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

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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
Final Environmental Impact Statement Rio de los Pinos Vegetation Management Project beetle populations can engulf entire landscapes and kill practically all spruce. Such intense outbreaks are not unheard of. Landscape scale outbreaks of spruce beetle have been recorded throughout the range of spruce, including locations in Alaska, New Mexico and Utah as well as numerous examples in Colorado. On the Rio Grande National Forest, we have experienced this phenomena in the County Line, Burro-Blowout, and Big Moose project areas. During field visits by the District Silviculturist, armillaria root disease was observed in small pockets within the Analysis Area. Extensive surveys for armillaria root disease have not been completed. It appears through field reconnaissance that the armillaria root disease in the Analysis Area is likely at, or near, endemic levels. Often times trees with armillaria root disease will blow down in scattered pockets. Scattered blowdown and stressed trees caused by armillaria root disease may have contributed, to a small degree, to the buildup of the spruce beetle population within the Analysis Area. Direct, Indirect, and Cumulative Effects Alternative 1 – No Action With no management action, it is likely that the scope and intensity of spruce beetle activity would continue. Units that currently have large beetle populations would continue to experience intense mortality, most likely until the mature spruce component is killed. During intense beetle outbreaks, the outbreak ends only when the beetles deplete their host and food supply. This scenario could be duplicated in most stands that have any spruce beetle activity at all, assuming that the dry weather conditions of the past several years continue. The Rio de los Pinos outbreak currently extends beyond the Analysis Area boundary into backcountry areas and into other inaccessible or inoperable spruce stands within and adjacent to the Analysis Area. Relatively contiguous suitable spruce beetle habitat is present around the Analysis Area and it is not unreasonable to expect spruce beetle activity to increase within the Analysis Area by infesting additional trees and spread across the landscape, infesting additional stands on the Districts. As Engelmann spruce is killed by spruce beetle the Engelmann spruce seed source will be lost. This loss of Engelmann spruce seed would affect the future stand composition and favor subalpine fir, which is less resistant to armillaria root disease than Engelmann spruce. This could potentially increase the future occurrence of armillaria root disease in the Analysis Area. Alternative 2 – Full Salvage Harvest This alternative proposes to apply Sanitation/Salvage to 878 acres. Salvage includes removal of dead trees from which spruce beetles have already exited. Salvage has minimal impact on overall beetle numbers. Sanitation harvesting of infested trees implies that immature spruce beetles are still infesting the tree and would be removed from the site with the host tree. The removal of trees with beetles in them would reduce the overall beetle population, which could reduce the rate of spread of the beetles at the stand level. However, it is not realistic to think that the proposed treatments would control the spruce beetle outbreak over vast areas adjacent to the treated areas. Chapter 3 – Affected Environment & Environmental Consequences Page 3-7
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