Index of Species Information
SPECIES: Hesperocyparis macnabiana
Introductory
SPECIES: Hesperocyparis macnabiana
AUTHORSHIP AND CITATION :
Esser, Lora L. 1994 Hesperocyparis macnabiana. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
https://www.fs.usda.gov/database/feis/plants/tree/hesman/all.html [2025, August 14].
Revisions:
17 October 2013: Scientific name changed from Cupressus macnabiana
to Hesperocyparis macnabiana; references 28-31 added.
ABBREVIATION :
HESMAN
SYNONYMS :
Callitropsis macnabiana (A. Murray bis) D.P. Little [31]
Cupressus macnabiana Murr. [14,18,24,28]
Neocupressus macnabiana (A. Murray bis) de Laub. [29]
NRCS PLANT CODE :
HEMA21
COMMON NAMES :
MacNab cypress
TAXONOMY :
The currently accepted scientific name of MacNab cypress is Hesperocyparis
macnabiana (A. Murray bis) Bartel [23,28]. There are no recognized infrataxa.
Natural hybridization between MacNab cypress and Sargent cypress
(H. sargentii) has been hypothesized, but evidence for it is
inconclusive [13,17,27].
LIFE FORM :
Tree
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
DISTRIBUTION AND OCCURRENCE
SPECIES: Hesperocyparis macnabiana
GENERAL DISTRIBUTION :
MacNab cypress occurs only in California and has the widest distribution
of any of the California cypress [14,27]. Numerous scattered groves
occur in the inner North Coast Ranges, the Sierra Nevada foothills, and
the Cascade Range [14,24,27]. Over 30 groves occur in the following
counties: Sonoma, Napa, Yolo, Mendocino, Lake, Colusa, Tehama, Shasta,
Butte, Nevada, Yuba, and Amador [27].
ECOSYSTEMS :
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES27 Redwood
FRES28 Western hardwoods
FRES34 Chaparral - mountain shrub
STATES :
CA
BLM PHYSIOGRAPHIC REGIONS :
3 Southern Pacific Border
4 Sierra Mountains
KUCHLER PLANT ASSOCIATIONS :
K005 Mixed conifer forest
K006 Redwood forest
K029 California mixed evergreen forest
K030 California oakwoods
K033 Chaparral
SAF COVER TYPES :
229 Pacific Douglas-fir
232 Redwood
233 Oregon white oak
244 Pacific ponderosa pine - Douglas-fir
245 Pacific ponderosa pine
247 Jeffrey pine
248 Knobcone pine
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
HABITAT TYPES AND PLANT COMMUNITIES :
MacNab cypress is a component of the northern interior cypress forest.
This community is an open, fire-maintained, scrubby forest similar to
the knobcone pine (Pinus attenuata) forest. It is associated with
serpentine chaparral, and intergrades on less severe sites with upper
Sonoran mixed chaparral, montane chaparral, or knobcone pine forest
community types. On more mesic sites the northern interior cypress
forest intergrades with mixed evergreen forest or montane coniferous
forest [11]. MacNab cypress is associated with redwood (Sequoia
sempervirens)-Douglas-fir (Pseudotsuga menziesii) forest and associated
North Coast forests in Mendocino County, California [6,26]. It is also
commonly associated with chaparral and pine-oak (Pinus-Quercus spp.)
woodland species [8,27]. The Magalia grove in Butte County is
surrounded by yellow pine forest (Pinus ponderosa and P. jeffreyi) [27].
MacNab cypress occurs sympatrically with Sargent cypress in Lake County,
California [16].
Publications naming MacNab cypress as a community dominant are listed below.
