Source: California Invasive Plant Council


URL of this page: http://www.cal-ipc.org/site/paf/538
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Cal-IPC Plant Assessment Form

For use with "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands"
by the California Invasive Plant Council and the Southwest Vegetation Management Association

Table 1. Species and Evaluator Information

Species name
(Latin binomial):
The official Latin binomial name for this species. Specify only one name here. Additional species names may go into the Synonyms field.

Eucalyptus globulus

Synonyms:
Additional Latin binomial names for this species. Separate multiple names with a ; character. Please avoid narrative descriptions, and list only the binomial names.
Eucalyptus maidenii subsp. globulus (Labill.) J.B.Kirkp.
Common names:
Common names for this species. Separate multiple names with a ; character.
blue gum; Tasmanian blue gum; blue gum eucalyptus; common eucalyptus; Southern blue gum; Victorian blue gum
Evaluation date:
The date(s) when this species PAF was filled out, modified, or reviewed. This is free-form text, so it may include multiple dates or other notes.
original 3/2004, re-assessed 3/14; finalized 3/2015
Evaluator #1 Kristina Wolf, PhD Candidate
UC Davis Dept. of Plant Sciences
PES 1210 Mail Stop 1, 1 Shields Ave., Davis, CA 95616
kmwolf@ucdavis.edu
Evaluator #2 Joseph DiTomaso, Cooperative Extension Weed Specialist
UC Davis Dept. of Plant Sciences
PES 1210 Mail Stop 1, 1 Shields Ave., Davis, CA 95616
jmditomaso@ucdavis.edu
List committee members: Joe DiTomaso (UC Davis), Dean Kelch (CDFA), Ramona Robison (State Parks), Elizabeth Brusati (Cal-IPC), Doug Johnson (Cal-IPC), Alison Forrestel (NPS), Peter Warner (consulting botanist)
Committee review date: August 2015
List date: 3/19/14
Re-evaluation date(s): 3/13/15
General comments
on this assessment:
Enter any additional notes about this assessment, such as factors affecting the reliability or completeness of the answers, likely affects of impacts, or research which is not specific to California but is still relevant in the evaluation of this species.

A pdf file of this information is available at http://www.cal-ipc.org/ip/inventory/eucalyptus2.php.

The document is an expert-reviewed assessment of the ecological impacts of Eucalyptus globulus in California. Of some 1,800 non-native plants that grow outside of cultivation in California, Cal-IPC has rated approximately 200 as Limited, Moderate, or High level invasive plants based on severity of impact, ability to spread, and extent. (For more information, see www.cal-ipc.org/ip/inventory.) Cal-IPC ratings are designed to inform those managing lands for ecological values (such as native wildlife habitat) about the potential impacts of a given plant. Ratings are informative, not prescriptive; they are generalized, not site-specific. Ratings do not determine the overall value of particular plants in particular places, and the term “invasive” should not be construed as a universal condemnation.


Eucalyptus globulus, Tasmanian blue gum, was last assessed by Cal-IPC in 2006 as part of a major initiative to update and document assessments for some 200 plant species. In 2014, Cal-IPC reassessed E. globulus. This new assessment revises scores for some criteria and results in a change in overall score from “Moderate” to “Limited.” To large degree this change is due to evaluating E. globulus across the entire state, rather than focusing on coastal areas where it is most prone to spreading.


Blue gum eucalyptus is unique among naturalized non-native plant species in California. Its rich cultural history is documented in detail by Jared Farmer in Trees in Paradise: A California History (Norton, 2013). While most plants listed by Cal-IPC have spread into wildlands on their own, blue gum was actively planted in natural areas for timber, windbreaks and aesthetics. The stands existing today are those that were planted in an earlier time. E. globulus were most typically planted in grasslands, yet their most logical native analog habitat is oak or bay laurel woodland; this assessment aims to assess the most relevant comparison for each criterion.


Some stands were planted so densely that few other plants grow within the stand, while less dense stands often contain more plant diversity. Some stands are regenerating and expanding in size, while others in less favorable conditions are not. Some stands are within areas now being managed primarily for ecological values, others are not. Where stands do occur in areas being managed for ecological values, it makes clear sense to assess their ecological impact as an invasive plant. Plantations that are not regenerating or expanding are not considered “invasive” in the customary use of the term. Management decisions for stands in urban areas will necessarily involve consideration of a range of factors, such as recreational and aesthetic values and the trees’ much-debated role in wildfire risk. For these stands, the information provided in this assessment can help assess impacts on native habitat, which may also be a factor in management decisions.

Table 2. Criteria, Section, and Overall Scores

Overall Score

Plant scoring matrix
Based on letter scores from Sections 1 through 3 below

ImpactInvasivenessDistribution
AA BAnyHighNo Alert
AC DAnyModerateAlert
BA BA BModerateNo Alert
BA BC DModerateAlert
BC DAnyLimitedNo Alert
CAA BModerateNo Alert
CAC DLimitedNo Alert
CBAModerateNo Alert
CBB DLimitedNo Alert
CCAnyLimitedNo Alert
DAnyAnyNot ListedNo Alert

Limited

Alert Status

Plant scoring matrix
Based on letter scores from Sections 1 through 3 below

ImpactInvasivenessDistributionAlert
AA or BC or DAlert
BA or BC or DAlert

No Alert

Documentation

The total documentation score is the average
of Documentation scores given in Table 2.

Reviewed Scientific Publication4 points
Other Published Material3 points
Observational2 points
Anecdotal1 points
Unknown or No Information0 points

3.1 out of 5

Score Documentation
1.1 Impact on abiotic ecosystem processes
Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include:
- fire occurrence, frequency, and intensity;
- geomorphological changes such as erosion and sedimentation rates;
- hydrological regimes, including soil water table;
- nutrient and mineral dynamics, including salinity, alkalinity, and pH;
- light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open).

