Counting the Endangered Wenatchee Mountains Checkermallow
We can now answer the question, with a high degree of confidence, of just how many Wenatchee Mountains checkermallow (Sidalcea oregana var. calva) plants there are. That’s due to a 9-year effort to count and map its largest known population at Camas Lands near Peshastin, WA. This population holds nearly 90% of all known individuals of this species; therefore, it is important to know how large this population is and how it is changing over time.
Wenatchee Mountains checkermallow was listed on the Endangered Species Act in 1999 and is known only from a 33-square-mile area near Leavenworth, Washington. At the time the Recovery Plan was published in 2004, it was estimated that Camas Lands held 11,000 plants based on a rough estimate from the 1990s, but an accurate census has never been undertaken until now. It turns out, that estimate might have underestimated the number of plants by a factor of three.
In 2012, then Washington Natural Heritage Program (WNHP) botanist, Joe Arnett, approached me with an idea of having Rare Care volunteers assist with monitoring a portion of the population at Camas Lands. Seven people, including Rare Care staff and volunteers, spent four days that July surveying the population in several areas of Camas Lands. Camas Lands is a 2,018-acre preserve managed by the Washington Department of Natural Resources (DNR) that protects a botanically rich area of extensive meadows and adjacent ponderosa pine and fir forests. The checkermallow population there is patchy, occurring in areas where there is adequate moisture and light such as along seasonally moist creeks and in forest openings. Therefore, it was important to document not only how many plants we found, but also to map the location of each patch of plants so we can track how these patches change over time.
Plants were counted by placing a pin flag next to each plant found in a contiguous area, mapping the perimeter of plant patch using GPS once all the plants had been flagged and then collecting all the pin flags and counting them. This labor-intensive approach benefits by having more people help locate and flag plants. In the first year, we counted 1,757 plants in 11 patches. With what we thought at the time was more than 10% of the population counted, we recruited more intensively and the next year 10 Rare Care volunteers participated. With more people, we made considerable headway and counted 30 patches in 2013. By 2014, our group expanded to include DNR Natural Areas staff and our momentum to map and count the entire population cemented into a firm goal to complete the census.
In 2021, we did just that. After nine years of annual summer surveys, we wrapped up the final patches of uncounted plants. All told, DNR estimates the population has 35,507 plants, quite a bit more than the earlier estimates suggested! Walter Fertig, the current rare plant botanist for the Natural Heritage Program, remarked “I have to say in doing this work for nearly 30 years across the West, the Camas Lands population may be the most thoroughly documented large occurrence of a listed plant of which I am aware.”
This detailed and accurate census will facilitate monitoring the population in the coming years to evaluate how it responds to management strategies such as prescribed burns and climate change. David Wilderman, DNR’s Natural Areas Program Ecologist, noted “it will be great to start revisits for some of these areas for comparison and to assess trends. One key question will be how frequently we want to target recounts of a given area – every year, every 3 years, 5 years? This will largely determine how many separate areas we can repeat the census in over time.” The mapping also provides an opportunity to better understand the habitat niche of this species. This will inform a new effort Rare Care and Washington Natural Heritage Program staff are working on together to identify sites where Wenatchee Mountains checkermallow can be introduced and attempt to establish new populations. The detailed mapping at Camas Lands will help identify microhabitat characteristics that may be key for persistence and recruitment of plants at new introduction sites.
In the meantime, I want to take a moment to mark this milestone of completing the census and to recognize the valuable contributions of everyone who pitched in. Rare Care volunteers helped get this project launched and played a vital role throughout the entire effort. DNR staff and WNHP botanists, Joe Arnett and Walter Fertig, were out every year to help and compiled all the data and produced detailed mapping. In addition to DNR staff, we were also joined by botanists and biologists from the US Fish and Wildlife Service and US Forest Service. We were also delighted to have the help of community members from the Washington Native Plant Society Wenatchee Valley Chapter and a volunteer service group from Pemco Mutual Insurance Company.