Terrestrial natural communities of California [9]
Terrestrial vegetation of California [27]
Species not previously mentioned but commonly associated with MacNab
cypress include gray pine (Pinus sabiniana), sugar pine (P.
lambertiana), incense-cedar (Libocedrus decurrens), California scrub oak
(Quercus dumosa), leather oak (Q. durata), interior live oak (Q.
wislizenii), valley oak (Q. lobata), Sierra coffeeberry (Rhamnus rubra),
California coffeeberry (R. californica), yerba santa (Eriodictyon
californicum), chaparral pea (Pickeringia montana), golden-fleece
(Haplopappus arborescens), Garrya congdonii (interior silktassel),
California hop tree (Ptelea crenulata), chamise (Adenostoma
fasciculatum), wedgeleaf ceanothus (Ceanothus cuneatus), musk brush (C.
jepsonii), whiteleaf manzanita (Arctostaphylos viscida), creeping sage
(Salvia sonomensis), and styrax (Styrax officinalis var. californica)
[6,24,26,27].
MANAGEMENT CONSIDERATIONS
SPECIES: Hesperocyparis macnabiana
WOOD PRODUCTS VALUE :
MacNab cypress has soft, close-grained wood [24]. Cypress (Hesperocyparis
spp.) wood is generally durable and stable. It is suitable for a wide
range of exterior uses including joinery, shingles, and boats. Possible
interior uses include moulding and panelling [17]. Cypress shelterbelts
provide good fuel. Most cypress species develop a large proportion of
heartwood, which splits well, dries quickly, and is clean-burning.
Cypress wood is moderately fast burning because of its medium density.
As cypress woods are prone to sparking, they are recommended only for
enclosed fires [17].
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
Rodents and deer consume cypress seedlings. Cypress are considered
undesirable forage for livestock, although young plants are browsed
[24].
PALATABILITY :
NO-ENTRY
NUTRITIONAL VALUE :
NO-ENTRY
COVER VALUE :
NO-ENTRY
VALUE FOR REHABILITATION OF DISTURBED SITES :
NO-ENTRY
OTHER USES AND VALUES :
NO-ENTRY
OTHER MANAGEMENT CONSIDERATIONS :
Grazing and trampling by livestock are detrimental to cypress seedlings [1].
MacNab cypress is unsuitable for use in windbreaks or hedges near the
coast or in areas that are waterlogged, because waterlogged soils may
result in dwarfed trees [24,27].
Seedlings are susceptible to damping-off fungi [27]. MacNab cypress is
moderately susceptible to coryneum canker (Coryneum cardinale), which
can kill trees [24]. It succumbs to various diseases when transplanted
from warm, dry interior locations to the cool, moist atmosphere of the
coast [24].
MacNab cypress is restricted to serpentine soils in many locations.
Using cypress wood to fuel the furnaces used to extract mercury from
sepentine soils has reduced California's cypress forests [1].
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Hesperocyparis macnabiana
GENERAL BOTANICAL CHARACTERISTICS :
MacNab cypress is a native, evergreen tree with a broad crown and
lacking a main trunk [10,24]. It grows from 9.9 to 33 feet (3-10 m)
tall [8]. It is unique among North American cypress because of the
flat, sprayed arrangement of its branches [2,24]. Mature leaves are
generally about 0.06 inch (1.5 mm) long, although they can be up to 0.4
inch (10 mm) on vigorous shoots [8,24]. Ovulate cones are solitary, up
to 1.0 inch (25 mm) long. Staminate cones are 0.08 to 0.12 inch (2-3
mm) long [8,24]. The bark is furrowed and fibrous, 2.54 to 5.1 inches
(1-2 cm) thick, and not exfoliating [24]. A well-defined taproot and
numerous laterals are formed the first year [10].
RAUNKIAER LIFE FORM :
Phanerophyte
REGENERATION PROCESSES :
MacNab cypress reproduces exclusively from seed. Cone production is
abundant. Staminate cones are produced on trees that are 6 to 7 years
old [24]. Ovulate cones are produced on trees that are 14 years of age
or older. The cones require 2 years to mature [2]. They contain from
75 to 105 seeds each [10,24]. The cones are closed; they persist on the
tree until opened by the heat of a fire or from desiccation due to age
[10,27]. Seeds are shed gradually over several months after the cones
are opened [27]. Detached cones will open, but they rarely result in
seedling establishment, usually due to the lack of a suitable seedbed
[2]. Seed dispersal is primarily by wind and rain [27].
