Walton Lake Restoration Project

Transcription

1 Walton Lake Restoration Project Fire and Fuels Specialist Report, February 2017 Ochoco National Forest Lookout Mtn. Ranger District Barry Kleckler Fuels Specialist, Prairie Division, Central Oregon Fire Management Service (COFMS) Existing Condition Moist mixed-conifer Currently, the moist mixed-conifer forested stands in the Walton Lake Developed Recreation Area are infested with laminated root disease (see Forest Health report). This disease spreads to host species (grand fir and Douglas-fir) through the root systems, and creates a public safety concern due to the tendency of affected trees to break and fall. Laminated root rot and other sources of pathogens have created a steady source of hazard trees within the recreation area; annual felling of these trees has resulted in an accumulation of surface fuels. Surface fuels have also accumulated in the project area due to trees falling naturally as a result of the disease. Surface fuels buildup associated with the root disease within the project area has resulted in a secondary public safety concern due to elevated wildfire risk. Dry mixed-conifer Dry mixed-conifer stands in the area with a mature ponderosa pine overstory are experiencing conditions that promote uncharacteristically severe wildfire that threatens the safety of firefighters and visitors and decreases resiliency to other natural disturbances, insects, and disease. Prior to the late 1800s frequent low to moderate intensity surface fire would have maintained these stands with less understory growth. Forest Management practices (grazing, fire suppression) have all but eliminated wildfire allowing for the growth of a fire-intolerant grand fir understory. In addition to increased competition for water and nutrients these relatively young grand fir, often with branches all the way to the ground, can act as a ladder fuel allowing surface fire to climb into the canopy of the otherwise firetolerant pine. Crown fire is significantly harder to suppress and can spread more quickly through spotting. Areas of the landscape adjacent to Walton Lake have been treated in recent years to restore resiliency and reduce the probability of crown fire using a mixture of commercial and non-commercial thinning, piling, and prescribed burning under the Canyon Fuels and Vegetation Management Project (EIS 2010). These treatments as analyzed have moderated some risk of wildfire reaching Walton Lake, but the project did not address fire behavior effects or the fuels hazard within the Developed Recreation Area. Wildland Urban Interface (WUI)

2 Walton Lake is within a larger area identified as WUI in the Crook County Community Wildfire Protection Plan (CWPP 2014). The Healthy Forests Restoration Act (HFRA) requires that CWPPs focus on fire-safety of both communities and critical infrastructure. The Crook County CWPP was developed as a tool to prioritize residential areas, critical infrastructure (access routes and communication sites), and high use recreational areas for mitigation and prevention opportunities associated with wildfire with goals of protecting against loss of life, property and natural resources from wildfire and instilling a sense of personal responsibility to reduce the risk of intense wildfire behavior on public and private lands. Walton Lake and the 22 Road corridor are considered WUI based on their public safety relationship with significant numbers of visitors, particularly throughout the summer and early fall when burning conditions are at their most severe. Temporary evacuation of the campground was required in the summer of 2014 due to multiple growing wildfires in the vicinity and the necessity of closing the 22 Road as a travel route through the Ochoco National Forest. Standards and Guidelines The Ochoco National Forest Land and Resource Management Plan (Forest Plan) provides Standards and Guidelines for Fire Management and for Natural Forest Residue accumulation. The Forest-Wide Standard and Guideline for Initial Attack is to apply aggressive suppression action to wildfires that threaten life, private property, public safety, improvements, or investments. Additional Standards and Guidelines for Developed Recreation Areas (MA-F13) dictate a strategy to control all wildfire, suppression should emphasize minimum physical disturbance. The Forest Plan also provides desired natural forest residue profiles across different forest types and Management Areas including Developed Recreation. These desired residues reference a photo series (PNW-GTR-105) and accompanying data sheets (Maxwell, 1980). Developed Recreation areas in Mixed Conifer fuel types are represented by photo 1-MC-3 as shown in Figure 1. The accompanying Data Sheet (Table 1) associated with this photo describes a total fuel loading of 11.1 tons per acre. The code 1-MC- 3, refers to the 1 st photo in the series (ranked lowest to highest fuel loading) - in the Mixed Conifer type (MC) - forest size class 3 (11 to 20 dbh). In an effort to consider increased loading due to the size of the trees around Walton Lake the photo (Figure 2) and fuel loading profile (Table 2) for 1-MC-4 (forest size class 4, >20 dbh) is also included in this report. Table 1: 1-MC-3 Size class (inches) Table 2: 1-MC-4 Weight Size class (tons/acre) (inches) Less than ¼ 0.7 Less than ¼ 0.5 ¼ to ¼ to to to to to to to Total 11.1 Total 20.9 Weight (tons/acre)

