Greenleaf Manzanita

More info for the terms: cover, density, fire suppression, fire use, forest, fruit, fuel, fuel moisture, litter, prescribed fire, seed, shrub, shrubs, stratification, tree, wildfire

General fire studies:
The following 2 studies do not discuss whether postfire growth is from seedlings or sprouting. In both
studies, burning increased greenleaf manzanita.

Prescribed burning increased greenleaf manzanita density on the Deschutes
National Forest. During the spring of 1979, moderate- and
high-severity prescription burns were
conducted in a Pacific ponderosa pine/antelope bitterbrush-greenleaf manzanita/western needlegrass
community. Prior to burning, 300 to 400 greenleaf manzanita shrubs/ha occurred on both
treatment sites. In postfire year 15 (1984), greenleaf manzanita averaged 2,590 shrubs/ha on
moderate-severity burns and 3,550 shrubs/ha on high-severity burn sites [180].

On Donner Pass, California, an August 1960 wildfire burned 40,000 acres (16,000 ha) in a
conifer forest consisting primarily of mixed pine and fir species. In 1963 and
1975 line transects were run throughout the burned areas. In 1963 greenleaf
manzanita was 0% on line transects. Greenleaf manzanita cover on transects increased to 3.8% in 1975 [26].

Seedlings:
In the following studies, an increase in greenleaf manzanita seedlings occurred
following fire. Higher-severity fires caused greater seedling establishment than
lower-severity fires [109,111,112,222].

Before and after a September 1927
fire on a chamise-dominated site in Mendocino County, California, greenleaf manzanita seedlings/milacre
were counted. Prior to the fire, there were no
greenleaf manzanita seedlings present. Seedling establishment was greatest during the
first postfire year. A survey of the area during postfire year 7 (1934) found that a
large proportion of greenleaf manzanita seedlings which were present in postfire
year 5 had survived and developed into robust plants [181].

Greenleaf manzanita seedlings/milacre
before and 1 to 5 years after burning
Prefire 1st postfire year 2nd postfire year 3rd postfire year 4th postfire year 5th postfire year
0 7.2 4.0 2.6 2.6 2.6

Sixty to 70-year-old white fir stands with an understory of snowbrush
ceanothus and greenleaf manzanita and/or pinemat manzanita (species not
differentiated in study) were burned before and after tree harvest in the Lassen
National Forest, California [222]. Prior to spring or fall burning and white fir
harvest in 1983, manzanita seedlings ranged from 0 to 1,700 seedlings/acre.
During the summer of 1984, manzanita seedling density ranged from 11,000 to
16,000/acre on sites burned in spring 1983 before harvest. Manzanita seedling
densities on sites burned after harvest in the spring and fall of 1983 ranged from 13,000
to 16,000/acre and 10,000 to 11,000/acre for spring and fall burns, respectively. The
density of manzanita seedlings after postharvest burning was considerably higher for spring
burns than for fall burns. This seasonal difference was attributed to
consistently higher percent burned area in spring than in fall; fall
fuels were wet due to rains [222].

Fall and spring prescribed burns of varying severities conducted in 1983 at 2
sites on the west slope of the Sierra Nevada and Cascade Range produced
significant greenleaf manzanita seedling increases (P<0.10) during either postfire year 1 or 2 [109,111,112]. The
first site, Blodgett Forest Research Station, sits at an elevation of 4,300 feet (1,300
m) and was dominated by white fir, ponderosa pine, incense-cedar,
and Douglas-fir, with a scattered and diverse shrub understory consisting of
whitethorn ceanothus, greenleaf manzanita, California black oak, deer brush (Ceanothus
integerrimus), giant chinquapin (Chrysolepis chrysophylla), tanoak (Lithocarpus
densiflora), Sierra mountain misery (Chamaebatia foliolosa), and pine
rose (Rosa pinetorium). The second site, Quincy Ranger District, sits at an
elevation of 4,432 feet (1,351 m) and was dominated by Jeffrey pine, coast
Douglas-fir, and incense-cedar. The most common understory shrubs included
California black oak, deer brush, thimbleberry (Rubus parviflorus), and
pale serviceberry (Amelanchier pallida). Greenleaf manzanita was a minor species at
Quincy; therefore, greenleaf manzanita seedlings were far fewer after Quincy
fires than fires at Blodgett [109,111,112].

Four burn treatments were conducted at each site. Researchers included an early
spring-moderate consumption burn; a late spring-high consumption burn; an early
fall-high consumption burn; and a late fall-moderate consumption burn. The early
spring-moderate consumption burn was conducted as soon as fuels could
carry fire. The late spring-high consumption burn was conducted as
late in the season as safely possible (prior to the active fire suppression
season). The early fall-high consumption burn was conducted as early in the fall
as possible and before major precipitation. Finally, the
late fall-moderate consumption burn was conducted 1 to 2 days after significant precipitation. Seedling densities of greenleaf
manzanita, particularly at the Blodgett site, were much higher on high-consumption burns
than moderate-consumption burns. Comparing high-consumption
burns, spring burns produced more greenleaf manzanita seedlings than fall burns
at Blodgett, while the opposite was true at Quincy. On spring sites,
excluding the early spring-moderate consumption burn at the Blodgett site, greenleaf
manzanita seedlings were not produced in postfire year 1 because the stratification period was
incomplete until the winter of 1985.
At 1 Blodgett site (late fall-moderate consumption) and 2 Quincy sites (early
fall-high consumption and late fall-moderate consumption),
greenleaf manzanita seedlings increased in postfire year 1 but decreased during
postfire year 2. This was attributed to shading: greenleaf manzanita seedlings occurred
under a dense canopy [109,111,112].

Most greenleaf manzanita seeds present in the seed bank had been cached by
rodents many years prior to the fires, likely before conifer establishment.
After postfire seedling establishment, the rodents dug into these caches in
search of seeds. This caused substantial mortality of fragile greenleaf
manzanita seedlings [112].

The table below describes density of greenleaf manzanita seedlings prior to
the prescription burns (1983), at the end of the 1984 and 1985 growing seasons
(postfire years 1 and 2), and on the unburned control sites [109,111,112].

Mean (SE) density/ha of greenleaf
manzanita seedlings at the Blodgett site
Treatment
Date of fire
1983 (prefire)
1984
1985
Early fall-high consumption 28 Sept. 1984 0 (0) ND* 11,833 (2,625)
Late fall-moderate consumption 8 Oct. 1983 2,042 (1,116) 4,875 (1,508) 958 (305)
Late spring-high consumption 26 June 1984 367 (200) 0 (0) 25,233 (5,832)
Early spring-moderate consumption 17 May 1984 233 (202) 34 (33) 4,600 (2,059)
Control 467 (210) 134 (65) 134 (65)
Mean (SE) density/ha of greenleaf
manzanita seedlings at the Quincy site
Treatment
Date of fire
1983 (prefire)
1984
1985
Early fall-high consumption 15 Sept. 1983 0 (0) 3,567 (769) 861.1 (285)
Late fall-moderate consumption 12 Oct. 1983 0 (0) 1,167 (356) 167 (87)
Late spring-high consumption 24 May 1984 0 (0) 0 (0) 833 (540)
Early spring-moderate consumption 7 May 1984 0 (0) 0 (0) 367 (155)
Control 0 (0) 0 (0) 0 (0)

*ND=no data

For a complete review of this study, see the Research Project Summary by Kauffman [109,111,112].

Repeated burning:
On Lookout Mountain in central Oregon,
a Pacific ponderosa pine/greenleaf manzanita community was burned twice over a
4-year period, causing nearly complete mortality of mature greenleaf manzanita and
complete mortality of greenleaf manzanita seedlings.
Prescription burning took place at 2 sites, designated as the upper and lower
plots [134].

Date, fuel, and weather
conditions during greenleaf manzanita prescribed burns
Date/conditions
Upper plot, 1st burn
Lower plot, 1st burn
Upper plot, 2nd burn
Upper plot, 2nd burn
Burn date 9/27/76 10/1/76 10/2/79 6/9/80
Temperature (°F) 56-71 70-74 56-67 50-52
Relative humidity (%) 37-61 30-38 38-54 42-43
Wind (mph) 0-8 0-5 0-5 2-7
Fuel moisture content/new litter (%) 12-15 10-11 7-20 5-8
Fuel moisture content/old litter (%) 10-36 11-15 11-21 6-14
Fuel moisture content/duff (%) 26-65 26-75 14-21 52-54

Following the fires, Martin [134] measured the percent of greenleaf
manzanita that was unburned, burned and sprouting after fire, or killed. Greenleaf manzanita seedling
mortality was measured after second fire. Unfortunately, the researcher did
not provide the date of postfire vegetation measurements. "Poor" postfire sprouting of
greenleaf manzanita occurred on both sites. The researcher expected this, since
greenleaf manzanita is a poor sprouter in the area and the overstory was a
closed Pacific ponderosa pine canopy. Results of the 2 fires are presented below [134]:

Cover (%) of greenleaf manzanita

Fire effects
Upper plot
Lower plot
1st fire
   Unburned 0 0
   Burned/sprouted 0 3.7
   Dead 100 96.3
2nd fire
   Unburned 10.4 0
   Burned/sprouted 2.9 0
   Dead 97.1 0
   Shrub seedlings dead 100 100

For further information on prescribed fire use and postfire responses of multiple plant species in this plant community, see Martin's [134] original Research Paper.

In a montane chaparral site in northern California, a prescribed fire
caused the germination of thousands of greenleaf manzanita seedlings. Three years later the site was reburned,
and only 1 greenleaf manzanita seedling emerged after fire. A third and fourth fire completely eliminated
greenleaf manzanita [24]. Presumably, the initial fire exhausted the
greenleaf manzanita seed bank, leaving few or no seeds to germinate
following subsequent fires. Since it can take 8 to 10 years for greenleaf
manzanita plants to flower and fruit [175], there was no
replenishing of the seed bank between the first and second fires.

greenleaf manzanita

green leaf manzanita

snowbrush manzanita

Information on state-level protected status of plants in the United States is available at Plants Database.

More info for the terms: drupe, fruit, lignotuber, shrub

This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g., [90,91,92,94,105,106,113,160,226,227]).

Greenleaf manzanita is an erect shrub with stout branches [94,106] that grows from 3 to 7 feet (1-2 m) tall [47,70,90,92,94,106,160]. Individual plants may have an ultimate spread of 10 feet (3 m) [197]. Spreading or drooping leaves (never vertical) [89,92,160] are 0.8 to 2 inches (2-6 cm) long, 0.6 to 2 inches (1.5-4 cm) broad [90,92,94,160,226], and produced on twisted, crooked, or gnarled stems [226]. The flowers, about 6 mm long [92], are borne on condensed, many-flowered panicles at the ends of some of the branches [94,167]. The fruit is a drupe, roughly 7-10 mm broad [90,92,160]. Each drupe contains approximately 5 stony, 1-seeded nutlets [70,120].

Underground parts: Unlike greenleaf manzanita populations elsewhere, greenleaf manzanita in the Sierra Nevada and southwestern Oregon has a lignotuber [1,89,94]. The lignotuber is described as a heavy, turnip- or globular-shaped organ that may form tabular platforms [92,99,102]. Greenleaf manzanita roots grow deep into the ground [119,197]. In the southern Sierra Nevada, greenleaf manzanita roots extend to a depth of no greater than 7 feet (2 m). Roots in the latter 5.74 feet (1.74 m) grew down through weathered, porous granitic bedrock [96]. The roots of greenleaf manzanita are commonly infected by ectomycorrhizae or arbutoid mycorrhizae in the Sierra Nevada [131].

Physiological characteristics: Greenleaf manzanita is a drought-tolerant shrub [83]. DeLucia and Schlesinger [54], based on data collected from Alpine County near Reno, Nevada, describe greenleaf manzanita as having high drought tolerance and nitrogen-use efficiency, but low water-use efficiency. Greenleaf manzanita is adapted to high levels of water stress. Greenleaf manzanita plants in the Sierra Nevada maintained a xylem potential of >-0.7 MPa throughout the growing season even during periods of drought [130].

Greenleaf manzanita is the most common manzanita in the Great Basin and much of the Sierra Nevada [157,205]. It occurs from Washington south to California and Baja California, east to New Mexico, and north to Montana [55,89,90,91,94,105,106,113,226,227]. Plants Database provides a distributional map of greenleaf manzanita.

More info for the terms: cover, crown fire, duff, fire exclusion, fire regime, fire-return interval, forest, fuel, lignotuber, litter, mean fire-return interval, scarification, seed, severity, shrub, shrubs, woodland

Fire adaptations: Greenleaf manzanita establishes after fire by seed [11,31,84,112,135,137,161,179,198,199] and sprouting from the lignotuber [15,24,31,89,97,137,157,198]. The dormancy of greenleaf manzanita seeds stored in soil and duff is broken by fire scarification [11,31,84,135,137,161,179,198,199]. Greenleaf manzanita seeds have a hard seed coat that requires fire (or other) scarification. Postfire lignotuber sprouting only occurs in some populations in California and southern Oregon, especially from parts of the Sierra Nevada, southernmost Cascade Range, and North Coast Ranges [94,99]. James [99] notes that greenleaf manzanita lignotubers may increase in size following fire in chaparral ecosystems. The physical and chemical characteristics of greenleaf manzanita produce a highly flammable shrub [30,49,114]. Kauffman [112] postulates that since greenleaf manzanita reproduction is partially dependent upon fire, heightened shrub flammability may be a fire adaptation.

