SPECIES: Descurainia pinnata
Choose from the following categories of information.
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| photo by Michael L. Charters |
Infrataxa designations are somewhat arbitrary [27,175]. There are intergradation and introgression among the subspecies; consequently, the subspecies are often difficult to distinguish [27,75].
LIFE FORM:| Location | Rank |
| Georgia | SR: Reported from the state, but without persuasive documentation [48] |
| Missouri (D. p. var. pinnata) | SH: Historical. Has not been relocated within the last 20 years, but may be rediscovered [117] |
| New Hampshire | SX: Extirpated from the state [126] |
| New York (D. p. var. brachycarpa) | S1: Critically imperiled because of extreme rarity (< 5 sites or very few remaining individuals) or extremely vulnerable to extirpation due to biological factors [195] |
| Vermont | S1: Very rare; generally 1-5 occurrences, believed to be extant, and/or some factor(s) making it especially vulnerable to extirpation from the state [169] |
| West Virginia | SH: Historical. Has not been relocated within the last 20 years, but may be rediscovered [176] |
| Wyoming (D. p. var. paysonii) | S2: Imperiled because of rarity (often known from 6-20 occurrences) or because of factors demonstrably making it vulnerable to extinction [167] |
| Devil's Tower National Monument, Wyoming | S3: Sparse (widely distributed but restricted to small, patchy habitats) [39] |
The following biogeographic classifications demonstrate
pinnate tansymustard could
potentially be found. These lists are speculative and may not be
accurately restrictive or complete.
ECOSYSTEMS [47]:
FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES12 Longleaf-slash pine
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES16 Oak-gum-cypress
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES21 Ponderosa pine
FRES23 Fir-spruce
FRES28 Western hardwoods
FRES29 Sagebrush
FRES30 Desert shrub
FRES31 Shinnery
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES41 Wet grasslands
FRES42 Annual grasslands
STATES/PROVINCES: (key to state/province abbreviations)
UNITED STATES
| AZ | AR | CA | CO | CT | DE | FL | GA | ID |
| IL | IN | IA | KS | KY | LA | ME | MD | MA |
| MI | MN | MS | MO | MT | NE | NV | NJ | NM |
| NY | NC | ND | OH | OK | OR | PA | RI | SC |
| SD | TN | TX | UT | VT | VA | WA | WI | WY |
| DC |
| AB | BC | MB | NT | NU | ON | PQ | SK | YK |
| B.C.N. | Chih. | Sin. | Son. |
Pinnate tansymustard also occurs in mesquite (Prosopis spp.), salt-desert shrubland, blackbrush/Indian ricegrass (Coleogyne ramosissima/Achnatherum hymenoides), and desert grassland communities [24,63]. In velvet mesquite (P. velutina) woodland of southeastern Arizona, pinnate tansymustard occurs with Wright's buckwheat (Eriogonum wrightii) and plains lovegrass (Eragrostis intermedia) [15]. Associates on the Desert Tortoise Research Natural Area in the Mojave Desert of southern California include creosotebush (Larrea tridentata), white bursage (Ambrosia dumosa), and other annuals, the most common being cutleaf filaree (Erodium cicutarium), red brome (Bromus madritensis ssp. rubens), and Mediterranean grass (Schismus spp.) [20,21].
Pinnate tansymustard is not as important in plains grasslands and communities further east as it is in desert shrublands [79]. It is usually listed as a "waste place" or disturbance-indicator weed in the Great Plains and ecosystems to the east (e.g., [27,49,56,108,119,172]).
Pinnate tansymustard is a native winter annual. Mature plants are 2.3 to 3.3 feet (0.7-1 m) in height. Stems are coarse, glandular, and sparsely to densely pubescent, depending on the subspecies. They are 1 to several at the base, branching towards the top. Leaves are basal or cauline. Basal leaves are bipinnate and may be as long as 4 inches (10 cm), becoming pinnate and smaller up the stem. The inflorescence is a glandular raceme of perfect flowers that spreads out 45o to 90o from the stem. The fruit is a dehiscent, 2-capsuled silique 4-20 mm in length, bearing 1 to 20 small seeds per capsule. Seeds are 0.5 to 1 mm long; their average mass is 0.12 mg [40,49,56,75,91,141,162,175]. Tansymustards (Descurainia spp.) have a short taproot [125,186].
