Treesearch

Each spring, thousands of female lesser long-nosed bats (Leptonycteris yerbabuenae) migrate from southern Mexico to northern Sonora and southern Arizona to have their young and take advantage of seasonably available forage resources, including nectar, pollen, and fruit of columnar cacti. Once the pups are volant, the population begins to disperse across the grasslands of southeastern Arizona, foraging on flowering paniculate agaves (Agave palmeri) and day-roosting in Madrean Sky Islands during their seasonal migration back to southern Mexico. Although the grasslands surrounding Arivaca,...

Developing a method of agricultural field reclamation to native grasses in the Lower San Pedro Watershed could prove to be a valuable tool for educational and practical purposes. Agricultural field reclamation utilizing native grass crop production will address water table depletion, soil degradation and the economic viability of the communities within the watershed. The focus of this study was to analyze the conversion of agricultural fields to native grass crops of three representative sites. Study sites include; a farm with fields that were seeded and allowed to grow for a period of...

The black-tailed prairie dog (Cynomys ludovicianus) was once widely distributed throughout the western United States; however, anthropogenic influences have reduced the species’ numbers to 2 percent of historical populations. Black-tailed prairie dogs are described as a keystone species in the grassland ecosystem, and provide many unique services, including burrows for other species (e.g. burrowing owls [Athene cunicularia] and rattlesnakes [Crotalus spp.]), nutrient rich soil that, in turn, provides rich vegetation for grazers, and food for many carnivores and birds of prey. Several...

Cattle have grazed continuously over the past three centuries in the Sky Island region and most work has focused on how these grazers have affected riparian and grassland habitats. I examined the effects of grazing on a fuller spectrum of desert habitats that occur in the close proximity to the San Bernardino Valley of Mexico and the United States. Plots in each of five habitats were placed in two adjoining areas: where grazing had not occurred for 25+ years and where grazing had only ceased 4+ years before this study. Vegetation responded quickly to removal of cattle in mesic environments...

Effects of low severity prescribed burning treatments and a wildfire on soil erosion and deposition in the oak savannas in the Southwestern Borderlands are reported. Measurements in the spring and fall, respectively, characterize soil movements following winter rains and high-intensity summer rainstorms. Annual values are also presented. Relationships between soil erosion and deposition and precipitation amounts, physiographic characteristics, and vegetation were analyzed to determine possible cause-and-effect implications. The information should be useful in developing strategies for...

Between February and July, 2011, over 360,000 acres burned across the Coronado National Forest during one of the most active fire seasons in recorded history. Burned Area Emergency Response (BAER) Teams evaluated post-fire watershed conditions and prescribed treatments based on threats to known values at risk. Hillslope stabilization treatments were prescribed and implemented for areas of high soil burn severity on both the Horseshoe 2 and Monument Fires. These treatments consisted of seeding on the Horseshoe 2 Fire and application of agricultural straw mulch and seed on the Monument Fire....

Management of the Madrean oak woodlands and the less dense and ecologically different oak savannas must be based on sound ecological information. However, relatively little is known about the Madrean oak ecosystems in spite of the fact that they cover about 80,000 km2 in the southwestern United States and northern Mexico. Emory oak (Quercus emoryi), the dominant tree in most stands, is usually associated with other oak and juniper species. Trees are utilized for firewood, fence posts, and construction materials and oak acorns are gathered as food by local inhabitants. The woodlands and...

Private and public land managers are attempting to reintroduce fire into the ecosystems of the Peloncillo Mountains to reduce the density of woody species, increase the herbaceous plant cover, and improve the area’s ecological diversity. The Cascabel Watershed Study, which includes 12 small gauged watersheds, was started in 2000 to evaluate the impacts of cool-season (November-April) and warmseason (May-October) prescribed fires on biological and physical components of the oak (Quercus spp.) savannas that are common to the Southwestern Borderlands Region. The Whitmire Wildfire in May 2008...

Due to a century of fire suppression practices, the Madrean Archipelago regions in Arizona have accumulated excessive fuel loads that increase wildfire sizes, intensities, and frequencies. Wildfire induced structural changes in forest ecosystems can either benefit or adversely impact wildlife species. Therefore, it is imperative to understand how wildlife species react to such ecosystem changes after wildfires in both the short-term and long-term time periods. We examined scientific literature to determine wildlife distribution, abundance, elevational migration, and behavioral changes...

Thousands of acres of giant saguaro (Carnegiea gigantea) habitat in the Sonoran Desert have been scorched by fire in recent decades. Resource managers struggle to maintain scenic landscapes featuring majestic saguaro faced with the challenges of fire, non-native species invasion, and recreational needs of millions of annual visitors. Successfully managing this iconic plant community requires understanding its fire resilience or intolerance. We compared survival of 162 saguaro 10 years after two wildfires on the Mesa Ranger District, Tonto National Forest, Arizona. Six 350-m point-quarter...