Poker Chip Project. Noxious Weed Risk Assessment Almanor Ranger District Lassen National Forest

Transcription

1 Noxious Weed Risk Assessment Almanor Ranger District Lassen National Forest June 3, 2013 Introduction When a ground-disturbing action or activity is proposed, a Noxious Weed Risk Assessment (NWRA) determines the risk of introducing or spreading noxious weeds associated with the proposed action. This document analyzes factors that contribute to noxious weed introduction and spread. It considers factors that are independent of the proposed action (current noxious weed inventory, current habitat vulnerability, vectors not related to project implementation) and factors that are associated with the proposed action (habitat alteration and increased vectors expected as a result of project implementation). This document will also discuss how Integrated Design Features may reduce risk factors, and will summarize the overall anticipated noxious weed response to the proposed action. Factors Independent of the Proposed Action 1. Current Noxious Weed Inventory The area is located on approximately 8,110 acres in the Butt Creek (#37), Prattville (#38), Soda Ridge (#45), and Mt. Hope (#47) Management Areas. Ninety-six percent of the project area is within the perimeter of the 2012 Chips Fire. Multiple surveys have been conducted within the project area in conjunction with past projects, but no project-specific, post-fire floristic surveys were conducted (Table 1). /// Appendix B Page 1

2 Table 1: Noxious Weed Surveys in the Area: Project Survey Date Storrie Fire 2001 TU-1 Creeks 2001 TU Big Meadows Inc, Water Pipeline 2002 Adams Windthrow Fuels Reduction 2003 Soda Springs Defense Zone 2003 Creeks Forest Health 2004 Foxfarm 2004 Storrie Plantation 2005 OHV Route Designation 2007 Rust Resistant Sugar Pine 2008 OHV Botany Survey (Plumas N.F.) 2008 Belden Botanical Survey (Plumas N.F.) 2009 Grizzly Restoration 2011, 2012 Storrie SIR 2012 Source: USDA FS 2012 The California Department of Food and Agriculture s noxious weed list (CDFA 2010) divides noxious weeds into categories A, B, and C. A-listed weeds are those for which eradication or containment is required at the state or county level. For B-listed weeds, eradication or containment is at the discretion of the County Agricultural Commissioner. C-listed weeds require eradication or containment only when found in a nursery or at the discretion of the County Agricultural Commissioner. One noxious weed occurrence is known to the area (Map 1): Rubus armeniacus (Himalayan blackberry), LNF #3, C-rated This occurrence is located in a riparian corridor where Forest Road 26N08 intersects Grizzly Creek. The occurrence was first located in 2005, when it numbered 15 plants. The occurrence has been manually treated in six of the last seven years. The occurrence numbered 79 plants in 2008, but reduced to 48 plants in 2009, 7 plants in 2010, and 3 plants in The occurrence is within a danger tree removal unit (#0028) and just adjacent to a reforestation unit (#0111) that would be handcut and interplanted. 2. Current Habitat Vulnerability The area ranges in elevation from 3,840 and 6,680 feet. The dominant post-fire cover type within the project area is Sierran mixed conifer forest, which occurs across 50 percent of the project area. Other cover types currently include barren/burned montane chaparral (16%), white fir forest (12%), barren/burned forest (11%), montane chaparral (5%) and small inclusions of red fire forest, ponderosa pine forest, and montane riparian areas (Silviculture Report, Record). Appendix B Page 2