FIRE REGIMES: Greenleaf manzanita is found in plant communities/ecosystems with varying FIRE REGIMES. Greenleaf manzanita may occur where fire-return intervals are as short as 1 year or as long as several hundred years. A more detailed description of greenleaf manzanita fire-return intervals follows.

Oak/chaparral woodland: The oak/chaparral woodland of Yosemite National Park, California, had a presettlement fire-return interval of 20 to 30 years. Presently, many areas have not burned for 60 to 100 years due to fire exclusion [30].

Lodgepole pine forests: Greenleaf manzanita occurs in lodgepole pine forests on the east side of the Cascade Range, the Blue Mountains, and the Okanogan Highlands of Washington north into British Columbia and south to Colorado and California. Inland Pacific Northwest lodgepole pine communities had an historic mean fire-return interval of 112 years. Lodgepole pine forests in areas susceptible to summer drought in the Inland Pacific Northwest historically had low- to medium-severity surface fires occurring at intervals of 25 to 50 years [38].

Mixed-conifer forests: Greenleaf manzanita is prevalent in open mixed-conifer forests, particularly in the Sierra Nevada. The minimum and maximum historic fire-return intervals for mixed-conifer forests of the Sierra Nevada ranged from approximately 3 to 8 years and 10 to 20 years, respectively [44,107,126,155,165]. Prior to fire exclusion in the Sierra Nevada, fires were generally low -severity surface fires, and fire-return intervals were frequent [126].

Elsewhere, the fire-return interval ranges from 15 to 29 years in mixed-conifer/chaparral sites in the San Bernardino Mountains [155], from 10 to 80 years in mixed conifer-hardwood forests of southwestern Oregon [38], and 4 to 7 years in mixed-conifer forests in Bryce Canyon National Park, Utah [32].

Using aerial photography and ground sampling, the approximate mean fire-return interval from 1925 to 1991 for the Sierra San Pedro Mártir, Baja California, was estimated at 52 years. The Sierra San Pedro Mártir is the last remaining mixed-conifer forest along the Pacific coast still subject to uncontrolled, periodic surface fires. It is estimated that the infrequent fires are severe surface fires. Heavy fuels result from the gradual buildup of shrub cover (predominately greenleaf manzanita, pointleaf manzanita (Arctostaphylos pungens), and pinkbracted manzanita (A. pringlei ssp. drupacea)), conifer recruitment, and litter accumulation [153].

Montane chaparral: Fire-return intervals for montane chaparral sites in the Sierra Nevada are variable [189]. Nagel and Taylor [161] studied the fire ecology of 6 montane chaparral sites codominated by greenleaf manzanita and huckleberry oak (Quercus vaccinifolia) in Lake Tahoe Basin in the northern Sierra Nevada. Prior to fire exclusion in the late 1800s and early 1900s, the mean fire-return interval was 28 years, with a range of 16 to 40 years. Other research estimates that the fire-return interval ranged from 30 to 60 years [38]. When fuel moistures drop below 100%, fire is likely to remove a large portion of the shrubs in this type. When moisture drops below 100%, explosive fire conditions with rapid rates of spread and flame heights greater than 10 feet (3 m) are expected [97]. High-severity fires are typical, with most shrubs being top-killed [38].

Pinyon-juniper woodlands: In the San Bernardino Mountains, greenleaf manzanita occurs in high-elevation (7,000 feet (2,000 m)) pinyon-juniper woodlands. Using fire scar data, Wangler and Minnich [220] estimate the fire-return interval was approximately 480 years. When fire occurs, it is generally high-severity crown fire [220].

Pacific ponderosa pine forests: Fire scar data from the years 1700 to 1875 on dry ridges in the southern Sierra Nevada showed that the minimum and maximum fire-return intervals were 2 and 12 years, respectively. The mean fire-return interval for that period was 5.5 years [126]. Fire historically occurred approximately every 13 years in ponderosa pine woodlands of Lava Bed National Monument, California [137]. Greenleaf manzanita occurs throughout ponderosa pine forests on the eastern side of the Oregon Cascade Range. Using fire scar analysis, Bork [29] found that the mean historic fire-return intervals at 3 sites, Cabin Lake, Pringle Butte, and Lookout Mountain, were 24, 11, and 15 years, respectively. In a Pacific ponderosa pine/incense-cedar (Calocedrus decurrens)/greenleaf manzanita community, the fire-return interval ranged from 9 to 42 years [150].

Red fir forests: For the period 1740 to 1985, the mean fire-return interval at Swain Mountain Experimental Forest in northeastern California was 12.9 years, with a range of 1 to 57 years. Larger fires (>10 acres (5 ha)) occurred every 26.2 years, with a range of 11 to 47 years. Average fire-free intervals were shorter during the settlement period (1851-1934, x = 7.9 years) than during the presettlement (1740-1850, x = 21.4 years) and fire-exclusion (1935-1985, x = 17.3 years) periods. Fires in red fir forests are generally of low and moderate severity [203].

The following table provides fire-return intervals for plant communities and ecosystems where greenleaf manzanita is important. 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".

Fire-return intervals for plant communities with greenleaf manzanita Community or Ecosystem Dominant Species Fire Return Interval Range (years) California chaparral Adenostoma and/or Arctostaphylos spp. <35 to <100 California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [168] sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica 218] paloverde-cactus shrub Cercidium spp./Opuntia spp. <35 to <100 [168] curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1,000 [8,184] western juniper Juniperus occidentalis 20-70 Rocky Mountain juniper Juniperus scopulorum <35 pinyon-juniper Pinus-Juniperus spp. <35 [168] Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [16,17,201] Sierra lodgepole pine* Pinus contorta var. murrayana 35-200 [5] Colorado pinyon Pinus edulis 10-400+ [64,71,115,168] Jeffrey pine Pinus jeffreyi 5-30 Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [5] interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [5,13,132] Arizona pine Pinus ponderosa var. arizonica 2-15 [13,48,185] quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [5,81,151] Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [5,6,7] coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [5,156,178] Pacific coast mixed evergreen Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii <35-130 [5,39] California oakwoods Quercus spp. <35 [5] oak-juniper woodland (Southwest) Quercus-Juniperus spp. <35 to <200 [168] coast live oak Quercus agrifolia 2-75 [78] canyon live oak Quercus chrysolepis <35 to 200 Oregon white oak Quercus garryana <35 [5] California black oak Quercus kelloggii 5-30 [168] redwood Sequoia sempervirens 5-200 [5,63,195] *fire return interval varies widely; trends in variation are noted in the species review

More info for the terms: cover, density, flame length, forest, fuel, fuel moisture, severity, shrub, shrubs

Avian community changes: In the 15-year period following a 39,000-acre (15,800 ha) August fire in a pine-fir (Pinus-Abies spp.) forest in the northern Sierra Nevada, the population of greenleaf manzanita increased, and with it, bird species characteristic of shrub stands. At postfire year 15, yellow warbler, green-tailed towhee, and fox sparrow populations "increased dramatically" from postfire year 8 [27].

Fire behavior: The fire behavior of 16 prescribed burned plots in montane chaparral communities codominated by greenleaf manzanita, huckleberry oak, and whitethorn ceanothus was measured in Yosemite National Park. These fires were separated in space and time. At the time of burning few shrubs exceeded 6 feet (2 m) in height [210].

Fire behavior in a montane chaparral site in Yosemite National Park Spread/minute (feet) Flame length (feet) Mean Range Mean Range 11.7 0.0-35.3 12.5 1.0-25.0

Fire economics: Literature is available on the costs associated with and the economic feasibility of burning greenleaf manzanita and other northern California chaparral species [182].

Live fuel moisture: In the Sierra Nevada and Cascade Range of California, greenleaf manzanita live fuel moisture during the 1984 fire season ranged from a high of approximately 150% on 29 May to a low of approximately 100% on 15 October [176]. On the Shasta-Trinity National Forest, greenleaf manzanita mature leaf moisture content varied widely throughout the year. Samples taken in November 1966 showed an average moisture content of 120%, which dropped to 86% by 25 June 1967. From the end of June to 10 July 1967, average moisture content increased rapidly to 125% and remained at or above 100% until April 1968. The moisture content of new leaves was substantially higher than mature leaves. On 13 July, when the moisture content of mature leaves was 123%, new greenleaf manzanita leaves had a moisture content of 259% [35].

Physical burning characteristics: On the eastern slopes of Mt Shasta at elevations ranging from 4,000 to 6,000 feet (1,200-1,800 m), greenleaf manzanita physical characteristics relevant to fire were studied over a 4-year period [49].

Average greenleaf manzanita physical characteristics Characteristics Foliage Woody fuel (inches diameter) < 0.25 0.26-0.50 0.51-1.0 > 1.0 Living fuel density (lb/ft²) 54.7 38.9 41.3 44.5 46.4 Solvent extractives in living fuel (%) 16.9 6.2 4.2 3.6 3.4 Solvent extractives in dead fuel (%) 0 2.6 1.2 1.4 1.9 Surface-to-volume ratio (ft²/ft³) 1,623 343 137 66 32 Heating value of living fuel (Btu/lb) 9,076 8,246 8,212 8,306 8,320 Heating value of dead fuel (Btu/lb) no data 8,280 8,367 8,201 8,429

Data on the average greenleaf manzanita biomass by fuel size class and crown cover across many areas of Oregon, Washington, and northern California east of the Cascade Range are available [136].

Soil: Data on the average bulk density and nutrient concentrations of soil on burned shrub sites dominated by snowbrush ceanothus and containing greenleaf manzanita are available in Johnson and others [103].

Surface and subsurface (3 to 4.3 inches (7-11 cm)) soil temperatures were measured during prescribed fires of high and low severity in greenleaf manzanita stands in the Sierra National Forest, California, at an elevation of 7,000 feet (2,000 m). High-severity fires were created by adding fine and woody fuels to the burn sites. Low-severity sites were burned with existing fuel loads. On the high-severity sites, temperatures reached over 600 °F (300 °C) at the soil surface and 400 °F (200 °C) in the subsurface zone. On the low-severity sites, temperatures reached 300 °F (150 °C) at the surface and 200 °F (100 °C) in the subsurface zone [166].

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More info for the term: phanerophyte

RAUNKIAER [174] LIFE FORM:
Phanerophyte

More info for the term: forest

Greenleaf manzanita is most commonly associated with dry sites in arid chaparral belts [117,161,181,189], on old and new burn sites [123,125,229], in open coniferous forests (particularly ponderosa pine), and in woodlands [90,94,106].

Climate: Greenleaf manzanita is well adapted to hot, dry climates and can withstand wide temperature extremes [149]. In the Sierra Nevada, where greenleaf manzanita is prevalent, the climate is characterized by hot, dry summers and mild, moist winters. Most of the precipitation occurs as snow from November to May [165,181,188].

Elevation: Greenleaf manzanita elevational range State/Region Elevation Arizona 7,000 to 8,500 feet [113] California 2,000 to 11,000 feet [90,160,183] Colorado 7,000 to 9,000 feet [88,119] Nevada 2,000 to 9,000 feet [106,192] Utah 4,500 to 9,300 feet [167,226] Sierra Nevada montane chaparral 5,000 to 7,000 feet [188]

Environmental conditions: Greenleaf manzanita is well adapted to high foliar temperatures and low soil moisture availability [42].

Slope and aspect: Greenleaf manzanita is most common on south and southwestern aspects where full sunlight is available [59,95].

Soil: Greenleaf manzanita typically occurs on soils that are well drained [96,119,149], shallow to moderately deep, and sandy loam to silty loam in texture [59,95,192]. Parent materials may include sandstone, limestone, pumice, and granite [25,53,95,138,214,230].

Detailed soil data for the Teakettle Experimental Forest in the Sierra Nevada [165] and a Pacific ponderosa pine/antelope bitterbrush-greenleaf manzanita community located in the Cascade Range of south-central Oregon [56] are available. Detailed descriptions of soil chemical and mineral composition in a midseral Jeffrey pine/greenleaf manzanita forest are also available [177].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

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SAF COVER TYPES [60]:




207 Red fir

210 Interior Douglas-fir

211 White fir

217 Aspen

218 Lodgepole pine

220 Rocky Mountain juniper

229 Pacific Douglas-fir

232 Redwood

233 Oregon white oak

234 Douglas-fir-tanoak-Pacific madrone

237 Interior ponderosa pine

238 Western juniper

239 Pinyon-juniper

241 Western live oak

243 Sierra Nevada mixed conifer

244 Pacific ponderosa pine-Douglas-fir

245 Pacific ponderosa pine

246 California black oak

247 Jeffrey pine

248 Knobcone pine

249 Canyon live oak

255 California coast live oak

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

ECOSYSTEMS [68]:




FRES20 Douglas-fir

FRES21 Ponderosa pine

FRES23 Fir-spruce

FRES26 Lodgepole pine

FRES27 Redwood

FRES28 Western hardwoods

FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the terms: forest, shrub, woodland

KUCHLER [127] PLANT ASSOCIATIONS:




K005 Mixed conifer forest

K006 Redwood forest

K007 Red fir forest

K008 Lodgepole pine-subalpine forest

K010 Ponderosa shrub forest

K011 Western ponderosa forest

K012 Douglas-fir forest

K015 Western spruce-fir forest

K018 Pine-Douglas-fir forest

K019 Arizona pine forest

K020 Spruce-fir-Douglas-fir forest

K022 Great Basin pine forest

K023 Juniper-pinyon woodland

K024 Juniper steppe woodland

K026 Oregon oakwoods

K029 California mixed evergreen forest

K030 California oakwoods

K031 Oak-juniper woodland

K032 Transition between K031 and K037

K033 Chaparral

K034 Montane chaparral

K037 Mountain-mahogany-oak scrub

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: cover, forb, shrub, shrubland, woodland

