Final Environmental Impact Statement Rio de los Pinos Vegetation ...

Final Environmental Impact Statement Rio de los Pinos Vegetation Management Project
Past timber management activities within the Analysis Area may or may not have affected the
occurrence of armillaria root disease within the Analysis Area. Partial cutting likely had
multiple, conflicting influences on disease dynamics. On one hand, stumps may provide
increased food to the pathogen and more energy to attack neighboring trees, but on the other
hand, partial cutting can lead to increased vigor and resistance of residual trees. Armillaria root
disease has been observed in the Analysis Area but is believed to be at only endemic levels.
Existing Condition
Field surveys were completed in 2005 by Rio Grande National Forest timber personnel and
Gunnison Service Center personnel. Spruce beetle was found throughout the Analysis Area in
small numbers, increasing steadily in the southern-most units. In 2007, during an effort to
prepare a preventative thinning timber sale, crew members found significantly more fresh spruce
beetle hits. New surveys were conducted in 2007 and 2008 to determine the current extent of
beetle activity. Small amounts of blown-down spruce were also observed in the units in 2006,
2007 and again in 2008. Table 3.4-1 shows the degree to which the salvage units have been
impacted by spruce beetles.
Table 3.4-1 Percentage of Trees Impacted by Spruce Beetles in
Salvage Units
Unit
Number
Current Spruce Beetle Risk
Rating
(Schmid/Frye)
Actual Percent
Infestation
(2008)
1 Moderate 20%
2 High-Moderate 20%
3 High-Moderate 47%
4 Moderate 86%
5 Moderate 86%
The spruce beetle have steadily moved north from the adjacent County Line middle and southern
units since 2003. Stands that were rated as a Moderate for outbreak potential have been heavily
infested (stands 4 and 5), indicating that stands 1-3 are on their way to severe infestation.
According to Forest Service Entomologist Tom Eager, mortality of every infested spruce tree is a
certainty because of the immense population of beetles present. Spruce trees currently not
infested are very likely to become infested for the same reason.
The dramatic increase in spruce beetle activity in the Analysis Area highlights the severity of the
recent drought conditions in this area and across the Forest. Various indicators of drought
severity including water yields, fuel moisture content and plant physiology indicators all set
records in 2002. It is likely that these conditions facilitated the rapid increase in beetle
population and activity when this outbreak first began. Prolonged drought conditions through
2006 further endangered the stands and promoted beetle population growth.
Large spruce beetle populations directly to the south of the Analysis Area are proving to be
detrimental to the stands in this analysis. Once a full-blown outbreak is underway, the huge
Chapter 3 – Affected Environment & Environmental Consequences Page 3-6