BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES : Ceanothus integerrimus | Deerbrush 


GENERAL BOTANICAL CHARACTERISTICS : 
Deer brush is a native, drought-deciduous shrub reaching 3 to 18 feet
(1-6 m) in height at maturity.  It is loosely branched and spreading in
form.  Flowers are borne in compound clusters.  The fruit is a sticky
capsule containing small, obovoid seeds [31,58].  Nitrogen-fixing
actinomycetes form nodules in deer brush roots [17,25].

Deer brush stems, excluding the root crown, live about 35 years.  The
stem of one specimen has been aged at 47 years.  Maximum age attained by
roots and root crowns has not been determined, but life span of these
organs can be more than 35 years if periodic top-kill occurs [22].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Deer brush reproduces from seed and by sprouting from the root crown
and/or stem [22].  It occasionally layers where branches contact soil
[15].

Seed reproduction:  Deer brush first produces seed at about 4 years of
age [21].  Ripe seed is forcibly ejected from the capsule when the
capsule dries and splits [63].  Deer brush is a seedbanking species.
Seed is stored in extremely high densities in duff and the upper few
centimeters of mineral soil.  Anderson [4] estimated that the deer brush
seed population in a mixed coniferous forest in northern California was
greater than 2 million seeds per hectare.  Viability of the seed
averaged 90.6 percent in the laboratory [4].  Similarly, Kauffman and
Martin [36,37] reported a range of 60 to 90 percent viability of deer
brush seed from three northern California mixed-conifer forests.
Viability of deer brush seed is generally high, and the seed is
long-lived.  Quick and Quick [61] reported 90 percent viability of
24-year-old seed.  Other researchers have suggested that deer brush seed
remains viable for well over 100 years [4,22,61].

Seed is dormant until the hard seedcoat is scarified by fire or
mechanical disturbance such as logging [19,22].  Optimal temperatures
for scarification range from 170 to 195 degrees Fahrenheit (77-90 deg C)
[35].  High-comsumptive fire (> 90% of duff burned) kills most seed in
duff, but most seed in mineral soil survives.  Anderson [4] found that
following one high-consumptive fire, 12.5 percent of seed in duff and
52.4 percent of seed in mineral soil was viable.  Seed requires
stratification follow scarification, and usually germinates in spring
[35].  Keeley [40] reported that light inhibited germination, an unusual
response, and that charate (charred wood powder) had no effect on
germination.

Best establishment occurs with seed in bare mineral soil [7,22].  In a
greenhouse study, seeds planted at one-half inch (1 cm) when in shade
and at 1 inch (2.5 cm) when in sun showed better seedling emergence than
seeds planted at greater or lesser depths.  Emergence did not occur with
seeds planted on the soil surface [1].  Nearly all seedling
establishment occurs in the first postfire spring; establishment after
the second postfire year is rare [22].  Plants typically average 3 to 4
inches (8-18 cm) in height at the end of their first growing season and
8 inches (20 cm) in height at the end of the second growing season
[21,22,76].

Vegetative reproduction:  Sprouts grow more rapidly than seedlings,
reaching a height of 30 or more inches (76 cm) in their first year [22].
Age at which deer brush sprouts first produce seed is undocumented;
however, sprouts of most Ceanothus species produce seed after 3 to 6
years [21].  When deer brush plants are top-killed before they become
decadent, roots remain alive, and root crowns retain the ability to
sprout for years beyond the 35-year life expectancy of other stem
tissue.  Without periodic top-kill, root systems and root crowns of
decadent plants die [22].


SITE CHARACTERISTICS : 
Deer brush grows on well-drained soils of all textures [22].  Slope
varies from gentle to steep [14].  In California, deer brush occurs
primarily on the west slope of the Cascade-Sierra Nevada crest [22,33].
In Oregon, deer brush occurs on both sides of the Cascade Range [79].

Elevational ranges of deer brush are as follows:

Arizona                  3,500 to 7,000 feet (1,100-2,100 m) [39]
northern California      2,000 to 4,000 feet (600-1,200 m) [22,63]
central Sierra Nevada    3,000 to 5,550 feet (900-1,700 m)   
southern California      5,000 to 7,000 feet (1,500-2,100 m) [22]
Oregon                   2,000 to 4,000 feet (600-1,200 m)
Washington               2,000 to 4,000 feet (600-1,200 m) [63]


SUCCESSIONAL STATUS : 
Deer brush grows in open sun to partial shade.  When overtopped by
trees, deer brush dies out [22,30,73].  It is typically successional
after fire, landslide, logging, mining, or other stand-replacing events
[7,22,33].  Deer brush seedlings establish in the initial
postdisturbance commmunity.  If fire or other distrubance is frequent
enough to prevent conifers from establishing a canopy, deer brush and
other shrubs may occupy a site indefinitely [7].  A brushfield
containing deer brush, on the Tahoe National Forest, has a history of
wildfire occurrence at approximate 10-year intervals.  The brushfield
has remained stable for over 100 years [85].  More often, deer brush is
replaced by conifers [7,22].  In montane chaparral, herbs, deer brush,
and other shrubs are replaced by pines (Pinus spp.).  In the absence of
fire, pines are replaced by firs (Abies spp.) and other shade-tolerant
tree species [30,75].

On the Klamath National Forest of California, Stuart and others [71]
identified two seral communities in which deer brush was an important
component of the vegetation after stand-replacing events in old-growth
Douglas-fir (Pseudotsuga menziesii).  After wildfire and no subsequent
salvage operation, a deer brush-canyon live oak-blue wildrye (Quercus
chrysolepis-Elymus glaucus) community developed.  After wildfire
followed by salvage, or logging followed by site preparation and
planting of Douglas-fir seedlings, a tanoak-Pacific madrone-(Lithocarpus
densiflorus-Arbutus menziesii)-deer brush community developed.  The
authors speculated that with either successional pathway, natural
release of Douglas-fir would not occur for at least 50 years, but the
long-term fertility of the deer brush-canyon live oak-blue wildrye
community may be greater because nitrogen-fixing deer brush is the
primary dominant.


SEASONAL DEVELOPMENT : 
Deer brush flowers from spring to early fall [31,39,58].  Heaviest
flowering occurs in May and June [72], with seeds dispersing in summer
[40].  Since deer brush is drought-deciduous, most leaves are shed in
summer.  A few leaves are usually retained throughout winter [21,31].

Related categories for SPECIES : Ceanothus integerrimus | Deerbrush