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SPECIES: Rhus trilobata

INTRODUCTORY


 

USDA-NRCS PLANTS Database

© 1995 Saint Mary's College of California

AUTHORSHIP AND CITATION:
Anderson, Michelle D. 2004. Rhus trilobata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: www.fs.usda.gov/database/feis/plants/shrub/rhutri/all.html [].

FEIS ABBREVIATION:
RHUTRI

SYNONYMS:
Rhus aromatica var. pilosissima [58]
   = Rhus trilobata var. pilosissima [76,115]
Rhus aromatica var. simplicifolia (Greene) Cronq. [153]
    = Rhus trilobata var. simplicifolia [76,155]
Rhus aromatica Aiton ssp. trilobata (Nuttall) Weber [152]
   = Rhus trilobata[76]
Rhus aromatica var. trilobata (Nutt.) Gray [58,153]
    = Rhus trilobata var. trilobata [76,115,155]

NRCS PLANT CODE [145]:
RHTR
RHTRA
RHTRP
RHTRQ
RHTRR
RHTRS
RHTRT

COMMON NAMES:
skunkbush sumac
fragrant sumac
three-leaf sumac

TAXONOMY:
The currently accepted scientific name of skunkbush sumac is Rhus trilobata Nutt. (Anacardiaceae) [47,48,69,71,76,77,115,155]. Infrataxa are as follows:

R. t. var. anisophylla (Greene) Jepson [76,155], skunkbush sumac
R. t. var. pilosissima Engelm. [76,115], pubescent skunkbush sumac
R. t. var. quinata (Greene) Jepson [76,155], Grand Canyon skunkbush sumac
R. t. var. racemulosa (Greene) Barkl. [76], skunkbush sumac
R. t. var. simplicifolia (Greene) Barkl. [76,155], skunkbush sumac
R. t. var. trilobata, skunkbush sumac

LIFE FORM:
Shrub

FEDERAL LEGAL STATUS:
None

OTHER STATUS:
None


DISTRIBUTION AND OCCURRENCE

SPECIES: Rhus trilobata
GENERAL DISTRIBUTION:
Skunkbush sumac occurs from Alberta and Saskatchewan south through the western states and Great Plains to Texas and Baja, California [47,48,58,69,71,76,77,99,105,115,152,153,155]. It also occurs rarely in Arkansas [76]. The following table presents distribution for skunkbush sumac infrataxa [76].

R. t. var. anisophylla Washington south to California, east to Utah and New Mexico
R. t. var. pilosissima California east to Texas, north to Colorado and Kansas
R. t. var. quinata Washington south to California, east to Nevada and New Mexico
R. t. var. racemulosa Arizona and New Mexico
R. t. var. simplicifolia Washington south to California, east to Colorado, New Mexico, and Oklahoma
R. t. var. trilobata entire range

ECOSYSTEMS [54]:
FRES15 Oak-hickory
FRES17 Elm-ash-cottonwood
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES28 Western hardwoods
FRES29 Sagebrush
FRES30 Desert shrub
FRES31 Shinnery
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands

STATES/PROVINCES: (key to state/province abbreviations)
UNITED STATES

AZ AR CA CO ID KS MT NE NV
NM ND OK OR SD TX UT WA WY

CANADA
AB SK

MEXICO
B.C.N.

BLM PHYSIOGRAPHIC REGIONS [19]:
3 Southern Pacific Border
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
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

KUCHLER [84] PLANT ASSOCIATIONS:
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine-Douglas-fir forest
K019 Arizona pine forest
K022 Great Basin pine forest
K023 Juniper-pinyon woodland
K024 Juniper steppe woodland
K026 Oregon oakwoods
K027 Mesquite bosques
K030 California oakwoods
K031 Oak-juniper woodland
K032 Transition between K031 and K037
K033 Chaparral
K034 Montane chaparral
K035 Coastal sagebrush
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
K039 Blackbrush
K045 Ceniza shrub
K050 Fescue-wheatgrass
K051 Wheatgrass-bluegrass
K053 Grama-galleta steppe
K054 Grama-tobosa prairie
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe
K057 Galleta-threeawn shrubsteppe
K058 Grama-tobosa shrubsteppe
K059 Trans-Pecos shrub savanna
K060 Mesquite savanna
K063 Foothills prairie
K064 Grama-needlegrass-wheatgrass
K065 Grama-buffalo grass
K066 Wheatgrass-needlegrass
K067 Wheatgrass-bluestem-needlegrass
K068 Wheatgrass-grama-buffalo grass
K069 Bluestem-grama prairie
K070 Sandsage-bluestem prairie
K071 Shinnery
K074 Bluestem prairie
K075 Nebraska Sandhills prairie
K076 Blackland prairie
K081 Oak savanna
K082 Mosaic of K074 and K100
K083 Cedar glades
K084 Cross Timbers
K085 Mesquite-buffalo grass
K087 Mesquite-oak savanna
K098 Northern floodplain forest
K100 Oak-hickory forest