Select the one letter below that best describes this species’ most severe impact on an abiotic ecosystem process:
A. Severe, possibly irreversible, alteration or disruption of an ecosystem process.
B. Moderate alteration of an ecosystem process.
C. Minor alteration of an ecosystem process.
D. Negligible perceived impact on an ecosystem process.
U. Unknown.
B. Moderate Reviewed Scientific Publication
Impact
Section 1 Scoring Matrix
Q 1.1Q 1.2Q 1.3Q 1.4Score
AAAnyAnyA
ABA,BAnyA
ABC,D,UAnyB
AC,D,UAnyAnyB
BAAAnyA
BABAA
BAB,CB-D,UB
BAC,D,UAA
BAC,D,UB-D,UB
BBAAA
BC,D,UAAB
BB-DAB-D,UB
BB-DB-D,UAnyB
BD,UC,D,UA-BB
BD,UC,D,UC,D,UC
C-D,UAAAnyA
CBAAnyB
CA,BB-D,UAnyB
CC,D,UAnyAnyC
DA,BBAnyB
DA,BC,D,UAnyC
DCAnyAnyC
DD,UAnyAnyD
UAB,CAnyB
UB,CA,BAnyB
UB,CC,D,UAnyC
UUAnyAnyU


Four-part score
BBBD

Total Score
B
1.2 Impact on plant community
Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include:
- formation of stands dominated (>75% cover) by the species;
- occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below;
- significant reduction or extirpation of populations of one or more native species.

Examples of impacts usually less than severe include:
- reduction in propagule dispersal, seedling recruitment, or survivorship of native species;
- creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer;
- change in density or depth of a structural layer;
- change in horizontal distribution patterns or fragmentation of a native community;
- creation of a vector or intermediate host of pests or pathogens that infect native plant species.

Select the one letter below that best describes this species’ impact on community composition, structure and interactions:
A. Severe alteration of plant community composition, structure, or interactions.
B. Moderate alteration of plant community composition.
C. Minor alteration of community composition.
D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions.
U. Unknown.
B. Moderate Reviewed Scientific Publication
1.3 Impact on higher trophic levels
Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species’ net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types.
Examples of severe impacts include:
- extirpation or endangerment of an existing native species or population;
- elimination or significant reduction in native species’ nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors.

Examples of impacts that are usually less than severe include:
- minor reduction in nesting or foraging sites, cover, etc. for native animals;
- minor reduction in habitat connectivity or migratory corridors;
- interference with native pollinators;
- injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species.

Select the one letter below that best describes this species’ impact on community composition and interactions:
A. Severe alteration of higher trophic populations, communities, or interactions.
B. Moderate alteration of higher trophic level populations, communities, or interactions.
C. Minor alteration of higher trophic level populations, communities or interactions.
D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions.
E. Unknown.
B. Moderate Reviewed Scientific Publication
1.4 Impact on genetic integrity
Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include:
- production of fertile or sterile hybrids that can outcompete the native species;
- production of sterile hybrids that lower the reproductive output of the native species.

Select the one letter below that best describes this species’ impact on genetic integrity:
A. Severe (high proportion of individuals).
B. Moderate (medium proportion of individuals).
C. Minor (low proportion of individuals).
D. No known hybridization.
U. Unknown.
D. None Other Published Material
2.1 Role of anthropogenic and natural disturbance in establishment
Assess this species’ dependence on disturbance—both human and natural—for establishment in wildlands. Examples of anthropogenic disturbances include:
- grazing, browsing, and rooting by domestic livestock and feral animals;
- altered fire regimes, including fire suppression;
- cultivation;
- silvicultural practices;
- altered hydrology due to dams, diversions, irrigation, etc.;
- roads and trails;
- construction;
- nutrient loading from fertilizers, runoff, etc.

Examples of natural disturbance include:
- wildfire;
- floods;
- landslides;
- windthrow;
- native animal activities such as burrowing, grazing, or browsing.

Select the first letter in the sequence below that describes the ability of this species to invade wildlands:
A. Severe invasive potential—this species can establish independent of any known natural or anthropogenic disturbance.
B. Moderate invasive potential—this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances.
C. Low invasive potential—this species requires anthropogenic disturbance to establish.
D. No perceptible invasive potential—this species does not establish in wildlands (though it may persist from former cultivation).
U. Unknown.
C. Low Other Published Material
Invasiveness
Section 2 Scoring Matrix
Total pointsScore
17-21A
11-16B
5-10C
0-4D
More than two U’sU


Total Points
8

Total Score
C
2.2 Local rate of spread with no management
Assess this species’ rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented.

Select the one letter below that best describes the rate of spread:
A. Increases rapidly (doubling in <10 years)
B. Increases, but less rapidly
C. Stable
D. Declining
U. Unknown
B. Increases less rapidly Reviewed Scientific Publication
2.3 Recent trend in total area infested within state
Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them.

Select the one letter below that best describes the current trend:
A. Increasing rapidly (doubling in total range statewide in <10 years)
B. Increasing, but less rapidly
C. Stable
D. Declining
U. Unknown
C. Stable Observational
2.4 Innate reproductive potential
(see Worksheet A)
Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.
C. Low Other Published Material
2.5 Potential for human-caused dispersal
Assess whether this species is currently spread—or has high potential to be spread—by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include:
- commercial sales for use in agriculture, ornamental horticulture, or aquariums;
- use as forage, erosion control, or revegetation;
- presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.;
- spread along transportation corridors such as highways, railroads, trails, or canals;
- transport on boats or boat trailers.

Select the one letter below that best describes human-caused dispersal and spread:
A. High—there are numerous opportunities for dispersal to new areas.
B. Moderate—human dispersal occurs, but not at a high level.
C. Low—human dispersal is infrequent or inefficient.
D. Does not occur.
U. Unknown.
C. Low Observational
2.6 Potential for natural long-distance dispersal
We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms:
- the species’ fruit or seed is commonly consumed by birds or other animals that travel long distances;
- the species’ fruits or seeds are sticky or burred and cling to feathers or hair of animals;
- the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water;
- the species has light propagules that promote long-distance wind dispersal;
- The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed).

Select the one letter below that best describes natural long-distance dispersal and spread:
A. Frequent long-distance dispersal by animals or abiotic mechanisms.
B. Occasional long-distance dispersal by animals or abiotic mechanisms.
C. Rare dispersal more than 1 km by animals or abiotic mechanisms.
D. No dispersal of more than 1 km by animals or abiotic mechanisms.
U. Unknown.
C. Rare Reviewed Scientific Publication
2.7 Other regions invaded
Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state.

Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range.
A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively).
B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state.
C. Invades elsewhere but only in ecological types that it has already invaded in the state.
D. Not known as an escape anywhere else.
U. Unknown.
C. Already invaded Other Published Material
3.1 Ecological amplitude/Range
(see Worksheet C)
Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades.
A. Widespread—the species invades at least three major types or at least six minor types.
B. Moderate—the species invades two major types or five minor types.
C. Limited—the species invades only one major type and two to four minor types.
D. Narrow—the species invades only one minor type.
U. Unknown.
A. Widespread Observational
Distribution
Section 3 Scoring Matrix
Q 3.1Q 3.2Score
AA, BA
AC,D,UB
BAA
BB,CB
BDC
CA,BB
CC,DC
DAB
DB,CC
DDD
A,BUC
C,DUD
UUU


Total Score
B
3.2 Distribution/Peak frequency
(see Worksheet C)
To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.
C. Low Observational

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".
Short citations may be used in this table. List full citations at end of this table.

Section 1: Impact

Reviewed Scientific Publication B Question 1.1 Impact on abiotic ecosystem processes
Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include:
- fire occurrence, frequency, and intensity;
- geomorphological changes such as erosion and sedimentation rates;
- hydrological regimes, including soil water table;
- nutrient and mineral dynamics, including salinity, alkalinity, and pH;
- light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open).

Select the one letter below that best describes this species’ most severe impact on an abiotic ecosystem process:
A. Severe, possibly irreversible, alteration or disruption of an ecosystem process.
B. Moderate alteration of an ecosystem process.
C. Minor alteration of an ecosystem process.
D. Negligible perceived impact on an ecosystem process.
U. Unknown.
Identify ecosystem processes impacted:

E. globulus alters fire regime and groundwater availability. (Potential for allelopathy was examined but is not included.) These impacts can be significant in circumstances where blue gum were planted at high density and growing conditions are favorable for the species, and less significant in other places.


Alteration of fire regime:
In comparing wildfire parameters in blue gum stands versus native oak woodland (a comparable native habitat structure) fuel loads are significantly greater. E. globulus stands can accumulate significantly higher fuel loads than native woodlands. One study found fuel loads of 31 tons/acre in E. globulus stands as compared to 19 tons/acre in California bay forest and 12 tons/acre in coast live oak woodlands (National Park Service 2006). (Factors of ignition and relative flammability are not considered here.)


Wildfire in grasslands is typically more frequent and less intense than wildfire in heavily wooded areas (whether native or non-native). Higher fire intensity can impact soils as well as seed mortality in the soil seed bank.


Alteration of groundwater availability:
The high water consumption of E. globulus is well known (Rejmanek & Richardson 2011) and eucalyptus species have been used by development agencies to drain swampy areas in efforts to reduce malaria (see for instance the Wikipedia entry for Eucalyptus). E. globulus and E. camuldensis (red gum) are used in environmental remediation projects. An example of this is PG&E’s 30 acre plantation in Lake County, California. At that site the trees are used to provide hydraulic control of groundwater beneath a landfill. The object of this remediation is to suppress groundwater and keep it from contacting geothermal wastes placed in the landfill (Deutsch 2015).


Lateral roots can extend 30 m or more from the trunk, and in deep soils with high water tables, roots can penetrate to depths of 14 m (DiTomaso & Healy 2007). According to DiTomaso & Healy (2007) E. globulus are able to withstand prolonged dry summers by tapping into deep water reservoirs as well as by economizing water use through stomatal control. Their far-reaching root systems can extract water from the soil at even higher soil moisture tensions than most mesophytic plants (Pryor 1976, Florence 1996). The National Park Service is beginning to study groundwater response to eucalyptus removal, for instance on the Channel Islands (Power 2014).


In coastal zones, fog drip under blue gum stands can be substantial, which accounts for the ability of coastal stands to regenerate (Yost 2014). A study in San Francisco found fog drip from eucalyptus drip can add as much as 42 cm of water during a single summer (Clarke et. al. 2008). This amount is comparable to annual rainfall and in such areas fog drip may significantly mitigate groundwater consumption.


Sources of information:

See references within text.


Reviewed Scientific Publication B Question 1.2 Impact on plant community composition,
structure, and interactions
Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include:
- formation of stands dominated (>75% cover) by the species;
- occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below;
- significant reduction or extirpation of populations of one or more native species.

Examples of impacts usually less than severe include:
- reduction in propagule dispersal, seedling recruitment, or survivorship of native species;
- creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer;
- change in density or depth of a structural layer;
- change in horizontal distribution patterns or fragmentation of a native community;
- creation of a vector or intermediate host of pests or pathogens that infect native plant species.

Select the one letter below that best describes this species’ impact on community composition, structure and interactions:
A. Severe alteration of plant community composition, structure, or interactions.
B. Moderate alteration of plant community composition.
C. Minor alteration of community composition.
D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions.
U. Unknown.
Identify type of impact or alteration:

E. globulus stands displace native plant communities. Plant communities can be severely altered in circumstances where blue gum was planted at high density and growing conditions are favorable. Plant communities in other places can be significantly less impacted.

Conditions are most favorable for blue gum growth and regeneration along the coast in northern and central California (Ritter and Yost 2012). Capacity for regeneration is based on environmental conditions; areas with reliable year-round moisture, such as along riparian corridors and along the coast from Monterey Bay north where summer fog drip provides seedlings with some moisture, are most likely to support naturally reproducing eucalyptus populations (Yost 2014). Juvenile foliage is seldom browsed by livestock or wildlife, aiding seedling survival (Skolmen and Ledig 1990).


E. globulus stands can form near monocultures in areas where they were planted at high densities (Griffiths & Villablanca 2013). On Angel Island in San Francisco Bay, native trees were only found in eucalyptus plantings where the blue gums had been widely spaced, and these natives were “not vigorous” (McBride, Sugihara, and Amme 1988).