Stand structure: Plant communities where tansymustard is important have an open structure, with sparse to no overstory. For example, structure of a Colorado pinyon-Utah juniper burn in northeastern Utah consisted of the skeletons of burned conifers and a ground cover of pinnate tansymustard and other annual forbs [51]. Excepting communities dominated by cheatgrass (e.g., [83,159,190]), descriptions of open-canopy stands dominated by annuals are sparse in the literature. Further studies of stand structure (including year-to-year fluctuations due to climate changes) in such communities would increase understanding of fuel loading, fire behavior, and current fire regimes in communities with a large component of pinnate tansymustard and other annuals.
RAUNKIAER [142] LIFE FORM:Breeding system: Mustards (Brassicaceae) are cross-pollinated. Selfing also occurs [74].
Pollination is insect-mediated. The sepals contain nectaries that attract insect pollinators [74].
Seed production: No information
Seed dispersal: Neither fruits nor seeds have specialized appendages for dispersal [92,95], and most pinnate tansymustard seed falls near the parent plant [147]. Wind, water, machinery, and animals transport seed long distances [115,147]. Animals disperse tansymustard seeds when the sticky seedcoat adheres to feathers or fur [192].
Seed banking: Pinnate tansymustard has soil-stored seed [24,26,66,76]. Soil samples from a needle-and-thread grass-blue grama (Hesperostipa comata-Bouteloua gracilis) community in Yellowstone National Park supported a mean of 13 pinnate tansymustard germinants/m2 in the greenhouse [26] .
Germination: Pinnate tansymustard has a temperature-dependent afterripening requirement that lessens with time and exposure to cold temperatures [192]. It is adapted to establishing in soils that may dry quickly. The seedcoat forms a thin layer of mucilage after wetting; the sticky layer helps germinating seeds retain water [189,192]. Best germination occurs with ample soil moisture, however. Seedling establishment is closely tied to favorable moisture levels at time of germination, and pinnate tansymustard cover fluctuates from year to year [31]. In undisturbed creosotebush-white bursage in the northern Mojave Desert of Nevada (where pinnate tansymustard germinates in winter), spring density of pinnate tansymustard ranged from 18 plants/m2 (the driest winter) to 212/m2 (the wettest winter) over 6 years [16].
In a study on germination of California chaparral species, heat treatments had no significant effect on germination of pinnate tansymustard; however, germination of pinnate tansymustard seeds was significantly (p <0.1) enhanced by treatment with an infusion of chamise (Adenostoma fasciculatum) foliage, and by application of charred, finely ground chamise stems to the seeds [96].
Seedling establishment/growth: Although pinnate tansymustard establishes on open, dry sites, establishment may be facilitated by shrubs, especially big sagebrush, which has been shown to increase water content of surface soil through hydraulic lift [144]. In Theodore Roosevelt National Park, North Dakota, pinnate tansymustard showed better establishment when in close proximity to big sagebrush plants compared to density of pinnate tansymustard away from big sagebrush crowns. Silver sagebrush crowns also enhanced pinnate tansymustard establishment, although the number of tansymustard plants was considerably less in the silver sagebrush community compared to the big sagebrush community. The average number of pinnate tansymustard growing within a circle around sagebrush stems (using the stems as the center of the radii) varied as follows [67]:
| Species | 0-30.4 cm away from stem base | 30.4-43 cm away | 43-52.7 cm away |
| Big sagebrush | 92 plants | 60 plants | 23 plants |
| Silver sagebrush | 6 plants | 1 plant | 0 plants |
Growth is enhanced on wet, nitrogen-rich sites. On the Jornada Experimental Range of New Mexico, pinnate tansymustard showed best growth (peak biomass=3.2 g/m2) on sites fertilized with nitrogen and given 25 mm of supplemental water/per week [61]. Nitrogen-fixing plants may increase pinnate tansymustard cover (review by [106]).