SAF COVER TYPES [51]:
40 Post oak-blackjack oak
42 Bur oak
46 Eastern redcedar
63 Cottonwood
66 Ashe juniper-redberry (Pinchot) juniper
67 Mohrs (shin) oak
68 Mesquite
210 Interior Douglas-fir
219 Limber pine
220 Rocky Mountain juniper
233 Oregon white oak
235 Cottonwood-willow
236 Bur oak
237 Interior ponderosa pine
238 Western juniper
239 Pinyon-juniper
240 Arizona cypress
241 Western live oak
242 Mesquite
243 Sierra Nevada mixed conifer
246 California black oak
247 Jeffrey pine
249 Canyon live oak
250 Blue oak-foothills pine
255 California coast live oak

SRM (RANGELAND) COVER TYPES [129]:
101 Bluebunch wheatgrass
102 Idaho fescue
104 Antelope bitterbrush-bluebunch wheatgrass
105 Antelope bitterbrush-Idaho fescue
107 Western juniper/big sagebrush/bluebunch wheatgrass
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
201 Blue oak woodland
202 Coast live oak woodland
203 Riparian woodland
205 Coastal sage shrub
207 Scrub oak mixed chaparral
209 Montane shrubland
210 Bitterbrush
212 Blackbush
301 Bluebunch wheatgrass-blue grama
302 Bluebunch wheatgrass-Sandberg bluegrass
303 Bluebunch wheatgrass-western wheatgrass
304 Idaho fescue-bluebunch wheatgrass
309 Idaho fescue-western wheatgrass
310 Needle-and-thread-blue grama
311 Rough fescue-bluebunch wheatgrass
312 Rough fescue-Idaho fescue
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
316 Big sagebrush-rough fescue
317 Bitterbrush-bluebunch wheatgrass
318 Bitterbrush-Idaho fescue
319 Bitterbrush-rough fescue
320 Black sagebrush-bluebunch wheatgrass
321 Black sagebrush-Idaho fescue
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
323 Shrubby cinquefoil-rough fescue
324 Threetip sagebrush-Idaho fescue
401 Basin big sagebrush
402 Mountain big sagebrush
403 Wyoming big sagebrush
404 Threetip sagebrush
405 Black sagebrush
406 Low sagebrush
407 Stiff sagebrush
408 Other sagebrush types
412 Juniper-pinyon woodland
413 Gambel oak
415 Curlleaf mountain-mahogany
416 True mountain-mahogany
417 Littleleaf mountain-mahogany
418 Bigtooth maple
419 Bittercherry
420 Snowbrush
421 Chokecherry-serviceberry-rose
422 Riparian
502 Grama-galleta
503 Arizona chaparral
504 Juniper-pinyon pine woodland
505 Grama-tobosa shrub
509 Transition between oak-juniper woodland and mahogany-oak association
601 Bluestem prairie
602 Bluestem-prairie sandreed
603 Prairie sandreed-needlegrass
604 Bluestem-grama prairie
605 Sandsage prairie
606 Wheatgrass-bluestem-needlegrass
607 Wheatgrass-needlegrass
608 Wheatgrass-grama-needlegrass
609 Wheatgrass-grama
610 Wheatgrass
611 Blue grama-buffalo grass
612 Sagebrush-grass
613 Fescue grassland
614 Crested wheatgrass
615 Wheatgrass-saltgrass-grama
701 Alkali sacaton-tobosagrass
702 Black grama-alkali sacaton
703 Black grama-sideoats grama
704 Blue grama-western wheatgrass
705 Blue grama-galleta
706 Blue grama-sideoats grama
707 Blue grama-sideoats grama-black grama
708 Bluestem-dropseed
709 Bluestem-grama
710 Bluestem prairie
712 Galleta-alkali sacaton
713 Grama-muhly-threeawn
714 Grama-bluestem
715 Grama-buffalo grass
716 Grama-feathergrass
717 Little bluestem-Indiangrass-Texas wintergrass
718 Mesquite-grama
719 Mesquite-liveoak-seacoast bluestem
720 Sand bluestem-little bluestem (dunes)
721 Sand bluestem-little bluestem (plains)
722 Sand sagebrush-mixed prairie
724 Sideoats grama-New Mexico feathergrass-winterfat
725 Vine mesquite-alkali sacaton
727 Mesquite-buffalo grass
728 Mesquite-granjeno-acacia
729 Mesquite
730 Sand shinnery oak
731 Cross timbers-Oklahoma
732 Cross timbers-Texas (little bluestem-post oak)
733 Juniper-oak
734 Mesquite-oak
735 Sideoats grama-sumac-juniper