Reports of plant diversity within E. globulus stands vary, reflecting the range of conditions, including original planting density, suitability of the microclimate for eucalyptus growth and regeneration, composition of native seed bank, size of the stand and diversity of the surrounding vegetation. Some studies report depauperate plant communities (Esser 1993, DiTomaso & Healy 2007, Bean & Russo 2014) limited by shading and a thick litter layer, while other studies report some native plant species being supported in the understory (LSA Associates 2009, San Francisco Recreation and Park Department 2006).


Sources of information:

See references within text.


Reviewed Scientific Publication B Question 1.3 Impact on higher trophic levels
Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species’ net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types.
Examples of severe impacts include:
- extirpation or endangerment of an existing native species or population;
- elimination or significant reduction in native species’ nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors.

Examples of impacts that are usually less than severe include:
- minor reduction in nesting or foraging sites, cover, etc. for native animals;
- minor reduction in habitat connectivity or migratory corridors;
- interference with native pollinators;
- injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species.

Select the one letter below that best describes this species’ impact on community composition and interactions:
A. Severe alteration of higher trophic populations, communities, or interactions.
B. Moderate alteration of higher trophic level populations, communities, or interactions.
C. Minor alteration of higher trophic level populations, communities or interactions.
D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions.
E. Unknown.
Identify type of impact or alteration:

E. globulus alters habitat for birds. Effects on terrestrial vertebrates and arthropods were reviewed but are not included in this assessment. Some blue gum stands provide habitat for monarch butterflies.


Impacts to birds
Many of the breeding bird species that are most representative of oak and riparian habitats make little or no use of eucalyptus. Decay-resistant wood offers limited nesting opportunities for woodpeckers and birds that excavate their own holes. Birds that glean insects from foliage are also present at notably lower densities than in native oak woodlands (Suddjian 2004, Williams 2002).


Eucalyptus stands do provide nesting habitat for large roosting birds such as herons, egrets, and cormorants and raptors such as red-shouldered and red-tailed hawks (Suddjian 2004, LSA Associates 2009). They also provide a nectar source for bees and hummingbirds (Rejmanek & Richardson 2011).


Depending on the abundance and health of grassland and oak woodland near blue gum stands, these stands may be considered to be damaging or complementing native habitat.


Monarch butterfly habitat
Some eucalyptus stands provide overwintering sites for Monarch butterflies, along with native trees such as coast redwoods, Monterey pine and Monterey cypress (Griffiths & Villablanca 2013).


Sources of information:

See references within text.


Other Published Material D Question 1.4 Impact on genetic integrity
Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include:
- production of fertile or sterile hybrids that can outcompete the native species;
- production of sterile hybrids that lower the reproductive output of the native species.

Select the one letter below that best describes this species’ impact on genetic integrity:
A. Severe (high proportion of individuals).
B. Moderate (medium proportion of individuals).
C. Minor (low proportion of individuals).
D. No known hybridization.
U. Unknown.
Identify impacts:

No congeners native to the United States; no hybridization between non-native Eucalyptus spp. and native plant species in California.


Sources of information:

Baldwin et al. 2012, Calflora 2014


Section 2: Invasiveness

Other Published Material C Question 2.1 Role of anthropogenic and natural disturbance
in establishment
Assess this species’ dependence on disturbance—both human and natural—for establishment in wildlands. Examples of anthropogenic disturbances include:
- grazing, browsing, and rooting by domestic livestock and feral animals;
- altered fire regimes, including fire suppression;
- cultivation;
- silvicultural practices;
- altered hydrology due to dams, diversions, irrigation, etc.;
- roads and trails;
- construction;
- nutrient loading from fertilizers, runoff, etc.

Examples of natural disturbance include:
- wildfire;
- floods;
- landslides;
- windthrow;
- native animal activities such as burrowing, grazing, or browsing.

Select the first letter in the sequence below that describes the ability of this species to invade wildlands:
A. Severe invasive potential—this species can establish independent of any known natural or anthropogenic disturbance.
B. Moderate invasive potential—this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances.
C. Low invasive potential—this species requires anthropogenic disturbance to establish.
D. No perceptible invasive potential—this species does not establish in wildlands (though it may persist from former cultivation).
U. Unknown.
Describe role of disturbance:

E. globulus was introduced to California in 1856 (Esser 1993) and is now naturalized in parts of California (Esser 1993, Ritter & Yost 2009). Purposeful cultivation was the primary mode of establishment (Skolmen & Ledig 1990, Esser 1993, HEAR 2007, LSA Associates 2009, Baldwin et al. 2012). E. globulus was planted on about 40,000 acres in California, extending from Humboldt County in the north to San Diego County in the south, with best growth in the coastal fog belt (Skolmen & Ledig 1990).

New populations independent of planting are rarely seen in California. Spread is typically limited to expansion along the periphery of an existing population. While eucalyptus bears abundant seed, it does not generally find appropriate conditions for germination (Tyrell 1999). Seeds germinate best on bare mineral soil so germination within dense forests is difficult (Bean & Russo 2014).


Sources of information:

See references within text.


Reviewed Scientific Publication B Question 2.2 Local rate of spread with no management
Assess this species’ rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented.

Select the one letter below that best describes the rate of spread:
A. Increases rapidly (doubling in <10 years)
B. Increases, but less rapidly
C. Stable
D. Declining
U. Unknown
Describe rate of spread:

Though not all E. globulus stands are expanding, those in moist coastal habitats often expand at a significant rate. New populations are rare; spread is almost entirely along the periphery of existing stands.

Most naturalized stands of E. globulus are present along the coast in northern and central California (Ritter & Yost 2012). Aerial photographs show a 50-400% increase in eucalyptus stand size between 1930 and 2001 across six sites in coastal California (Van Dyke 2004). On Angel Island, blue gum “invaded areas adjacent to all sites where it was originally planted,” resulting in an expansion from 24 acres to 86 acres, a 360% expansion, over a century (McBride, Sugihara and Amme 1988). Potential spread rate has been estimated at 10-20 feet per year under favorable conditions (Bean & Russo 2014).


Some studies show that this is not the case with all populations. An assessment of changes in cover over a 58-year period at three regional parks in the East Bay hills indicates a decline in eucalyptus cover at all three locations (Russell and McBride 2003), though it is unclear how management activities may have affected stand size in these locations.


