March of the Chollas

The cholla cactus (Cylindropuntia imbricata) is a fairly common sight in the Arkansas River basin of southeast Colorado, where it can occur as scattered individuals or in fairly dense stands. Eleven years after first monitoring cholla cactus and other shrubs at the Pueblo Chemical Depot (PCD), in Pueblo County, CHNP ecologist Renée Rondeau has documented a significant increase in cholla density in the greasewood shrubland at the site.

Anyone else hear that music from The Sorcerer's Apprentice?

In 1999 chollas averaged 550 individuals/hectare. By 2010, cholla density had increased to 720 individuals/hectare. Half of the plots were grazed by cattle up until 1998 while the other half have not been grazed since 1945; there was no difference in cholla densities between grazed/ungrazed plots.

Mean cholla densities for each year of monitoring. Bars show one standard error.

So why the increase in cholla density? Renée and others will be looking into this during the winter months, investigating climate changes as well as management changes. If anyone has any ideas about what might have caused this increase in chollas, feel free to leave a comment below, or email your thoughts to Renée (email can be found on our Contacts page).

Photograph of one of the transects at PCD in 1999. A few chollas are visible in the distance.

The same transect in 2010. The circles highlight "new" chollas. (Note: the buildings visible in 1998 were dismantled, but the water tower is still present.)

New Report: Lesser Prairie Chicken Habitat Assessment at the Comanche National Grasslands

A storm advances over the prairie at the Comanche National Grasslands.

The Lesser Prairie-Chicken (Tympanuchus pallidicinctus) is one of several gallinaceous birds native to Colorado's eastern plains. Its historic distribution covers parts of 5 states in the southern Great Plains. The southeastern corner of Colorado represents a small portion of the historic range of this species, which once inhabited a substantial portion of southwestern Kansas, eastern New Mexico, western Oklahoma, and north-central Texas. In Colorado, the species has been documented in Baca, Cheyenne, Kiowa, and Prowers counties within the past ten years.

The geographic distribution of the Lesser Prairie-Chicken is believed to have declined by over 90% since European settlement. Within this greatly reduced range, population numbers have also suffered dramatic declines. Recent years appear to have been especially hard on populations in southeastern Colorado. Habitat conditions recovered somewhat from past drought years, however, the area was hit by a series of blizzards in the winter of 2006-2007 that may have had a serious impact on population numbers.

The Comanche National Grasslands encompass more than 440,000 acres in Otero, Las Animas, and Baca counties in southeastern Colorado. CNHP assessed high priority Lesser Prairie-Chicken habitat on 9,300 acres the Comanche National Grasslands. For more information about the study's methods and conclusions, see our Documents and Reports Page.

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

Ecological systems: Shortgrass Prairie

This ecological system once covered most of Colorado east of the mountain front. Today, nearly 50% of our historic shortgrass prairie has been converted to agriculture or other uses - the largest loss of all of Colorado's ecosystems. In the early 1800s the shortgrass prairie was home to massive herds of free-ranging bison and pronghorn, as well as huge prairie dog colonies, deer and elk, and top predators including gray wolves and grizzly bears. Today, the most conspicuous animals on the prairie are domestic cattle. Pronghorn and prairie dogs still inhabit Colorado's prairies in reduced numbers, and the former top predators have been replaced by coyotes. Large-scale ecological processes such as climate, fire, and grazing by large animals exert strong influences in this ecosystem. Consequently, the short grasses that dominate this ecosystem are have evolved to be extremely tolerant of drought and grazing.

The pronghorn (Antilocapra americana) - survivors on the plains.

Prairie dogs, burrowing owl, and cows share the same landscape.

Many of Colorado's declining animal species are associated with the shortgrass prairie. Grassland bird species may constitute one of the fastest declining vertebrate populations in North America. The federally endangered black-footed ferret was lost to Colorado's shortgrass prairie prior to re-introduction of experimental populations in recent years. Species of conservation concern that still inhabit native prairie habitats in Colorado include: burrowing owl, ferruginous hawk, mountain plover, McCown's longspur, chestnut-collared longspur, and long-billed curlew, as well as northern pocket gopher, ornate box turtle, massasauga rattlesnake, and Texas horned lizard. The rarest plants in the shortgrass prairie are associated with isolated shale barren outcrops.

The Texas horned lizard (Phrynosoma cornutum).

Unlike the high elevation ecosystems such as spruce-fir and alpine tundra, shortgrass prairie lands are almost all in private ownership. Even so, some very large expanses of native prairie in good condition still exist, thanks to the stewardship of our ranching families. Unfortunately, in the absence of formal, legal protection (such as conservation easements), long-term tenure of private lands is not secure. Ongoing impacts to this landscape include renewable and non-renewable energy production (wind, solar, geothermal, oil and gas, and biofuels) and the continuing expansion of urban and exurban communities, especially along the Front Range.

