Overview

Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

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Global Range: Most sites occur in the Willamette Valley of Oregon, from southern Benton County northward through the central and western Willamette Valley to central Washington County. Also found at several higher elevation meadows in the northern Coast Range of Oregon that flank the western Willamette Valley in Yamhill, Washington, Tillamook, Clatsop, and Columbia counties, extending west to the crest of the Coast Range. Two outlying populations are known from the Puget Trough of adjacent southwest Washington, in Cowlitz and Lewis counties. Using GIS tools, extent of occurrence was calculated to be approximately 10,500 square km.

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Historic Range:
U.S.A. (OR, WA)

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Physical Description

Diagnostic Description

Sidalcea nelsoniana can be distinguished from S. virgata by its smaller, more tightly clustered pink flowers (vs. distinctively deep pink to rose-colored flowers), its presence in wetland habitats (vs. drier, more upland sites), its nearly smooth calyx (vs. sepals uniformly finely stellate), its simple stem hairs (vs. forked-branched stem hairs), its taller height, and its later flowering time. It can be distinguished from S. campestris by its smaller, pink flowers (vs. larger white to pale pink flowers) and its shorter height. It can be distinguished from S. cusickii by its simple stem hairs (vs. generally forked stem hairs), its narrower calyx lobes, and its less prominently-veined petals. It can be distinguished from S. hirtipes by its shorter and less hairy calyx, its shorter petals, its stem with fewer, shorter hairs, and its lack of occurrence in coastal habitats. It can be distinguished from S. hendersonii by its shorter calyx, its reduced amount of pubescence, and its lack of occurrence on tidal flats (USFWS 1998, Washington NHP 1999, Oregon Flora project 2007).

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Ecology

Habitat

Comments: Generally found in soils that become saturated during the rainy season, with plants frequently becoming inundated for several weeks or longer. Other than this, soils are relatively variable, ranging from gravelly, well drained loams, to poorly drained, hydric clay soils. Currently, plants are found in both relatively undisturbed sites and in sites with greater disturbance; however, it is unclear to what degree seedling recruitment occurs in weedy sites, and how long populations can persist under such conditions after mature plants with large, established root systems die. Although sites are generally moist and open, the character of the habitat differs somewhat between the Willamette Valley and Coast Range. In the Willamette Valley, sites occur within a mosaic of urban and agricultural areas from 45-200 m elevation. Sites are usually open or at the edge between open areas and deciduous woodlands, although populations occasionally occur in the understory of woodlands or among woody shrubs. However, it is uncertain how long plants can persist under closed canopies, and it is thought that the few populations currently found in these conditions likely colonized the sites at earlier successional stages (Gisler 2004). Habitats are often native prairie remnants, and include old cemeteries, roadsides, fencerows, edges of plowed fields adjacent to wooded areas, margins of streams, sloughs, ditches, drainage swales, hay fields, and fallow fields. Most known sites have been densely colonized by invasive weeds, especially introduced forage grasses. Associated species in the Willamette Valley include tall fescue (Festuca arundinacea), rose (Rosa spp.), common rush (Juncus effusus), Canada thistle (Cirsium arvense), common St. John's-wort (Hypericum perforatum), blackberry (Rubus spp.), sedge (Carex spp.), Timothy (Phleum pratense), velvet grass (Holcus lanatus), yarrow (Achillea millefolium), vetch (Vicia spp.), Western spiraea (Spirea douglasii), bird's-foot trefoil (Lotus corniculatus), ox-eyed daisy (Chrysanthemum leucanthemum), colonial bent-grass (Agrostis tenuis), meadow foxtail (Alopecurus pratensis), reed canary-grass (Phalaris arundinacea), Douglas' hawthorn (Crataegus douglasii), wild carrot (Daucus carota), large-leaved avens (Geum macrophyllum), geranium (Geranium spp.), and Oregon ash (Fraxinus latifolia). In the Coast Range, populations primarily occupy open, grassy sites within a larger matrix of coniferous forest from 490-610 m elevation. Habitats include open wet to dry meadows, intermittent stream channels, and margins of coniferous forests. These areas generally support higher components of native vegetation than Willamette Valley sites. Associated species in the Coast Range include tansy ragwort (Senecio jacobaea), spear-head senecio (S. triangularis), strawberry (Fragaria virginiana), velvet grass (Holcus lanatus), timothy (Phleum pratense), rush (Juncus spp.), sedge (Carex spp.), and yarrow (Achillea millefolium).

