The University of San Francisco USF Scholarship: a digital repository @ Gleeson Library | Geschke Center Master's Projects and Capstones Theses, Dissertations, Capstones and Projects Spring 5-15-2020 Impacts of medusahead (Elymus caput-medusae L.) management on plant communities in California’s valley grasslands Nicole Carpenter [email protected] Follow this and additional works at: https://repository.usfca.edu/capstone Part of the Natural Resources and Conservation Commons Recommended Citation Carpenter, Nicole, "Impacts of medusahead (Elymus caput-medusae L.) management on plant communities in California’s valley grasslands" (2020). Master's Projects and Capstones. 1034. https://repository.usfca.edu/capstone/1034 This Project/Capstone is brought to you for free and open access by the Theses, Dissertations, Capstones and Projects at USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. It has been accepted for inclusion in Master's Projects and Capstones by an authorized administrator of USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. For more information, please contact [email protected]. This Master's Project Impacts of medusahead (Elymus caput-medusae L.) management on plant communities in California’s valley grasslands by Nicole Carpenter is submitted in partial fulfillment of the requirements for the degree of: Master of Science in Environmental Management at the University of San Francisco Submitted: Received: ...................................……….. ................................…………. Nicole Carpenter Date Aviva Rossi, M.S. Date Table of Contents List of Figures .............................................................................................................................................. ii List of Tables .............................................................................................................................................. iii Abstract ....................................................................................................................................................... iv 1. Introduction ............................................................................................................................................. 1 1.1 Objective of this Study ........................................................................................................................ 3 2. Background ............................................................................................................................................. 4 2.1 California’s Valley Grasslands .......................................................................................................... 4 2.2 Ecology of Medusahead...................................................................................................................... 7 2.3 Impacts of Medusahead ...................................................................................................................... 9 2.3.1 Loss of Biodiversity .................................................................................................................... 9 2.3.2 Forage Decline .......................................................................................................................... 10 2.3.3 Thatch Accumulation ................................................................................................................ 10 2.3.4 Economic Cost .......................................................................................................................... 11 2.4 Medusahead Control Methods .......................................................................................................... 11 3. Methods .................................................................................................................................................. 12 4. Results .................................................................................................................................................... 13 4.1 Herbicides......................................................................................................................................... 18 4.1.1 Advantages ................................................................................................................................ 19 4.1.2 Disadvantages ............................................................................................................................ 20 4.1.3 Impacts on Plant Community .................................................................................................... 21 4.2 Grazing ............................................................................................................................................. 22 4.2.1 Advantages ................................................................................................................................ 24 4.2.2 Disadvantages ............................................................................................................................ 25 4.2.3 Impacts on Plant Community .................................................................................................... 26 4.3 Prescribed Burning .......................................................................................................................... 28 4.3.1 Advantages ................................................................................................................................ 28 4.3.2 Disadvantages ............................................................................................................................ 29 4.3.3 Impacts on Plant Community .................................................................................................... 30 4.4 Mechanical control ........................................................................................................................... 33 4.4.1 Advantages ................................................................................................................................ 34 4.4.2 Disadvantages ............................................................................................................................ 34 4.4.1 Impacts on Plant Community .................................................................................................... 35 5. Discussion............................................................................................................................................... 36 i 5.1 Integrated Pest Management ............................................................................................................ 39 5.2 The Knowing-Doing Gap ................................................................................................................. 40 5.3 Revegetation Implementation ........................................................................................................... 42 5.4 Climate Change and Drought........................................................................................................... 43 5.5 Study Limitations .............................................................................................................................. 44 6. Conclusion and Management Recommendations .............................................................................. 45 6.1 Restoration Research ........................................................................................................................ 46 6.2 Funding for Weed Management Areas ............................................................................................. 46 6.3 Monitoring and Adaptive Management ............................................................................................ 47 References .................................................................................................................................................. 49 List of Figures Figure 1: The invasion curve .......................................................................................................... 2 Figure 2: Current distribution of California’s grasslands ............................................................... 5 Figure 3: Medusahead seed head with visible awns ....................................................................... 8 Figure 4: Medusahead distribution in California ............................................................................ 9 Figure 5: Medusahead thatch ........................................................................................................ 11 Figure 6: Medusahead control with the pre-emergent application of the herbicides .................... 20 Figure 7: The Green and Brown grazing strategy ......................................................................... 23 Figure 8: Spring timing of sheep grazing on medusahead cover .................................................. 24 Figure 9: Medusahead cover from grazed and ungrazed plots ..................................................... 26 Figure 10: Effect of grazing densities and timing on response ratios of medusahead, native plants, and non-native forage plants ............................................................................................. 27 Figure 11: Percent cover of thatch and bare ground between unburned and burned plots in a vernal pool ecosystem ................................................................................................................... 29 Figure 12: