Human Disturbance in Colorado’s Potential Conservation Areas

by the ESS 440 Anthropogenic Disturbance Team

Throughout the spring 2017 semester at Colorado State, seniors in the ecosystem science program have been working through their senior project with the help of a local Colorado agency or organization. This blogpost is an overview of one of the team's collaboration with the Colorado Natural Heritage Program. For more information on the team and an overview of this project, please see our previous blog post, found here.


The Colorado Natural Heritage Program (CNHP) has worked in Colorado since 1979, cataloguing information about the rare and endangered species that exist within the state.  One aspect of their work has been the creation of potential conservation areas (PCAs) in Colorado. A PCA is an area created to denote some level of biodiversity significance. CNHP has identified these areas in the hopes of protecting the plants and animals that reside within it. The main objective of the following project is to build upon CNHP's work in order to better understand the level at which potential conservation areas (PCAs) in Colorado have been disturbed by human activities.

Location and rank of Colorado's potential conservation areas (PCAs)

The map above gives the location and rank of each PCA that has been identified by CNHP in Colorado. An area shown in pink, given the rank of B1, surrounds species that are deemed to have outstanding levels of biodiversity significance. These are highly important areas for conservation and contain Colorado's rarest or most imperiled species. Orange sites given a rank of B5 on the other hand, hold species of more general biodiversity significance, likely containing communities that are healthy and relatively abundant in the state.

This map helps focus conservation efforts by ranking areas of biodiversity significance that may be currently unprotected. Areas given a higher ranking such as B1 or B2, are higher priority for conservation. However, to add another layer of information to this idea, our team wanted to find how much anthropogenic, or human, disturbance has taken place in each of these areas.

The first thing the team did was use the location and rank information from each of Colorado's PCAs and combine it with a landscape disturbance index (LDI) dataset. The LDI dataset contains information about a type of disturbance that has been created and that disturbance type's severity level.

Distance decay curves used to determine the disturbance range of each anthropogenic activity
(reproduced from Rondeau et al. 2011)

Above, you can see the distance decay curves that were used as part of the LDI dataset. Each curve is associated with one of the nine types of mappable anthropogenic disturbance. The curve assigns an impact weight, the amount of disturbance created, over a distance to each type of disturbance activity. Some activities have a further reaching effects than others. For example, low intensity urban development has an initial impact weight of 300, however it still creates some level of disturbance up to 2000 meters away. Agriculture on the other hand, also carries an initial impact weight of 300, but its furthest reaching effects end at 500 meters.

Anthropogenic disturbance in Colorado displayed on a color scale ranging from green to red (CNHP 2016). Green denotes undisturbed areas. Red denotes highly disturbed areas. The PCAs that were the focus of this study are highlighted in various colors.


In general, areas along the Front Range and the eastern plains of Colorado have experienced the greatest amounts of anthropogenic disturbance. This is due to the high population density along the Front Range and eastern Colorado's agricultural activity. From the Rocky Mountains westward, there are much lower level of disturbance in the state. A major factor of this is the ruggedness of the terrain. Mountain areas are less accessible to people and have lower population density. Many mountain areas may also currently have some level of protection surrounding them, such as a state or national forest.

Having this new information about the level of disturbance an area experiences, allows conservation efforts to be balanced. While a B1 area may have greater biodiversity significance than a B2 area, it is possible that the B2 area is experiencing a greater amount of anthropogenic disturbance and therefore may be considered a higher priority for conservation.

Through our analysis, we identified the most and least disturbed B1 PCAs in the state. In the above map, you can see an area in western Colorado highlighted in blue. This area is the Colorado River PCA. It is a B1 PCA and home to the endangered Colorado pikeminnow, humpback chub, and razorback sucker. It is the most disturbed B1 PCA in Colorado primarily due to its proximity to the I-70 urban corridor. Not addressed in the LDI are additional significant impacts, such as the large amount of agricultural water diversion used for irrigation. Water diversions use dams and canals to draw water out of the river.

In contrast, Colorado's Hankins Gulch, located in central Colorado and shown in pink, is the least disturbed B1 PCA in the state. The area has a minimum elevation of 8,305 ft., meaning the mountainous terrain puts this area out of reach for many activities and land uses. Additionally, motorized vehicle usage is also prohibited within the area, further reducing accessibility to the area for most people. Hankins Gulch receives its B1 PCA status because it is home to the critically imperiled budding monkeyflower (Mimulus gemmiparus).