SITE CHARACTERISTICS:Soils: Pinnate tansymustard is common on sandy, gravelly, and eroded soils [27,28,40,54,75,76,81,108,141,172]. Hinds and Sauer [76] found pinnate tansymustard was associated with eroded soils on the Arid Lands Ecology Reserve of Washington. Pinnate tansymustard tolerates alkaline and limestone soils [27,28,50,75,119,172]. In the San Bernardino National Forest, California, pinnate tansymustard was a constant species on singleleaf pinyon (P. monophylla)-Utah juniper sites previously mined for limestone, and on noncarbonate soils [50].
Aspect/topography: Pinnate tansymustard occurred on both cool northern and warm southern exposures following fall prescribed fire in a pinyon-juniper community in the Green River corridor of Utah [53].
Elevational range by state is:
| Arizona | <7,000 feet (2,100 m) [91] |
| California | 8,200 feet (2,500 m) [75] |
| Colorado | 4,000-8,000 feet (1,200-2,400 m) [65] |
| New Mexico | 4,500-7,500 feet (1,400-2,300 m) [110] |
| Utah | 2,500-10,700 feet (750-3,250 m) [175] |
| Wyoming | 6,000 to 7,200 feet (2,000-2,200) [40] |
SUCCESSIONAL STATUS:
Pinnate tansymustard is an early seral species. It occurs on open, disturbed sites such as railroad
rights-of-way [40,172], overgrazed rangelands [14,19], and early seral burns
[32,33,51,53]. Pinnate tansymustard and other annuals are common following
disturbances such as fire or grazing. They become increasingly
scarce as the canopy closes [3,32,33,51,104].
Pinnate tansymustard does not form mycorrhizal associations [14,134]; thus, it can
occur on sterile sites and on sites undergoing primary succession.
A common pattern of succession in disturbed sagebrush steppe begins with Russian-thistle. Pinnate tansymustard, flixweed tansymustard, and/or tumblemustard follow successionally. Russian-thistle may in turn reinvade the mustard stands with grazing disturbance, but more commonly, the mustards are succeeded by cheatgrass [68,78,78,139,185]. In desert environments, cheatgrass usually requires litter for successful germination and establishment. The dried skeletons of pinnate tansymustard and other annual forbs may facilitate cheatgrass establishment by providing litter [34,125]. Pinnate tansymustard and other annual forbs achieve greater cover in early seral sagebrush communities when cheatgrass is absent [193]. For information on the interactions of pinnate tansymustard and cheatgrass, see FEIS reviews on flixweed tansymustard and cheatgrass.
Pinnate tansymustard and the exotic flixweed tansymustard are apparently equally invasive, and fill similar ecological niches [118]. They sometimes codominate in early seral communities [2].
Pinnate tansymustard may persist into late succession if the canopy remains open [150]. For example, pinnate tansymustard was common (20% frequency) in a relict, 80-year-old Colorado pinyon-Utah juniper burn in northeastern Utah. It was less common, but present (2% frequency), on another relict Colorado-pinyon-Utah juniper site that had not experienced stand-replacement fire for at least 150 years. Structure at both sites was very open, with few, scattered trees [52]. Sagebrush communities may also retain open conditions into late succession [171,188]. In the Columbia River Basin of south-central Washington, pinnate tansymustard occurs in big sagebrush communities through all stages of succession but is most common in early successional stages. It is the most common native annual on newly disturbed sites and old fields [18]. Pinnate tansymustard occurs in pristine, late-successional communities. For example, it occurs in undisturbed, climax mountain meadows (Idaho fescue-bearded wheatgrass (Festuca idahoensis-Elymus caninus)) in Grand Teton National Park [174].
