United States Department of Environmental Agriculture Forest Assessment Service December 2011 Invasive Plant Treatment Project San Gabriel River Ranger District, Angeles National Forest and San Dimas Experimental Forest, Pacific Southwest Research Station Los Angeles and San Bernardino Counties, California Portions of T1N, R8W, R9W, R10W, and R11W; T2N, R8W, R9W, R10W, and R11W; and T3N, R8W, R9W, and R10W, SBM For Information Contact: Marian Kadota Adaptive Management Services Enterprise Team (805) 220-6388 http://www.fs.usda.gov/goto/angeles/projects The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. 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Environmental Assessment Invasive Plant Treatment Project Table of Contents Chapter 1 - Introduction ................................................................................................................... 1 Chapter 2 - Alternatives, including the Proposed Action ................................................................. 6 Chapter 3 - Affected Environment and Environmental Consequences .......................................... 46 Human Health and Safety .......................................................................................................... 46 Invasive Plants and Native Vegetation ...................................................................................... 58 Special Status Plants .................................................................................................................. 67 Wildlife ...................................................................................................................................... 70 Soils and Hydrology .................................................................................................................. 82 Special Land Designations (Wilderness and Research Natural Areas)...................................... 87 Recreation and Scenic Resources .............................................................................................. 92 Consequences Relative to Significance ..................................................................................... 95 Chapter 4 – List of agencies and persons consulted ..................................................................... 101 Interdisciplinary (ID) Team Members ..................................................................................... 101 Federal, State, And Local Agencies ......................................................................................... 101 References .................................................................................................................................... 103 Appendix A - Summary of Public Comments During Scoping ................................................... 108 Appendix B - Additional Invasive Plant Information .................................................................. 110 Appendix C - Potential Treatment Prescription Options .............................................................. 120 Appendix D –Responses to Comments on Preliminary EA ......................................................... 126 Appendix E –T&E Species Accounts ........................................................................................... 148 List of Figures Figure 1. Project Area Map. ................................................................................................ 7 Figure 2. Decision key for invasive plant treatments. ...................................................... 10 Figure 3. Map of known populations of invasive plant species densities. ........................ 61 Figure 4. Map showing potential vectors and pathways in and near project area. ......... 117 List of Tables Table 1. List of high and moderate priority invasive plants. ..........................................................10 Table 2. Summary of treatment methods proposed. .......................................................................12 Table 3. Summary of range of and typical application rates for each herbicide proposed. ............14 Table 4. Herbicides considered for use, including examples of trade names, and how they affect plants. ...............................................................................................................................15 Table 5. Distances (in miles) and acres by branch name. ...............................................................16 Table 6. Summary of maximum annual treatment by branch and species. ....................................18 Table 7. Maximum annual treatment by branch and invasive plant species/type ..........................27 Table 8. Comparison of alternatives. ..............................................................................................44 iii Table 9. Summary of hazard indicators and toxicity categories for pesticides. ............................ 49 Table 10. Signal Word used for each acute toxicity category.37 .................................................... 49 Table 11. Rating of risk to human health and safety for each herbicide and adjuvants (in general) considered in alternative 1. ........................................................................................... 58 Table 12. Approximate acres by vegetation type within project area ........................................... 59 Table 13. High and moderate priority invasive plant species that are known to occur within 75 feet of the project area ................................................................................................... 60 Table 14. Highlighted specific toxicities to plants by herbicide. .................................................. 69 Table 15. Herbicide Behavior in the Environment. ....................................................................... 85 Table 16. Invasive plants known to occur in and near the project area. Cal-IPC inventory categories, CDFA ratings, and the San Gabriel River Ranger District (SGRRD) priority. ........................................................................................................................ 111 Table 17. High and moderate priority species reproductive mechanisms that have been identified (Warner et al. 2003). ................................................................................................... 113 Table 18. Dispersal vectors for high and moderate priority invasive plants. .............................. 115 Table 19. Vegetation type high and moderate priority invasive plant species are known to occur in. ................................................................................................................................. 118 iv Environmental Assessment Invasive Plant Treatment Project CHAPTER 1 - INTRODUCTION Background _____________________________________ Executive Order 13112 defines invasive plants as “non-native plants whose introduction does, or is likely to, cause economic or environmental harm or harm to human health” (http://ceq.hss.doe.gov/nepa/regs/eos/eo13112.html). Some invasive plants can change ecosystem processes such as hydrology, fire regimes, and soil chemistry. These invasive plants have a competitive advantage because they are no longer controlled by their natural predators, and can quickly spread out of control. They spread with no consideration for land ownership boundaries. Furthermore, invasive plants that grow along stream channels can easily and often increase their infestation because their seeds, effortlessly, are capable of traveling downstream. The purpose of this environmental assessment is to update and expand the original project’s purpose and need, project area, and approved activities. The San Gabriel River Ranger District (District) has been implementing an arundo (Arundo donax) eradication project since 1998. The District has been successful in controlling the expansion of the populations, but the invasive plant species has not been completely eradicated from the District and needs continued treatment. The original decision is over 10 years old. This project covers the majority of the main drainages on the San Gabriel River Ranger District and San Dimas Experimental Forest (i.e., San Gabriel, Big and Little Dalton, San Dimas drainages). The project is located in portions of T1N, R8W, R9W, R10W, and R11W; T2N, R8W, R9W, R10W, and R11W; and T3N, R8W, R9W, and R10W, SBM in Los Angeles and San Bernardino Counties, California. During the past 20 years invasive plant species have invaded and/or expanded in the San Gabriel, Big and Little Dalton, and/or San Dimas drainages, including but not limited to: tamarisk (Tamarix spp.), tree-of-heaven (Ailanthus altissima), castorbean (Ricinus communis), Spanish broom (Spartium junceum),