HABITAT TYPES AND PLANT COMMUNITIES:
Skunkbush sumac may grow in pure stands [131,137,144], but is often found in association with other plant communities. Common associates are listed below by community type.

Grassland: Common associates in mixed-prairie communities are thickspike wheatgrass (Elymus lanceolatus), needle-and-thread grass (Hesperostipa comata), prairie Junegrass (Koeleria macrantha), western wheatgrass (Pascopyrum smithii), plains reedgrass (Calamagrostis montanensis), Sandberg bluegrass (Poa secunda), sedges (Carex spp.), green needlegrass (Nassella viridula), Indian ricegrass (Achnatherum hymenoides), hairy grama (Bouteloua hirsuta), blue grama (B. gracilis), little bluestem (Schizachyrium scoparium), dropseeds (Sporobolus spp.), big bluestem (Andropogon gerardii var. gerardii), and switchgrass (Panicum virgatum) [1,26]. Woody plant associates include cherry (Prunus spp.), smooth sumac (Rhus glabra), lead plant (Amorpha canescens), golden currant (Ribes aureum), snowberry (Symphoricarpos spp.), American elm (Ulmus americana), and hackberry (Celtis occidentalis) [1].

Shrubland: Skunkbush sumac is frequently found with sagebrushes (Artemisia spp.) and rabbitbrushes (Chrysothamnus spp.) [150]. In mountain shrub communities, skunkbush sumac is associated with Gambel oak (Quercus gambelii), chokecherry (P. virginiana), true mountain-mahogany (Cercocarpus montanus), bluegrass (Poa spp.), needlegrass (Nassella spp.), Indian ricegrass, and broom snakeweed (Gutierrezia sarothrae) [72]. In Colorado steppe communities, common associates include sleepygrass (Achnatherum robustum), western wheatgrass, blue grama, buffalo grass (Buchloe dactyloides), fourwing saltbush (Atriplex canescens), and rubber rabbitbrush (Chrysothamnus nauseous) [101].

Skunkbush sumac is a common constituent of Arizona chaparral communities. Associates include shrub live oak (Q. turbinella), Emory oak (Q. emoryi), Palmer oak (Q. dunnii), true and birchleaf mountain-mahogany (Cercocarpus montanus var. glaber, C. betuloides), pointleaf and Pringle manzanita (Arctostaphylos pungens, A. pringlei), desert ceanothus (Ceanothus greggii), catclaw acacia (Acacia greggii), catclaw mimosa (Mimosa biurcifera), Bigelow's nolina (Nolina bigelovii), sugar sumac (Rhus ovata), jojoba (Simmondsia chinensis), redberry buckthorn (Rhamnus crocea), California coffeeberry (R. californica), and Wright and chaparral silktassel (Garrya wrightii, G. congdonii) [25,33,34,68,98,137,150]. Chaparral associates in Baja California include Parry pinyon (Pinus quadrifolia), singleleaf pinyon (P. monophylla), Muller oak (Q. cornelius-mulleri), redberry buckthorn, sugar sumac, flannelbush (Fremontodendron californicum), and desert agave (Agave deserti) [99].

