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Eucalypt Biology

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Eucalypt Biology Eucalyptus Workshop Los Angeles County Arboretum, June 28, 2019 Jenn Yost, Ph.D. Ma# Ri#er, Ph.D. Outline • Australian trees in California • Eucalyptus names and taxonomy • Worldwide plan6ng and uses • History, plan6ng, and use in California • Diseases • Eucalyptus as weeds and naturalized species in California (specifically Eucalyptus globulus) • Allelopathy in Eucalyptus • Eucalypt Tree Failures Origins of California’s Urban Trees Africa 1% New Zealand 2% California 6% Remainder of North America 9% Australia 33% South & Central America 11% Europe & Mediterranean East Asia, China, 13% & Japan 25% Australian Trees in California CulLvaLon • Acacias (Acacia spp.) • BoFle Trees (Brachychiton spp.) • BoFle Brushes (Callistemon spp.) • Paperbarks (Melaleuca spp.) • Carrot Wood (Cupaniopsis anacardioides) • PiFosporums (Pi:osporum spp.) • Brush Box (Lophostemon confertus) • Sheoaks (Casuarina spp.) • Eucalypts (Eucalyptus spp.) Major Australian VegetaLon Groups Champion Eucalyptus in Australia ‘Old Blotchy’, New South Wales Wilmington, South Australia 59 M tall, 10.8 M girth 32 M tall, 14.1 m girth Tasmania 800+ species of Eucalypts – Eucalyptus, Angophora, and Corymbia Corymbia Eucalypt Taxonomy • Family: Myrtaceae (guavas, cloves, allspice) • Subfamily: Leptospermoideae (woody fruits) • Genera • Angophora – 12 spp. • Corymbia – ~100 spp. • Eucalyptus – ~800 spp. Eucalypt Taxonomy The Eucalypts Angophora Angophora Corymbia (apples, rusty gums, Corymbia etc.) Blakella – 12 species Eucalyptus Eudesmia Corymbia Symphyomyrtus (bloodwoods, ghost gums, etc.) Bisectae – about 100 species Dumaria Adnataria Eucalyptus Exsertaria (gums, mallees, ashes, Maidenaria stringybarks etc.) – about 800 species Monocalyptus Eucalypts Worldwide • 2nd most important solid 6mber and paper pulp trees in the world • Timber, plywood, fiberboard, pulp, poles, firewood, charcoal, essen6al oils, honey, shelter, and ornament • 20 million ha (75,000 square miles) planted worldwide Eucalyptus in California • 374 species introduced into CA, 202 species alive as of 2016 • 38 species – widely planted = represented by 10 or more trees in 15 or more different loca6ons • 18 species naturalized E. globulus in California (Blue gum) Mediterranean Summer Rain >100 species grown in Cal. >250 species grown in Cal. NO NATURALIZED SPECIES ALL 18 NATURALIZED SPECIES Jared Farmer - Trees in Paradise • Plan6ng of eucalypts began in California in the 1850s • First in the Bay Area, then throughout the state “The single tree upon which the hope of the nation is fastened, the only tree that can possibly avert the inevitable ravages of the hastening timber famine, is the miracle tree - the Eucalyptus” Out West magazine, 1909 Tasmanian blue gum (Eucalyptus globulus) • First planted in 1856 • Extensively planted in 1870s and 1910 • ~40,000 acres currently planted • Tallest flowering plant in North or South America - 75.05 M (246.2’) blue gum on Santa Cruz Island Tasmania California The Rise of Eucalypts in California d27 The fall of California eucalypts Pacific Rural Press 1913 Eucalyptus in CA • Most abundant and controversial non-na6ve trees in California • Admired - erosion control, wildlife habitat, valuable landscape and heritage trees • Demonized - America’s largest, most fire prone, most dangerous, bird killing, weeds IntroducLon of Eucalypt Pests into California IntroducLon of Eucalypt Pests into California • “The accumula6on of herbivores on Eucalyptus in California has aFracted concern and interest among the arborist, nursery, and regulatory communi6es. Sixteen species arrived in a period of just 20 years ager ︎ ~100 years without any introduc6ons at all.” ︎ • “There are temporal and spa6al paFerns of introduc6on that could be coincidence and nothing but the summa6on of random economic or popula6on-driven processes.” • “Alterna6vely, we suggest that the mul6ple paFerns may be nonrandom; instead, they suggest the possibility of inten6onal introduc6ons.” Eucalyptus Invertebrate Diseases • Eucalyptus snout beetle • Eucalyptus tortoise beetle and Eucalyptus leaf beetle • Foliage-feeding caterpillars • Omnivorous looper • Orange tortrix • Gall makers • Eucalyptus gall wasps • Glassy-winged sharpshooter • Psyllids • Blue gum psyllid • Eucalyptus redgum lerp psyllid • Lemondrop lerp psyllid • SpoFedgum psyllid • Roundheaded Borer • Eucalyptus longhorned borer • Whiteflies • Giant whitefly Eucalyptus Diseases NaturalizaLon • 52 unique stands observed • 11 = extensive naturaliza6on • 21 = no naturaliza6on 2008 2008, www.californiacoastline.org 1979, www.californiacoastline.org Conclusions • There are at least 4 introduc6ons of blue gum to CA • Most CA blue gums are from Southeastern Tasmania • Gene6c diversity in blue gum in greater in Southern CA • Blue gum naturaliza6on does not correlate with provenance • Blue gum naturaliza6on likely depends on environmental factors Eucalyptus globulus plantations in California Can the lack of an understory be explained by allelopathy? What is allelopathy? • The direct or indirect influence of one plant on another, via a biochemical interac6on Testing plant growth in soil Blue gum plantaLon Coastal Scrub Other explanations: …. light? …. water? …. crushing? …. nutrients? Eucalypt Tree Failures 0 • Most commonly reported genera : Quercus (23.4%), Pinus (16.9%), Eucalyptus (12.5%) and Hesperocyparis (8.6%). .
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