SEASONAL DEVELOPMENT:Fire regimes: In wet years, the dried skeletons of pinnate tansymustard and other annuals provided the fine, flashy fuels that helped spread fire in presettlement desert ecosystems. Year-to-year fluctuations and longer-term southern oscillations resulted in variable cover of annuals and their subsequent fuel loads [164], so fire return intervals in presettlement desert ecosystems were highly variable. Historic fire return intervals in desert ecosystems ranged from 10 to 100 or more years [8,23,114,133,171,194]. Expansion of annual alien grasses has dramatically changed fire regimes and plant communities over vast areas of western rangelands by creating an environment where fires are easily ignited, spread rapidly, cover large areas, and occur frequently [190]. Cheatgrass, red brome, and Mediterranean grasses (Schismus spp.) provide large amounts of persistent flammable fuels [20,21,116]; consequently, fire may return every 10 years or sooner in desert systems infested with exotic grasses [135,180]. Pinnate tansymustard's role in facilitating establishment of cheatgrass and other weedy species in dry environments by providing litter (and subsequently, more mesic conditions for germination and seedling growth of other species) [34,35] needs further investigation.
Historic fire return intervals ranged from 10 to 70 years in sagebrush-dominated ecosystems [8,23,114,133,171,194]. Fire was historically uncommon in salt-desert shrubland ecosystems [22,84,129]. Native annuals such as pinnate tansymustard, lacey phacelia (Phacelia tanacetifolia), and small fescue (Vulpia microstachys) provided fuels, but frequent breaks in the continuity of fuels hindered fire spread [20,21].
The following table provides fire return intervals where pinnate tansymustard may be an important component of the vegetation. For further information on fire regimes in these communities, see the FEIS summary on the dominant species listed below.
| Community or Ecosystem | Dominant Species | Fire Return Interval Range (years) |
| maple-beech-birch | Acer-Fagus-Betula | > 1000 [173] |
| California chaparral | Adenostoma and/or Arctostaphylos spp. | < 35 to < 100 [133] |
| bluestem prairie | Andropogon gerardii var. gerardii-Schizachyrium scoparium | < 10 [100,133] |
| silver sagebrush steppe | Artemisia cana | 5-45 [73,140,183] |
| sagebrush steppe | A. tridentata/Pseudoroegneria spicata | 20-70 [133] |
| basin big sagebrush | A. tridentata var. tridentata | 12-43 [148] |
| mountain big sagebrush | A. tridentata var. vaseyana | 15-40 [8,23,113] |
| Wyoming big sagebrush | A. tridentata var. wyomingensis | 10-70 (40**) [171,191] |
| coastal sagebrush | A. californica | < 35 to < 100 |
| saltbush-greasewood | Atriplex confertifolia-Sarcobatus vermiculatus | < 35 to < 100 |
| desert grasslands | Bouteloua eriopoda and/or Pleuraphis mutica | 5-100 [133] |
| plains grasslands | Bouteloua spp. | < 35 [133,183] |
| blue grama-needle-and-thread grass-western wheatgrass | B. gracilis-Hesperostipa comata-Pascopyrum smithii | < 35 [133,146,183] |
| blue grama-buffalo grass | B. gracilis-Buchloe dactyloides | < 35 [133,183] |
| grama-galleta steppe | B. gracilis-Pleuraphis jamesii | < 35 to < 100 [133] |
| cheatgrass | Bromus tectorum | < 10 [135,180] |
| California montane chaparral | Ceanothus and/or Arctostaphylos spp. | 50-100 [133] |
| curlleaf mountain-mahogany* | Cercocarpus ledifolius | 13-1000 [9,151] |
| mountain-mahogany-Gambel oak scrub | C. ledifolius-Quercus gambelii | < 35 to < 100 |