While this was just one example of the scope at which human disturbance can affect a PCA, identifying areas in Colorado that are heavily disturbed by humans is an important step in prioritizing conservation efforts in order to most effectively protect Colorado's biodiversity. For more information, please follow this link to an interactive Story Map created about the project.

Special thanks to Michelle Fink and David Anderson of CNHP for their contributions and guidance with this project.
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CNHP. 2016. Landscape Disturbance Index Layer for Colorado. Edition 12_2016. Raster digital data. Colorado Natural Heritage Program, Colorado State University, Fort Collins, CO.

Rondeau, R., K. Decker, J. Handwerk, J. Siemers, L. Grunau, and C. Pague. 2011. The state of Colorado's biodiversity 2011. Prepared for The Nature Conservancy. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado.

CSU Students Create Project with CNHP on Priority Conservation Areas and Land Ownership Using COMaP Data

Group Members: Tatum VanDam, Madison Wood, Alexa Grafton, Dylan Heser, Anna Banwart, and Nicole Chirban

Through our senior level Ecosystem Science and Sustainability class, we were given the opportunity to connect with resources from around Fort Collins to create a research and development capstone project. Working alongside the Colorado Natural Heritage Program (CNHP), we were able to communicate and develop a research project that allowed us to apply the knowledge we have gained through our four years of education at Colorado State University.

Our team was lucky to be advised by David Anderson, the director and chief scientist at CNHP. David helped us navigate COMaP (Colorado Ownership, Management, and Protection) to determine the distribution of land management and ownership types within specific parcels of land. Each parcel of land that CNHP has deemed of significant ecological/ biological importance is known as a Potential Conservation Area (PCA).

We chose sites of interest for our project based on a biological significance scale from B1 – B5, B1 being of highest importance and B5 being of lower/lowest importance. Of those sites, we chose three B1/B2 PCAs to focus on, including one in Gunnison Basin, Horsetooth Reservoir Hogbacks, and Rabbit Mountain. B1 areas are described as having outstanding biodiversity significance, and B2 areas are described as having very high biodiversity significance. Each site has a unique characteristic that gives it the potential to be a conservation site. In the Gunnison Basin, the sage brush area is of high importance (B1) to conserve because of the habitat it provides to the native Sage Grouse. The Horsetooth Reservoir Hogbacks have a high importance rating (B2) because of the occurrence of vulnerable plant communities and butterfly species native to the area. Like the Horsetooth Reservoir Hogbacks and Gunnison Basin, Rabbit Mountain is also rated highly as a B1 because of the native shrub lands and habitat for Black-tailed Prairie Dogs.

Our group worked extremely hard to evaluate the data of land management and ownership types given to us by CNHP. Madison, a master creator in GIS, was an amazing leader for the analysis of COMaP data. She was able to take an enormous amount of land data and break it down to a manageable size. Madison created a Storymap visual presentation with the help of Anna, Alexa, Dylan, and Nicole. CNHP will use this presentation for public education on the management of local lands and the distribution of PCA’s, allowing for more public understanding and possibly better collaboration on private ownership lands.

Finishing up the semester, we presented our findings at the ESS symposium in April as well as in class for our stakeholders from CNHP. This project was a growing experience as well as an opportunity to build connections with CNHP. We would like to thank all who took the time to help us with this project and we hope CNHP finds much benefit in our final product.

CNHP group meeting with Dave 

Gunnison Basin: Sage Brush

CSU Seniors Join CNHP to Address Anthropogenic Disturbances in Colorado

By George Simpson

Ecosystem Science and Sustainability is one of the majors offered through Colorado State’s Warner College of Natural Resources. The degree program teaches students how to better manage the Earth’s natural resources through the application of science in decision and policy making areas. After four years in the program, many students are finishing their final semester and preparing to graduate. For most, this means enrolment in the curriculum’s capstone class ESS 440. The distinguishing feature of the class is a semester long project working with a local agency. The projects are designed to allow students to apply the skills they have been carefully refining over the past four years in order to help practitioners solve a local sustainability problem. Student have multiple project choices to choose from, and thus are divided into smaller teams to work in throughout the semester.

