Welcome, Review, and Introduction

Home , Elkhorn Slough

Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

The Elkhorn Slough Coastal Training Program & The California Invasive Plant Council Welcome, Review,

- Present - and Introduction

Grey Hayes, PhD Control of Blue Gum Eucalyptus Coordinator in Coastal California Elkhorn Slough Coastal Training Program

History of Eucalyptus in California

Blue Gum Eucalyptus in the Elkhorn Slough Watershed

By Eric Van Dyke

Ellwood Cooper, 1876 Out West, 1909

Introduction 1 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Out West, 1909

Does Blue Gum Spread??

An Elkhorn Case Study

Out West, 1909

Brothers North

1931 1956

1980 2001

Introduction 2 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

For Birds, 2 Important Invaded Habitats in the Monterey Bay Birds and Eucalyptus on the Central California Coast: A Love – Hate Relationship • Oak Woodland

David L. Suddjian • Riparian Biological Consulting Services

Affects on Birds Depends on: On the “Up” Side

• 14% of Santa Cruz County’s nesting birds nest regularly in blue gum (20 of the 148) • Canopy density – Most birds nesting in blue gum also nest in mixed conifer woodlands, while others nest otherwise in riparian or live oak • Tree density woodland • Tree age • Great Blue Herons, Great Egrets, and Double-crested Cormorants currently nest in Santa Cruz County only in • Tree architecture blue gum groves

• Proximity of trees to water • Red-shouldered and Red-tailed hawks and Great Horned Owls nest preferentially in blue gum

• Often the only significant tree groves in more urbanized areas

On the Down Side Oak, Eucalyptus, and Singing • Blue gum is generally missing cavities Birds

• Foliage gleaning birds are fewer in blue gum

• Riparian birds: Downy Woodpecker, Warbling Vireo, Or the effects of exotic versus native Tree Swallow, Violet-green Swallow, Swainson’s Thrush, and Yellow, Orange-crowned, and Wilson’s warblers forest cover on abundance, composition, diversity, and evenness of • Oak woodland birds: Western Screech-Owl, Acorn and avian species Nuttall’s woodpeckers, Ash-throated Flycatcher, Hutton’s Vireo, Oak Titmouse, House Wren, Western Bluebird, Orange-crowned Warbler, and Lark and Chipping Diana Kiyo Wakimoto, UC Santa Cruz sparrows

Introduction 3 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Overall Number of Species Abundance per plot 40 120 Bewick’s Wren Effects of Woodlot 35 100 30 and Season 80 25 20 60 12 15 40 10 Number of Species Number 10 Number of Individuals Number 20 5 0 0 8 eucalyptus oak eucalyptus oak eucalyptus 6 Richness per plot Total Abundance oak 22.5 400 4 20 350 17.5 300 2 15 Number of Individuals 250 12.5 200 10 0 fall spring 7.5 150 5 ofIndividuals Number 100 Season Number of Individuals Number 2.5 50 P= 0.0273 0 0 eucalyptus oak eucalyptus oak

European Starling Woodlot & Comparative Ecological Value of Season effects Coastal Live Oak and

35 Australian Blue Gum Woodlands

20 eucalyptus oak 15

5 Number of Individuals 0 fall spring 2003 A. Kopitov 2003 A. Season Kopitov P= 0.0508 Anna M. Kopitov Nicholas School of the Environment Resource Ecologist and Earth Sciences June 2004 Duke University

Bird Community Breeding Birds Oak Species 28 Euc 7

Individuals 148 5

Describe breeding bird community for oak Richness Species and eucalypt woodlands Oak Euc 1 Richness 22 12 euc oak Exclusivity 16 6 Woodland Type Oak Species richness and Individuals 85 63 2.0 Euc diversity indices 1.5

1.0 Median values for species SWDI

richness and Shannon Weiner 0.5

Diversity Index are dissimilar. 0.0

euc oak TYPE

Two sample t-test statistically significant: P < OBJECTIVE 1/ANALYSIS RESULTS 0.05

Introduction 4 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Bird Indicators in Oak Woodlands Bird Indicators O, Spotted Towhee Do species occur preferentially in oak or B IV = 72 eucalyptus habitat? P = 0.04

