Treesearch

The habitat associated with riparian, understory, rare and endangered plant populations of the Southwest includes rocky places in high-altitude canyons, mostly along shady streams, pools, and dripping cliffs. The composition of these insular plant populations, which are separated by intervening desert, is influenced by several local environmental conditions. The understory light environment, which is influenced by canopy cover, is a key determinant of vegetation patterns; it varies spatially within and among populations, and is determined by intermediate closure and light availability....

Lepidospartum burgessii is designated a Species of Concern by the U.S. Fish and Wildlife Service. This shrub is endemic to gypsum soils in north Culberson County, Texas and southern Otero County, New Mexico. In 1991-92 the condition and number of plants in New Mexico were examined but otherwise little was known about the ecology or biology of this species. Our objectives were to define its habitat characteristics and status. We found that L. burgessii colonizes more diverse habitats than previously thought. In New Mexico the plants generally grew on stabilized, microbiotic-covered, gypsum...

Penstemon clutei, a rare perennial beardtongue endemic to the ponderosa pine forest of the Sunset Crater volcanic field of northern Arizona, presents an opportunity to test the hypothesis that restoration of historic ecosystem conditions may enhance the sustainability of a rare species. We tested prescribed burning and root trenching treatments as proxies for the surface fires and reduced tree densities characteristic of historic ponderosa pine ecosystems in a study area at O'Leary Peak, part of the Sunset Crater volcanic field (Coconino National Forest, AZ). Prescribed burning killed many...

Imperiled plants are sometimes protected as endangered or threatened species at state and national levels. However, politically based geographic units fall short for conservation purposes. For example, only 19 percent of plant species considered imperiled in the San Juan region of Colorado and New Mexico appeared on recent state or federal endangered species lists. Conservation of imperiled plants by ecological area is proposed. This would help (a) safeguard plant populations of evolutionary significance; (b) maintain the integrity of biotic communities; (c) draw attention to imperiled...

Landscape anomalies are regionally restricted habitats created by unusual geologic, edaphic, or hydrologic factors. Barrens, cliff faces, canyons, hanging gardens, and playas are all examples of landscape anomalies in the arid Southwest. Such sites often harbor an unusual and rich flora, including endemic, disjunct, or relictual plant species. Using examples from our studies on the chalk barrens and riparian canyons of southeast Colorado, we show how regional diversity can be enriched by the biota of habitats that are small in extent but biologically distinctive. Landscape anomalies are...

Erigeron parishii and Eriogonum ovalifolium var. vineum are federally listed local endemic plants occurring almost exclusively on carbonate soils in the northeastern San Bernardino Mountains. In 1991 and 1992, both species were planted onto a barren cut slope above a limestone quarry haul road. The plants were irrigated through the first summer and fall after planting. No soil amendments were provided other than the nursery potting mix surrounding their roots at planting. No effort was made to restore other components of natural habitat (e.g., soil conditions or plant associates). Each...

The white-margined penstemon (Penstemon albomarginatus Jones) is a rare Mohave Desert species with an unusual tripartite distribution with disjunct localities in Arizona, California, and Nevada. The Arizona population is the largest single population occurring with a range of 15 miles by 5 miles in Dutch Flat near Yucca, Arizona in Mohave County. The land ownership pattern in Dutch Flat was a checkerboard of public and private land, a legacy of railroad lands. Although the Bureau of Land Management (BLM) designated the white-margined penstemon Area of Critical Environmental Concern (ACEC)...

In south-central Utah, lands within and adjacent to Capitol Reef National Park contain populations of nine rare plant species. In an effort to enhance the combined knowledge about these species, the Bureau of Land Management, the USDA Forest Service, and the National Park Service signed an Interagency Agreement and hired an interagency biologist and field crew to conduct field surveys for each of these species. Eight of these species are federally listed and one is a candidate for listing. Survey efforts, beginning in 2000 and continuing through 2002, will satisfy the inventory requirements...

Gilia caespitosa Gray (Rabbit Valley gilia) is a rare species restricted to scattered occurrences from the northern Waterpocket Fold to Thousand Lakes Mountain and Rabbit Valley in Wayne County, Utah. This species is a very narrow endemic, known only from unstable and faulting soils of detrital Navajo Sandstone. Species occurrences are often found with limited numbers of plants and minimal potential for increasing. Information available regarding historic abundance, ecology, biology, and demographics is limited. These factors contribute to the need to develop a Conservation Agreement and...

Wright fishhook cactus (Sclerocactus wrightiae Benson) is a small barrel cactus endemic to the San Rafael Swell in south-central Utah. It was listed as an endangered species in 1979 due to its small population size, threats of over-collecting, and development associated with oil and gas. Demographic monitoring was initiated in 1993 with the following objectives: to establish permanent plots to monitor growth, fecundity, recruitment, and mortality for at least 10 years; to identify habitat factors positively associated with cacti presence; and to identify important insect visitors and...