Forest: Associates in Rocky Mountain forest communities include ponderosa pine (P. ponderosa), limber pine (P. flexilis), Douglas-fir (Pseudotsuga menziesii), Rocky Mountain juniper (Juniperus scopulorum), rubber rabbitbrush, prairie rose (Rosa arkansana), common snowberry (Symphoricarpos albus), true mountain-mahogany, chokecherry, wax currant (Ribes cereum), big sagebrush (Artemisia tridentata), silver sagebrush (A. cana), and antelope bitterbrush (Purshia tridentata) [94,121].

In pinyon-juniper (Pinus spp.-Juniperus spp.) communities, skunkbush sumac is commonly found with Colorado pinyon (P. edulis), oneseed juniper (J. monosperma), Bigelow sagebrush (A. bigelovii), true mountain-mahogany, groundcherry (Physalis spp.), agarito (Mahonia trifoliolata), wolfberry (Lycium spp.), galleta grass (Pleuraphis jamesii), blue grama, and creeping muhly (Muhlenbergia repens) [4,43]. Associates in Rocky Mountain juniper communities are chokecherry, silver buffaloberry (Shepherdia argentea), silver sagebrush, and shrubby cinquefoil (Dasiphora floribunda) [123].

Classifications listing skunkbush sumac as a plant community dominant include the following:

Alberta [88]
Arizona [15,136]
California [93]
Colorado [11,82]
Montana [29,120]
Nevada [93]
New Mexico [45,136]
South Dakota [39,132]
Wyoming [142]

Plant community codominants include Arizona white oak (Q. arizonica), Colorado pinyon, oneseed juniper, New Mexico muhly (M.  pauciflora) in the Southwest [15,45,136];  narrowleaf cottonwood (Populus angustifolia) in Nevada and southern California [93]; Rio Grande cottonwood (P. deltoides ssp. wislizeni) [11] and mountain muhly (M. montana) in Colorado [82]; bluebunch wheatgrass (Pseudoroegneria spicata) in Montana [29] and Wyoming [142]; and true mountain-mahogany [132], bur oak (Q. macrocarpa), bluebunch wheatgrass, and Idaho fescue (Festuca idahoensis) [39] in the Black Hills of South Dakota.


BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Rhus trilobata
GENERAL BOTANICAL CHARACTERISTICS:
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g. [58,69,71]).

Skunkbush sumac is a deciduous, flowering native shrub [22,34,74,75,76,86,131]. It grows 2 to 12 feet (0.6-3.6 m) tall, averaging 4 feet (1.2 m) tall [34,40,56,105,107,115,144,150]. Taller shrubs are found on more favorable habitats [22,56]. Growth form is erect to spreading with a dense crown [40,74,107,135]. Shrub width may reach 6.5 feet (2 m) [105]. Skunkbush sumac has many irregularly branched stems, and leaves are formed by 3 leaflets [22]. The fruit of skunkbush sumac is a 1-seeded drupe [107].

Skunkbush sumac has a taproot [135] and a fibrous root system [74,75]. Roots are deep and extensively branched with somewhat shallow, spreading woody rhizomes [150]. Individual shrubs and patches of skunkbush sumac may be connected by underground structures that can exceed 20 feet (6 m) in length and 30 years in age [123]. It sprouts readily from the root crown [74,107].

RAUNKIAER [118] LIFE FORM:
Phanerophyte

REGENERATION PROCESSES:
Skunkbush sumac propagates by seed and root sprouts [75]. It sprouts readily from the root crown after severe disturbance [74,107] but is unlikely to reproduce vegetatively in the absence of disturbance [107]. Skunkbush sumac reproduces only rarely from seed [74,94].

Breeding system: Skunkbush sumac has been reported as dioecious [94] and as polygamomonoecious [110].

Pollination: Skunkbush sumac is animal-pollinated [110], presumably by small mammals.

Seed production: Skunkbush sumac reportedly has low seed production [94]. It was estimated that only 5 to 15% of skunkbush sumac flowers in a North Dakota shrub community actually produced fruit. Branches from 6 to 10 years of age produced the most viable fruit [123].

Seed dispersal: Seeds are eaten and dispersed by birds and animals [107,110,134].

Seed banking: No information is available on this topic.