California State Parks personnel submitted the following recent reports:

  • Tim Hyland (2014) in the Santa Cruz District reports that nine coastal units have E. globulus patches that have moved into riparian, coastal prairie, and coastal scrub habitats. Two units have E. globulus patches that exist in forested settings and show no signs of reproduction.
  • Vince Cincero (2014) in the San Luis Obispo Coast District referred to a 1990 report compiled by Susan Bicknell of Humboldt State University on eucalyptus at Montana de Oro State Park in Los Osos. The report describes an original plantation established in 1907/08, with the earliest aerial photos from 1949 showing 7 species of eucalyptus covering 119 acres. Forty years later in 1989, the grove had expanded 52% to 181 acres, of which E. globulus covered 108 acres (the original portion comprising blue gum is unknown).
  • Suzanne Goode (2014) in the Angeles District reports that: at Mulholland Highway and Pacific Coast Highway, E. globulus is spreading upslope; at Nicholas Flats Natural Preserve, E. globulus (and possibly other eucalyptus species) are spreading from an original plantation homestead;and at the Will Rogers State Historic Park E. globulus continues to spread from plantings into the hillsides.
  • Michelle Forys (2014) in the North Coast Redwoods District reports that the few planted clumps of E. globulus located on district property are actively controlled to stop spread beyond the historical planted area. Additionally, she has observed a planting on the west side of along Highway 101 between Arcata and Eureka spreading across to the east side of the highway.

Sources of information:

See references within text.

 


Observational C Question 2.3 Recent trend in total area infested within state
Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them.

Select the one letter below that best describes the current trend:
A. Increasing rapidly (doubling in total range statewide in <10 years)
B. Increasing, but less rapidly
C. Stable
D. Declining
U. Unknown
Describe trend:

Some stands of E. globulus along the California coast are regenerating and expanding, while others are stable or even shrinking. CalWeedMapper (2014) shows that E. globulus is thought (by local land managers) to be spreading in about 47% of the USGS quadrangles where it is present in the state, and stable in the rest (decreases are not documented in the system, other than through active management).


Sources of information:

See references within text.


Other Published Material C Question 2.4 Innate reproductive potential
Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.
Describe key reproductive characteristics:

1. Reaches reproductive maturity in 2 years or less: No

Most sources estimate trees usually begin to produce seeds at 4 to 5 years and yield heavy seed crops in most locations at 3- to 5-year intervals (Skolmen & Ledig 1990, HEAR 2007). Metcalf (1924) stated that flowers and fruits could be found on sprouts only two or three years old, although not in great quantities.

2. Dense infestations produce >1,000 viable seed per square meter: Unknown 

Sources indicate prolific seed production, but viable seeds produced per square meter are not given. There are 18 to 320 seeds per gram (500 to 9,100/oz) of seeds and chaff, or about 460 clean seeds per gram (13,000/oz) (Skolmen & Ledig 1990). Germination rates are typically very low: a 1% germination rate is good, given the more usual 0.1% germination success rate (Bean & Russo 2014). This does not indicate the amount of viable seed, as germination can be limited by other factors as well (e.g., allelopathy, thick litter layer, moisture, etc).
3. Populations of this species produce seeds every year: unknown, assume no
Skolmen & Ledig (1990) indicate that E. globulus yields heavy seed crops in most locations at 3- to 5-year intervals. This does not indicate whether seed is produced every year and only heavily at several year intervals, or whether seed is produced only at 3- to 5-year intervals.
4. Seed production sustained over 3 or more months within a population annually: Yes 
Blue gum eucalyptus in California flowers from November to April during the wet season. The fruit (a distinctive top-shaped woody capsule 15 mm long and 2 cm in diameter) ripens in October to March, about 11 months after flowering (Skolmen & Ledig 1990).
5. Seeds remain viable in soil for three or more years: No 
Germination occurs readily (within 26 days) after seeds are released if conditions are suitable (Skolmen & Ledig 1990). When stored, seeds can remain viable for several years, but in field conditions, viable seed banks are not expected to be maintained beyond a year (Rejmanek & Richardson 2011).
6. Viable seed produced with both self-pollination and cross-pollination: No 
When the cap covering the reproductive organs (the operculum) is shed, the anthers have mature pollen, but the stigma does not become receptive until some days later. This sequence impedes self-pollination of an individual flower. Flowers are pollinated by insects, hummingbirds, and other pollen and nectar feeders. There is no evidence that wind plays anything but a minor role in eucalypt pollination. The flowers of eucalypts are not highly specialized for insect pollination (HEAR 2007).
7. Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes: No
Blue gum eucalyptus can sprout from the bole, from stumps of all sizes and ages, from the lignotuber, and from the roots. The lignotuber can live for many years in the soil after stems die back (Esser 1993). This contributes to re-growth, but not spatial spread of the plant. One professional land manager reports that stand spread may arise from root sprouts in addition to seed sprouts (Heath 2014), but this has not been confirmed.
8. Fragments easily and fragments can become established elsewhere: No
No evidence found.
9. Resprouts readily when cut, grazed, or burned: Yes 
Blue gum coppices readily from stumps of all sizes and ages when the tree is damaged. If the tree is cut down, lignotubers become active and each bud produce a shoot bearing foliage. Such shoots are commonly known as "sucker growth" or coppice shoots, and a large number are usually formed. E. globulus resprouts after being burned (Skolmen & Ledig 1990, Bean & Russo 2014).


Sources of information:

See references in text.


Observational C Question 2.5 Potential for human-caused dispersal
Assess whether this species is currently spread—or has high potential to be spread—by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include:
- commercial sales for use in agriculture, ornamental horticulture, or aquariums;
- use as forage, erosion control, or revegetation;
- presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.;
- spread along transportation corridors such as highways, railroads, trails, or canals;
- transport on boats or boat trailers.

Select the one letter below that best describes human-caused dispersal and spread:
A. High—there are numerous opportunities for dispersal to new areas.
B. Moderate—human dispersal occurs, but not at a high level.
C. Low—human dispersal is infrequent or inefficient.
D. Does not occur.
U. Unknown.
Identify dispersal mechanisms:

Given the large seed size, there is very little potential for people to accidentally start new populations through unintentional seed “hitchhiking”.