3 The Chips Fire of 2012 burned within 96% of the area. Of these acres, roughly 23 percent burned at high intensity, 22 percent at moderate intensity, 33 percent at low intensity, and 22 percent was either unburned or burned at very low intensity. Habitat conditions associated with moderate to high intensity burns include a lack of surface vegetation and duff and a reduction in overstory cover. Early seral habitats, characterized by full sun conditions and lack of established native plant cover, are vulnerable to noxious weed establishment. In addition, Chips Fire suppression efforts included the creation of fire line throughout the project area, an action that is associated with soil disturbance and removal of surface vegetation. The project area has also experienced ground disturbance over time from routine road construction and maintenance activities, timber harvest activities, the creation and maintenance of pine plantations, prescribed fire activities, and the Storrie Fire of 2000, which burned approximately 50% of the area. In sum, areas that burned at moderate to high intensity (3,570 acres) in the Chips Fire of 2012 are highly vulnerable to noxious weed establishment. Current habitat vulnerability is therefore high for noxious weed establishment. 3. Vectors Not Related to Project Implementation Several types of vectors may contribute to the spread of noxious weeds even though they are not associated with implementation. Fire lines created during the Chips Fire suppression effort constitute a network of disturbed ground that provides greater connectivity between patches of early seral habitat that are vulnerable to noxious weed invasion. In addition, the ongoing recreational use of roads within the project area creates vectors for noxious weed spread; particularly Road 26N26 that links the high-use Yellow Creek Campground north of the project area with hunting camps along Yellow Creek. Noxious weed vectors are also associated with proposed timber harvest activities on adjacent private and public lands. This includes timber harvest operations on 1,418 acres of private inholdings within the Lassen National Forest administrative boundary, and ongoing Lassen National Forest vegetation management activities associated with the Fox Farm DFPZ and Storrie Fuels Reduction Project (3,002 acres). System roads within and adjacent to the project area would receive increased traffic from timber harvest activities on adjacent lands, and may serve as vectors for weed spread as weed seeds or propagules affix to mud on vehicle tires. These increased vectors constitute short-term effects that would not persist beyond the implementation of these projects. Motorized vehicle traffic associated with other ongoing actions within and adjacent to the project area constitute additional noxious weed vectors. These include hazard tree removal associated with recreation sites, recreation facility maintenance and construction, fuelwood and Christmas tree cutting, and trail and road maintenance (see Poker Chip PORFFA, Record for a complete list of ongoing actions). Appendix B Page 3

4 Livestock and wildlife may also serve as vectors for weed spread. The is within the Chips Creek, West Humbug and Soda Creek grazing allotments. Of these, only the Soda Creek Allotment (1940 acres within the project area) is active, and permits a maximum of 54 head of cattle a year across these acres. Livestock and wildlife may spread weeds when propagules stick to hair, feathers, or hooves, or are deposited in droppings, however due to the low stocking levels on the Soda Creek Allotment, livestock grazing is of only minor concern. Overall, weed vectors that are not related to project implementation pose a moderate to high risk of noxious weed invasion due to proposed timber harvest activities on adjacent lands and high recreational use within the project area. Factors Related To Proposed Action 4. Habitat Alteration Expected as a Result of Project Implementation Project activities with the greatest potential to alter habitat include activities that would result in changes to existing canopy cover and activities that would create patches of disturbed soils. Danger tree removal would occur on 1,589 acres, and area salvage harvest activities would harvest trees with a high probability of mortality on 547 acres. While these fire-killed trees would provide some short-term shade in the absence of the proposed action, their removal would have only a negligible effect on long-term tree canopy cover. Site preparation and release activities in area salvage harvest units (547 acres) and reforestation units (3,296 acres) would result in a short-range decrease in shrub cover, which may increase habitat vulnerability to noxious weed invasion. This would be offset, however, by reforestation activities that would re-establish tree canopy cover within these units. As these trees establish and grow, they would increase tree canopy cover and over the long-term, decrease habitat vulnerability to noxious weed invasion. Ground disturbed by project activities would increase favorable habitat for noxious weeds within the project area. Vegetation removal and soil disturbance associated with the harvest of fire-killed trees, site preparation activities, release activities, and the construction of one mile of temporary road would create patches of bare ground that opportunistic noxious weed species could exploit, should seeds or propagules be introduced to the disturbed areas. Pile burning activities within all treatment units would scorch or kill understory vegetation and remove duff within burn pile footprints. In addition, mechanical, groundbased equipment used for machine piling activities would create patches of soil compaction and/or soil disturbance. Overall, the noxious weed risk due to project-related habitat alteration is moderate. 5. Increased Vectors as a Result of Project Implementation The has the potential to increase the risk of noxious weed invasion by creating new vectors for weed spread or increasing the probability that existing vectors would bring weeds into the project area. System roads within the project area would receive increased traffic from project-related activities. Mechanical ground-based equipment may serve as vectors for weed spread as weed seeds or Appendix B Page 4

