Treesearch

Pediocactus knowltonii is a rare, endemic cactus that is presently known to occur on a single 10-hectare hill in northwestern New Mexico near the Colorado border. It was listed as federally endangered in 1979. Population monitoring and recovery actions were initiated when the Recovery Plan was adopted in 1985. The land at the type locality has been donated to The Nature Conservancy and long-term monitoring plots have been annually studied since 1986. This population reached peak density in 1994 and is presently in decline. A total of 301 clones were made and transplanted to two nearby...

During the summer of 1992, a natural wildfire burned 250 acres of juniper savanna on Rawhide Ridge in the Guadalupe Mountains of southeastern New Mexico. This fire burned through the center of a Kuenzler's hedgehog cactus population. This threatened cactus is locally sympatric with the more abundant nylon hedgehog cactus, which has similar growth form and stature. The local populations of both cacti were assessed within equal areas of burned and unburned habitats in May 1999. Burn area density of Kuenzler's hedgehog cactus was about one-third the density of unburned habitat. Nylon hedgehog...

Arabis johnstonii Munz (Johnston’s rock cress) is a small herbaceous perennial plant endemic to the San Jacinto Mountains of southern California. It is considered rare by the California Native Plant Society and is a Forest Service Sensitive species. Three A. johnstonii occurrences grow within an area that the San Bernardino National Forest plans to burn for hazardous fuel reduction. Prior to this study little was known about fire effects on A. johnstonii. We used a 1.1 m diameter cylindrical stainless steel wire “fire cage” within which we conducted small-scale experimental burns on twenty...

Nichol’s Turk’s Head Cactus (Echinocactus horizonthalonius var. nicholii L. Benson; Cactaceae) occurs in a few isolated populations in the Sonoran desert of southcentral Arizona (Pima and Pinal counties). The populations of this variety are disjunct from the more widespread variety that occurs in the Chihuahuan desert of Texas and Mexico. This species occurs only on limestone-derived soils, and the nicholii variety was federally listed as endangered in 1979. Since 1995 we have monitored study plots of this cactus in the Waterman Mountains (AZ), measuring growth and reproduction of about...

One prerequisite to the use of light detection and ranging (LiDAR) across disciplines is differentiating ground from nonground returns. The objective was to automatically and objectively classify points within unclassified LiDAR point clouds, with few model parameters and minimal postprocessing. Presented is an automated method for classifying LiDAR returns as ground or nonground in forested environments occurring in complex terrains. Multiscale curvature classification (MCC) is an iterative multiscale algorithm for classifying LiDAR returns that exceed positive surface curvature thresholds...

A complex geologic history has shaped the distribution of Arizona willow (Salix arizonica Dorn) and the Mogollon paintbrush (Castilleja mogollonica Pennell). These subalpine plants do not appear to be strict substrate specialists, but they do seem to favor coarse-textured and well-watered soils. Most of their occupied habitats were shaped by Quaternary glaciations, but are ultimately derived from felsic substrates formed before the Pliocene period. Populations of Arizona willow have been identified in the White Mountains of Arizona, the High Plateaus of Utah, and in the Southern Rocky...

In recent years, more researchers are collecting data either on active wildfires or immediately after wildfire occurrence. Known as Rapid Response Research, this important undertaking provides real-time information, useful data, and improved tools for managers.

Burn severity is mapped after wildfires to evaluate immediate and long-term fire effects on the landscape. Remotely sensed hyperspectral imagery has the potential to provide important information about fine-scale ground cover components that are indicative of burn severity after large wildland fires. Airborne hyperspectral imagery and ground data were collected after the 2002 Hayman Fire in Colorado to assess the application of high resolution imagery for burn severity mapping and to compare it to standard burn severity mapping methods. Mixture Tuned Matched Filtering (MTMF), a partial...

The Arizona willow (Salix arizonica Dorn) is a rare species growing in isolated populations at the margins of the Colorado Plateau. Although its habitat in the White Mountains of Arizona has been mischaracterized as basaltic, the area is actually a complex mixture of felsic, basaltic and epiclastic formations. Comparing the distribution of the Arizona willow to mapped geologic formations revealed that occupied sites are strongly associated with felsic, coarse-textured Mount Baldy formations. The most robust subpopulations are located in three glaciated reaches, but about half occur in...

Accurate production of regional burned area maps are necessary to reduce uncertainty in emission estimates from African savannah fires. Numerous methods have been developed that map burned and unburned surfaces. These methods are typically applied to coarse spatial resolution (1 km) data to produce regional estimates of the area burned, while higher spatial resolution (65% at the MODIS scale, presumably because of the decrease in signal-to-noise ratio as compared to the Landsat scale. At the MODIS scale the Mid-Infrared Bispectral Index (MIRBI) using a fixed threshold of >1.75 was determine...