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

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Final Environmental Impact Statement Rio de los Pinos Vegetation Management Project Table 3.3-3. Alternative 3 effects on the Key Issues Key Issue Indicators Alternative 3 – Reduced Salvage Harvest 2. Forest Condition a. Salvage harvesting (acres) b. Late-successional habitat structural class changed (percent) c. Spruce beetle risk rating (average) d. Heavy fuels removed from project area (tons/acre) 607 acres 12.3% Moderate 19 tons/acre Key Issue 1. Approximately 607 acres would be salvaged under this alternative. No new system road construction would occur, but no new temporary road construction would occur, to be closed following management activities. Approximately 2.5 miles of old road would be reopened, also to be closed following management activities. Segments of system road reconstruction/spot reconstruction (representing 8.1 miles) would occur to meet watershed restoration opportunities. Project design criteria would be implemented to limit the amount of potential structural changes in watershed integrity tied to vegetation type, soil type, moisture availability, or other ecological characteristics due to timber harvesting and road construction/reconstruction activity. Erosion and stream sedimentation concerns from existing road conditions would be repaired. Key Issue 2. This alternative would treat the a smaller area, allowing the utilization of dead material, and providing an opportunity to assist the treated stands in regenerating by utilizing artificial regeneration methods. A smaller change in late-successional habitat structural class would occur in treated stands, speeding a process that will occur naturally. A lesser amount of heavy fuels would be removed from the area under this alternative. 3.4 Forest Health Scope of Analysis This analysis focuses on the Analysis Area described in Chapter 1, section 1.4 with regard to the forest condition resulting from the impacts of spruce beetle (Dendroctonus rufipennis) and to a lesser extent Armillaria root disease (Armillaria ostoyae). Western spruce budworm (Choristoneura occidentalis) was also considered, but no observable budworm activity was found in the analysis area. The spruce beetle has had the greatest impact on the forest condition in the Analysis Area and armillaria root disease may have contributed to increased susceptibility of some stands to spruce beetle within the Analysis Area. The spruce beetle is a native insect that is responsible for substantial tree mortality on the Rio Grande National Forest and has been particularly active on the Conejos Peak and Divide Ranger Districts. Armillaria root disease is a native pathogen that is present in most spruce/fir stands in the Southern Rockies and usually results in scattered, isolated patches of mortality in older stands. The recent history of the Rio de Chapter 3 – Affected Environment &Environmental Consequences Page 3-4
Final Environmental Impact Statement Rio de los Pinos Vegetation Management Project los Pinos Analysis Area will be discussed as well as potential future conditions as affected by each of the three alternatives. Spruce Beetles and Factors Affecting Epidemics The potential for an outbreak of bark beetles is determined by three primary factors: current bark beetle population levels, the susceptibility of individual stands, and weather patterns. In the case of the Conejos Peak Ranger District, these three factors are all indicative of increased spruce beetle activity. In order for a bark beetle outbreak to occur, there must be sufficient beetles to respond to conditions favorable to spruce beetles. The extent of recent spruce beetle caused mortality in the Analysis Area indicates that spruce beetle populations are at a generally elevated to an epidemic level. Stand conditions are also a primary determinant of bark beetle activity. Stands that are old and dense are generally more susceptible to bark beetles. In the case of Engelmann spruce, a risk rating system derived by Schmid and Frye (1976) documented that mortality as a result of spruce beetle activity is most likely to be initiated in stands that: a) consist of larger size classes, b) stands that are more dense (more trees per acre), c) stands that have a higher percentage of spruce and d) stands in the higher site classes. Stands in the Rio de Los Pinos drainage meet all of these criteria for stands conducive to beetle activity. The propensity of high-risk stands can in a certain sense be attributed to these large dense trees competing for sunlight and particularly, moisture. This “competition” for moisture is naturally more intense among older, denser stands of trees. The Rio Grande National Forest has undergone a severe drought within the past six years (Webb et al. 2004). Low availability of moisture has generally reduced the tree’s ability to resist bark beetle attack. The overall lack of moisture has allowed spruce beetle populations to increase, and has also increased the susceptibility of adjacent stands. For some insects, the end of the the drought usually means the end of the outbreak. However, with mountain pine beetles and spruce beetles, once the beetles have killed a large number of trees and produced abundant offspring, their numbers may become so great that they can overwhelm even healthy trees (Romme et al. 2006). Past Actions that have affected the Existing Condition There is no evidence of significant insect or disease activity occurring in the Analysis Area until only recently. Increased spruce beetle activity was noted in the adjacent Wolf Creek drainage in 2003 and has spread across the Analysis Area at epidemic rates since that time. Spruce beetle is a native insect and generally occurs at endemic levels in all spruce stands. It is likely that spruce beetle has been present in the Analysis Area at endemic levels for many years. Past timber management activities in the Rio de los Pinos Analysis Area include the Hanson (1957) and Flat (1983) timber sales. The Hanson Timber Sale consisted of a shelterwood preparatory cut over 562 acres that reduced the basal area and allowed the establishment of spruce and fir regeneration. The past management activities did reduce the risk of spruce beetle affecting these stands but could not protect against the elements of high beetle populations and drought-related stress. Chapter 3 – Affected Environment & Environmental Consequences Page 3-5
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