MacNab cypress germination rates are extremely low, less than 5 percent
[16]. Seeds require bare mineral soil for germination and
establishment. Seedling mortality is greater on shaded sites with
abundant litter because of damping-off fungi [2,27]. Seedlings are
sensitive to excessive moisture [24].
SITE CHARACTERISTICS :
In many areas MacNab cypress is restricted to serpentine soils, but in
other locations it occurs on clay loam (up to 5.0 feet [1.5 m] deep),
silty loam, alluvial, granitic, and volcanic soils [13,16,27]. It is
found on dry slopes, exposed hillsides, and ridgetops [8,16,20]. It
occurs at elevations from 1,000 to 2,800 feet (300-850 m) on north- to
northeast-facing slopes [8,20].
SUCCESSIONAL STATUS :
Site requirements for cypress seedlings are typical of those for pioneer
conifers. Seedlings are shade intolerant and survive best in full
sunlight on bare mineral soil [27]. Perhaps due to its shorter, bushier
habit, MacNab cypress is found on more exposed sites than Sargent
cypress where the two species occur together [16].
SEASONAL DEVELOPMENT :
MacNab cypress starts shedding its pollen around October 28 [24]. Seeds
mature 15 to 18 months after pollination. Ovulate cones remain closed
until opened by heat or age [10,24].
FIRE ECOLOGY
SPECIES: Hesperocyparis macnabiana
FIRE ECOLOGY OR ADAPTATIONS :
MacNab cypress is a fire-adapted, fire-dependent species. Successful
cypress (Hesperocyparis spp.) reproduction is generally restricted to burned
sites [27]. The serotinous cones persist on the trees for years [25].
Cone opening is erratic, slow, and almost negligible except when cones
are exposed to extreme heat; then it is rapid and uniform [25]. When
opened by the heat of a fire, the seeds fall on exposed mineral soil
[14,24]. Most seed falls in the first few months following fire [25].
Fires that occur in late summer and fall and are followed by winter
rains ensure seed dissemination on bare mineral substrates [27]. No
information was available on fire-free intervals for communities
dominated by MacNab cypress. However, Tecate cypress (Hesperocyparis
forbesii), a cypress found in southern California,
has an average interval between fires of 25 years, ranging from 15 to 63
years [2]. Cypress trees of southern California generally reach
cone-bearing age before another fire occurs [27].
FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find Fire Regimes".
POSTFIRE REGENERATION STRATEGY :
Tree without adventitious-bud root crown
Crown residual colonizer (on-site, initial community)
Initial-offsite colonizer (off-site, initial community)
FIRE EFFECTS
SPECIES: Hesperocyparis macnabiana
IMMEDIATE FIRE EFFECT ON PLANT :
Most fires probably kill MacNab cypress. Cypress thickets are conducive
to crown fires, which usually kill almost all trees in the stand [27].
At the Rancho Santa Ana Botanic Garden in southern California on October
8, 1943, a severe fire killed all but three MacNab cypress trees [24].
Cones of the California cypress open as the resin melts and boils.
Rapid charring of the thick cone scales extinguishes the flames, leaving
seeds unburned [2].
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
NO-ENTRY
PLANT RESPONSE TO FIRE :
MacNab cypress release large quantities of seed after fire [24]. In
Lake County, it occurs on recently burned areas with Sargent cypress
[16].
In Aukum, California, many decadent MacNab cypress were reported in
1948. The prevalence of "overmature and decadent" Macnab cypress trees
was attributed to the absence of fire, which was veiwed as unusual for
this species. A few miles south, in Hooker Canyon, Sonoma County, a
chaparral atand of chamise and California scrub oak contained a few old
MacNab cypress, numerous burned MacNab cypress stumps, and many young
MacNab cypress trees [24].
Seedling regeneration is not as extensive for MacNab cypress as for
other cypress species, possible due to low germination rates [24].
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
NO-ENTRY
FIRE MANAGEMENT CONSIDERATIONS :
Fires occurring too frequently in McNab cypress groves may destroy them,
as reproduction could be eliminated before it had a chance to produce
cones. Conversely, fire suppression could threaten the species.
REFERENCES
SPECIES: Hesperocyparis macnabiana
REFERENCES :
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