A rare legume plant found only at Mesa Verde National Park and in the Ute Mountain Ute Tribal Park is being considered for federal protection and recovery.
The U.S. Fish and Wildlife Service has proposed to list the Chapin Mesa milkvetch, Astragalus schmolliae, as threatened under the Endangered Species Act and designate critical habitat for the species. A 60-day public comment period goes until Nov. 16.
Chapin Mesa milkvetch is a narrow, endemic, upright perennial herb. It grows to about 2 feet tall and blooms with an abundance of yellow-white flowers. Characteristics of the species are its leathery, inch-long seed pods that curve downward and its dormancy adaptation.
It previously was known as Schmoll’s milkvetch, named after Hazel Schmoll, who collected the species in 1925 and was Colorado’s state botanist from 1919 to 1935.
The only known population of the Chapin Mesa milkvetch globally is at Mesa Verde National Park and on Ute Mountain Ute land to the south.
The main population is limited to 2,000 acres mainly on Chapin Mesa, with smaller populations on West Chapin Spur, Park Mesa and Ute Mountain Ute Tribal Park.
Its preferred habitat is among the microclimates of piñon-juniper woodlands, which provide some shade, insulate the ground during winter and hold moisture and snowpack for the soil, Ann Timberman, Western Colorado field supervisor for U.S. Fish and Wildlife Service, said in a phone interview.
The plant stays underground in the winter then emerges in the spring, blooming in late April into June.
During drought years, it has evolved to stay dormant underground year-round and does not emerge to bloom, said Tova Spector, chief of natural resources at Mesa Verde National Park.
It thrives after big snow years, like in 2018.
“Their blooms were really showy that year,” Spector said. “Then, during dry times, they know to go dormant.”
Populations fluctuateThe park has a conservation plan in place with designated protection areas for the plant, she said. The park also promotes its recovery in the area of the 2002 Long Mesa Fire, which badly degraded the plant’s woodland habitat.
“In the protected areas, we limit activity and practice avoidance,” Spector said. “We’re working collaboratively with different agencies and the Ute Mountain Tribe to promote a natural recovery.”
Wildfires and invasive nonnative plants, especially cheatgrass, but also musk thistle, are the primary threats to the Chapin Mesa milkvetch, Timberman said.
Climate change is also a concern for the plant, according to research papers, as models forecast warmer temperatures and a decrease in precipitation, or change in the timing and type of precipitation, by the year 2035.
Because the species is made up of a single, genetically linked population, it is highly vulnerable to catastrophic events such as fire, Timberman said.
“Populations have been fluctuating, and tend to dip down after wildfires that degrade piñon-juniper forest habitat and the native understory,” Timberman said. “The fires open up the habitat to nonnative species like cheatgrass.”
According to the Fish and Wildlife Service, a “threatened” status is being proposed because of the high potential for a damaging event that could affect all or a large portion of the species’ range, which puts it at increased risk of extinction in the foreseeable future.
For conservation and recovery of the Chapin Mesa milkvetch, Fish and Wildlife is proposing to designate about 3,635 acres of critical habitat for the species. About 69% of the proposed critical habitat is on federal lands in Mesa Verde National Park, with the remaining on Ute Mountain Ute land.
Critical habitat is defined by the environmental site assessment as areas that contain features essential for the conservation and recovery of a listed species, which may require special management considerations or protections.
Based on estimates from the early 2000s, the population size of the Chapin Mesa milkvetch is between 294,499 and 482,782 plants. An individual is thought to live up to 20 years.
“The Chapin Mesa milkvetch needs multiple resilient subunits distributed across its range to maintain its persistence into the future and to avoid extinction,” according to the 2018 Species Status Assessment Report for the plant.
“Because there is only one large representative unit and three very small units, this species is already at some risk of catastrophic events and may have low adaptability to changing conditions,” the report said.
Recovery management involves limiting or avoiding construction of trails, roads and infrastructure in its habitat along with management of prescribed burns and wildfires so they don’t cause harm, Timberman said.
Visit the plantChapin Mesa milkvetch can be viewed off the Soda Canyon Trail and on the back side of the Petroglyph Trail. They can also be spotted around the Chapin Mesa Archaeological Museum or tucked in the piñon-juniper forests along the Mesa Top and Cliff Palace Loop roads. Viewers must stay in areas open to the public and not disturb the plant or pick its flowers.
Botany enthusiast Al Schneider of Cortez, author of the Southwest Colorado Wildflowers website, has studied and documented Astragalus schmolliae at the park.
“They are beautiful, and Mesa Verde is the only place in the world that they are found,” he said. “I urge people to go out on the trails and look for them. You are not going to see them driving by at 35 mph. We should protect as many as possible when the population is that limited.”
To comment or for more information about the Chapin Mesa milkvetch and its proposed threatened status, visit its federal register webpage. Comments can be sent electronically at http://www.regulations.gov in the search box enter docket number FWS-R6-ES-2018-0055
Comments are also accepted by U.S. mail at: Public Comments Processing, Attn: Docket No. FWS-R6-ES-2018-0055, U.S. Fish and Wildlife, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.