Germination: Skunkbush sumac seeds have both seed coat impermeability and embryo dormancy [18,89,131,151]. They germinate poorly without scarification which is necessary to crack or soften the hard seed coat. Little evidence exists that skunkbush sumac seeds are physiologically dormant. Breaking embryo dormancy may require a cold stratification [18,107,151]. High temperatures (>180 oF (82oC)) associated with fire have been shown to break seed dormancy in greenhouse experiments [31]. Some laboratory experiments have demonstrated that neither temperature or light stratification affects germination rates [89]. However, Keeley [79] found that germination of skunkbush sumac was significantly decreased (p<0.001) by the absence of light.

A study of skunkbush sumac seeds found seeds ingested by bears and deposited in scat had much higher germination rates than noningested seeds. Furthermore, chilling the seeds resulted in even lower germination rates. Prewarming of seeds, on the other hand, significantly increased germination of seeds (p<0.05) [9].

Skunkbush seeds remain viable in cool storage (37-41 oF/3-5 oC) for 5 years [18].

Seedling establishment/growth: Seedling establishment may be rare in established skunkbush sumac stands [74,107,123]. Seedlings are very susceptible to damping-off fungus [131].

Asexual regeneration: The primary means of short-range skunkbush sumac dispersal is vegetative [40,123,150]; shrubs in North Dakota up to 20 feet (6 m) apart were found to be connected [123]. Skunkbush sumac may form thickets as large as 30 feet (9 m) in diameter [123,131,143,150]. Undisturbed plants produce few sprouts, while those subject to browsing, trampling or burning produce many sprouts [40,94,150].

SITE CHARACTERISTICS:
Skunkbush sumac grows on dry, rocky hillsides and sandhills, as well as along streams, canyon bottoms, and wetlands [40,56,75,76,91,105,131,135,137,144,150,153]. It is found in grassy flats and openings in woodland areas [63,74,75,76,94].

Elevation: Skunkbush sumac grows principally from 3,500-9,000 feet (1,065-2,740 m), though it also occurs at lower elevations [75,144]. The following table gives the elevation range of skunkbush sumac by state:

Arizona 2,500-7,500 feet (760-2,285 m) [34,77,137]
California 500-6,000 feet (152-1,830 m) [40,74]
Montana <6,000 feet (1,830 m) [94]
Southern New Mexico and southern Texas 4,220-6,000 feet (1,286-1,830 m) [55]
Utah 2,900-7,700 feet (885-2,350 m) [110,153]

The relationship between skunkbush sumac and slope aspect is ambiguous. It is reportedly more prevalent on north slopes in the mixed-prairie, where it is protected from prevailing winds and receives more water from wind-drifted snow [1]. It is also more abundant on north-facing slopes in pinyon-juniper communities in the Southwest [113]. In Alberta coulees, however, skunkbush sumac is largely restricted to south-facing slopes [42]. In Montana, it is also found more often on south slopes, with slope gradients between 40 and 80% [94]. In another study, skunkbush sumac in the North Dakota badlands had higher relative densities on steep southwest slopes; however, it was denser and larger on northeast slopes [123].

Climate: Skunkbush sumac is adapted to a wide range of climates, particularly the 10 to 20 inches (254-508 mm) annual precipitation zones [144,150]. In Montana, sites supporting skunkbush sumac have an average January temperature of 20 oF (-6.7 oC) and average July temperature of 64 oF (18 oC). Average annual precipitation is 14 inches (355 mm) per year, with 50% falling from May through July. The growing season varies from 50 to 130 days, with moderate to high density stands found on sites having 120 or more frost-free days [94]. The climate in North Dakota has January temperatures averaging 11 oF (-11 oC) and July temperatures averaging 69 oF (20 oC). Average annual precipitation is 15.6 inches (396 mm), with 80% falling between April and September [123].

In contrast, the Arizona chaparral climate has cool, wet winters extending into March, followed by warm, dry weather for 2 or 3 months. Following summer rains, dry weather returns in October and persists until winter rains in December. Average annual precipitation ranges from 16 to 25 inches (406-635 mm), generally increasing with elevation. Average monthly temperatures range from less than 40 oF (4 oC) in January to more than 80 oF (26 oC) in July [68].

Skunkbush sumac is moderately drought tolerant [60,131,143,150], though seedlings may be severely affected by drought conditions [37]. Acute drought may shorten twig growth and prevent fruit production [150].