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 300

Comments: 85 occurrences are currently believed extant, 83 in Oregon and 2 in Washington. Of the 83 Oregon occurrences, 3 are re-introductions and 4 are introductions. In Oregon, an additional 13 occurrences are ranked as historical/unknown, and a further 4 are believed extirpated.

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Life History and Behavior

Reproduction

This species has a gynodioecious breeding system, whereby individuals can either be hermaphroditic (bearing flowers with both male and female sex organs) or female (bearing male-sterile flowers). Because female flowers do not produce pollen, they require insect-mediated outcrossed pollen in order to produce seeds. Although hermaphroditic flowers produce pollen, within-flower self-fertilization is discouraged by protandry, whereby pollen dehisces 2-3 days prior to stigma emergence and receptivity. However, self-fertilization can still occur in hermaphroditic plants through pollen transfer between different flowers on the same inflorescence or between adjacent ramets of the same genet (Gisler 2004). Note that this species can also reproduce vegetatively via rhizomes, but rhizomes are more likely to reproduce vegetatively through breaking, with the broken-off part being moved away from the parent plant, than they are by sending out long rhizomes that give rise to new plants. It is currently unknown to what extent population maintenance in this species is dependent upon asexual expansion versus sexual reproduction (Gisler 2004).

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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N2 - Imperiled

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NatureServe Conservation Status

Rounded Global Status Rank: G2 - Imperiled

Reasons: Endemic to the Willamette Valley and adjacent Coast Range of Oregon, as well as two occurrences in adjacent southwestern Washington. The moist, open habitats preferred by this species have been severely reduced from historical levels (especially the Willamette Valley) due to widspread agricultural and urban development. Currently, approximately eighty occurrences remain, many of which are small. However, propagation and reintroduction efforts have successfully established several additional populations. Threats to this species are significant, particularly in the Willamette Valley, and include continuing agricultural and urban development; encroachment by woody plants in the absence of natural disturbance processes; competition with aggressive exotic plants; herbiciding, ditching, and other road maintenance practices; and pre-dispersal seed predation by weevils. Habitat degradation is thought to be a particular problem for population recruitment from seedlings and colonization of new sites. Plant numbers are expected to decline in the absence of active management.

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Current Listing Status Summary

Status: Threatened
Date Listed: 02/12/1993
Lead Region:   Pacific Region (Region 1) 
Where Listed:


Population detail:

Listing status: T

For most current information and documents related to the conservation status and management of Sidalcea nelsoniana, see its USFWS Species Profile

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Global Short Term Trend: Decline of 10-30%

Comments: Since 1990, three occurrences are known to have been extirpated by construction at an airport, bulldozing for a housing development, and raising of the water level in a reservoir, respectively. In another eleven occurrences, no plants were found as of the most recently survey; these occurrences are ranked historical or possibly extirpated. On the other hand, recent introduction and reintroduction efforts at several sites appear to have resulted in established populations. At the Finley National Wildlife Refuge, one of the few remaining places in the Willamette Valley where this species occurs in a relatively natural habitat, plant numbers are declining, likely due to habitat degradation of the sort widespread throughout the Valley (i.e. encroachment of woody plants and competition from aggressive exotic species) (M. B. Naughton, personal observation cited in Wilson 2004). Guerrant (2001) suggests that, overall, "population numbers are declining."

Global Long Term Trend: Decline of 10 to >90%

Comments: Prior to European settlement, the moist, open habitats preferred by this species were likely maintained by natural wildfires, fires set by Native Americans, and sporadic flooding. These landscape processes have been dramatically suppressed since that time, resulting in successional woody overgrowth of many formerly open sites. In addition, livestock grazing, agricultural and urban land conversion, and stream channel alterations have greatly reduced the quantity and quality of this species' preferred habitat, especially in the Willamette Valley; Bartels and Wilson (2003) state that land use changes over the past 150 years have altered or destroyed more than 99% of Willamette Valley wetland habitats. Although there is no direct evidence of this species' abundance prior to European settlement, the vast declines in its preferred habitat strongly suggest that plants historically occurred more extensively throughout native Willamette Valley grasslands. In the Coast Range, habitat decline since European settlement does not appear to have been as severe, although habitat quality impacts (e.g. aggressive introduced species) are still apparent. Interestingly, some sources have suggested that this species may have been more recently introduced into Coast Range mountain meadows via livestock feed originating in the Willamette Valley (CH2M Hill 1986 cited in USFWS 1998).