Overall biodiversity, threat, and protection status scores for shortgrass prairie in Colorado.

A "windrose" graph depicting shortgrass prairie status for individual scoring factors.

Herrickia horrida (Canadian River spiny aster)

CNHP botanist Jill Handwerk and conservation planner Lee Grunau recently took a trip down to Lake Dorothy State Wildlife Area on the Colorado-New Mexico border to search for rare plants. Situated on the southern flank of Fishers Peak Mesa near Raton Pass, the area features thickly wooded canyons filled with oak and mixed conifer.

Lake Dorothy State Wildlife Area

Jill took these photos of Herrickia horrida (=Eurybia horrida) the Canadian River spiny aster. This narrow regional endemic G2 plant is found only in the upper Canadian River basin, primarily in northern New Mexico, and a small area in Las Animas County, southern Colorado. The genus name of this plant honors Clarence L. Herrick, geologist, amateur botanist, and president of the University of New Mexico from 1897 to 1901. The specific epithet horrida refers to the prickly or spiny holly-like leaves – the plants are actually rather attractive.

What's so horrid about that?

The Water Way: Botany Surveys Along the Gunnison River

By Bernadette Kuhn, CNHP Botanist

Burgundy and cinnamon-colored walls of the Wingate Formation along the Gunnison River.

Field work means walking, and usually lots of it. That is, unless there is a river and you happen to have a raft. This mode of transport makes sense when you are trying to reach some of the more far-flung canyons along the Gunnison River. And it is not only practical, it’s heavenly.

Peggy Lyon and I recently needed to reach one such canyon to update population information on a known Sclerocactus glaucus (Colorado hookless cactus) site. Our survey site was located in the newly designated (2009) Dominguez-Escalante National Conservation Area. The recreation staff at the Montrose BLM office allowed us to hop on a raft with one of their river rangers, Shawn Folkerts. Not only did Shawn bring his raft and considerable guide skills, but he also rowed the whole way!

Escalante Boat Launch along Gunnison River (or rather, the sign for it).

Shawn signs in.

Peggy wonders how everyone plus the gear are going to fit in this raft.

Our trip began at the Escalante boat launch. Shawn signed the logbook after giving advice to other floaters, loaning out his raft pump, and giving Peggy and me the routine safety talk. We boarded the raft and headed down the Gunnison. We pulled the raft onto shore at noon to eat lunch, where we were greeted by a northern leopard frog and a red-spotted toad.

Red-spotted toad action shot.

Northern leopard frog along a muddy shoreline of the Gunnison River.

We threw on our packs after lunch and began our cactus survey in the sizzling sun. Our search was successful, and we documented a large population of Colorado hookless cactus growing among the shadscale (Atriplex confertifolia) and galleta (Pleuraphis jamesii).

Sclerocactus glaucus, smaller than a golf ball!

From our parched vantage point, the river valley looks inviting. The Gunnison River supplies irrigation water to the croplands below.

Some hours later we finished our survey and headed back to the raft and our patiently waiting guide. After a quick dip to cool off, Shawn paddled us to the Bridgeport boat launch. We made it back to Bridgeport after about 8 hours on the river. At Bridgeport, we dragged the raft back to the truck, heaved it onto the trailer, and headed home. Special thanks to Shawn for the extremely helpful assistance!

Shawn is ready to head back after patiently waiting for us to finish our survey.

Rare Plant Survey of Dominguez-Escalante National Conservation Area

By Peggy Lyon and Bernadette Kuhn

Big Dominguez Canyon as seen from Cactus Park

CNHP was privileged this summer to work in the recently designated Dominguez-Escalante National Conservation Area (NCA) in western Colorado. The 66,192 acre Dominguez Canyons Wilderness is within the greater 210,000 acre NCA, which crosses Mesa, Delta and Montrose counties. It contains three major red rock canyons, Big Dominguez, Little Dominguez and Escalante. Rare plants that we documented include the Colorado hookless cactus (Sclerocactus glaucus) and Grand Junction milkvetch (Astragalus linifolius).

The Colorado hookless cactus (Sclerocactus glaucus)

This project was sponsored by the Grand Junction and Montrose Bureau of Land Management (BLM) Field Offices. Our work will help to inform the management plan now being formulated for the area. Currently, the BLM is requesting input from the public on issues to be considered when they begin drafting the plan. For information on this "scoping" process and BLM open houses, see the news release from the BLM.

Peggy posing with a Grand Junction milkvetch (Astragalus linifolius).