¾ Assigns indicator values ranging from 0 to O

100

O O

O = Overall Community Indicators, B = Breeding Bird Indicators OBJECTIVE 3/ANALYSIS RESULTS

Bird Indicators in Eucalypt Woodlands Understory Community European Starling

Describe understory vegetation community IV = 71 of oak and eucalypt woodlands P = 0.01 Species richness and diversity indices

Estimated Percent Cover, Strata, and Tree Diameter

*No breeding bird Photos: Institut National de la Recherche Agronomique indicators RESULTS OBJECTIVE 1/ANALYSES

Distribution and median values for Oak understory plant species richness for 21 oak and eucalypt sites (N = 7 for Percent Cover by 100+ cm each type).

16 Strata Class 75 - 100 cm

50 - 75 cm

Species Richness Oak sites dominated by: 30 - 50 cm Median values for Class Strata

6 species richness and SWDI •Forbs and Shrubs 15 - 30 cm Euc Oak are nearly identical. 0 - 15 cm 1 •30 cm – 100 cm strata classes euc oak Woodland Type Eucalypt sites dominated by: 0 10203040506070

•Eucalypt Debris (~56% cover) Euc 100+ cm 1.6 •Forbs 15-30 cm strata class 75 - 100 cm Distribution and median of understory

Shannon Weiner Diversity Index (SWDI) 1.1 50 - 75 cm for oak and eucalypt sites (N = 7 for each SWDI Forbs Ferns Oak Debris type). 30 - 50 cm Shrubs Vines Bare Class Strata 0.6

15 - 30 cm Grasses Euc Debris Oak Saplings Euc Oak 0 - 15 cm 0.1 Euc Saplings euc oak Woodland Type 0 10203040506070 Estimated Percent Cover RESULTS RESULTS

Introduction 5 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Understory Indicators

Oak Sites Eucalypt Sites Sax, 2002 • Bracken * •Common Chickweed** (Pteridium aquilinum) (Stellaria media) •Showed similar species richness • Hedge Nettle* • Miner’s Lettuce* (Stachys ajugoides) (Claytonia perfoliata) • Italian Thistle* and diversity for oak and • Stickey Monkeyflower* (Carduus pycnocephalus) eucalyptus understory plants • Ripgut Grass* (Mimulus aurantiacus) (Bromus diandrus) • California Blackberry* •Majority of species sampled did (Rubus ursinus) not occur in both woodland types, • California Coffeeberry** *P < 0.05 (Rhamnus californica) **P < 0.10 with only 39% in common • Common Snowberry** (Symphoricarpos albus) between the two • Poison Oak* Bold text => Natives (Toxicodendron diversilobum) RESULTS

Allelopathic Influences of Oak and Eucalyptus on the Vegetation of the Jason’s research: Elkhorn Slough • Investigated the direct effect of by Jason Nicholson allelochemicals derived from the leaf litter of Quercus agrifolia and Eucalyptus globulus on native and non-native understory plants • Carried out a series of germination experiments, in which seeds were exposed to varying light intensity, substrate composition, and concentrations of leaf litter leachate

Allelopathic Seed bank composition 40 compounds 35 30 •Oaks produce mostly tannins, 25 Euc 20 which are a sub-group of phenolics 15 Oak 10 5 •Eucalyptus produce several Total plants germinated compounds, mostly terpenes and 0 s m s r li is ta s s e rus liu hu a ga ia dium c r phenolics hal pe Malva o g p Ga phanus Ana ce Cy erfol a Son R nop no P e c ta nown oth Ch known k py ni s o Un Un u M rdu Ca

Introduction 6 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Drip method Seed bank results: Effect of same source leachate leachate extraction Eucalyptus 1A Oak 1A seed bank 12 seed bank 12

10 10

8 8

6 6

4 4 Mean seeds germinated 2 2

0 0 DI Euc DI Oak Somewhat significant for Euc p = 0.091 Two-way ANOVA

Germination of Germination of Baccharis Bromus carinatus On filter paper: Day 9 On soil: Day 13 18 18 25 On filter paper: Day 9 25 On soil: Day 13 16 16 22.5 22.5 14 14 20 20 17.5 17.5 12 12

