BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Eucalyptus globulus | Bluegum Eucalyptus 



GENERAL BOTANICAL CHARACTERISTICS : 
Bluegum eucalyptus is an introduced, deciduous tree that generally grows
from 98 to 180 feet (30-55 m) tall [3,10].  Some bluegums have attained
heights of 260 feet (80 m) in California [32].  Most height growth of
bluegum eucalyptus occurs within the first 5 to 10 years; 60 to 70
percent of total height growth is achieved by about age 10.  Bluegum
eucalyptus typically grows in dense monocultures [42].

The sclerophyllous leaves are 4 to 11 inches (10-30 cm) long [10].  The
flower clusters develop within an envelope formed by two bracteoles
which split and are shed, exposing the flower buds [24].  The fruit is a
woody capsule 0.25 to 1 inch (6-25 mm) in diameter [24].  The bark is
shreddy, peeling in large strips [7].

Bluegum eucalyptus generally does not form a taproot.  It produces roots
throughout the soil profile, rooting several feet deep in some soils [7].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Seed production and dissemination:  Flowers are pollinated by insects
and hummingbirds [7].  Seed set begins at approximately 4 to 5 years of
age.  Good seed crops are produced in most locations at 3- to 5-year
intervals [7].  The seeds of are relatively small and abundant [24].
Capsules open immediately on ripening, and the seed is dispersed by wind
within 1 to 2 months [7,24].  Dispersal distance from one 131-foot (40
m) tree, with winds of 6 mph (10 km/h), was 66 feet (20 m) [7].  Newly
released seeds germinate within a few weeks under suitable conditions.
Germination is epigeal.  Seed collections from individual trees in
California had highly variable germination rates, ranging from 2 to 80
percent within a 30-day germination period [24].  Soil-stored seed under
older stands often germinates prolifically following logging or other
disturbance [7].

Vegetative reproduction:  Bluegum eucalyptus sprouts readily from the
bole, from stumps of all sizes and ages, from the lignotuber, and from
the roots [7,17].  The lignotuber can live for many years in the soil
after stems die back [42].  Bluegum eucalyptus also reproduces by
layering [7].


SITE CHARACTERISTICS : 
Bluegum eucalyptus grows best in mediterranean climates, characterized
by cool, wet winters and dry, warm summers [37].  In coastal California,
it does well with only 21 inches (530 mm) of annual rainfall accompanied
by a pronounced dry season, primarily because frequent fogs compensate
for lack of rain [7].

Bluegum eucalyptus grows well on a wide range of soils, but requires
good drainage, low salinity, and a soil depth of 2 feet (0.6 m) or more.
In California, it grows best on deep alluvial soils because of the
greater moisture supply [7].  Hawaiian soils supporting bluegum
eucalyptus are about 3 feet (0.9 m) deep.  They are usually acidic,
moderately well-drained, silty clay loams [40,42].  

In California, bluegum eucalyptus occurs at elevations below 1,000 feet
(300 m) [32].  It occurs at 1,400 to 6,000 feet (425-1,800 m) in Hawaii
[40,42].
   


SUCCESSIONAL STATUS : 
Obligate Initial Community Species

In Hawaii and California, bluegum eucalyptus regenerates within and near
the edges of plantations.  It does not spread far and rarely invades
wildlands [2,7].  It has, however, invaded an oak woodland on Angel
Island in the San Francisco Bay [6].

Bluegum eucalyptus is shade intolerant; failure to regenerate within
forests in the absence of fire is related to low light intensities [3].
Bluegum eucalyptus is drought tolerant and somewhat frost hardy.  Frost
resistance increases with maturity [7].
  


SEASONAL DEVELOPMENT : 
In California, flowering occurs from November to April.  Fruit ripens
from October to March, about 11 months after flowering.  In Hawaii, some
trees flower throughout the year, but flowering is heaviest in February
and March.  Fruit ripens throughout the year [7].

Related categories for Species: Eucalyptus globulus | Bluegum Eucalyptus