Weeds or Wilds? The Threat of Invasive Plants
Ron Vanderhoff CA Native Plant Society, Orange County OCCNPS.org [email protected] Roger’s Gardens rogersgardens.com [email protected] Weeds or Wilds?
Invasive Plants: • Plants that invade natural ecosystems, multiply, and disrupt the native ecology
• Second largest threat to our native plants and wildlands (development is #1) • 1500 plant species in the wilds of Orange County, about 500 of which are non‐native • A much smaller number are invasive
• Half of these, or more, were introduced through horticulture! Emergent Invasive Plant Management Program
What’s the big deal about invasive plants?
Emergent Invasive Plant Management Program
Our focus is specifically invasive species that are:
• Newly arrived in the region or of limited distribution • High potential for invasiveness • High probability of significant ecological disruption
Our Goal: County‐wide early detection and facilitation of the effective management of specific emergent invasive weeds within our region Emergent Invasive Plant Management Program
The List: 2017 Emergent Invasive Plants Aegilops triuncialis Barbed goatgrass • A dynamic list Cenchrus echinatus Southern sandbur Cenchrus longispinus Mat sandbur • Plant candidates are suggested Centaurea solstitialis Yellow starthistle • Must qualify as emergent Chrysanthemoides monilifera Boneseed Delairea odorata Cape ivy • A data –driven scoring and review Dittrichia graveolens Stinkwort process Ehrharta calycina Perennial veldt grass Hypericum canariense Canary Island St. John's Wort • Highest priority plants are “Red Alert” Iris pseudacorus Yellow flag Iris Melinis repens Natal grass Oncosiphon piluliferum Stinknet Parthenium hysterophorus Santa Maria feverfew Rubus armeniacus Himalayan blackberry Senecio linearifolius Australian fireweed Volutaria tubuliflora Egyptian knapweed
Candidate List ‐ Considered 46 species Watch List –Not yet recorded in Orange County 39 species Former List – Removed from the Emergent List Senecio linearifolius var. linearifolius 9 species Emergent Invasive Plant Management Program
A data driven score ‐ using objective measurements Scoring Protocol: (Abundance+Distribution+Invasiveness+Reproductive rate)/4 + Alert status Abundance Distribution Ecological Impact Rate of Spread Variables: Cal‐IPC ranking/alert ID difficulty
Published data Unpublished data Local knowledge Land managers Botanical consultants Active field experts Yellow flag iris (Iris pseudacorus) Fountain grass (Pennisetum setaceum) Pampas grass (Cortaderia sellowana) Natal grass (Melinis repens) Natal grass (Melinis repens) Seashore paspalum (Paspalum vaginatum) Yellow flag iris (Iris pseudacorus) Asphodel (Asphodelus fistulosus) Cape ivy (Delairea odorata) Cape ivy (Delairea odorata) Himalayan blackberry (Rubus armeniacus) Sage leaf rockrose (Cistus salviifolius) Pride of Madiera (Echium candicans) Fennel (Foeniculum vulgare) Artichoke thistle (Cynara cardunculus) Artichoke thistle (Cynara cardunculus) Brazillian pepper (Schinus terebinthifolius) OC CNPS Emergent Invasive Plant Management Program
A weedy story . . .
Examples of Invasive Species Along Orange County’s Coastline and Canyon Lands Aliso Canyon, South Laguna Boneseed (Chrysanthemoides monilifera ssp. monilifera) Boneseed (Chrysanthemoides monilifera) Boneseed (Chrysanthemoides monilifera ssp. monilifera) Boneseed (Chrysanthemoides monilifera) Big Canyon, Upper Newport Bay Moroccan Knapweed (Volutaria tubuliflora) Emergent Invasive Plant Management Program
If you find any of the invasive plants on these pages, at a NEW site: Known locations can be seen at http://www.occnps.org/invasives/locations‐and‐status‐updates.html
• Record the plant’s location as exactly as you can (GPS coordinates, if possible), the date you saw it, and an estimate of how many there were. Include the site’s landowner or manager, if known. • Take some identifying photos, especially clear close‐ups of flowers and/or leaves from different angles. • If you take a sample, place it immediately into a sealed bag. • To avoid spreading the plant, check your clothing and shoes thoroughly before leaving the area, and remove and bag all traces of seeds. • Report the find immediately to [email protected].
Emergent invasive plants are non‐native species that have appeared recently in Orange County, are not yet widely distributed here, and are known or presumed to spread readily.
http://www.occnps.org/invasives.html [email protected] So What?
• Make smart plant choices in your garden –don’t plant invasives
• Support PlantRight and others adressing this problem • Be an activist –talk to neighbors, nurseries, landscapers, governments • Volunteer (CNPS, Laguna Canyon Foundation)
• Support invasive plant detection and management