| blackbrush | Coleogyne ramosissima | < 35 to < 100 [133] |
| California steppe | Festuca-Danthonia spp. | < 35 [133,161] |
| juniper-oak savanna | Juniperus ashei-Q. virginiana | < 35 |
| western juniper | J. occidentalis | 20-70 |
| Rocky Mountain juniper | J. scopulorum | < 35 |
| cedar glades | J. virginiana | 3-7 |
| creosotebush | Larrea tridentata | < 35 to < 100 [133] |
| wheatgrass plains grasslands | Pascopyrum smithii | < 5-47+ [133,140,183] |
| Great Lakes spruce-fir | Picea-Abies spp. | 35 to > 200 |
| northeastern spruce-fir | Picea-Abies spp. | 35-200 |
| black spruce | P. mariana | 35-200 [30] |
| pine-cypress forest | Pinus-Cupressus spp. | < 35 to 200 [7] |
| pinyon-juniper | Pinus-Juniperus spp. | < 35 [133] |
| Mexican pinyon | P. cembroides | 20-70 [120,163] |
| shortleaf pine | P. echinata | 2-15 |
| shortleaf pine-oak | P. echinata-Quercus spp. | < 10 [173] |
| Colorado pinyon | P. edulis | 10-400+ [42,55,93,133] |
| slash pine | P. elliottii | 3-8 |
| slash pine-hardwood | P. elliottii-variable | < 35 [173] |
| longleaf-slash pine | P. palustris-P. elliottii | 1-4 [124,173] |
| longleaf pine-scrub oak | P. palustris-Quercus spp. | 6-10 [173] |
| Pacific ponderosa pine* | P. ponderosa var. ponderosa | 1-47 [7] |
| interior ponderosa pine* | P. ponderosa var. scopulorum | 2-30 [7,10,105] |
| red pine (Great Lakes region) | P. resinosa | 10-200 (10**) [30,46] |
| red-white-jack pine* | P. resinosa-P. strobus-P. banksiana | 10-300 [30,69] |
| loblolly pine | P. taeda | 3-8 |
| loblolly-shortleaf pine | P. taeda-P. echinata | 10 to < 35 [173] |
| galleta-threeawn shrubsteppe | Pleuraphis jamesii-Aristida purpurea | < 35 to < 100 |
| eastern cottonwood | Populus deltoides | < 35 to 200 [133] |
| aspen-birch | P. tremuloides-Betula papyrifera | 35-200 [30,173] |
| quaking aspen (west of the Great Plains) | P. tremuloides | 7-120 [7,60,112] |
| mesquite | Prosopis glandulosa | < 35 to < 100 [111,133] |
| mesquite-buffalo grass | P. glandulosa-Buchloe dactyloides | < 35 |
| Texas savanna | P. glandulosa var. glandulosa | < 10 [133] |
| mountain grasslands | Pseudoroegneria spicata | 3-40 (10**) |
| California oakwoods | Quercus spp. | < 35 [7] |
| oak-hickory | Quercus-Carya spp. | < 35 [173] |
| oak-juniper woodland (Southwest) | Quercus-Juniperus spp. | < 35 to < 200 [133] |
| northeastern oak-pine | Quercus-Pinus spp. | 10 to < 35 [173] |
| oak-gum-cypress | Quercus-Nyssa-spp.-Taxodium distichum | 35 to > 200 [124] |
| southeastern oak-pine | Q.-Pinus spp. | < 10 [173] |
| coast live oak | Q. agrifolia | 2-75 [57] |
| canyon live oak | Q. chrysolepis | <35 to 200 |
| blue oak-foothills pine | Q. douglasii-P. sabiniana | <35 |
| Oregon white oak | Q. garryana | < 35 [7] |
| bur oak | Q. macrocarpa | < 10 [173] |
| oak savanna | Q. macrocarpa/Andropogon gerardii-Schizachyrium scoparium | 2-14 [133,173] |
| shinnery | Q. mohriana | < 35 [133] |
| interior live oak | Q. wislizenii | < 35 [7] |
| cabbage palmetto-slash pine | Sabal palmetto-Pinus elliottii | < 10 [124,173] |
| blackland prairie | Schizachyrium scoparium-Nassella leucotricha | < 10 |
| Fayette prairie | S. scoparium-Buchloe dactyloides | < 10 |
| little bluestem-grama prairie | S. scoparium-Bouteloua spp. | < 35 |
| tule marshes | Scirpus and/or Typha spp. | < 35 [133] |
| elm-ash-cottonwood | Ulmus-Fraxinus-Populus spp. | < 35 to 200 [30,173] |
Pinnate tansymustard is common in early postfire communities [121]. It typically occurs in the earliest,
annual-dominated
stage of postfire succession in pinyon-juniper and sagebrush communities [51].
