Decision Memo Monarch Pass U.S. Forest Service San Isabel National Forest Salida Ranger District Chaffee County, Colorado BACKGROUND AND PURPOSE & NEED Background: Beginning in the early 2000’s in the Weminuche Wilderness of southern Colorado, a spruce beetle (Dendroctonus rufipennis) epidemic began expanding north. During stand exam field procedures in 2012, within the Monarch Mountain Ski area, active spruce beetle infestation was discovered on several plots. Further reconnaissance discovered scattered spruce beetle populations in the Monarch Mountain Ski area, Old Monarch Pass and Monarch Park areas. Prior to this time no active spruce beetle infestation had been observed in these areas. Since 2012, spruce beetle activity has increased and is now at epidemic levels across the Monarch Pass area. In some stands, mortality of the mature overstory is approaching 75 percent. In Colorado, spruce beetle has affected over 1.7 million acres since 1996. Figure 1. Example of forest conditions in the Monarch Pass area (early spring 2017). Photo by A. Rudney. — Decision Memo — Page 1 of 23 Figure 2. Example of trees killed by spruce beetle. Photo by A. Rudney. Western balsam bark beetle (Dryocoetes confusus) has been affecting stands within the ski area and across the Monarch Pass area since the early 2000’s. Lodgepole pine (Pinus contorta) forests in the area are at high risk for mountain pine beetle infestation (Dendroctonus ponderosae) due to mature age, tree size and density. In addition, increased snag (dead standing trees) levels within the ski area have exposed visitors to a higher risk of falling trees. The increase in mortality is leading to increased fuel loading and higher risks for firefighters attempting initial or extended attack on wildland fires within the project area. Purpose and Need: The purpose of the Monarch Pass project is to reduce the extent of spruce beetle infestation, western balsam bark beetle infestation, improve forest resiliency to insect and disease infestations, improve watershed health and aquatic habitat, reduce fuel loading, protect infrastructure and developed sites (e.g., ski area, campground, trail corridors), and provide for firefighter and public safety in the Monarch Pass area. The need for the project is due to an ongoing insect infestation resulting in significant mortality of Engelmann spruce (Picea engelmanii) and subalpine fir (Abies lasiocarpa) trees as well as highly susceptible forest conditions to insect outbreaks in the area. The need is also to improve the watershed health along the South Arkansas River by reducing the amount of sedimentation reaching the stream. The Monarch Pass project encompasses approximately 2,809 acres near the crest of Monarch Pass about 20 air miles west of Salida, Colorado. The predominant tree species on the site is Engelmann spruce, with a lesser component of subalpine fir and lodgepole pine and minor amounts of aspen and Douglas-fir. — Decision Memo — Page 2 of 23 DECISION Project Activities I have decided to proceed with the removal of insect infested and susceptible trees in the Monarch Pass area, as well as watershed improvement projects to reduce current sedimentation and erosion issues that are occurring in the project area. My decision incorporates feedback from the collaborative participants, public comments I received during the scoping period, recommendations from Forest Service Regional insect and disease experts, and my resource specialists. Resource concerns identified through the collaborative process and internal meetings with resource specialists were addressed through project design criteria listed below. I believe my decision best addresses the purpose and need for the project while protecting forest resources and meeting Forest Plan standards and other regulatory requirements. Treatments in spruce/fir stands: Sanitation and salvage will be the primary methods used on approximately 1,676 acres of spruce/fir forests. Sanitation is the removal of trees to improve stand health by stopping or reducing the actual or anticipated spread of insects and disease (Helms, 1998). Salvage is the removal of dead trees. Singletree and group selection treatments will be completed on areas within the project that have little or no insect infestation or mortality. Single tree selection is a method where individual trees of all size classes are removed more or less uniformly throughout the stand, to promote growth of remaining trees and provide space for regeneration (Helms, 1998). Under the group selection method, trees are removed and new age classes established in small groups to regenerate and maintain a multiage structure (Helms, 1998). In this case groups may be as small as 3 – 5 trees or up to ¼ acre (59 feet radius) in size. Singletree and group selection may be used on up to 450 acres (approximately 25 percent) of the spruce/fir acres within the project. For all treatments in spruce/fir, retain 10 percent of the stands in untreated reserves ranging in size from 1/10th to 2 