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Threats

Degree of Threat: Very high - high

Comments: Overall, Willamette Valley populations face a higher degree of threat than Coast Range populations. (1) Habitat destruction due to agricultural, residential, and urban development continues to threaten many populations, particularly those on private lands in the Willamette Valley; these threats are generally less severe in the Coast Range, as many occupied meadows there are relatively isolated from development. However, one significant land use threat in the Coast Range is the potential construction of a dam and reservoir by McMinnville Water and Light on Walker Creek, which would inundate a very large population found in a natural habitat, features which are rare among known occurrences. This project has been contested since the mid-1980s; currently, the Nestucca River is listed under the Oregon Scenic Waterway System and a portion of the population is managed as an Area of Critical Environmental Concern by the BLM, but these protections are not considered permanent (e.g. the Oregon legislature can remove the Scenic Waterway designation). (2) Habitat quality is also highly threatened by successional encroachment of trees and shrubs, primarily resulting from suppression of natural disturbance regimes such as periodic flooding and fires. Encroachment occurs in both the Willamette Valley and Coast Range, but appears to be more problematic in the Willamette Valley since Coast Range meadows are to some degree kept open by elk and deer browsing and occasional floods and forest fires, and invading woody plant species appear to be less pervasive in the Coast Range than in the Willamette Valley. (3) Competition with aggressive exotic plant species is also a significant threat, again particularly in the Willamette Valley. Although mature, established plants appear to compete effectively with aggressive exotics such as Canada thistle, the dense stands and thatch produced by the exotic species that dominate much S. nelsoniana habitat in the Willamette Valley are thought to significantly limit seedling recruitment at occupied sites, as well as colonization of additional, potentially suitable sites. Although some exotic species have invaded preferred mountain meadow habitat in the Coast Range, native plants generally are still well-represented at those sites, and the habitats are less fragmented with more stable composition. (4) Particularly on lands without a conservation management mandate (including roadsides and agricultural field edges), populations also often experience collateral impacts from management practices such as herbicide spraying, inappropriately-timed mowing, road widening and maintenance, deposition of debris, plowing, ditching, and stream channel alteration. (5) In the Coast Range, populations within or adjacent to logged areas are potentially threatened by drift from the herbicides often sprayed on these site just prior to reforestation. (6) The habitat of several Coast Range populations is also disturbed by recreational use by motorcyclists. (7) Particularly in the Willamette Valley, populations are also subject to significant pre-dispersal seed predation by a weevil (Macrohoptus sidalceae); for example, Gisler and Meinke (1997) found that production of undamaged seeds averaged just 14.6% of total ovules across eight predated populations they studied. Predation can be reduced by applying an insecticide to inflorescences early in the flowering season, but since the weevil is native, specific to Pacific Northwest Sidalcea, and itself hosts an unidentified species of parasitic wasp, this strategy may not be attractive from an overall biodiversity conservation perspective (Gisler 2004). (8) Finally, the potential for genetic swamping via hybridization with other Sidalcea species needs careful management. Currently, various pre- and post-mating barriers discourage such hybridization, but these barriers could be overcome if species are planted beyond their current distributions or if different species are grown in close proximity for cultivation purposes. The potential for hybridization with S. cusickii is a particular concern, as this species is fully interfertile with S. nelsoniana; the only current reproductive isolation is by geographic separation of ranges (Gisler 2004).

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Relevance to Humans and Ecosystems

Risks

Stewardship Overview: At sites where natural disturbance processes no longer serve to prevent encroachment by woody species, active management is necessary to keep habitats in the open state preferred by S. nelsoniana. Active management may also be required to allow S. nelsoniana recruitment from seeds at sites with significant invasion by exotic species and associated thick thatch layers. The best methods by which to achieve optimal open habitat for this species are still a matter of active research. The U.S. Fish and Wildlife Service (1993) reported that "plants found in areas that have been burned to benefit geese are more robust than those plants in non-burned locations," suggesting that prescribed burning could be an effective management tool. However, Wilson (2004) found that experimental prescribed burning treatments did not provide short-term benefits to S. nelsoniana plants, although he allowed that benefits may become evident in the longer term. Wilson found that burning appeared both to directly damage S. nelsoniana plants as well as to stimulate growth of herbaceous competitors, particularly at wetter sites. Additional study of prescribed burning's effects on this species may reveal the reason for the apparently conflicting results of these two reports. Wilson (2004) also experimented with mowing as a management technique, but there was little convincing evidence of short-term benefit to S. nelsoniana from this treatment either. However, mowing did provide some benefit under some of the experimental conditions and did not directly damage S. nelsoniana plants to the same extent as burning. It is possible that appropriately-timed mowing in combination with other strategies, such as hand-removal of herbaceous competitors, may prove to be useful for management. Managing to increase the duration of flooding at S. nelsoniana sites has also been considered. However, Bartels and Wilson (2003) found that plants flooded past mid-spring (the historical end of the flooding season in the Willamette Valley) exhibited poor survival and vigor, suggesting that managers should not flood sites past this time.