5 propagules affix to mud on vehicle tires and equipment. Though there is only one known noxious weed occurrence within the project area, several weed occurrences along Highway 89 may be at risk of spreading further through project-related vectors. In addition, approximately one mile of temporary roads would be constructed for project implementation; however, these roads would be decommissioned after use, reducing the risk for the establishment of noxious weeds into the project area. Overall, risk from increased weed vectors that would result from project implementation is low to moderate. 6. Integrated Design Features The following Integrated Design Features implemented as part of the proposed action would greatly reduce the noxious weed risk factors described in this document: 1. All off-road equipment would be weed-free prior to entering Lassen National Forest. Staging of equipment would be done in weed-free areas. 2. Known infestations of Rubus armeniacus (Himalayan blackberry) would be identified, flagged and avoided, and mapped for this project. Locations would be displayed on contract maps. Identified noxious weed sites within or adjacent to the project area containing isolated patches with small plant numbers would be treated (hand pulled or dug) by forest botany staff prior to project implementation. 3. New small infestations of priority weed species identified prior to or during project implementation would be treated and avoided by project activities. If larger infestations are identified, they would be isolated and avoided by equipment, or equipment used would be washed after leaving the infested area and before entering an uninfested area. 4. Post-project monitoring for implementation and effectiveness of weed treatments and control of new infestations would be conducted as soon as possible and for a period multiple years after completion of the project. 5. If project implementation calls for mulches or fill, they would be certified weed-free. Seed mixes used for re-vegetation of disturbed sites would consist of locally-adapted native plant materials to the extent practicable. 7. Summary of Anticipated Weed Response to Proposed Action The area contains one C-rated noxious weed species (Rubus armeniacus, Himalayan blackberry), which occurs in a riparian channel that is within a danger tree unit and adjacent to a reforestation unit. Due to the recent history of wildfire within the project area (2000, 2012), current habitat vulnerability is high. Because of heavy recreational use and project proximity to salvage timber harvest projects on adjacent private and federal lands, non-project-dependent vectors pose a moderate to high risk for noxious weeds introduction and spread. While project-related factors are addressed through the development of Integrated Design Features, factors not related to project implementation are not. Such Appendix B Page 5

6 vectors operate independently of the proposed action, and would pose a moderate to high risk of spreading weeds even in the absence of the proposed project Several components of the proposed action (timber harvesting activities in danger tree removal and area salvage units, site preparation activities, pile burning, release activities) increase favorable habitat for noxious weeds where soils are disturbed. This is partially offset by the long-term net gain in tree canopy anticipated as a result of reforestation activities. Overall, project-related habitat alteration presents a moderate risk of noxious weed introduction and spread. Project-related weed vectors present an overall low to moderate risk, due to increases in mechanical equipment traffic related to project implementation, and the construction of one mile of temporary road. With the incorporation of Integrated Design Features as part of the proposed action, risk factors for noxious weed invasion and spread within the project area would be reduced. Overall, with incorporation of IDFs, there is a moderate potential for weed introduction and spread with the implementation of the (Table 3). Table 3: Summary of risk assessment Factors Independent of Proposed Action Current noxious weed inventory Current habitat vulnerability Non-project-dependent vectors One occurrence of a C-rated species within project area (Rubus armeniacus) High vulnerability Moderate to high risk Factors Related to Proposed Action Habitat alteration expected as a result of project Increased vectors as a result of project implementation Integrated Design Features Anticipated Weed Response to the Proposed Action Moderate risk Low to Moderate risk Reduced risk Moderate potential for weed spread 8. Costs Noxious weeds can reduce the value of public lands. Timber production, grazing, wildlife habitat and recreational opportunities are all negatively impacted by noxious weeds. Furthermore, noxious weed control is expensive and labor-intensive. Prevention and control of small infestations can reduce these impacts and decrease overall weed control expenditures. Noxious weed surveys, control of small infestations, and post-project monitoring are therefore vital in reducing overall impacts and costs from noxious weeds. Appendix B Page 6

7 9. References California Department of Agriculture (CDFA) Pest Ratings [Online]. Available: [accessed online February 14, 2013]. USDA Forest Service (USDA FS) (HFQLG FEIS and ROD) Herger-Feinstein Quincy Library Group Forest Recovery Act. Final Environmental Impact Statement and Record of Decision. Lassen, Plumas, and Tahoe National Forests, Pacific Southwest Region, USDA Forest Service. USDA Forest Service (USDA FS) Lassen National Forest noxious weed occurrence forms, Forest atlases, project documentation and GIS databases. Lassen National Forest, Supervisor s Office, Susanville, CA. Appendix B Page 7

8 Map 1: Noxious Weed Occurrences within the Area Appendix B Page 8