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4 Figure 1: PNW-105 Residue descriptive code 1-MC-3 (Maxwell, 1980) Forest Plan Standard Figure 2: PNW-105 Residue descriptive code 1-MC-4 (Maxwell, 1980)

5 Laminated root rot is a disease which can cause extensive mortality that is often associated with windthrow within disease centers involving several conifer species of diverse age classes (Rippy, et al., 2005). Based on current photos in unit 3 (Figures 3, 4, and 5), fuel loadings in affected areas are roughly estimated at tons per acre and can be expected to increase as the disease spreads through host species. Figure 3: Current pocket of blowdown in Unit 3 Figure 4: Current pocket of blowdown in Unit 3

6 Figure 5: Current pocket of blowdown in Unit 3 Effects of No Action If no action is taken, course woody debris can be expected to continue to accumulate in units 2, 3, and 4, perhaps at an accelerated rate as there would be increased disease spread, mortality, and associated windthrow. For each 14 dbh Douglas-fir that falls approximately 0.5 tons of woody debris accumulates on the forest floor. 20 dbh trees supply approximately 1 ton of debris, and 30 dbh trees supply over 3 tons (Brown, Reinhardt, & Kramer, 2003). This accumulation of fuels would increase wildfire hazard resulting in increased risks to firefighter and public safety in the Developed Recreation Management Area by influencing both fire behavior and resistance to control, as well as potential for uncharacteristic fire severity due to increased residence time and soil heating (Brown, Reinhardt, & Kramer, 2003). In the dry mixed conifer stands of units 1 and 5, surface fuels and ladder fuels would remain and potentially increase in the absence of treatment. The potential would remain high for human or naturally caused wildfire beginning in the area or moving in from adjacent stands to transition from the surface into the crowns of the trees greatly increasing the risk to public safety in the campground and decreasing the safety and effectiveness of aggressive initial attack by firefighters as dictated by the Forest Plan. Effects of Treatment Treatments in units 2, 3, and 4 to reduce impacts of laminated root rot include removal of host species and favoring of more resistant species (Rippy, et al., 2005). This treatment in conjunction with removal of much of the material already on the ground both mechanically and by piling and burning would bring the area back in line with Forest Plan Standards for forest residues, while still retaining a beneficial

