Treesearch

The Forest Service Remote Sensing Applications Center (RSAC) and the U.S. Geological Survey Earth Resources Observation and Science (EROS) Data Center produce Burned Area Reflectance Classification (BARC) maps for use by Burned Area Emergency Response (BAER) teams in rapid response to wildfires. BAER teams desire maps indicative of fire effects on soils, but green and nonphotosynthetic vegetation and other materials also affect the spectral properties of post-fire imagery. Our objective was to assess how well satellite image-derived burn severity indices relate to a suite of immediate...

The number of catastrophic wildfires in the U.S. has been steadily rising. The nation has spent more than $1 billion annually to suppress such fires in eight of the past 10 years. In 2005 a record 8.7 million acres burned, only to be succeeded by 9.9 million acres in 2006. And this year is off to a furious start. To a great extent, the increase in fires stems from a buildup of excess fuel, particularly deadwood and underbrush. Forests harbor more fuel than ever in large part because for decades, land management agencies, including the U.S. Forest Service, have followed a policy of trying...

In principle, natural selection should have endowed species with the ability to assess their normal surroundings and respond to changes that enhance, or at least do not diminish, their fitness (Emlen et al. 1998). Hence, the chameleon changes colors to match its background to avoid being eaten, or a sweet pea's tendrils wrap around supporting structures. Buffalo gourds assess the level of phosphorus in determining their floral sex ratios (Pendleton 2000), and animals use photoperiod to precisely time the onset and termination of breeding activities for successful reproduction under...

This study using a modified Robel pole was conducted in the central Black Hills, South Dakota. The objectives were to test the relationship between visual obstruction readings and standing herbage, develop guidelines for monitoring, and estimate sample size. The relationship between visual obstruction and standing herbage was linear with 2 segments in a piecewise model. Regression coefficients were highly significant (P [less than/equal to] 0.001). Standard error of the estimate for a single mean was 373 kg [dot] ha-1. Herbage ranged from 89 to 3821 kg [dot] ha-1 with a mean of 1416 kg...

In western North America, quaking aspen (Populus tremuloides Michx.) is the most common hardwood in montane landscapes. Fire suppression, grazing, wildlife management practices, and climate patterns of the past century are some of the threats to aspen coverage in this region. Researchers are concerned that aspen-dependent species may be losing habitat, thereby threatening their long-term local and regional viability. Though lichens have a rich history as air pollution indicators, I believe that they may also be useful as a metric of community diversity associated with habitat change. To...

The Great Basin is a series of unique ecosystems. Starting at the western edge of the Sierra Nevada mountain range in California it stretches east to the Wasatch Mountains of Utah. In the north it starts in central Oregon and Idaho and stretches south through out most of Nevada. In all the Great Basin is found in five states of the western U.S. The Great Basin supports three dominant plant communities: sagebrush, salt desert, and pinyon-juniper (BLM 2000). Sagebrush communities, consisting of a mix of shrubs, perennial grasses, and forbs, are the Great Basin's most common. The whole basin...

As part of the Great Basin Restoration Initiative, the effects of browsing, competition removal, pruning, fertilization and seed collection methods on increasing seed production in Wyoming big sagebrush (Artemisia tridentata Nutt. spp wyomingensis Beetle & Young) were studied. Study sites were located in Idaho, Nevada, and Utah. A split-plot design with a complete factorial arrangement was implemented to determine the effects of the treatments. Removal of competition from Wyoming big sagebrush shrubs increased seed production significantly (P < 0.05) at both the regional and site levels,...

Helianthus paradoxus (the Pecos or puzzle sunflower) is a threatened, federally listed annual species that is found in a few locations in west Texas and New Mexico. Two greenhouse experiments were conducted to evaluate the ability of H. paradoxus to compete with its progenitors and a with potential ecosystem competitor, Distichlis spicata (saltgrass) in simulated salt marsh and non-salt marsh environments. The results were usually dependent on soil salinity. Helianthus paradoxus was the better competitor in high saline soil and its progenitor H. annuus (common sunflower) was the better...

Astrophytum asterias, commonly called star cactus, is a federally listed endangered cactus endemic to the Tamaulipan thornscrub ecoregion of extreme southern Texas, USA, and Tamaulipas and Nuevo Leon, Mexico. Only three metapopulations totaling less than 4000 plants are presently known in Texas. Star cactus, known locally as “star peyote”, is highly sought by collectors. This small, dome-shaped, spineless, eightribbed cactus is sometimes mistaken for peyote (Lophophora williamsii), which grows in the same or adjacent habitats. Peyote is harvested from native thornscrub habitats in Texas by...

Populations of long-spur columbine (Aquilegia longissima) with spurs 10-16 cm long are known only from a few populations in Texas, a historical collection near Baboquivari Peak, Arizona, and scattered populations in Coahuila, Chihuahua, and Nuevo Leon, Mexico. Populations of yellow columbine with spurs 7-10 cm long are also found in Arizona, Texas, and Mexico, and are now classified as A. longissima in the recent Flora of North America. In a multivariate analysis of floral characters from 11 yellow columbine populations representing a continuous range of spur lengths, populations with...