Our team will be collaborating with the Colorado Natural Heritage Program (CNHP) throughout this semester. The Colorado Natural Heritage Program works with rare and imperiled species in Colorado, conducting research and sharing their expert information with stakeholders in order to help ensure that Colorado’s biodiversity is not diminished. CNHP has mapped over 1,800 Potential Conservation Areas (PCAs) in the state that contain species of biodiversity significance. Our team will be running an analysis of their PCAs to determine what areas in Colorado have experienced the greatest impacts from anthropogenic disturbances. This information will allow us to prioritize conservation efforts by combining knowledge about the biodiversity these areas contain, and the level of disturbance the area has experienced from anthropogenic activities. Included with this assessment, the team will create a summary of its findings to be shared with the general public.  

While a seemingly complex task such as this may appear daunting at first glance, 2017’s ESS 440 CNHP project team has fielded some real talent, fully qualified to complete the task at hand. Aspiring young scientists Julia, Alex, Daniel, Caden, Leo and George, working under the guidance of CNHP’s Michelle Fink and David Anderson, will use this semester to better understand the sources of anthropogenic disturbance in Colorado. The team’s composition has allowed us to blend technical expertise and creativity skills to best complete this project.

The ESS 440 project team from left to right: Leo, Caden, Danielle, George, Julia, and Alex.

Alex and Julia are the team's ArcGIS wizards. They cast virtual ArcGIS spells to extract, clip, interpolate, overlay and buffer CNHP’s data so that it can be grown into a map that tells the story of anthropogenic disturbance in Colorado. Their work will produce a map of Colorado depicting potential conservation areas in the state and the extent to which they are affected by a number human activities.

The next step in the team’s analysis will be to pick apart the results, identifying overlying trends and drivers of anthropogenic disturbances. Danielle and George will pore over the results, looking for spatial patterns and reoccurring themes between sites. The two will compile the team’s work into a digestible, easy readin’ scientific report that details the project’s goals, methods, results, and outcomes.

The team’s final members, Caden and Leo, are in charge of crafting the projects final piece, a summary of our work designed to be shared with the general public. They will shape the project's key points into an interactive story of the project that people can access to learn more about this project and the work that CNHP does.

As the semester winds down, stay tuned for our team’s completed project and access to our Storymap that you can use to learn about sources of anthropogenic disturbance that affect outdoor areas in Colorado near you.

Gunnison Sage Grouse Conservation Easement in Dove Creek, CO

In 2006, CNHP collaborated with Colorado Parks and Wildlife biologist to create the Dove Creek Potential Conservation Area (PCA) in southwestern Colorado. This PCA was drawn to identify habitats that support one of the seven remaining populations of the federally listed Gunnison sage-grouse. As of 2014, this population (referred to as the Monticello-Dove Creek population) contains only 98 individuals, according to the final listingrule issued by U.S. Fish and Wildlife Service. Lek count data from 19 years of monitoring are generally well below the Rangewide Conservation Plan population target of 500 breeding birds.

In recent years, in an effort to reverse the population trend, Montezuma Land Conservancy has worked with private landowners to conserve important sage-grouse habitat with conservation easements.  Since 2012, the Conservancy has conserved 3,340 acres of occupied habitat for the Gunnison sage-grouse – 2,700 of which is located within the CNHP Dove Creek PCA. The most recent project protected approximately 680 acres of the Dove Creek PCA under a conservation easement. The property contains sagebrush habitats, as well as areas formerly used to grow dryland pinto bean crops which have been replanted into sage brush.  The conservation easement contains a total of 788 acres, and borders BLM land and the Coalbed Canyon State Wildlife Area.

Sagebrush habitats and former pinto bean cropland near Dove Creek, Colorado offer habitat for Gunnison sage-grouse, a species listed as threatened in 2014 by the U.S. Fish and Wildlife Service.

Data on website updated for 2011

The data that we have available for download and viewing on our website has been updated for 2011. This includes updated potential conservation area reports; downloadable GIS data for element lists by 7.5 minute quad, potential conservation areas, and network conservation areas; updated tracking lists; and an updated interactive map of where CNHP is working this year.

These datasets get updated annually and they are available for free for non-commercial purposes only. For more up-to-date, detailed, specific, and/or commercial use information please contact our Environmental Review Coordinator, Michael Menefee.