In a mountain big sagebrush
community in Idaho, frequency of pinnate tansymustard was more than 100% greater
(p <0.05) in fall-burned compared to unburned control plots [109]. Although fire creates an open canopy and bare mineral soil, which favors tansymustard establishment,
pinnate tansymustard is not an obligate "fire
follower." Any area with bare ground, open sunlight, and a seed source is
vulnerable to pinnate tansymustard invasion [71,72]. In greenhouse trials, there was no significant difference in emergence of
pinnate tansymustard seedlings from unburned, "lightly" burned, and severely
burned soils. Greenhouse emergence of pinnate tansymustard (seedlings/m2) from soil samples collected
after
prescribed burning near Burns, Oregon was as follows [25]:
| Control | "Cool" burn | "Hot" burn |
|
Basin big sagebrush site |
||
| 5.5 | 4.5 | 7.3 |
|
Wyoming big sagebrush site |
||
| 8.8 | 21.3 | 15.3 |
Fire may not increase postfire cover of pinnate tansymustard [190]. In his classic study of postfire succession of pinnate tansymustard and other annuals in big sagebrush, Piemeisel [138] wrote "the mere statement that a field has been burned is not sufficient information to foretell what the effect will be on the succeeding plant cover." For example, a 1977 June wildfire burned rough fescue (Festuca altaica)-bluebunch wheatgrass mountain grassland in Missoula, Montana. In fall 1977, spring 1978, and summer 1978, pinnate tansymustard was present in low amounts on burned and unburned sites, with no significant differences (p <0.05) between pinnate tansymustard cover on burned and unburned sites [4]. Piemesel [138] stated that site grazing history, postfire weather patterns, and level of postfire cheatgrass cover will affect cover and relative abundance of tansymustards and other early successional forbs.
Because it is an annual, pinnate tansymustard population size is highly dependant upon year-to-year variations in postfire climate [123]. Following 1964 wildfires in northeastern Nevada, pinnate tansymustard frequency fluctuated greatly for the next 3 years (41% in 1965, 6% in 1966, and 66% in 1967; pooled from 32 plots on 3 burns) [153]. Pinnate tansymustard was found on fall-burned plots in postfire years 4 and 11 (but not other years) in a pinyon-juniper community in the Green River corridor of Utah [53].
Pinnate tansymustard cover generally decreases with postfire succession. In Colorado pinyon-Utah juniper stands in Mesa Verde National Park, pinnate tansymustard showed 44% frequency on a 4-year-old burn. It was not present on 30- or 90-year-old burns [33]. However, pinnate tansymustard may remain a component of postfire vegetation as long as the site remains open.
Fuels: It is unclear how pinnate tansymustard
contributed to fuel spread in the Southwest when presettlement fire regimes were
functioning. Researchers have speculated that following a wetter-than-average
growing season, dead, dry native annuals provided the fuels that carried
infrequent spring or summer fire [55]. In a creosotebush-white bursage community
in the Mojave Desert of southern California, however, experimental fires set in August
1995 were fueled entirely by red brome, cheatgrass, and Mediterranean
grasses (Schismus spp.). Precipitation the preceding winter was 200% of
average, so cover of annuals was high (~36% for all annual species). Where
exotic grasses dominated, mean spring (prefire) cover of annuals was
approximately 58%, whereas mean spring cover where native annuals dominated was
approximately 30%. (At 30%, pinnate tansymustard cover matched overall forb
cover.) Fire did not spread
in areas dominated by native annuals due to low fuel loads [20]. This
suggests that in desert shrublands of the Southwest, presettlement fires were probably small and
patchy.
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
Disturbance level and fire severity:
Fire disturbance generally favors pinnate tansymustard; however, severe fire may
reduce pinnate tansymustard's seed bank. On singleleaf pinyon-Utah juniper of west-central Utah,
pinnate tansymustard was about equally frequent on burned plots and on plots
that were burned and chained [131]. After wildfire in a Utah juniper community
in Nevada, pinnate tansymustard was present at postfire year 1, with abundance
peaking at postfire year 4. Sites where severe fire killed the junipers and
reduced the understory to ash were devoid of vegetation until postfire year 4,
when pinnate tansymustard and cheatgrass established [153]. Absence of
vegetation prior to postfire year 4 on severely burned sites suggests that the seedbank was destroyed,
and pinnate tansymustard and cheatgrass seeds were transported to the site after fire.
