Experimental reintroduction of plants from greenhouse-grown stock with the goal of establishing new, self-perpetuating populations. Approximately 89% of seedlings survived the first growing season. (CH2M 1986) By 1997, approximately 57% of the original transplants remained (CH2M 1997). In an attempt to establish new populations capable of self-perpetuating, 200 rhizomes were collected in early September of 1986. They were transplanted to a similar habitat in the vicinity, By 1997, approximately 87% of the original transplant remained. (CH2M 1997).

A regional endemic. Most occurrences are in the Willamette Valley of Oregon. ?It is also known from the Coast Range in Oregon and two populations in southwest Washington. The moist, open habitats preferred by this species have been severely reduced from historical levels (especially the Willamette Valley) due to widespread agricultural and urban development. Approximately ninety occurrences remain, many of which are small. However, propagation and reintroduction efforts have had some success. 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; herbicide application, 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.

Potential construction of a dam and reservoir by McMinnville Water and Light (USFWS 1993). Stochastic extinction (random events causing extinction) because of the small population (less than 100) size (USFWS 1993). Herbicide spraying (Meinke 1982).

In 1985, 22 populations held a total to 4,781 plants. Many more were discovered when active searching began. By 1991, 48 populations were known with a total of 24,158 plants (Glad et al. 1994). By 1997, 58 populations were known, containing a total of 26,467 plants (CH2M 1997). There are 2 known populations in Washington (WNHP 1999). The populations are divided in to 6 population centers. Four centers are in the Willamette Valley of Oregon, one is in the Coast Range of Oregon, and one is in the Cost Range of Southwestern Washington (USFWS 1993). Approximately 48% of known sites contain 100 plants or fewer, while 31% contain 25 plants or fewer (USFWS 1993). In 1985, 22 populations held a total to 4,781 plants. Many more were discovered when active searching began. By 1991, 48 populations were known with a total of 24,158 plants (Glad et al. 1994). By 1997, 58 populations were known, containing a total of 26,467 plants (CH2M 1997). There are 2 known populations in Washington (WNHP 1999). The populations are divided in to 6 population centers. Four centers are in the Willamette Valley of Oregon, one is in the Coast Range of Oregon, and one is in the Cost Range of Southwestern Washington (USFWS 1993). Approximately 48% of known sites contain 100 plants or fewer, while 31% contain 25 plants or fewer (USFWS 1993).

Experimental reintroduction of plants from greenhouse-grown stock with the goal of establishing new, self-perpetuating populations. Approximately 89% of seedlings survived the first growing season. (CH2M 1986) By 1997, approximately 57% of the original transplants remained (CH2M 1997). In an attempt to establish new populations capable of self-perpetuating, 200 rhizomes were collected in early September of 1986. They were transplanted to a similar habitat in the vicinity, By 1997, approximately 87% of the original transplant remained. (CH2M 1997). Experiments were conducted to study the germination requirements and patterns. Fully mature seeds were found to germinate successfully without treatment but immature seeds only occasionally germinated if scarified. In order for water and oxygen to enter the seed and promote embryo expansion, a large piece of the seed coat from the dorsal surface of the seed had to be removed. Germination occurred 1-4 days after scarification (Halse and Mishaga 1988). Determination of detailed habitat conditions including vegetation cover type, air temperature, soil pH, soil temperature, soil moisture, soil texture, and soil chemistry at the largest population. S. nelsoniana was found to be tolerant of a wide variety of habitats (Glad et al. 1987). Taxonomic studies a) comparing S. nelsoniana, S. cusickii, S. campestris, and S. virgata and b) comparing various populations of S. nelsoniana were conducted. All four were found to be distinct species. S. nelsoniana was found to be morphologically consistent throughout its range, and the study supported the hypothesis that the Walker Flat population was not genetically distinct (Halse et al. 1989). Monitoring of reintroduced plants at Walker Flat, Neverstill and South McGuire populations. (Guerrant 1997). The effects of weevils on plants were studied. Researchers found that seed mortality rates from weevil parasitism ranged from 0% to 84% of total ovules. Consequently, seed abortion and weevil predation limited fitness and could potentially inhibit any seed set for an individual plant. Frequency of seedling and juvenile plants was low, suggesting that many population structures are skewed towards older, more established plants (Gisler and Meinke 1997). Preliminary results suggest that weevils prefer Sidalcea nelsonia over other, more common related species. There is no correlation between population size and parasitism, suggesting that small populations are just as vulnerable as large populations (Gisler and Meinke 1997). Research on controlling seed predation by weevils with insecticides (Gisler, pers comm.). Research on hybridization between Sidalcea nelsoniana and related species found in the same area (Gisler, pers comm.).

Walker Creek, around which many S. nelsoniana are found, is protected as part of the Oregon Scenic Waterways System Plants found in areas that have been burned to benefit geese, are more robust than those plants in non-burned locations (USFWS 1993). Monitoring of Walker Flat (a naturally occurring population), Neverstill and South McGuire (reintroduced populations) sites conducted in 1997 by The Berry Botanic Garden (Guerrant 1997). Large-scale cultivation in a greenhouse setting has been initiated for reintroduction projects in Yamhill and Benton Counties (Gisler, pers comm.). The height of the Trask River Dam near Hillsboro, OR was raised to increase the storage capacity of Barney Reservoir by 5 times. This inundated the land with water, destroying Sidalcea nelsoniana habitats and extirpated the population (USFWS 1993). As part of a mitigation, some plants were moved to higher ground. Additional plants were grown at the Berry Botanic Garden for transplantation.

Conduct searches for additional populations, especially in southern Washington. Because this species spreads by rhizomes, it is important to count genets (genetic individuals) when conducting a study as opposed to counting the number of ramets (individual plants) (Kagan and Yamamoto 1986). Therefore, a study of the genetic structure of the populations would be important to ensure genetic variation within the species was being maintained. Maintain or create large populations (>1000 individuals) so that even after weevil predation, adequate live seed will be dispersed (Gisler and Meinke 1997). Further work to determine how much seed must be lost in order for the population to be unviable. Further research on the relationship between Sidalcea nelsoniana and the weevils that feed on the seed may be helpful (Gisler and Meinke 1997).

Study genetic diversity of populations (Kagan and Yamamoto 1986). Collect and store seed from across the known range.