Site profile: Big Creek Lakes, Jackson County

B2: Very High Biodiversity Significance

Big Creek Lakes was visited as part of the North Platte Watershed inventory in 2009. The area lies on the east flank of the Park Range, and encompasses the Big Creek Lakes as well as the North Fork of the North Platte River and its tributaries in the area. Here, extensive deposits of glacial drift from the Pinedale and Bull Lake glaciations shroud the foothills of the Park Range.

This large site includes an unusually dense concentration of glacial kettle ponds and associated wetlands. Kettle ponds are formed by the melting of stranded blocks of ice left behind by retreating glaciers. The Big Creek Lakes area is one of the most extensive kettle pond areas in Colorado. Open water areas of kettle ponds are often dominated by water lilies (Nuphar lutea ssp. polysepala), water smartweed, (Persicaria amphibia), pondweed (Potamogeton natans), buckbean (Menyanthes trifoliata), and other species, while margins may have extensive swaths of sedge dominated meadows and floating mats.

Menyanthes trifoliata (buckbean) showing off its pretty flowers.

A still picture doesn't really get at the essence of a quaking fen. Go watch the video.

This site holds documented occurrences of three rare amphibians (wood frog, northern leopard frog, and boreal toad), and a number of state rare plants, including slender cottongrass (Eriophorum gracile, G5/S2), bristly stalk sedge (Carex leptalea, G5/S1), livid sedge (Carex livida, G5/S1), roundleaf sundew (Drosera rotundifolia, G5/S2), lesser bladderwort (Utricularia minor, G5/S2), mud sedge (Carex limosa, G5/S2), slender sedge (Carex lasiocarpa, G5/S1), and marsh cinquefoil (Comarum palustre, G5/S1S2).

Comarum palustre, the marsh cinquefoil

Site Profile: Grays Peak, Summit and Clear Creek Counties

B2: Very High Biodiversity Significance

The twin summits of Grays and Torreys peaks are familiar to countless hikers who have climbed these two "fourteeners" in quick succession. Named for Asa Gray and John Torrey, authors of the 1838 Flora of North America, these peaks anchor a high elevation massif with four summits that reach over 13,000 feet above sea level. These spectacular mountains are dominated by scree and talus slopes with outcrops of bedrock. Vegetation is limited, consisting of small mossy areas around snow melt rivulets, and a few other microhabitats where opportunistic species have taken advantage of a bit of soil development.

The Grays Peak site is home to at least eight plant species of concern in Colorado, five of which belong to the genus Draba. Draba is the largest genus within the mustard family, both worldwide and in North America. There are currently over 100 recognized species in North America, with the greatest concentration of species in the western United States. These inconspicuous plants are often found at high elevations, and it is common for species to be endemic to local mountain ranges.

The species of primary concern at this site is the globally imperiled Draba grayana (Gray's Peak whitlow-grass, G2/S2). It is endemic to Colorado, and known from fewer than 20 extant occurrences, all with very low total number of individuals documented. Other rare species at the site include:

Aquilegia saximontana (Rocky Mountain columbine, G3/S3)
Askellia nana (dwarf hawksbeard, G5/S2)
Draba exunguiculata (clawless draba, G2/S2)
Draba fladnizensis (arctic draba, G4/S2S3)
Draba porsildii (Porsild's whitlow-grass, G3G4/S1)
Draba streptobrachia (Colorado Divide whitlow-grass, G3/S3)
Ranunculus gelidus ssp. grayi (tundra buttercup, G4G5/S2)

Draba streptobrachia (Colorado Divide whitlow-grass)

Draba exunguiculata (clawless draba)

Draba fladnizensis (arctic draba)

Data on website updated for 2010

The data that we have available for download and viewing on our website has been updated for 2010. This includes updated potential conservation area reports; downloadable GIS data for element lists by 7.5 minute quad, potential conservation areas, and network conservation areas; updated tracking lists; and an updated interactive map of where CNHP is working this year.

These datasets get updated annually and they are available for free for non-commercial purposes only. For more up-to-date, detailed, specific, and/or commercial use information please contact our Environmental Review Coordinator, Michael Menefee.

Site profile: Parachute Creek, Garfield County

B2: Very High Biodiversity Significance

This site was visited in 2000 as part of the Garfield County Inventory. This large site encompasses the Parachute Creek drainage as it descends from the top of the Roan Plateau toward the Colorado River west of Rifle. Here Parachute Creek and its tributaries have excavated a geologic section in sedimentary strata of the Tertiary Green River and Wasatch formations. Each tributary makes a dramatic plunge off the Roan Plateau over 100 to 200 foot shale cliffs.