7 amount of course woody debris to benefit wildlife and site productivity (Brown, Reinhardt, & Kramer, 2003). Other proposed treatments in the dry mixed conifer and ponderosa pine forest types to thin from below and either remove or handpile the slash would decrease the hazard to firefighters and increase public safety within the recreation area by reducing the potential for crown fire. Crown fire potential is determined using predicted surface fire flame length, along with multiple factors including canopy base height (the distance from the ground to the lowest branches of the canopy), canopy cover (a measure of how continuous canopy fuels are), and crown bulk density. Crown fire potential can be reduced though treatments that reduce ladder fuels and increase canopy base height (thin to remove small trees and reduce the number of fire-intolerant trees with low hanging branches), and decrease canopy cover (thin larger trees to increase canopy spacing and reduce potential for wildfire to spread from tree to tree). Firefighters would experience less risk and generally be more successful suppressing surface fire within the campground, adhering to Forest Plan Standards and Guidelines, and fuel treatments would be maximized within the high use recreation area and public transportation routes as prioritized in the CWPP. Modeling the Effects of Proposed Treatments At the stand level, the Forest Vegetation Simulator (FVS (Dixon, 2002)) was used to model treatments proposed to Unit 1 in the dry mixed-conifer portion of the Walton Lake Restoration Project (Silviculture Report). The Fire and Fuels Extension to FVS (FFE-FVS (Rebain, 2010)) was then used to simulate the follow-up slash removal and pile burning in the unit. FFE-FVS predicts potential fire behavior under both severe and moderate conditions (fuel moisture conditions associated with typical wildfire vs. prescribed fire). A comparison of the results is shown in Table 3. Crown index is defined as the windspeed required at 20 feet above the tree canopy for a sustained crown fire run. Torching Potential is an index from 0 1 describing the potential for torching in any area of the stand, not necessarily the probability. Table 3: Comparison of FFE-FVS outputs in Unit 1 Treated vs. Untreated. Untreated Treated Fire Type Crown Surface Crown index Torching Potential (Severe) Torching Potential (Moderate) Potential Mortality - % BA loss (Severe) Potential Mortality - % BA loss (Moderate) 17 7 Finally, FVS was used to simulate a wildfire in Unit 1 with and without proposed treatments using severe but not uncommon late fire season wind speeds and fuel moistures. The default Very Dry fuel moisture conditions for the Blue Mountains Variant were used (Rebain, 2010) with a wind speed of 17 miles per hour at 20 feet above the canopy. Images representing the FVS outputs were created using the

8 Stand Visualization System (SVS (McGauphey, 2004)). Figures 6 and 7 are representations of Wildfire simulated in 2020 in both treated and untreated scenarios. Figure 6: Wildfire modeled in Unit 1 with no treatment Figure 7: Wildfire modeled in Unit 1 with proposed thinning and slash removal.

9 The untreated scenario resulted in 100% crown fire throughout the stand with complete mortality which would create numerous future hazard trees in the campground, while the treated scenario resulted in more manageable surface fire with minimal mortality of overstory trees and greatly decreased resistance to control by firefighters. Cumulative Effects As described previously, nearby activities associated with the Canyon Fuels and Vegetation Management Project (2010) have reduced fuels and moderated the risk of wildfire entering the Walton Lake Developed Recreation Area from the outside. Fuels reduction associated with the Proposed Action would combine with the Canyon activities to further reduce wildfire risk within the Walton Lake area. Project Design Criteria and Mitigations as related to Fuels/Fire Trees commercially harvested would be whole-tree yarded when possible and processed at the landing to reduce the amount of slash left in the woods. Trees too large to be skidded whole would have tops attached to the last log. Cull logs (including logs on the ground) would be removed and hauled off site from moist mixed conifer units. Remaining slash and pre-commercial thinning slash would be concentrated in handpiles to be burned outside of fire season. Works Cited Brown, J. K., Reinhardt, E. D., & Kramer, K. A. (2003). RMRS-GTR-105 Coarse Woody Debris: managing benefits and fire hazard in the recovering forest. Ogden, UT: USDA Forest Service, Rocky Mountain Research Station. (2014). Crook County Community Wildfire Protection Plan. Dixon, G. E. (2002). Essential FVS: A user's guede to the Forest Vegetation Simulator. Fort Collins, CO: U.S.. Maxwell, W. G. (1980). GTR-PNW-105 Photo Series for Quantifying Natural Forest Residues in Common Vegetation Types of the Pacific Northwest. Portland, OR: Pacific Northwest Forest and Range Experiment Station, USDA Forest Service. McGauphey, R. J. (2004). Stand Visualization System, Version Pacific Northwest Research Station: US Department of Agriculture. Rebain, S. A. (2010). The Fire and Guels Extension to the Forest Vegetation Simulator. Fort Collins, CO. Rippy, R. C., Stewart, J. E., Zambino, P. J., Klopfenstein, N. B., Tirock, J. M., Kim, M.-S., & Theis, W. G. (2005). RMRS-GTR-141 Root Diseases in Coniferous Forest of the Inland West: Potential

10 Implications of Fuels Treatments. Fort Collins, CO: USDA Forest Service, Rocky Mountain Research Station.