SRM (RANGELAND) COVER TYPES [187]:




109 Ponderosa pine shrubland

202 Coast live oak woodland

204 North coastal shrub

206 Chamise chaparral

207 Scrub oak mixed chaparral

208 Ceanothus mixed chaparral

209 Montane shrubland

210 Bitterbrush

409 Tall forb

411 Aspen woodland

412 Juniper-pinyon woodland

415 Curlleaf mountain-mahogany

420 Snowbrush

503 Arizona chaparral

504 Juniper-pinyon pine woodland

509 Transition between oak-juniper woodland and mahogany-oak association

More info for the term: lignotuber

Greenleaf manzanita is generally top-killed by fire where it forms a lignotuber [11,84,94,118,157,166]. In the absence of a lignotuber, fire may kill greenleaf manzanita [94,135].

More info for the term: cover

Greenleaf manzanita foliage has little value as browse for livestock and wildlife [82,94,183]. Its value as browse is primarily limited to winter forage or when little else is available [19,52,82,183]. Rocky Mountain mule deer tend to favor greenleaf manzanita more than other browsing ungulates [128,133,192]. Following fire or other disturbances, most livestock and deer lightly browse greenleaf manzanita sprouts and seedlings [82,94,97,183].

The fruits and seeds of greenleaf manzanita are important to a variety of birds and mammals [86,122,146,149]. The fruits are a food source for American black bears in northern California and southern Oregon during late summer and early fall [69,94,95,97,169]. Grouse, wild turkeys, songbirds, and deer mice also consume the fruits [85,94,97,100].

Palatability/nutritional value: The palatability of greenleaf manzanita is described as "poor to worthless" for domestic goats and "worthless" for cattle and horses [104,183]. It is palatable to domestic sheep [79,144] (see Other Management Considerations).

The crude protein of greenleaf manzanita taken from California ranges from a low of 5.2% in February to a high of 7.8% in August and September [22]. In Truckee River Canyon on the California-Nevada border, crude protein of greenleaf manzanita ranged from a low of 6.0% in January to 7.8% in August and September [183]. The ash content of greenleaf manzanita foliage taken from Mt Shasta at elevations of 4,000 to 6,000 feet (1,200-1,800 m) averaged 3.9% [49].

Cover value: While there is little in the literature on the cover value of greenleaf manzanita, it is likely valuable to numerous animal species due to the dense thickets it produces. It is described as an important cover species for small mammals, birds, insects, and arthropods [33,94,208].

More info for the terms: forest, habitat type, hardwood, phase

Greenleaf manzanita is described as a dominant species in the following
vegetation classifications and locations.



California:

• 
  

  
  Black oak (Quercus velutina)/greenleaf manzanita in the hardwood rangelands [3]



• 
  

  
  Whitethorn ceanothus (Ceanothus cordulatus)-greenleaf manzanita-bush chinquapin
  (Chrysolepis sempervirens) in the San Bernardino Mountains [154]



• 
  

  
  Jeffrey pine (Pinus jeffreyi)/greenleaf manzanita-snowbrush ceanothus (Ceanothus velutinus),
  found throughout the Sierra Nevada at mid- to upper elevations (5,920-9,520 feet (1,800-2,900 m)) [170]



• 
  

  
  Canyon live oak (Q. chrysolepis)/whiteleaf manzanita-greenleaf manzanita in Castle Crags State Park, Shasta County



• 
  

  
  Wedgeleaf ceanothus-California coffeeberry (C. cuneatus-Rhamnus californica)-greenleaf manzanita
  in Castle Crags State Park [196]



• 
  

  
  Pacific ponderosa pine (Pinus ponderosa var. ponderosa)/greenleaf
  manzanita in Lava Beds National Monument



• 
  

  
  Pacific ponderosa pine/antelope bitterbrush (Purshia tridentata)-greenleaf
  manzanita near the extreme southern border of Lava Beds National Monument



• 
  

  
  Pacific ponderosa pine/antelope bitterbrush-greenleaf manzanita/western needlegrass (Achnatherum
  occidentale ssp. occidentale) at the highest elevations of Lava Beds
  National Monument [58]

Nevada:

• 
  

  
  Quaking aspen-white fir (Populus tremuloides-Abies concolor)/greenleaf
  manzanita community type in the Snake Range of the Humboldt National Forest from 8,300 to 9,500 feet (2,500-2,900 m)
  [2,158,163]

• 
  

  
  Singleleaf pinyon/pale serviceberry (Pinus monophylla-Amelanchier pallida)/
  greenleaf manzanita in the eastern part of Mathews Canyon Watershed [25]

• 
  

  
  Greenleaf manzanita/snowbrush ceanothus-prostrate ceanothus (C. prostratus)
  shrublands [163]

• 
  

  
  Singleleaf pinyon/Saskatoon serviceberry (A. alnifolia)/greenleaf manzanita woodlands [163]

Oregon:

• 
  

  
  Pacific ponderosa pine/antelope bitterbrush-greenleaf manzanita community in the Cascade
  Range of south-central Oregon [56]



• 
  

  
  Tanoak (Lithocarpus densiflorus)/manzanita (greenleaf, whiteleaf, and hairy
  manzanita (Arctostaphylos columbiana)/beargrass (Xerophyllum tenax) east of the Coast Ranges crest
  in the southwestern portion of the state from approximately 3,000 to 3,700 feet (900-1,100 m) [9]



• 
  

  
  Pacific ponderosa pine/greenleaf manzanita/Idaho fescue (Festuca idahoensis)
  on the Silver Lake mule deer range from 4,900 to 6,500 feet (1,500-2,000 m) [53] and in other south-central portions
  of the state [65]



• 
  

  
  Pacific ponderosa pine/antelope bitterbrush-greenleaf manzanita
  on pumice soils in the south-central portion of the state [65]



• 
  

  
  Pacific ponderosa pine/antelope bitterbrush-greenleaf manzanita/yellow sedge (Carex
  pensylvanica) on pumice soils on the east slopes of the Cascade Range [65,214]



• 
  

  
  Greenleaf manzanita/snowbrush ceanothus in the eastern Siskiyou Mountains [65]



• 
  

  
  Pacific ponderosa pine/antelope bitterbrush-greenleaf manzanita/Idaho fescue in the Fremont
  and Deschutes National Forests from 3,100 to 6,000 feet (940-2,000 m) [95,214]