Thalictrum heliophilum basking in the sun in its shaley habitat

The site supports numerous occurrences of several rare plants, including Roan Cliffs blazing star (Mentzelia rhizomata, G2/S2), Utah fescue (Argillochloa dasyclada, G3/S3), and sun-loving meadow rue (Thalictrum heliophilum, G3/S3), as well as an excellent example of a hanging garden of the type characteristic of the Utah High Plateau, dominated by hanging garden sullivantia (Sullivantia hapemanii var. purpusii).

Mentzelia rhizomata - the Roan Cliffs blazing star

South-facing slopes are dominated by sagebrush (Artemisia tridentata), serviceberry (Amelanchier), and mountain spray (Holodiscus dumosus), while Douglas-fir / spruce - fir (Psuedotsuga menziesii - Picea) forests cover north-facing slopes. The more gentle slopes dropping off the Roan Plateau support high quality grasslands and sagebrush shrublands. Although the canyon bottom has been heavily impacted by gas well development, there is lush riparian vegetation remaining in portions of the canyon, including examples of the globally vulnerable (G3/S2) box elder / chokecherry (Acer negundo / Prunus virginiana) montane riparian deciduous forest and the globally vulnerable (G3/S3) narrowleaf cottonwood / skunkbrush (Populus angustifolia / Rhus trilobata) riparian forest.

Site profile: Mee Canyon, Mesa County

B2: Very High Biodiversity Significance

This site was visited in 2002 as part of the Mesa County Wetland Inventory. In western Colorado's Black Ridge Canyons Wilderness, this scenic redrock canyon contains an enormous cavern cut by a meander of a small stream which drains to the Colorado River. The canyon is rimmed with red Entrada sandstone, and its steep sides are formed in the Kayenta and Wingate formations.

Above the canyon, the mesas supports an excellent example of the Utah juniper/saline wildrye (Juniperus osteosperma/Leymus salinus) community, as well as characteristic stands of black sage (Artemisia novum), Indian ricegrass (Achnatherum hymenoides) and needle and thread grass (Hesperostipa sp.). Dry slopes on the side of the canyon have scattered Utah juniper (Juniperus osteosperma), Fremont barberry (Mahonia fremontii), and cliffrose (Cowania mexicana).

Sandstone walls oozing moisture that supports rare species

The canyon bottom is ungrazed, and the difficulty of access to the upper reaches has probably protected it from human impacts. In the narrow riparian area at the bottom of the canyon, the stream banks are covered by dense growth of scouring rushes (Hippochaete sp.), with giant helleborine orchids (Epipactis gigantea) and scattered box elders (Acer negundo) growing among them. Not far from the cavern is a grotto with seeping walls that supports a good example of the globally imperiled hanging garden community (Aquilegia micrantha-Mimulus eastwoodiae), characterized by the yellow Mancos columbine. The state imperiled canyon tree frog (Hyla arenicolor) also occurs here, close to the northern limit of its distribution.

The Mancos columbine (Aquilegia micrantha)

A canyon treefrog (Hyla arenicolor)

Site profile: Chico Basin Shortgrass Prairie, Pueblo County

B2: Very High Biodiversity Significance

This site was visited in 2002 as part of the Pueblo County Inventory. The site encompasses over 250 square miles of shortgrass prairie in northern Pueblo and southern El Paso counties. Here, extensive tracts of native blue grama grass (Bouteloua gracilis) prairie on open flats or gently rolling terrain are home to numerous large towns of the black-tailed prairie dog (Cynomys ludovicianus).

A black-tailed prairie dog checks out the scene from its burrow.

Burrowing Owl (Athene cunicularia) are commonly seen within these prairie dog colonies, and the site also supports many breeding locations for the Mountain Plover (Charadrius montanus). These declining shortgrass prairie birds typically use areas with low vegetation and a high percentage of bare ground such as is found around prairie dog towns. Other shortgrass prairie wildlife species documented from the site include swift fox (Vulpes velox), McCown's Longspur (Calcarius mccownii), Long-billed Curlew (Numenius americanus), and massasagua (Sistrurus catenatus).