acres. Scatter these reserves in a mosaic throughout the stands but focus on areas used by wildlife (i.e., middens, nest trees, etc.), areas containing large snags and down wood, doghair stands, rocky areas or areas that possess other unique features. The spruce beetle epidemic is evolving each year with new trees and new stands being impacted. In order to meet the purpose and need of the project a flexible implementation strategy will be necessary. Stands and areas selected for the single tree and group selection methods that become infested with spruce beetle affecting 30 percent or more of the basal area of the mature overstory will be converted to sanitation and salvage. Singletree and group selection treatments are generally limited to removing no more than 25 – 30 percent of the pre-treatment basal area of a stand. Allowing sanitation harvest of these acres allows the treatments to meet the purpose and need of the project. Treatments in lodgepole pine stands: Bark beetles are native to Colorado and do not typically pose a significant threat to healthy trees. Thinning remains the most effective treatment to improve forest health by reducing abiotic stress and thus, reducing the risk of insect infestation (Fettig 2012). Thinning combined with a reduction of accumulated surface fuels and shrubs also effectively reduces susceptibility to stand-replacing fires. Thinning implemented to promote landscape heterogeneity (i.e., age, size, density, and species composition) is most effective at increasing stand resistance to insect infestations (and other natural disturbances) as homogeneous forested landscapes provide large contiguous areas of susceptibility to similar disturbances (Fettig et al. 2007, Fettig and Hilszczanski — Decision Memo — Page 3 of 23 2015). Insect infestations and outbreaks, for example, tend to occur when favorable host conditions (i.e., stands with little heterogeneity) coincide with favorable environmental conditions (i.e., drought). When these conditions align, the probability of encounters with a suitable host increases (i.e., one in which resistance mechanisms (resin) can be overcome) (Fettig et al. 2007). Approximately 569 acres of lodgepole pine within the project area will be treated using a combination of thinning, patch cuts (group selection) and reserve. (Thinning is a treatment made to reduce stand density of trees primarily to improve growth or enhance forest health.) The treatments will be designed to reduce susceptibility to insect infestation, regenerate mature lodgepole stands and create age class diversity. Thin 80 percent of the stands generally from below to an average of 80 – 120 BA/A. Thinning should be irregular in character and fall in all BA/A values across the range. When thinning, remove 20 – 40 percent of the existing basal area on any given site. Example, if an area currently contains 240 BA/A, thin to no lower than 145 BA/A by removing 40 percent of the existing BA or thin 80 B/A to 60, removing 25 percent. If thinning will not meet the 80 – 120 BA/A target; this is OK. This target is designed to reduce the probability of blowdown within the residual stand. Thinning will be across diameter ranges. Leaving well-formed disease free trees with better crown ratios and conical shaped crowns (evidence of more rapid growth) is the goal. It is permissible to remove larger slow growing individuals to favor more vigorous, well-formed smaller trees. Leave trees should have greater than 40 percent crown ratios where possible. Under the patch cut (group selection) method trees are removed and new age classes established in small groups to regenerate and maintain a multiage structure (Helms, 1998). Treat up to 10 percent of the stands with group selection (1/4 to 1 acre in size) openings where all trees are removed. Retain 10 percent of the stands in untreated reserves ranging in size from 1/10th to 2 acres. Scatter these reserves in a mosaic throughout the stands but focus on areas used by wildlife (i.e., middens, nest trees, etc.), areas containing large snags and down wood, doghair stands, rocky areas or areas that possess other unique features. Additional Information for All Treatments: Treatments will occur on slopes up to 60 percent. On slopes up to 35 percent, conventional logging equipment (i.e., harvesters and skidders) and high floatation equipment (i.e., cut-to-length systems) will be utilized. On sustained slopes between 35 – 60 percent, high floatation equipment (i.e., cut-to-length systems) or aerial yarding techniques (i.e., skyline or helicopter yarding) will be utilized. In order to increase species diversity and resilience to insect and disease, as well as ensure regeneration of cut over areas, planting of new trees may be necessary. Where appropriate and needed, a mix of tree species will be planted. A mixture of Engelmann spruce, sub-alpine fir, lodgepole pine, bristlecone pine (Pinus aristata), limber pine (Pinus flexilis), Douglas-fir (Pseudotsuga menziesii) and aspen (Populus tremuloides) may be planted.