• 
  

  
  White fir-Pacific ponderosa pine/greenleaf manzanita-pinemat manzanita-Oregon-grape
  (A. nevadensis-Berberis repens) in the Fremont-Winema National Forest from 5,000 to 6,500 feet
  (1,500-2,000 m) [95]



• 
  

  
  Sierra lodgepole pine (Pinus contorta var. murrayana)/snowbrush
  ceanothus-greenleaf manzanita-pinemat manzanita in the Deschutes and Fremont-Winema
  National Forests from 4,800 to 6,000 feet (1,500-2,000 m)



• 
  

  
  Sierra lodgepole pine/pinemat manzanita-greenleaf
  manzanita in the Deschutes and Fremont-Winema National Forests from 5,800 to
  7,000 feet (1,800-2,000 m)



• 
  

  
  Pacific ponderosa pine/antelope bitterbrush-greenleaf
  manzanita/Columbia needlegrass (Achnatherum nelsonii) in the Deschutes and
  Fremont-Winema National Forests from 3,000 to 5,900 feet (900-1,800 m)



• 
  

  
  Pacific ponderosa pine-white fir-sugar pine (Pinus lambertiana)/snowbrush
  ceanothus-greenleaf manzanita in the Deschutes and Fremont-Winema National
  Forests from 4,100 to 5,900 feet (1,200-1,800 m)



• 
  

  
  Pacific ponderosa pine-Sierra lodgepole pine-white fir/greenleaf
  manzanita-snowbrush ceanothus/yellow sedge-glaucous beardtongue (Penstemon euglaucus) in the
  Deschutes National Forest from 4,300 to 5,600 feet (1,300-1,700 m)



• 
  

  
  California red fir (Abies magnifica)-white fir-western white pine (Pinus
  monticola)/pinemat manzanita-greenleaf manzanita in the Deschutes and
  Fremont-Winema National Forests from 5,450 to 7,000 feet (1,660-2,000 m) [214]

Utah:

• 
  

  
  Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca)/greenleaf
  manzanita in the central and southern mountains from 7,200 to 8,700 feet (2,200-2,700 m) [2,230]



• 
  

  
  White fir/greenleaf manzanita in the southern mountains from 8,100 to 8,500 feet (2,500-2,600 m) [2,230]



• 
  

  
  Interior ponderosa pine (Pinus ponderosa var. scopulorum)/Idaho
  fescue (greenleaf manzanita phase) in the south-central Uinta Mountains; this
  habitat type is associated with warm, dry sites [138]



• 
  

  
  Interior ponderosa pine/greenleaf manzanita in Garfield County and east to the LaSal and
  Abajo mountains [230]

Regions:

• 
  

  
  Interior ponderosa pine/greenleaf manzanita in the Rocky Mountain and Intermountain West
  regions of southern Utah and western Colorado [2]



• 
  

  
  Interior ponderosa pine/Idaho fescue greenleaf manzanita phase in the Rocky Mountain
  and Intermountain West regions of eastern Washington, Idaho, northern Utah, central and
  southeastern Montana, and north-central Wyoming from 2,500 to 6,000 feet
  (760-2,000 m), and south-central Colorado from 8,800 to 9,300 feet (2,700-2,800 m) [2]

More info for the term: shrub

Shrub

More info for the terms: forest, wildfire

Browsing:
Domestic sheep browsing reduces greenleaf manzanita
biomass. Over a 7-year period, 1,000 to 1,500 domestic sheep grazed a 2,000+
acre (800 ha) site containing large amounts of greenleaf manzanita and snowbrush ceanothus from
approximately 1 May until late August to late September. The site, on the Plumas
National Forest, California, sits at an elevation of 6,600 feet (2,000 m) and
had been burned by wildfire 2 to 3 years prior to stocking. After 7
years, volume of greenleaf manzanita on grazed sites was 1,302 ft³/acre
compared to 5,232 ft³/acre on ungrazed sites [144].

Herbicides:
Research papers are available on the effects of greenleaf manzanita herbicide treatments on
conifer species [40,41,45,75,121,140,143,147,148,221].

Host species:
Greenleaf manzanita is a host to the manzanita leaf-gall aphid, which produces
galls on the leaves and flower
buds [152]. On the Deschutes National Forest, greenleaf
manzanita is host to at least 12 fungal species, 3 of which are "important" plant pathogens [50].

Mechanical control: While the
work is arduous, greenleaf manzanita can be successfully controlled by grubbing.
In a young northern California Pacific ponderosa pine plantation, greenleaf
manzanita was significantly reduced (P<0.05) over a 10-year period
on grubbed sites [62]. Other mechanical control studies are available [145].

Greenleaf manzanita is used as an ornamental [19,193,200].

Greenleaf manzanita had many uses for Native Americans. The fruits were eaten whole, made into cider and jelly, and brewed into tea to treat poison-oak (Toxicodendron diversilobum) exposure [94,200]. The leaves were used as an emetic, for treating insect bites, and to relieve bronchitis, dropsy, and other diseases [94,200]. Dried leaves were also used in herbal smoking mixtures [59,200].

More info on this topic.

More info for the terms: forest, shrub

The flowering period of greenleaf manzanita in several states and regions is presented below.

Greenleaf manzanita flowering period State/region Flowering period Arizona May to June [113] California April to June [160] Nevada April to June [106,192] southern California May to June [159] Utah April to June [197] Great Basin May to June [157] Pacific Northwest May to June [92] Baja California March to June [227]

Flowering of greenleaf manzanita may be triggered by summer moisture stress [20]. The number of flowers produced is partially dependent upon the amount of the previous year's precipitation. Flower buds form 1 year prior to maturity. They are dormant the following summer, fall, and winter, and bloom the next spring [157].

Fruits ripen in late summer to early fall [205]. Generally, this species fruits over its entire range between July and October [20,217]. In Nevada, fruiting occurs from May to September [217]. The fruits may occasionally persist on the shrub year-round [209]. Most chaparral species experience the greatest amount of growth in May and June. Growth ceases in mid-July due to high air temperatures and low soil moisture [99].

The seasonal development of greenleaf manzanita was as follows in a Pacific ponderosa pine forest [51]:

Greenleaf manzanita phenological development in central Oregon Date

Developmental stage

6 May Few blossoms beginning to develop 27 May Blossoming near completion 5 July Blossoming complete and new fruits formed 22 September No visible sign of growth

More info for the terms: duff, lignotuber, scarification, seed, shrubs, stratification

Greenleaf manzanita establishes after fire by seed [11,31,84,112,135,137,161,179,198,199] and sometimes, sprouting from the lignotuber [15,24,31,89,97,137,157,198]. The dormancy of greenleaf manzanita seeds stored in soil and duff is partially broken by fire treatment [11,31,84,135,137,161,179,198,199]. Following scarification, greenleaf manzanita seeds require a period of cold stratification [18,109,112]. Greenleaf manzanita seedlings typically appear in large numbers during the spring of postfire year 1 [74,109,111,112,123,124,125].