 Mountain Plovers in the kind of habitat that they love.

Site profile: North St. Vrain, Boulder County

B2: Very High Biodiversity Significance

This site was visited in 2007 as part of the Boulder County Inventory. The North St. Vrain in northwestern Boulder County east of Allenspark is one of the few remaining roadless canyons along the Front Range. Here the North St. Vrain Creek and its tributaries have carved deep, narrow canyons through the granite outcrops. The surrounding slopes support an extensive mosaic of ponderosa pine forest, shrublands, grassland openings, and cliffs and rock outcrops above the riparian corridors.

The ridgelines and rocky outcrops of the North St. Vrain site support one of the largest known concentrations of the globally rare Larimer aletes (Aletes humilis) in the world. This species is narrowly endemic to Silver Plume granite in the montane zone of the Colorado Front Range, where it thrives in the shallow, gravelly surface soils around rock outcrops. Other important elements within the site include the globally vulnerable wavy-leaf stickleaf (Nuttallia sinuata) and the globally imperiled (G2/S2) Rocky Mountain cinquefoil (Potentilla rupincola). In addition, the site contains excellent examples of montane shrublands and grasslands, as well as riparian forest, shrublands, and willow carrs.

 Aletes humilis (low-growing plants in foreground) in its favorite habitat.

Site Profile: Mount Princeton, Chaffee County

B2: Very High Biodiversity Significance

The site was visited in 2008 during the Chaffee County Inventory. With an elevation of 14,197 feet, Mount Princeton is one of over 50 Colorado summits known as "fourteeners", and is part of the southern extension of the Collegiate Peaks range in central Colorado. Together with neighboring Mount Shavano and Mount Antero, Mount Princeton has formed through erosion of a batholith (large igneous intrusion originating deep in the earth's crust) of middle Tertiary age (20-40 million years old).

A krummholz bristlecone pine

The south-facing slopes of Mount Princeton support a good example of the bristlecone pine (Pinus aristata) forest that is found scattered throughout the Collegiate Peaks from 10,000-12,250 feet elevation, just below timberline, on moderate to steep slopes on south and east-facing aspects. The forest growing here is subject to difficult conditions, with desiccating winds, broadly fluctuating temperatures, and rocky soils. At the upper limit of the forest where conditions are harshest, trees grow in stunted "krummholz" form. Although they are only a few feet tall, these trees can be hundreds of years old.

Site Profile: Troublesome Creek, Grand County

B1: Outstanding Biodiversity Significance

This site was visited during 2005 as part of the Grand County Inventory. Troublesome Creek joins the Colorado River east of Kremling. The site is dominated by the sandstones and siltstones of the Troublesome Formation, which are generally sparsely vegetated. These fine-textured, grayish-brown soils may not look like much, but are home to two Grand County endemic plant species that are Federally Listed as Endangered: Penland beardtongue (Penstemon penlandii) and Osterhout milkvetch (Astragalus osterhoutii), as well as the regional endemic dog parsley (Aletes nuttallii).

Osterhout milkvetch (Astragalus osterhoutii)

This site includes all known occurrences for Penland beardtongue. Due to the concentration of globally critically imperiled (G1/S1) plants, this site is of outstanding biodiversity value, in essence irreplaceable.

Penland beardtongue (Penstemon penlandii)

Site Profile: Trickle Mountain, Saguache County

B2: Very High Biodiversity Significance

The Trickle Mountain site was identified during the 1997 Closed Basin Inventory in Saguache and Alamosa Counties. Here, a scenic landscape of mesas and small mountains dissected by short canyons supports a mosaic of montane woodlands and grasslands. In Colorado, this type of terrain is more typical of lower elevations to the west

The vegetation of the Trickle Mountain area reflects its unusual setting. The mesa tops are dominated by an arid mixed-grass grassland of ring muhly (Muhlenbergia filiculmis) and lichen. The higher elevations of Trickle mountain are covered by Bristle cone pine (Pinus aristata) with Arizona fescue (Festuca arizonica), while ponderosa pine (Pinus ponderosa) with Arizona fescue or grasslands of mountain muhly (Muhlenbergia montana), ring muhly, and Arizona fescue dominate the lower slopes. The valleys between the plateaus are mostly a winterfat/blue grama (Krascheninnikovia lanata/Bouteloua gracilis) short-grass shrub-steppe that provides good habitat for Gunnison prairie dogs (Cynomys gunnisoni gunnisoni). The site also supports populations of two Colorado endemic plants: Weber’s catseye (Cryptantha weberi) and rock-loving aletes (Neoparrya lithophila).