Soils: Skunkbush sumac may grow to 2 to 3 feet (0.6-0.9 m) on dry sites, and 10 to 12 feet (3-3.6 m) with more favorable moisture availability [56]. Skunkbush sumac is tolerant of most soil textures but prefers well-drained sites [94,120,131,139,150,150]; it may be found in higher density at mid-slope positions than at the bottom of slopes [123]. Skunkbush sumac prefers deep soil [74,94] or thin soils with a gravel base. Extensive stands have been reported on steep slopes where topsoils were thin or absent [94]. Soil pH is often mildly alkaline [94,116]; in Montana, large stands were found on soil pH of 7.4 [94]. Soils may be high in potassium and low in organic matter, phosphorus, and salt [94]. Skunkbush sumac is intolerant of flooding and high water tables [150].

SUCCESSIONAL STATUS:
Skunkbush sumac is commonly found on disturbed sites [18,24]. It prefers full sun or partial shade [131].

SEASONAL DEVELOPMENT:
Annual growth of skunkbush sumac occurs primarily in spring and early summer [86,94,137,150]. In a North Dakota study, growth of new twigs was complete by July 9 [123]. Skunkbush sumac flowers in early spring, 1 to 3 weeks before leaves appear [40,75,94,105,115,135,150]. Fruit matures July through October [18,22], and persists into winter [75]. Seeds are dispersed from August through the following summer [134]. Leaf drop occurs in October [94].


FIRE ECOLOGY

SPECIES: Rhus trilobata
FIRE ECOLOGY OR ADAPTATIONS:
Fire adaptations: Skunkbush sumac sprouts vigorously from the root crown following fire [12,33,34,150]. The high temperatures (>180 oF (82 oC)) associated with fire have been shown to break seed dormancy in greenhouse experiments [31].

Fire regimes: No information is available regarding fire regimes in plant communities where skunkbush sumac is dominant, and little is known about its response to different fire regimes. Frequent or severe fires will restrict skunkbush sumac to protected sites or to areas of light fuel loadings, even though vigorous sprouting occurs after fire. The absence of fire allows seedling establishment on favorable microsites, and may result in an increase of skunkbush sumac on a site [107].

Skunkbush sumac grows in a wide variety of plant communities, where fire return intervals range from less than 10 years up to hundreds of years. Fire return intervals for plant communities and ecosystems in which skunkbush sumac occurs are summarized below. Find further 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".

Community or Ecosystem Dominant Species Fire Return Interval Range (years)
California chaparral Adenostoma and/or Arctostaphylos spp. < 35 to < 100 [109]
bluestem prairie Andropogon gerardii var. gerardii-Schizachyrium scoparium < 10 [83,109]
Nebraska sandhills prairie Andropogon gerardii var. paucipilus-Schizachyrium scoparium < 10
coastal sagebrush Artemisia californica < 35 to < 100 [109]
silver sagebrush steppe Artemisia cana 5-45 [67,117,156]
sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [109]
basin big sagebrush Artemisia tridentata var. tridentata 12-43 [124]
mountain big sagebrush Artemisia tridentata var. vaseyana 15-40 [6,32,97]
Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (40**) [147,157]
desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100 [109]
plains grasslands Bouteloua spp. < 35 [109,156]
blue grama-needle-and-thread grass-western wheatgrass Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii < 35 [109,122,156]
blue grama-buffalo grass Bouteloua gracilis-Buchloe dactyloides < 35 [109,156]
grama-galleta steppe Bouteloua gracilis-Pleuraphis jamesii < 35 to < 100
blue grama-tobosa prairie Bouteloua gracilis-Pleuraphis mutica < 35 to < 100 [109]
cheatgrass Bromus tectorum < 10 [111,154]
California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [109]
curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1,000 [8,127]
mountain-mahogany-Gambel oak scrub Cercocarpus ledifolius-Quercus gambelii < 35 to < 100
blackbrush Coleogyne ramosissima < 35 to < 100
western juniper Juniperus occidentalis 20-70
Rocky Mountain juniper Juniperus scopulorum < 35 [109]
cedar glades Juniperus virginiana 3-22 [61,109]
wheatgrass plains grasslands Pascopyrum smithii < 5-47+ [109,117,156]
pinyon-juniper Pinus-Juniperus spp. < 35 [109]
Mexican pinyon Pinus cembroides 20-70 [102,140]
Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [13,14,141]
Colorado pinyon Pinus edulis 10-400+ [53,57,78,109]
Jeffrey pine Pinus jeffreyi 5-30 [5]
interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [5,10,87]
Arizona pine Pinus ponderosa var. arizonica 2-15 [10,41,128]
galleta-threeawn shrubsteppe Pleuraphis jamesii-Aristida purpurea < 35 to < 100 [109]
mesquite Prosopis glandulosa < 35 to < 100 [96,109]
mesquite-buffalo grass Prosopis glandulosa-Buchloe dactyloides < 35
Texas savanna Prosopis glandulosa var. glandulosa < 10 [109]
Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [5,6,7]
California oakwoods Quercus spp. < 35 [5]
oak-juniper woodland (Southwest) Quercus-Juniperus spp. < 35 to < 200 [109]
canyon live oak Quercus chrysolepis <35 to 200
blue oak-foothills pine Quercus douglasii-P. sabiniana <35 [5]
California black oak Quercus kelloggii 5-30 [109]
bur oak Quercus macrocarpa < 10 [149]
oak savanna Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium 2-14 [109,149]
shinnery Quercus mohriana < 35 [109]
post oak-blackjack oak Quercus stellata-Q. marilandica < 10
blackland prairie Schizachyrium scoparium-Nassella leucotricha < 10 [149]
little bluestem-grama prairie Schizachyrium scoparium-Bouteloua spp. < 35 [109]
*fire return interval varies widely; trends in variation are noted in the species review
**mean