Though some landowners may still plant E. globulus for windbreaks or ornamentals on a limited scale, the conclusion of the California Horticultural Invasives Prevention (Cal-HIP) partnership and the PlantRight campaign is that E. globulus is effectively no longer in the trade. Annual surveys of retail nurseries around California indicate that few (<1%) nurseries now sell E. globulus and it has been moved to their “retired” list of plants because it is so rarely found for sale (PlantRight 2014).


Sources of information:

See references in text.


Reviewed Scientific Publication C Question 2.6 Potential for natural long-distance dispersal
We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms:
- the species’ fruit or seed is commonly consumed by birds or other animals that travel long distances;
- the species’ fruits or seeds are sticky or burred and cling to feathers or hair of animals;
- the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water;
- the species has light propagules that promote long-distance wind dispersal;
- The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed).

Select the one letter below that best describes natural long-distance dispersal and spread:
A. Frequent long-distance dispersal by animals or abiotic mechanisms.
B. Occasional long-distance dispersal by animals or abiotic mechanisms.
C. Rare dispersal more than 1 km by animals or abiotic mechanisms.
D. No dispersal of more than 1 km by animals or abiotic mechanisms.
U. Unknown.
Identify dispersal mechanisms:

In general, E. globulus seed is not easily dispersed over large distances (Skolmen & Ledig 1990, HEAR 2007, Rejmanek & Richardson 2011). E. globulus seeds are distributed by wind and gravity; calculated dispersal distance from a 40 m (131 ft) height, with winds of 10 km/hr (6 mi/hr), was only 20 m (66 ft) (Skolmen & Ledig 1990). Some seed may be moved by such agents as flood, erosion and birds, but usually seed is dropped within 100 feet of the parent tree (Bean & Russo 2014).


Sources of information:

See references in text.


Other Published Material C Question 2.7 Other regions invaded
Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state.

Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range.
A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively).
B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state.
C. Invades elsewhere but only in ecological types that it has already invaded in the state.
D. Not known as an escape anywhere else.
U. Unknown.
Identify other regions:

E. globulus has wide climatic adaptability, with the most successful introductions worldwide in locations with mild, temperate climates, or at somewhat higher elevations in tropical areas (E. globulus does not tolerate frequent freezes). Although it generally grows well in countries with a Mediterranean or cold season maximum rainfall, it grows well also in summer rainfall climates of Ethiopia and Argentina (Skolmen & Ledig 1990). In California, E. globulus populations already exist in the regions suitable to the species’ naturalization (CalWeedMapper 2014).


Sources of information:

See references in text.


Section 3: Distribution

Observational A Question 3.1 Ecological amplitude/Range
Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades.
A. Widespread—the species invades at least three major types or at least six minor types.
B. Moderate—the species invades two major types or five minor types.
C. Limited—the species invades only one major type and two to four minor types.
D. Narrow—the species invades only one minor type.
U. Unknown.
Describe ecological amplitude, identifying date of source information and approximate date of introduction to the state, if known:

Invades five major habitat types: scrub and chaparral; grasslands; bog and marsh; riparian; and forest. These are ecotypes where blue gum stands are found in California, though that presence is typically due to intentional planting. Blue gum is unlikely to actively spread into dense forest vegetation. See Worksheet C.


Sources of information:

Observational


Observational C Question 3.2 Distribution/Peak frequency
To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.
Describe distribution:

See Worksheet C. 5-20% is the highest portion of occurrences invaded in any of the invaded ecotypes.


Sources of information:

Observational


References

List full citations for all references used in the PAF (short citations such as DiTomaso and Healy 2007 may be used in table above). Websites should include the name of the organization and the date accessed. Personal communications should include the affiliation of the person providing the observation. Enter each reference on a separate line.

Note: All sources cited in the assessment are listed below. Additional sources were reviewed but not used in the assessment; these are also listed below.

 

Aggangan, R. G., A. T. O'Connell, J. F. McGrath, and B. Dell. 1999. The effects of Eucalyptus globulus leaf litter on C and N mineralization in soils from pasture and native forest. Soil Biology and Biochemistry 31:1481-1487.

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, eds. 2012. The Jepson manual: Vascular plants of California. 2nd ed. University of California Press, Berkeley and Los Angeles, CA.


Bean, C., and M. J. Russo. 2014. Eucalyptus globulus. Bugwood Wiki. Based on 1989 Elemental Stewardship Abstract for Eucalyptus globulus (revised). The Nature Conservancy, Arlington, VA. Accessed 22 Mar 2014 online at http://wiki.bugwood.org/Eucalyptus_globulus.

Bicknell, S. H. 1990. Montana de Oro State Park presettlement vegetation mapping and ecological status of eucalyptus. Humboldt State University, CA.

Bossard, C. C., J. M. Randall, and M. C. Hoshovsky. 2000. Invasive plants of California's wildlands. University of California Press, Berkeley, CA.

Boyd, D. 1997. Eucalyptus removal on Angel Island. Presentation to the California Exotic Pest Plant Council. Accessed 25 Mar 2014 online at http://www.cal-ipc.org/symposia/archive/pdf/1997_symposium_proceedings1936.pdf.

Callaham, Jr., M. A., J. A. Stanturf, W. J. Hammond, D. L. Rockwood, E. S. Wenk, and J. J. Obrien. 2013. Survey to evaluate escape of Eucalyptus spp. seedlings from plantations in southeastern USA. International Journal of Forestry Research 2013:1-10.

CalWeedMapper. 2014. Eucalyptus globulus. California Invasive Plant Council, Berkeley, CA. Accessed 28 Mar 2014 online at http://calweedmapper.cal-ipc.org/maps.

Cicero, V. 2014. Personal communication from Vince Cicero, California State Parks. Email received 4/11/2014.

Clarke, K. M., B. L. Fisher, and G. LeBuhn. 2008. The influence of urban park characteristics on ant communities. Urban Ecosystems 11:317-334.

Costa, E. Silva F., A. Shvaleva, J.P Maroco, M.H. Almeida, M.M. Chaves, J.S. Pereira. 2004. Responses to water stress in two Eucalyptus globulus clones differing in drought tolerance. Tree Physiology. 24(10):1165-72.