Fall prescribed burning in a basin big sagebrush community in east-central Oregon had no significant effect on pinnate tansymustard frequency in postfire year 1 or 2 [148]. See the Research Project Summary of this work for more information on fire effects on pinnate tansymustard and 60 additional forb, grass, and woody plant species.
The Research Project Summary Nonnative annual grass fuels and fire in California's Mojave Desert also provides information on prescribed fire and postfire response of pinnate tansymustard and other plant community species.
FIRE MANAGEMENT CONSIDERATIONS:| Cover type | Pinnate tansymustard | Flixweed tansymustard |
|
1997 |
||
| Gambel oak/Utah serviceberry* mountain shrubland | 3 | 16 |
| Gambel oak-Colorado pinyon-Utah juniper | 1 | 12 |
| Colorado pinyon-Utah juniper | 2 | 10 |
|
1998 |
||
| Gambel oak/Utah serviceberry mountain shrubland | 31 | 0 |
| Gambel oak-Colorado pinyon-Utah juniper | 24 | 0 |
| Colorado pinyon-Utah juniper | 27 | 0 |
Interactions with cheatgrass: On dry sites where fire or other disturbance has consumed the litter, pinnate tansymustard may pioneer, building up litter for subsequent cheatgrass establishment [34,35]. Postfire climate may greatly affect relative coverage of annual species. West [177] noted that in the Curlew Valley of northwestern Utah, pinnate tansymustard and clasping pepperweed were common in the extremely wet period of 1983-1984, an El Niño year. The 2 forbs dominated and were the main source of fuels in shadscale (Atriplex confertifolia) and Gardner's saltbush (A. gardneri) communities; bottlebrush squirreltail (Elymus elymoides) dominated the understory of winterfat communities. Although cheatgrass typically follows tansymustard and other mustards successionally [138,139], during the El Niño event cheatgrass was "less abundant ... than it had been before or since." Cheatgrass dominated the site after El Niño passed [177].
Fire as a control agent: There are no published studies on using fire to control pinnate tansymustard, but given its strong response to increased light and nutrients and open ground, fire alone is unlikely to provide control. If pinnate tansymustard is already onsite in the seed bank, or as a few plants, fire is likely to increase the species' importance in the early postfire community.Large grazing animal use of pinnate tansymustard varies, but is generally heaviest for new growth. On the Jornada Experimental Range of south-central New Mexico, cattle grazed pinnate tansymustard in March (31% of diet) and December (8% of diet) [62]. Cattle on the Arid Land Ecology Reserve of eastern Washington used it lightly in spring [168]. Desert mule deer in Arizona and New Mexico consumed pinnate mustard lightly (1-5% of diet) to moderately (6-15% of diet) in winter and spring [99,155,156]. A review by Kufeld and others [102] notes Rocky Mountain mule deer use pinnate tansymustard in spring, summer, and fall. Pronghorn in northeastern Colorado preferred pinnate tansymustard in the spring, and ate it in trace amounts in summer [152].
Small mammals consume pinnate tansymustard. Grazing rodents and lagomorphs eat pinnate tansymustard [88,107,187]. Black-tailed jackrabbit in southern Idaho showed greatest use in August (12.4% of the total diet) and least in June (2.2% of total diet) [38]. Granivorous rodents also use pinnate tansymustard. In sand shinnery oak-honey mesquite/threeawn (Quercus harvardii-Prosopis glandulosa/Aristida spp.) communities of New Mexico, capture/stomach analyses trials showed Ord's kangaroo rat, spotted ground squirrel, and northern grasshopper mouse ate pinnate tansymustard seeds [13]. On the Arid Land Ecology Reserve, eastern Washington, pinnate tansymustard seeds formed 8% of the Townsend ground squirrel diet [87].