POSTFIRE REGENERATION STRATEGY [133]:
Small shrub, adventitious bud/root crown
Ground residual colonizer (on-site, initial community)
Secondary colonizer (on-site or off-site seed sources)

FIRE EFFECTS

SPECIES: Rhus trilobata
IMMEDIATE FIRE EFFECT ON PLANT:
Skunkbush sumac is top-killed by fire [108].

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:
No additional information is available on this topic.

PLANT RESPONSE TO FIRE:
Skunkbush sumac sprouts vigorously from the root crown following fire [12,33,34,40,74,80,108,137,148].

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
A study in the Chihuahuan Desert region found postfire sprouts of 3 to 4 inches (7.6-10 cm) within 2 months postfire, up to 2 feet (0.6 m) in 1 year and up to 3 feet (0.9 m) in 3 years [80]. Another study found sprouts up to 40 inches (101.6 cm) in 1 season [137] after fire, and a desert field study in California found sprouts up to 3.2 feet (1 m) tall 1 year after fire [12]. A prescribed burn study in Arizona, however, found that skunkbush sumac did not sprout prolifically until the 2nd growing season after fire[114].

Skunkbush sumac typically increases after fire, though average plant size is reduced in the short-term. The following table describes the impact of a 1979 prescribed fire on skunkbush sumac in a Black Hills ponderosa pine forest [21]:

  1979 - preburn 1980 1981
  Control Burn Control Burn Control Burn
Total # of plants 48 19 57 23 65 23
Mean max. height 28.2 cm 39.9 cm 28.6 cm 17.9 cm 30.6 cm 25.4 cm
Mean max. crown width 31.0 cm 33.2 cm 31.5 cm 17.7 cm 30.6 cm 25.4 cm

Response of vegetation to prescribed burning in a Jeffrey pine-California black oak woodland and a deergrass meadow at Cuyamaca State Park, California, provides information on prescribed fire use and postfire response of many mixed-conifer woodland species including skunkbush sumac.

FIRE MANAGEMENT CONSIDERATIONS:
No additional information is available on this topic.

MANAGEMENT CONSIDERATIONS

SPECIES: Rhus trilobata
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Skunkbush sumac is browsed by big game [17], including elk [104], bighorn sheep [126] pronghorn [27,38], mule deer [20,30,81,85,92,94,100,126], and white-tailed deer [2,70,95,126]. It is occasionally browsed by cattle and domestic sheep [135,144] and goats [59].

Skunkbush sumac is also browsed by small mammals. Porcupines utilize it [66], and it is also browsed, sometimes heavily, by jackrabbits and cottontail [28,44], particularly after heavy snow when branches extend above drifts [119].

Skunkbush sumac fruit is an important winter food source for birds, including songbirds, prairie chickens, Merriam turkeys, ring-necked pheasants, sage-grouse, ruffed grouse, sharp-tailed grouse, and bobwhite, valley, Gambel, and scaled quail [107,135,138,139]. Fruit is also eaten by black bears [65], and occasionally, white-tailed deer [95].