Daves Garden 2014. Eucalyptus globulus. Accessed 31 Mar 2014 online at http://davesgarden.com/guides/pf/go/62576/.

Del Moral, R., and C. H. Muller. 1969. Fog drip: A mechanism of toxin transport from Eucalyptus globulus. Bulletin of the Torrey Botanical Club 96:467-475.

Deutsch, P. 2015 Personal communication from Paul Deutsch, Amec Geomatrix, Inc. Email received 3/12/15.

Dickinson, K. J. M., and J. B. Kirkpatrick. 1985. The flammability and energy content of some important plant species and fuel components in the forests of southeastern Tasmania. Journal of Biogeography 12:121-134.

DiTomaso, J. M., and E. A. Healy 2007. Tasmanian blue gum. In: Weeds of California and other western states. Vol. 2 Geraniaceae-Zygophllaceae. pp.951-954. Regents of the University of California, Oakland, CA.

Esser, Lora L. 1993. Eucalyptus globulus. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Accessed 28 May, 2014 online at http://www.fs.fed.us/database/feis/plants/tree/eucglo/all.html.

FEMA 2013. East Bay Hills hazardous fire risk reduction environmental impact statement. Accessed 24 Mar 2014 online at http://ebheis.cdmims.com/Documents.aspx.

Florence, R. G. 1996. Ecology and silviculture of eucalyptus forests. CSIRO Publishing, Victoria, Australia.

Fork, S. 2004. Arthropod diversity in native and exotic woodlands. Ecology and impacts of blue gum eucalyptus in coastal California, Moss Landing Marine Laboratories, Moss Landing, CA, June 3, 2004. Accessed 28 Apr 2014 online at http://www.elkhornsloughctp.org/uploads/files/1108146921S. Fork Presentation.pdf.

Forys, M. 2014. Personal communication from Michelle Forys, Environmental Scientist, North Coast Redwoods District, California State Parks. Email received 4/11/2014.

Goode, S. 2014. Personal communication from Suzanne Goode, Angeles District, California State Parks. Email received 4/11/2014.

Griffiths, J., and F. Villablanca 2013. Management of monarch butterfly (Danaus plexippus) overwintering habitat: Recommendations based on patterns of tree use. Monarch Alert, California Polytechnic State University, San Luis Obispo, CA.
Accessed 28 May 2014 online at http://monarchalert.calpoly.edu/pdf/Griffiths and Villablanca 2013 Eucalyptus White Paper.pdf.


HEAR 2007. Eucalyptus globulus Risk Assessment. Hawaiian Ecosystems at Risk. Accessed 22 Mar 2014 online at http://www.hear.org/pier/wra/pacific/eucalyptus_globulus_htmlwra.htm.

Heath, M. 2014. Personal communication from Mark Heath, Shelterbelt Builders, Inc. Email received 5/28/2014.

Hyland, T. 2014. Personal communication from Tim Hyland, Resource Ecologist, California State Parks. Emails received 4/15/2014 and 6/9/2014.

Lacan, I. V. H. Resh, and J. R. McBride. 2010 .Similar breakdown rates and benthic macroinvertebrate assemblages on native and Eucalyptus globulus leaf litter in Californian streams. Freshwater Biology 55:739-752.
Lange, R. T., and T. Reynolds. 1981. Halo effects on native vegetation. Transactions of the Royal Society of South Australia 105:213-214.


LSA Associates, Inc. 2009. Wildfire hazard reduction and resource management plan. V. Vegetation management plan. East Bay Regional Park District, Oakland, CA. Accessed 23 Mar 2014 online at http://www.ebparks.org/Assets/files/fireplan/ebrpd_whrrm_plan/5-VegMan.pdf.


May, F. E., and J. E. Ash 1990. An assessment of the allelopathic potential of eucalyptus. Australian Journal of Botany 38:245-254.


McBride, J.R., N. Sugihara, and D. Amme. 1988.The effects of eucalyptus establishment on native plant communities. In Focused Environmental Study: Restoration of Angel Island Natural Areas Affected by Eucalyptus. California Dept. of Parks and Recreation, Sacramento CA.


Meade, D. E. 1999. Monarch butterfly overwintering sites in Santa Barbara County, California. County of Santa Barbara Planning and Development Department, Santa Barbara, CA.


Metcalf, W. 1924. Growth of eucalyptus in California plantations. Bulletin No. 380. University of California Publications, Berkeley, CA.


National Park Service 2006. Eucalyptus. San Francisco Bay Area National Parks, Fire Education Office, Point Reyes Station, CA. Accessed 23 Mar 2014 online at http://biomass.forestguild.org/casestudies/1001/Eucalyptus.pdf.


PlantRight. 2014. California Horticultural Invasives Prevention website: Invasive plants in your region. Accessed 2 April 2014 online at http://www.plantright.org/regions.


Power, P. 2014. Personal communication from Paula Power, Ecologist, National Park Service, Channel Islands National Park. Email received 5/28/2014.


Pryor, L.D. 1976. The biology of eucalypts. Edward Arnold (Publishers) United, London, UK.


Rejmanek, M., and D. M. Richardson 2011. Eucalypts. In: Simberloff, D., and M. Rejmanek, eds. Encyclopedia of biological invasions, pp. 203-209. University of California Press, Berkeley, CA.


Riley, C. V., and A. E. Bush 1881. Trees attractive to butterflies. American Naturalist 15:572.


Riley, C. V., and A. E. Bush. 1882. The butterfly trees of Monterey again. American Naturalist 16:64.


Ritter, M., and J. Yost. 2009. Diversity, reproduction, and potential for invasiveness of Eucalyptus in California. Madrono 56:155-167.


Ritter, M., and J. Yost. 2012. Blue gum weediness in California is not genetically based. California Native Plant Society conference, January 10-14, 2012, San Diego, CA. Abstract available online at http://www.cnps.org/cnps/conservation/conference/2012/pdf/cnps2012-presentation_abstracts.pdf.


Rottenborn, S. C. 2000. Nest-site selection and reproductive success of urban red shouldered hawks in central California. Journal of Raptor Research 34:18-25.