Greenleaf manzanita with lignotubers sprout after fire unless the entire periphery of the lignotuber is deeply charred, which rarely happens [15,181]. Shrubs produce new sprouts from dormant buds on the lignotuber in as little as 10 days to 3 weeks [31,93,99,157]. Greenleaf manzanita plants with a lignotuber can withstand repeated burnings [31,52]. However, Martin [134] found that repeated burning of greenleaf manzanita plants with a lignotuber can cause plant mortality.

More info for the terms: adventitious, initial off-site colonizer, root crown, secondary colonizer, seed, shrub

POSTFIRE REGENERATION STRATEGY [194]:
Tall shrub, adventitious buds and/or a sprouting root crown
Initial off-site colonizer (off site, initial community)
Secondary colonizer (on-site or off-site seed sources)

More info for the terms: basal area, charate, density, forest, fruit, layering, lignotuber, scarification, seed, stratification, top-kill

Greenleaf manzanita regenerates from seeds [59,62,94,99,120,149,167,188], layering [24,90,94,98,106,113,140,141], and in the Sierra Nevada and southwestern Oregon, sprouting from the lignotuber [59,62,80,89,93,94,98,99,149,188].

Pollination: Greenleaf manzanita is insect pollinated [139].

Breeding system: The mating system of greenleaf manzanita is primarily outcrossing [139].

Seed production: Greenleaf manzanita produces large seed crops nearly every year [149]. In a mixed-conifer community of the Sierra Nevada, greenleaf manzanita populations produced a mean of 10,000 seeds/acre [188]. In general, greenleaf manzanita plants do not begin to flower and fruit until the age of 8 to 10 [175]. Where greenleaf manzanita populations sprout from a lignotuber, seed production is less than in nonsprouting populations [98,120].

Seed dispersal: Greenleaf manzanita seeds are dispersed by birds [139,175] and mammals including rodents, American black bears, and coyotes [112,117,139,175]. Seeds are dispersed from late summer [116] until the following spring [139,175]. The vast majority of Arctostaphylos spp. seeds are dispersed beneath the parent's canopy [117].

Seed banking: Greenleaf manzanita utilizes a seed bank [143,171,202]. The hard seeds of greenleaf manzanita can remain dormant in the soil for hundreds of years until stimulated to germinate [50,108].

Germination: Greenleaf manzanita seeds require scarification (by heat or disturbance such as logging activities) [67,99,109] followed by a period of cold stratification [18,109] for germination to occur. Seeds generally germinate on burned sites in the spring [117]. Seedling densities as high as 25,233/ha have been reported following fire in the northern Sierra Nevada [110].

Fire-induced germination: Seeds can be stimulated to germinate by heat and/or chamise (Adenostoma fasciculatum) charate, followed by stratification [116,117]. Keeley [116] investigated the effects light, darkness, temperature, and charate had on greenleaf manzanita seed germination. Germination trials were conducted on filter paper and in soil. Greenleaf manzanita seeds germinated significantly (P<0.001) better in the filter paper treatment, and the following results are from the seeds germinated on filter paper. Temperature treatments were an unheated control, 158 °F (70 °C) for 1 hour; 212 °F (100 °C) for 5 minutes; and 248 °F (120 °C) for 5 minutes. One set of seeds received a 0.50-g application of chamise charate prior to temperature treatments. Following charate and temperature treatments, the seeds were stratified for 1 month at 41 °F (5 °C) and then incubated in the light or dark treatment for 3 weeks at 73 °F (23 °C). Light had a significant (P<0.001) negative effect on greenleaf manzanita germination. Further, in the light treatment, seeds subjected to 248 °F for 5 minutes germinated significantly (P<0.05) better than either seeds exposed to 158 °F for 1 hour or the no-heat control seeds. In the dark treatment, seeds exposed to charate and either no heat or 212 °F for 5 minutes germinated significantly (P<0.05) better than seeds not exposed to charate and either no-heat or 212 °F treatments. Further, in the dark/charate treatments, greenleaf manzanita seed germination significantly (P<0.05) decreased in the 248 °F treatment [116].

Greenleaf manzanita germination with light, heat, and charate treatments

Germination (%)

Treatment Light Dark Control 158 °F
(1 hour) 212 °F
(5 min) 248 °F
(5 min) Control 158 °F
(1 hour) 212 °F
(5 min) 248 °F
(5 min) Control 1 3 4 6 6 12 10 7 Charate 1 3 1 4 17 19 18 10

Seedling establishment/growth: Greenleaf manzanita seedlings rarely occur on unburned or undisturbed sites [24]. James [99] states that "fire prepares a soil environment conducive to greenleaf manzanita seedling growth by increasing both the ash layer and soil pH, and destroying allelopathic soil chemicals". Seedling establishment generally occurs the first postfire year [117]. In a montane chaparral site in northern California, greenleaf manzanita seedlings establishing after fire reached a height of 3 feet (1 m) within 3 years [24].

In the first few years of development, greenleaf manzanita seedlings generally grow multiple stems. In May 1992, greenleaf manzanita seedlings ranging from 2 to 4 inches (5-10 cm) tall were planted at an elevation of 3,600 feet (1,100 m) on an unburned site in the Shasta-Trinity National Forest, California. Greenleaf manzanita seedlings were single stemmed at the time of planting and remained so throughout the first growing season. New sprouts appeared by the second growing season. At the end of the second growing season, 76% of seedlings had multiple stems, and that proportion remained constant throughout the 4-year study. At the end of the 1995 growing season, 89% of the seedlings had survived, yet none had produced flowers [149].

Mean growth of greenleaf manzanita seedlings at the end of the 1992-1995 growing seasons Growth characteristics 1992 1993 1994 1995 Height (cm) 12.4 31.1 47.1 63.2 Crown width (cm) 10.9 27.8 47.7 68.6

Vegetative regeneration: Greenleaf manzanita regenerates vegetatively by layering [24,90,94,98,106,113,140,141] and sprouting from the lignotuber [59,62,76,80,93,94,98,99,149,188,224,225].

Greenleaf manzanitas with lignotubers sprout following total or partial top-kill. In an early May clipping study in the Siskiyou Mountains in southwestern Oregon, greenleaf manzanita was either cut to ground level or had 50% of the plant removed. While plants cut to ground level did not show immediate growth, plants with growth only partially removed sprouted by 1 July. By posttreatment year 1, greenleaf manzanita density was substantially greater after clipping than before treatment on both sites [93].

