CNHP is continually mapping locations of rare plants through surveys and monitoring projects to understand our rarest plants and develop the most comprehensive spatial database of rare plant locations in Colorado. Below we highlight long-term projects that help us meet these goals.
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The Chapin Mesa milkvetch (Astragalus schmolliae) is a plant species restricted to 18 square kilometers in extreme southwest Colorado in Montezuma County. Among Colorado’s rarest plant species, it is included as a Tier 1 species in the 2015 Colorado State Wildlife Action Plan (SWAP) Rare Plant Addendum, and was proposed but ultimately not listed by the U.S. Fish & Wildlife Service in 2020 as a threatened species under the Endangered Species Act. In order to better understand population status and trends, the National Park Service has funded CNHP to conduct ongoing monitoring of the species since 2001. Monitoring over this period has documented the response of the species to severe drought and the Long Mesa Fire in 2002, which burned almost 40% of the species known distribution.
Results of density and demography data strongly suggest that the positive effects on plant density that were originally seen after the 2002 Long Mesa Fire have reversed. By 2015-2016 the recruitment and reproductive output in the burned area was far below that in the unburned woodland, suggesting that fires may have an overall long-term negative impact. Observations of the vegetation community, soil quality, and moisture and temperature regime paired with Chapin Mesa milkvetch demography data suggest abundant grass cover in the burned area, predominantly cheatgrass, smooth brome and Western wheatgrass, has depressed the milkvetch population. Hypothesized effects in the burned area include:
- Seedlings suppressed due to competition for soil moisture with grasses
- Soil moisture further depleted by higher shallow soil temperature, suppressing pollinators and seedling germination
- Ground nesting bees, an important pollinator, inhibited by lack of bare soil
- Flowers killed by late frosts, which are more common in areas without tree cover
As climate change increases the likelihood of large-scale wildfires and intense drought, an understanding of the response of this species to environmental conditions is critical to determine appropriate management for conservation. This research supports management objectives to prevent catastrophic fires in remaining old-growth pinyon pine forests and reduce the post-fire establishment of cheatgrass, smooth brome and western wheatgrass, as the presence of these species may slow pinyon regeneration.
The Parachute penstemon (Penstemon debilis) is a species which is endemic to Garfield County, Colorado, with only four known populations in the world. It is listed by the US Fish & Wildlife Service as a threatened species under the Endangered Species Act and is also listed as a Tier 1 plant species in the 2015 Colorado State Wildlife Action Plan (SWAP) Rare Plant Addendum. Monitoring of population trends is one of the high priority actions listed in the SWAP to meet Parachute penstemon conservation goals. Monitoring enables proactive management by allowing early identification of potential threats or downward trends in population size, and development of strategies to enhance long-term population viability.
With funding from the Colorado Natural Areas Program/Colorado Parks and Wildlife, CNHP has established a long-term monitoring plot for this species on a privately owned state natural area. The habitat occupied by Parachute penstemon is characterized by sparsely vegetated, steep slopes of white and tan shale talus. Because the unstable shale slopes make sampling dangerous and disturb plant habitat, alternative monitoring methods for data collection were developed, using both photo monitoring and taking ocular counts with binoculars within transects marked by telescoping rods. This data establishes a visual record of plant abundance as well as a record of plant and site condition.
Further innovations have continued with a project to monitor and survey for this species using small Unmanned Aerial Systems (sUAS or drones). In 2020, through a partnership with private consultants Aridlands, LLC and EcoloGIS and funding from the National Fish & Wildlife Foundation, 80 flights were flown to develop a safe and effective survey protocol and generate high resolution maps of Parachute penstemon habitat. These data were compared to data collected on the ground by CNHP botanists and the protocol was found to be equally successful for detection. As the project continues, these methods will be used to update population numbers in known occurrences, search for new populations and refine the model of suitable habitat for the species.
The Pagosa skyrocket (Ipomopsis polyantha) is another of Colorado’s most endangered species. Endemic to Archuleta County, Colorado, with two populations centered on the town of Pagosa Springs, this species is listed by the US Fish & Wildlife Service (USFWS) as an endangered species under the Endangered Species Act, and is a Tier 1 species in the 2015 Colorado State Wildlife Action Plan (SWAP) Rare Plant Addendum. In 2016, Colorado Parks & Wildlife (CPW) purchased an 88-acre property conserving over half the world’s known population of the species, funded in large part by a Recovery Land Acquisition grant from USFWS. The property was subsequently designated a state natural area through the Colorado Natural Areas Program (CNAP). In order to determine the trend of the skyrocket on the property and better understand the life history traits of the species, CNHP, in partnership with CNAP and collaborating with experts from multiple agencies, developed a monitoring protocol for the species. Annual monitoring on this property has been conducted since 2017.
In 2020, with funding from the USFWS, CNHP expanded the use of this monitoring protocol, adding permanent plots to additional properties across the skyrocket’s range. CNHP staff also repeated census work from previous monitoring efforts conducted from 2005 – 2014, surveyed new properties for the skyrocket, and conducted investigations of soil conditions and environmental variables in relation to skyrocket density. The body of knowledge generated by these projects will support the conservation of this globally critically imperiled species by providing insight into the response of the species to environmental conditions and monitoring the trend of the populations over time.
With support from the U.S. Fish and Wildlife Service and the Colorado Natural Areas Program, CNHP has spent the past decade building a more complete and accurate spatial dataset for all Threatened and Endangered plant species known from Colorado. Since 2004, the number of source features for Threatened and Endangered plant species increased significantly from 399 to over 6,000. This increase is the result of both the incorporation of backlog data into our BIOTICS database along with remapping existing data to meet our new polygon-centric mapping methodology. Further, the number of source features changed dramatically for species such as Colorado hookless cactus (Sclerocactus glaucus) due to increased survey efforts for listed species in the past 10 years. Despite extensive survey efforts in recent years, the number of known locations of several listed species remains extremely low, with several species still having less than 40 mapped source features: Mancos milkvetch (Astragalus humillimus), Parachute beardtongue (Penstemon debilis), and Penland beardtongue (Penstemon penlandii). In 2011, the information contained in our database was used by the USFWS to support listing decisions and critical habitat designations for three rare plant species in Colorado: Pagosa skyrocket (Ipomopsis polyantha), Parachute penstemon (Penstemon debilis), and Debeque phacelia (Phacelia submutica).
Accurate and precise information on rare plant locations is necessary to inform management and listing decisions. Our database provides the most comprehensive data set in Colorado for Threatened and Endangered plant species. However, information on the life history of many of the listed species is lacking, and private and tribal lands are under-surveyed.
To further the conservation of Colorado’s listed species we recommend the following:
- Maintain consistent funding and dedicated resources
- Continue to collaborate and acquire data from agency staff, academic institutions, and private consultants
- Continue field surveys on public, private and tribal lands
- Increase demographic monitoring