Russell, W. H., and J. R. McBride. 2002. Vegetation change and fire hazard in the San Francisco bay area open spaces. In: Blonski, K.S., M.E., and T. J. Morales. Proceedings of the California's 2001 wildfire conference: Ten years after the East Bay Hills fire; October 10-12, Oakland California. Technical Report 35.01.462, pp. 27-38. University of California Forest Products Laboratory, Richmond, CA. Accessed 24 Mar 2014 online at http://www.diablofiresafe.org/pdf/proceedings2001.pdf.


Russell, W. H., and J. R. McBride 2003. Landscape scale vegetation-type conversion and fire hazard in the San Francisco bay area open spaces. Landscape and Urban Planning 64:201-208.


San Francisco Recreation and Park Department. 2006. Significant Natural Resource Areas Management Plan. p6.2-2.


Santos, R. L. 1997. The eucalyptus of California. Section three: Problems, cares, economics, and species. Accessed 25 Mar 2014 online at http://www.library.csustan.edu/bsantos/section3.htm.


Sax, D. 2002. Equal diversity in disparate species assemblages: A comparison of native and exotic woodlands in California. Global Ecology and Biogeography 11:49-57.


Shepardson, L. 1914. The butterfly trees. The James H. Barry Company, San Francisco, CA.


Skolmen, R. G., and F. T. Ledig. 1990. Blue gum eucalyptus. In Burns, R.M. and B.H. Honkala, technical coordinators. Silvics of North America, Volume 2: Hardwoods. USDA Forest Service, Washington, DC.
Eucalyptus globulus assessment – March 2015 12
Accessed 20 Mar 2014 online at http://na.fs.fed.us/pubs/silvics_manual/volume_2/eucalyptus/globulus.htm.


Stallcup, R. 1997. Deadly eucalyptus. Observer No. 108. Point Reyes Bird Observatory.


Tyrrell, I. 1999. True gardens of the gods: Californian-Australian environmental reform, 1860-1930. University of California Press, Berkeley.


USDA Forest Service. 2009. Sikkink, P.G., D.E. Lutes, and R.E. Keane. Field guide for identifying fuel loading models. Rocky Mountain Research Station. General Technical report RMRS-GTR-225. May 2009. Accessed 6 Jun 2014 online at http://www.fs.fed.us/rm/pubs/rmrs_gtr225.pdf.


USDA PLANTS Database. Eucalyptus globulus Labill. Accessed 23 Mar 2014 online at http://plants.usda.gov/java/charProfile?symbol=EUGL.
Van Dyke, E. 2004. Blue gum eucalyptus in the Elkhorn Watershed: 1930 - present. Ecology and impacts of blue gum eucalyptus in coastal California, Moss Landing Marine Laboratories, Moss Landing, CA, June 3, 2004. Accessed 28 Apr 2014 online at http://www.elkhornsloughctp.org/uploads/files/1108143446Vandyke Presentation.pdf.


Warner, P.J. 2004. Personal observations from 1980-2004 working in and adjacent to eucalyptus stands in Marin, Sonoma, and Mendocino Counties. 707/937-9172; pwarner@mcn.org.


Watson, K. 2000. The effect of eucalyptus and oak leaf extracts on California native plants. Masters Thesis, University of California, Berkeley. Accessed 31 Mar 2014 online at http://nature.berkeley.edu/classes/es196/projects/2000final/watson.pdf.
Xerces Society. 2014a. Western monarch Thanksgiving count data 1997-2013. Accessed 31 Mar 2014 online at http://www.xerces.org/wp-content/uploads/2011/04/WMTC-Data-1997-2013-Updated-30-Jan-2014.pdf.


Xerces Society. 2014b. Number of monarch butterflies overwintering in California holds steady, but still well below the 1990s. Accessed 31 Mar 2014 online at http://www.xerces.org/2014/01/31/number-of-monarch-butterflies-overwintering-in-california-holds-steady-but-still-well-below-the-1990s/.


Yost, J. Personal communication from Jenn Yost, Biological Sciences Dept., California Polytechnic State University. Phone call 4/29/2014.


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less No
Dense infestations produce >1,000 viable seed per square meter Unknown
Populations of this species produce seeds every year. Unknown
Seed production sustained over 3 or more months within a population annually Yes, 1 points
Seeds remain viable in soil for three or more years No
Viable seed produced with both self-pollination and cross-pollination No
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes, 1 points
Total points: 2
Total unknowns: 2
Total score: C
Scoring Criteria for Worksheet A
A. High reproductive potential (6 or more points).
B. Moderate reproductive potential (4-5 points).
C. Low reproductive potential (3 points or less and less than 3 Unknowns).
U. Unknown (3 or fewer points and 3 or more Unknowns).
Note any related traits:
Return to Table 2

Worksheet B - Arizona Ecological Types is not included here


Worksheet C - California Ecological Types
 
(sensu Holland 1986)

Major Ecological Types Minor Ecological Types Code
A means >50% of type occurrences are invaded;
B means >20% to 50%;
C means >5% to 20%;
D means present but ≤5%;
U means unknown (unable to estimate percentage of occurrences invaded)
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuaries
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrubD. < 5%
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparralC. 5% - 20%
Grasslands, Vernal Pools, coastal prairieD. < 5%
Meadows, and other Herbvalley and foothill grassland
CommunitiesGreat Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swampC. 5% - 20%
Riparian and Bottomland habitatriparian forestD. < 5%
riparian woodlandD. < 5%
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forestC. 5% - 20%
North Coast coniferous forestC. 5% - 20%
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth)   A
Distribution (highest score)   C
Return to Table 2

Addendum J - Jepson Regions Infested
 
Click here for a map of Jepson regions

Infested Jepson Regions:
Check the boxes to indicate the Jepson floristic provinces in which this species is found.














Addendum L - External Links & Resources

Cal-IPC Plant Profile
The Cal-IPC Plant Profile for this species.
http://www.cal-ipc.org/ip/management/plant_profiles/Eucalyptus_globulus.php
Calflora Plant Profile:
The Calflora Plant Profile for this species.
http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=3534
CalWeedMapper:
Load CalWeedMapper with this species already selected.
http://calweedmapper.cal-ipc.org/maps/?species=121