Site profile: Hay Gulch, Rio Blanco County

B2: Very High Biodiversity Significance

This site was visited in 2007 during the Rio Blanco County Inventory. Hay Gulch is a large draw southwest of Meeker, on the south side of the White River. Here the Parachute Creek member of the Green River Formation (oil shale, marlstone and siltstone) is exposed. This geologic formation includes the Mahogany ledge, one of the richest oil-shale zones in the basin, as well as potentially valuable deposits of nahcolite and dawsonite. The Parachute Creek substrate supports a good (B-ranked ) occurrence of the Colorado endemic Piceance Twinpod (Physaria obcordata), a plant that is critically imperiled globally (G1G2/S1S2) and that is Federally listed as Threatened. The site also includes a good (B-ranked) occurrence of a bluebunch wheatgrass (Pseudoroegneria spicata) grassland community, considered globally imperiled (G2/S2?).

Piceance Twinpod (Physaria obcordata)

East Fork Park PCA receives conservation easement protection

Back in 1998, CNHP Ecologist Renée Rondeau led the Biological Survey of Mineral County, and one of the resulting Potential Conservation Areas (PCA) was the East Fork Park. This PCA contains both wetland and upland features that make it import to the biodiversity of the area. In particular, Renée noted that East Fork Park supports one of the healthiest riparian areas in Mineral County.

Douglas fir old growth at East Fork Park PCA (photo by Renée Rondeau)

Now, more than a decade later, we are very pleased to see, from the Durango Herald News, that East Fork Park has been protected through a conservation easement. Renée and our Director, Dave Anderson, had written a letter of support for this proposed conservation easement project last year at the request of the parties involved.

Our congratulations go out to the Southwest Land Alliance and the McCarthy family for completing this conservation easement. We are delighted to be reminded that CNHP's inventories are important testimonies to conservation actions.

Site profile: Indian Creek Hogback, Larimer County

B2: Very High Biodiversity Significance

This site was visited during our Larimer County Inventory of 2004. The red sandstones of the Fountain Formation overlain by Ingleside Formation form the hogback cliffs that are the dominant feature of this site. These cliffs extend at least six miles from Devil's Backbone to Horsetooth Reservoir. The dominant vegetation along the cliffs is mountain mahogany (Cercocarpus montanus) with a variety of native grasses. Bell's twinpod (Physaria bellii), a globally imperiled (G2/S2) plant, is found patchily throughout the site. Where it occurs, it grows from the base of the cliff to the toe of the slope and is most abundant where vegetation is sparse such as in areas of active erosion. This site supports a good (B-ranked) occurrence of Bell's twinpod. The species is known only from shale or sandstone hogbacks along the foothills of the Front Range from Jefferson County north to near the Wyoming border. Bell's twinpod has long been considered to be primarily restricted to Niobrara shale, so occurrences on Fountain and Ingleside formation sandstones such as within this Potential Conservation Area are little studied.

Bell's twinpod (Physaria bellii) in fruit

Site profile: Mineral Creek, Hinsdale County

B2: Very High Biodiversity Significance

This site was visited during our Hinsdale County wetland survey, and features a small, isolated fen wetland in the La Garita Wilderness. The site is a closed-basin, lake-fill peatland with multiple small inlets and rivulets throughout, and has a large area of floating mat towards the center and grounded peat accumulations along edges. The fen supports an excellent (A-ranked) occurrence of the globally imperiled (G2/S1S2) mud sedge (Carex limosa) montane wetland community, as well as a good (B-ranked) occurrence of the globally vulnerable (G3/S3) woolly sedge (Carex pellita) montane wet meadows community. These two herbaceous communities form a mosaic where Carex limosa dominates the central floating mat, covering approximately 35% of the wetland, and Carex pellita dominates the surrounding extensive area of grounded peat mat. Uplands to the west of the wetland grade to steep talus slopes and those to the east have mixed quaking aspen (Populus tremuloides) and Engelmann spruce (Picea engelmannii) forest that slopes down towards Mineral Creek.

Carex limosa at Mineral Creek PCA