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Wikipedia

Sidalcea nelsoniana

Sidalcea nelsoniana is a rare species of flowering plant in the mallow family known by the common names Nelson's checkerbloom and Nelson's checkermallow. It is native to the Willamette Valley and Coast Range of Oregon and the southwestern corner of Washington in the United States. It is threatened by the destruction and degradation of its habitat, and it is a federally listed threatened species of the United States.[1]

This plant is a perennial herb producing several erect stems up to a meter tall from a thick taproot. The blades of the leaves are variable in shape. In general, the basal leaves are palmate in shape and the upper leaves are more deeply divided. Each stem can bear up to 100 pink flowers in a spikelike raceme. The species is gynodioecious, producing bisexual flowers and female flowers that lack the ability to produce pollen. Each flower has a purple-tinged calyx of sepals and five petals up to 1.5 centimeters in length. The fruit is a schizocarp with one seed in each of its seven to nine segments. Blooming occurs in late May through mid-July. The plants reproduce sexually via seed and vegetatively by sprouting from broken-off pieces of the root.[1]

This plant can be found in a number of wetland habitat types and is not limited to a specific kind.[2] It grows in wet open habitat such as sedge and grass meadows and the transition zone from prairie to woodland.[3] It can grow on sunny forest edges and in riparian habitat and it is tolerant of disturbance, occurring even near campgrounds.[2]

There are six main population centers, four in the Willamette Valley and one each in the Coast Range and southwestern Washington State. The latter is made up of two populations.[3] A large population is present in William L. Finley National Wildlife Refuge.[4] The largest population in the Oregon Coast Range is located at Walker Flat in Yamhill County.[2] Most populations are small. About 48% of them contain fewer than 100 plants and 31% contain under 25.[3]

This plant faces a number of threats. Fire suppression is a main threat because the habitat becomes overgrown with thick vegetation in the absence of the normal fire regime that maintains open clearings. Wildfires are beneficial for this plant, because they clear the large and woody vegetation that prevent sunlight from reaching it.[3]

Despite the plant's tolerance of disturbance, populations occurring near roads and cultivated fields are vulnerable. Many populations in the Willamette Valley are threatened or already extirpated by agricultural and urban development. Over the last 150 years 99% of the wetland habitat in the Willamette Valley has been altered or destroyed. The possible future construction of a dam threatens a large population. Even in protected areas the plant is threatened by the invasion of non-native plant species.[1] Such weeds include reed canary grass (Phalaris arundinacea).[5] Other threats include herbicides and predation by the weevil Macrohoptus sidalceae. This checkerbloom is known to hybridize with its Sidalcea relatives, such as Sidalcea cusickii, a process that can lead to genetic pollution of the rare plant.[1]

References[edit]

  1. ^ a b c d Unattributed (2011). "Sidalcea nelsoniana". NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Retrieved 07-28-2011. Retrieved 29 July 2011. 
  2. ^ a b c Glad, J. B.; Mishaga, Richard; Halse, Richard R. (1987). "Habitat characteristics of Sidalcea nelsoniana Piper (Malvaceae) at Walker Flat, Yamhill County, Oregon.". Northwest Science 61 (4): 257–263. Retrieved 29 July 2011. 
  3. ^ a b c d Guerrant, Edward & others (03-04-2010). "Sidalcea nelsoniana". CPC National Collection Plant Profile. Center for Plant Conservation. Retrieved 29 July 2011.  Check date values in: |date= (help)
  4. ^ Wilson, M. V. (2004). The analysis of management strategies to restore and enhance Nelson’s Checker-mallow (Sidalcea nelsoniana) habitat at William L. Finley National Wildlife Refuge: Response to two years of restoration techniques in an existing Sidalcea nelsoniana habitat: Final report (Report). USFWS. http://people.oregonstate.edu/~wilsomar/PDF/W_Sine_04.pdf. Retrieved 29 July 2011.
  5. ^ Bartels, M. R.; Wilson, M. V. (2001). Berntrein, Neil P., ed. "Proceedings of the 17th North American Prairie Conference". Ostrander, Laura J. pp. 59–65. Retrieved 29 July 2011.  |chapter= ignored (help)
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