Pinnate tansymustard is a larval food for several species of butterfly [82] including the desert orangetip (Anthocharis cethura pima), a sensitive subspecies in Region 3 (Southwest) of the U.S. Forest Service [6].
Palatability/nutritional value: Pinnate tansymustard is palatable and nutritious. In the Mojave desert of California, domestic sheep showed strong preference for pinnate tansymustard early in the growing season [137]. In free-choice trials, Montana cattle preferred pinnate tansymustard to flixweed tansymustard. From the rosette to bud stage, average protein and phosphorus content of pinnate tansymustard in Montana was 22.4% and 0.38%, respectively [136]. Nutritional content of pinnate tansymustard forage collected in the great Basin of Nevada and Utah was [157]:
| Cal/kg | 3,660 |
| protein (%) | 27.2 |
| carbohydrates (%) | 63.3 |
| fat (%) | 0.50 |
| ash (%) | 2.9 |
| moisture (%) | 6.1 |
Cover value: No information
VALUE FOR REHABILITATION OF DISTURBED SITES:Horticulturalists plant pinnate tansymustard in butterfly gardens to attract orangetip, white checkered, and white cabbage butterflies [82].
OTHER MANAGEMENT CONSIDERATIONS:Grazing appears to favor pinnate tansymustard in disturbed communities. Moderate grazing in late-seral communities may not increase pinnate tansymustard cover, although the data are limited and further studies are needed. In west-central Utah, pinnate tansymustard cover was similar (3%) in basin big sagebrush communities with moderate cattle grazing and without grazing (13-year exclusion) [179]. In southern Alberta, moderate to heavy levels of stocking in undisturbed needle-and-thread grass-blue grama prairie slightly increased pinnate tansymustard; however, in old fields, pinnate tansymustard cover was greatly increased on grazed plots compared to ungrazed plots. Cover (%) of pinnate tansymustard was [29]:
| Prairie | Old field | ||
| grazed | ungrazed | grazed | ungrazed |
| 1.9 | 1.5 | 10.4 | 0.1 |
Pinnate tansymustard can persist on open sites free of grazing or other disturbance. In a shadscale-winterfat community of west-central Utah, pinnate tansymustard occurred on a variety of domestic sheep grazing treatments (exclosure, light, moderate, and heavy grazing; and early- to mid-winter vs. late-winter grazing, with intensity ignored). It was most common in exclosures, but was found on plots of all treatments [64]. In the Grand Canyon, pinnate tansymustard occurs on sites with a long history of livestock grazing, and on relict sites that have never supported livestock and have seldom burned [150].
Pinnate tansymustard may differentially affect seed production of desert shrubs in heavily grazed and ungrazed areas. On the Desert Experimental Range Station of west-central Utah, seed production of shadscale and winterfat was enhanced by presence of pinnate tansymustard on sites that had not been grazed for >50 years, but depressed by pinnate tansymustard on heavily grazed sites [45]. Mechanisms by which pinnate tansymustard may have affected shrub seed production were not studied.
In a big sagebrush community of northeastern Nevada, pinnate tansymustard, cheatgrass, and clasping pepperweed volunteered on post-wildfire rehabilitation sites that were contour ripped and seeded to crested wheatgrass (Agropyron cristatum). However, seedling density of pinnate tansymustard and exotic species was much greater on untreated burn plots compared to the ripped, seeded-in burn plots. Pinnate tansymustard density exceeded that of cheatgrass on the untreated burns [153].
Pinnate tansymustard is an agricultural weed [5,118] and an alternate host for beet leafhoppers, which transmit curly top virus to sugar beet (Beta vulgaris) crops [77].
Control: Pinnate tansymustard does not usually persist in late-seral communities and may not require special control measures. Canopy closure, litter accumulation and/or growth interference from later-successional species tend to exclude tansymustard over time. Probably because it is a native invader that is largely controlled by succession, there is scant wildland-management interest in using resource monies to control pinnate tansymustard with fire (see Fire as a control agent), herbicides, or other treatments.
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