Arundo donax Distribution and Impact Report March 2011 Agreement No. 06-374-559-0 State Water Resources Control Board Prepared by: California Invasive Plant Council Arundo donax (giant reed): Distribution and Impact Report March 2011 Agreement: No. 06-374-559-0 Submitted to: State Water Resources Control Board Submitted by: California Invasive Plant Council (Cal-IPC) Authors: Jason Giessow, Dendra Inc. (Chapters 2, 4.2, 5.2, 6-10) Jason Casanova, Los Angeles and San Gabriel Rivers Watershed Council (Chapters 3, 5.2) Rene Leclerc, Robert MacArthur, Northwest Hydraulic Consultants (Chapter 5.1) Genie Fleming, Consultant (Chapter 4.1) Jesse Giessow (Else), Dendra Inc. (Chapter 1) With contributions by: Elizabeth Brusati, Cal-IPC John Tangenberg, Los Angeles and San Gabriel Rivers Watershed Council Brad Roth, Consultant Doug Johnson, Cal-IPC This report and spatial data set (GIS geo-database) are available for download at: http://www.cal-ipc.org/ip/research/arundo/index.php or http://www.cal-ipc.org/ip/mapping/arundo/index.php The spatial data set is also viewable at the DFG BIOS web site: http://bios.dfg.ca.gov/ BIOS project data sets are named: Invasive Plants (Species) - Central_So. Cal Coastal Watersheds [ds645] Invasive Plants (Prct Cover) - Central_So. Cal Coastal Watersheds [ds646] TABLE OF CONTENTS EXECUTIVE SUMMARY............................................................................................................................ 1 1.0 INTRODUCTION ................................................................................................................................. 4 2.0 ARUNDO BIOLOGY ............................................................................................................................ 5 2.1 Physiology......................................................................................................................................... 5 2.2 Genetic variation............................................................................................................................... 5 2.3 Physical Structure ............................................................................................................................. 5 2.4 Biomass and Cane Density ............................................................................................................. 21 2.5 Growth Rate.................................................................................................................................... 23 2.6 Reproduction and Spread................................................................................................................ 24 2.6.1 Within Stand Spread ................................................................................................................ 24 2.6.2 Spread Within A Watershed..................................................................................................... 25 2.6.3 Historic Air photo Analysis: Stand Growth Rates and Spread Within Watershed.................. 26 2.6.4 Spread Between Watersheds.................................................................................................... 26 2.7 Ecological Function: Abiotic and Biotic......................................................................................... 26 2.7.1 Abiotic..................................................................................................................................... 26 2.7.2 Biotic....................................................................................................................................... 27 2.7.2.1 Vegetation........................................................................................................................ 27 2.7.2.2 Arthropods ....................................................................................................................... 27 2.7.2.3 Wildlife ............................................................................................................................ 28 2.8 Arundo Biology: Conclusions......................................................................................................... 29 3.0 SPATIAL DATA SET: The Distribution and Abundance of Arundo from Monterey to Mexico......... 30 3.1 Methodology................................................................................................................................... 30 3.1.1. Step-by-Step Process............................................................................................................. 30 3.1.2. Data Quality.......................................................................................................................... 34 3.2 Results: Acreage by Watershed and Region................................................................................... 37 3.3 Conclusions: Distribution and Abundance ..................................................................................... 38 4.0 IMPACTS OF ARUNDO: Arundo Water Use and Stand Transpiration............................................ 40 4.1 Determining Arundo Water Use (Stand transpiration) ................................................................... 40 4.1.1 Background:............................................................................................................................. 40 4.1.2 Methods.................................................................................................................................... 40 4.1.3 Results and Discussion ............................................................................................................ 46 4.2 Arundo Water Use Across Study Area ........................................................................................... 47 5.0 IMPACTS OF ARUNDO: Hydrology, Geomorphology and Flooding .............................................. 50 5.1 Hydraulics, Sediment Transport, Geomorphology ......................................................................... 50 5.1.1. Introduction............................................................................................................................. 50 5.1.2 Arundo and River Morphology ................................................................................................ 51 5.1.2.1 Arundo in the River Environment..................................................................................... 51 Arundo donax Distribution and Impact Report i General Characteristics ............................................................................................................. 51 Dispersal & Establishment........................................................................................................ 52 Rates of Spread ......................................................................................................................... 52 Erosion of Arundo Stands by Floods ........................................................................................ 52 5.1.2.2 Observed Effects on Rivers .............................................................................................. 53 Introduction and Context .......................................................................................................... 53 Long-term Historical Studies.................................................................................................... 53 General Observations................................................................................................................ 53 Trends in Width and Planform.................................................................................................. 54 Vertical Adjustments of the Bed and Floodplain...................................................................... 54 Lateral Migration and Bank Erosion......................................................................................... 55 5.1.2.3 Observed Effects on Hydraulics and Sediment Transport................................................ 55 Response to Arundo Removal or Eradication........................................................................... 56 5.1.2.4 Summary of Understanding .............................................................................................. 56 5.1.3 Southern California Study Streams.......................................................................................... 57 5.1.3.1 Introduction....................................................................................................................... 57 5.1.3.2 Study Streams ................................................................................................................... 57 5.1.3.3 CAL-IPC GIS Analysis..................................................................................................... 57 5.1.3.4 Study Stream Characteristics ............................................................................................ 58 General Morphology................................................................................................................. 58 Arundo Characteristics.............................................................................................................. 59 5.1.4. Santa Margarita River Case Study ......................................................................................... 63 5.1.4.1 Introduction....................................................................................................................... 63 5.1.4.2 Santa Margarita Watershed..............................................................................................