Mean density and basal area of greenleaf manzanita plants subjected for total and partial top-kill

Treatments

Stems/ha Basal area (m²/ha) Total removal     pretreatment 40,895 4.01     immediate posttreatment 0 0     1 year after treatment 308,504 1.40 Partial removal     pretreatment 73,389 7.54     immediate posttreatment 56,092 4.65     1 year after treatment 208,098 4.72

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

BLM PHYSIOGRAPHIC REGIONS [21]:




1 Northern Pacific Border

2 Cascade Mountains

3 Southern Pacific Border

4 Sierra Mountains

5 Columbia Plateau

6 Upper Basin and Range

7 Lower Basin and Range

8 Northern Rocky Mountains

9 Middle Rocky Mountains

10 Wyoming Basin

11 Southern Rocky Mountains

12 Colorado Plateau

13 Rocky Mountain Piedmont

(key to state/province abbreviations)
United States AZ CA CO MT NV NM OR UT WA
Mexico B.C.N.

More info on this topic.

More info for the terms: cover, density, forest, fuel, interference, litter, shrub, shrubs, woodland

Greenleaf manzanita is shade intolerant [4,96,149], prefers disturbed sites [96], and typically is an early to midseral species [12,87,149,150,175,177]. Its ability to colonize quickly after disturbance and interfere with conifer seedling growth allows it to dominate for many decades after disturbance. Without further disturbance, conifers eventually overtop greenleaf manzanita. Greenleaf manzanita may still inhibit conifer growth after being overtopped until canopy closure shades it out [42,43,46,198]. In the absence of further disturbance, it may take from 30 to 100 years for conifers to gain dominance over shrubs [23,24,59,116,130,172,186,188,192].

Effect on conifers: Greenleaf manzanita inhibits the growth of Pacific ponderosa pine (Pinus ponderosa var. ponderosa) [10,34,129,142,186,202,219] and coast Douglas-fir (Pseudotsuga menziesii var. menziesii) [101,204] seedlings. Greenleaf manzanita's ability to severely deplete available soil moisture is the greatest contributing factor in greenleaf manzanita inhibition of Pacific ponderosa pine seedling growth [172,173]. The ability to extract water from moisture-depleted soil is likely attributable to a better-developed root system than that of conifer seedlings.

In plots with 0% greenleaf manzanita cover and 100% Pacific ponderosa pine seedling cover, Pacific ponderosa pine seedling production 2.5 years after establishment averaged 5 kg/300 m². In plots with 25% greenleaf manzanita and 75% Pacific ponderosa pine cover, seedling production was reduced to 2 kg/300 m², a 60% decrease. Anderson and Helms [4] found that greenleaf manzanita seedling mean root:shoot ratio and mean root:total root length were 30% and 35%, respectively: greater than ponderosa pine seedling ratios. Tinnin and Kirkpatrick [204] found that Douglas-fir seedling root growth was significantly (P<0.05 and P<0.001) less when growing in greenleaf manzanita leaf litter than in the absence of greenleaf manzanita leaf litter. In a review by Tappeiner and others [202], greenleaf manzanita was described as reducing pine (Pinus spp.) volume by 9% to 37%, reducing conifer height, crown volume, and biomass, and causing ponderosa pine moisture stress that decreased productivity.

In a review by Aune [10], increased shrub cover (greenleaf manzanita, snowbrush ceanothus, and Klamath plum (Prunus subcordata)) is shown to decrease Pacific ponderosa pine survival and growth rates.

Effects of shrub interference on survival, height, and diameter of Pacific ponderosa pine
at Mt Shasta, California, over an 18-year period Pacific ponderosa pine characteristics % shrub cover 0 21 35 44 Survival (%) 98 98 98 80 Height (feet) 16.5 12.0 9.3 5.8 Diameter (inches) 5.1 3.9 2.9 1.3

Greenleaf manzanita fields may cause substantial mortality of white fir and sugar pine seedlings. On the Teakettle Experimental Forest east of Fresno, California, fields of greenleaf manzanita were burned in October 1999, either lightly (no added fuel, some foliage burned) or with a "hot" fire (fuels added before burn, near complete foliage burned off and some stems charred). Burn and unburned control plots were planted with either white fir or sugar pine seedlings in October 2000. At the end of the second growing season (October 2002), total white fir survival rate across both treatments was 0.6%, which was significantly lower (P=0.02) than total survival of sugar pine (3.8%). Only early on (spring 2001) was there a significant difference (P=0.01) between treatments and survival rates. In spring 2001 white fir and sugar pine survival was lower on "hot" burn sites for both species than the light-fuel treatments [77].

Fire: Within its range, greenleaf manzanita is very prevalent as a pioneer species following fire [50,66,123,125,181,229]. Following crown fires in white fir and yellow pine forests of the Sierra Nevada, burn sites are "rapidly" occupied by montane chaparral shrub species including greenleaf manzanita [44,97,199].

In the pinyon-juniper (Pinus monophylla, P. edulis-Juniperus occidentalis) woodlands of the San Bernardino Mountains at elevations greater than 7,000 feet (2,000 m), greenleaf manzanita had 10.7% cover and a density of 1,416/ha on 70-year-old burn sites. Following fires in the pinyon-juniper woodlands, which were mostly severe canopy fires, shrub cover and density increased for 30 to 50 years. Based on observation from other sites and aerial photography, chronosequence sampling, and replication of the 1929 to 1935 California Vegetation Type Map, the researchers concluded that mature shrubs acted as nurse plants for singleleaf pinyon, which established beneath shrubs at approximately 25 to 40 years after fire. Around postfire year 50, shrubs began to decline, and by postfire years 100 to 150, a mature woodland returned [220].

Logging: Greenleaf manzanita thrives following logging in mixed-conifer forests [61,72,228]. Forty years following logging of mixed-conifer forests on the Blacks Mountain in northeastern California, greenleaf manzanita cover was significantly greater (P<0.05) on 30-year-old cut sites than uncut sites [215,216].

Arctostaphylos acutifolia Eastw. [105]

  =A. patula

Arctostaphylos parryana Lemmon var. pinetorum (Rollins) Wies. & Schreib.[105]

  =A. patula

Arctostaphylos patula Greene ssp. platyphylla (Gray) P.V. Wells [105,159,223,227]

  =A. patula

Arctostaphylos patula Greene var. coalescens W. Knight [105]

  =A. patula

The scientific name of greenleaf manzanita is Arctostaphylos patula
Greene (Ericaceae) [55,89,90,91,94,105,106,113,226,227]. Greenleaf manzanita likely
hybridizes with whiteleaf manzanita (A. viscida) [14,162]
and Mariposa manzanita (A. v. ssp. mariposa) [57] in the Sierra Nevada
of California.

More info for the term: shrub

Greenleaf manzanita is a valuable species for revegetating severely disturbed sites [36,37] and rated as a superior shrub for erosion control [190,191,192].

A greenleaf manzanita cultivar ('Altura') is available [206].

Arctostaphylos patula is a species of manzanita known by the common name greenleaf manzanita. This manzanita is native to western North America where it grows in coniferous forests at moderate to high elevations.