15 15 10 10 12.5 12.5 8 8 10 10 6 6 7.5 7.5 Mean seeds germinated Mean seeds germinated 4 4 5 5 2 2 2.5 2.5 0 0 0 0 DI Euc Oak DI Euc Oak DI Euc Oak DI Euc Oak Significant for Oak p = 0.043 Two-way ANOVA Two-way ANOVA

Germination of Germination of Achillea millefolium Mimulus aurantiacus

On filter paper: Day 9 22.5 On paper: Day 9 On soil: Day 13 10 20

17.5 8

15 6 12.5

10 10 4 7.5 8 Mean seeds germinated Mean seeds germinated 5 6 2 4 2.5 2 0 0 0 DI Euc Oak DI Euc Oak DI Euc Oak Significant for Significant for Oak p = 0.0040 Oak p = 0.0059 Euc p = <0.0001 Euc p = 0.0059 Two-way ANOVA Two-way ANOVA

Introduction 7 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Field methods - Pitfall traps

Arthropod diversity in native and exotic woodlands Captures surface-active, larger terrestrial arthropods (e.g. beetles, spiders, ants, isopods) by Susie Fork

Field methods – Winkler (litter) traps Field methods - Sticky traps

Samples aerial insects and those associated with foliage Captures slower-moving, arthropods hidden within litter layer (ants, springtails, mites), some of which are not caught in pitfall traps.

Sorting and identification Average abundance of top orders

100 ** 90

60 euc 50 oak 40

Abundance 30

20 *

Diptera Collemb. Acari Coleopt. Araneae Hymenopt. Arthropods keyed to level of order

ANOVA, *P< .05; **P < .02)

Introduction 8 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Overall habitat comparisons Overall habitat comparisons

8 Order richness 6 200 average per sample 4 Total abundance 150 average per sample 2 100

0 50 euc oak 0 No significant different between woodland types euc oak (ANOVA, P>.05). Abundance greater in eucalyptus groves than in oak woodlands (ANOVA, P>.05).

Previous research on native and Overall habitat comparisons eucalyptus woodlands

.6 • Sax (2002) surveyed arthropod diversity of Diversity (Shannon-Weaver) native (oak and bay) and eucalyptus woodlands. .4 average per sample – equal species richness (approximately 40 sp. in each .2 habitat). – About half of species were shared by both woodland 0 types. euc oak – Species composition was different between woodland Diversity is greater in oaks- i.e. same number of orders types. but more evenly spread in oaks than eucs (ANOVA, – Eucs had higher invertebrate diversity than native P>.05). woodlands (spring only).

Comparison of two studies Stuart Weiss & Monarchs

• Taxa richness equal in eucs and native • Blue gum used because of woodlands – Proximity to ocean (no frost) – Order richness (present study) and species – Light richness (Sax study) • Diversity results differ –Wind – oaks have higher diversity than eucs (present study) while Sax detected higher diversity in eucs • It is necessary to manage blue gum groves to continue to be useful as habitat

Introduction 9 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

Summary of 2004 Workshop More 2004 Workshop Summary

• Blue gum is significantly spreading from existing • The plant community associated with blue stands gum is different in structure and • Some blue gum groves may support important composition than coast live oak woodland birds (especially by the water or in urban areas) • These differences may not be well • Riparian and cavity-nesting birds are likely to be described by allelopathy the most affected by blue gum invasion • Blue gum may affect oak-associated birds, • Blue gum vs. live oak insect abundance – especially breeding birds jury out – may have species specific effects

But first, a word of caution… And, now onto today…. Assumption: Blue Gum Needs Eradicating

Evidence: Appropriate Biological Review

Introduction 10 Control of Blue Gum Eucalyptus in Coastal California Workshop Coastal Training Program Elkhorn Slough National Estuarine Research Reserve

In Your Packet:

Infamous Blue CalIPC Take Home Messages Gum Angel Membership Island Story Brochure

CalIPC Portions of presentations • A little review on what we know about the Publications Order Form ecology and impacts of blue gum CalIPC 2005 • How to minimize public outcry against Conference Announcement control measures Summary from last • What to do with blue gum after it falls year’s workshop published in CalIPC newsletter • Methods for restoration and monitoring Contact List Agenda after control • How others have approached this issue

Introduction 11