Palatability/nutritional value: Skunkbush sumac has poor palatability for domestic livestock throughout most of its range [46,135], but may be fair to good for cattle and domestic sheep in the Southwest and Colorado [144]. It is highly palatable for domestic goats in the Southwest [144]. Skunkbush sumac provides good browse for deer and pronghorn [135].

The National Academy of Sciences reports the following nutritional information for skunkbush sumac (% dry matter) [106]:

Crude fiber 13.7 Protein 8.0
Ether extract 4.4 Digestible protein:  
N-free extract 68.4 cattle 4.7
Calcium 1.93 goats 4.0
Magnesium 0.28 horses 4.3
Phosphorus 0.11 rabbits 4.8
Potassium 1.69 sheep 4.4

A study in the southern Great Plains found the following monthly nutrient content for skunkbush sumac (5-year means, % dry weight) [125]:

  Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.
Calcium 0.925 1.343 --- 0.927 0.757 0.682 1.015 0.958 1.272 1.247 1.138 1.280
Phosphorus 0.151 0.117 --- 0.407 0.291 0.185 0.139 0.150 0.115 0.137 0.116 0.144
Protein 6.98 5.43 5.64 16.84 13.89 10.71 8.86 6.93 7.26 6.16 7.19 5.97
Fat 4.03 3.72 3.48 2.43 3.96 4.18 7.03 5.16 10.39 5.46 4.07 3.66
N-free extract 61.92 58.71 50.21 49.81 55.60 65.98 63.07 64.41 60.68 60.36 51.92 46.49
Crude fiber 21.24 28.91 29.61 21.79 16.27 14.08 16.43 18.57 18.73 21.52 41.86 27.14

Monthly variation in crude protein content of skunkbush sumac from California samples was reported as follows (% oven dry weight) [20]:

Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.
--- --- --- 19.4 --- 14.9 10.7 10.5 11.1 6.1 8.5 ---

Cover value: Skunkbush sumac provides useful cover and nesting sites for birds [75,139]. It provides poor to fair cover for elk; fair to good cover for white-tailed deer, mule deer, and pronghorn; good cover for upland game birds, nongame birds, and small mammals; and poor cover for waterfowl [46].

VALUE FOR REHABILITATION OF DISTURBED SITES:
Skunkbush sumac is useful for landscape planting [60,73], wind barriers [75,139], and reclamation of disturbed areas [75]. It is excellent for erosion control [74,143] and survives on untreated mine spoils [50]. Skunkbush sumac is commercially available (e.g. cultivar "Autumn Amber") [73,146] and grows well from seed (especially when planted in fall and winter) or transplants [143]. Skunkbush sumac has an average of 20,300 seeds per pound (44,750 seeds/kg) [107]. For best survival, plant 2-0 container stock [103] in deep soil and full sun [74]. Excellent transplant success has been reported (100% on 3 out of 4 sites) [23]; however, a study in the Tahoe Basin found poor transplant establishment and survival [130].

In laboratory experiments, optimum germination was achieved with both sulfuric acid treatment and moist prechilling [64]. Acid scarification is useful in encouraging seed germination due to the impermeable seedcoat [90,151]. Other experiments found that germination of skunkbush sumac was significantly decreased (p<0.001) by the absence of light, while the addition of powdered, charred wood significantly increased (p<0.01) germination rates [79].

OTHER USES:
Southwestern Native Americans ate the fruits of skunkbush sumac, either fresh or after being ground to form meal [16,35]. The berries have a distinct lemon flavor and could be mixed with various foods for seasoning [35] or dried and made into jam [36,49]. Berries were also mixed with water to make a beverage [16]. Leaves of skunkbush sumac were dried and mixed with tobacco for smoking [62]. The leaves were also used for medicinal purposes (stomachache, diuretic, toothache pain, bleeding, head colds, poison ivy rashes) [16,62,112].

Native Americans burned skunkbush sumac to stimulate production of long, straight sprouts which could be used for making baskets and handcrafted items [3,16,22,49,143].

OTHER MANAGEMENT CONSIDERATIONS:
Reports regarding skunkbush sumac response to grazing are conflicting, with some authors reporting increased growth due to sprouting [94,135,150] and others reporting decreased growth [86,158].


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