

The low-intensity fires thinned out young trees and shrubs and also reduced the buildup of deep layers of pine needles, leaves, and twigs. The older, thick-barked trees survived this type of fire. As a result, the forest was dominated by patches of large, mature trees with a sparse understory.

This is no longer the case for Tahoe’s forest.

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Tahoe’s Forest Timeline

1870 – Original Forest

Prior to 1870, low-intensity fires burned routinely in the Tahoe Basin. These fires created an open, patchy forest dominated by large trees. The raging, high-intensity wildfires portrayed in today’s newspaper headlines were uncommon

1900 – Logging Era

During the 1870s to 1890s, much of the Tahoe Basin was logged. E.B. Scott in “The Saga of Lake Tahoe” states, “By the fall of 1897 nothing remained at Incline but stripped forest land.”

The New Forest

A new forest establishes in the aftermath of the logging era. But now, fire has been effectively eliminated as a natural influence. Without frequent, low-intensity fires to thin dense stands of trees, the forest becomes overcrowded.

2000 – Tahoe Today

Tahoe’s current forest is typically thick with tees, brush and dead vegetation. In many areas, fire has been absent for over a hundred years. As a result, there has been a great buildup of wildfire fuel. Homes have now been added to Tahoe’s wildfire mix. The likelihood for uncontrollable, high-intensity wildfire that impacts watersheds, destroys neighborhoods, and takes human life is high in many areas of the Lake Tahoe Basin.

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Tahoe’s Current Forest and Fire Threat

Today’s forest is much different than the forest that existed prior to 1870. The low elevation mixed conifer forest of the Lake Tahoe Basin, where most homes are located, has four times more under-story trees today than it did prior to 1870. In addition, there has been a substantial increase in the amount of shrubs present.

The photographs of Emerald Bay, below, are of the same location, but taken 100 years apart. Notice that large trees in the 1890s photograph are still present in the more recent photograph. However, there has been a considerable increase in the density of trees and shrubs in the understory. A major cause of the increase in woody plants has been the lack of frequent, low- intensity fires. With European-American settlement, these fires were effectively suppressed.

Under these unnatural conditions, uncontrollable, high-intensity fires are much more likely. The Angora, Martis and Gondola Fires are recent examples of these types of fires in the Tahoe area. Furthermore, the forest is less healthy and more susceptible to disease and insects, particularly during drought.

Unfortunately, given Tahoe’s current conditions, homes and lives are at risk.

Emerald Bay - 1890s

Emerald Bay - 1990s

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