Treesearch

The Middle Rio Grande (MRG) riparian forest, or "bosque", represents the largest cottonwood gallery riparian forest in the southwestern United States. This reach of the Rio Grande extends from Cochiti Dam downstream 260 Km to San Marcial, New Mexico. It constitutes 8% of the river’s total length and 34% of if its length in New Mexico. The valley traverses three major biotic communities, as defined by Brown and Lowe (1980). The MRG reach can be subdivided into 4 reaches which coincide roughly with the 4 geologic basins or "grabens" along this portion of the Rio Grande Rift. This system has...

In midwestern steppes, precipitation peaks in summer, whereas west of the Rocky Mountains, steppes are characterized by summer drought. In western deserts, the amount of precipitation is highly variable. These different climatic regimes result in differences in prevalence of and resilience to disturbances such as herbivory, and differences in susceptibility to invasion by exotic plants and animals. The timing and predictability of precipitation influences plant phenology and life forms, which in turn influence the distributions and annual cycles of animals such as bison (Bison bison) and...

In this study, we used a modified version of a meta-analysis (compilation and analysis of the literature in which an individual area is subjected to the disturbance and its response is noted) to analyze grazing effects on grassland ecosystems. Prior efforts have focused on one aspect of ecosystem behavior such as productivity or species diversity. In this analysis, we examined several components of ecosystem function that are seldom explored including measures of nutrient cycling and soil compaction. In general, cattle grazing appears to decrease production measures, increase soil compactio...

The ecology of fire in shortgrass prairie of the southern Great Plains includes a complex interaction between the shortgrass prairie ecosystem and its inhabitants, all inextricably linked to land-use patterns. The history of the relationship between man and fire has been filled with ambivalence and mistrust, along with an appreciation of the power of fire as a management tool. Fire is now used as a management tool on at least a limited scale in all areas of North America, and perhaps nowhere is the role of fire in community organization more widely acknowledged than in grassland ecosystems....

The modern North American grassland herpetofauna has evolved in situ since the Miocene. Pleistocene glaciation had a minimal effect except in the far North, with only minor displacements of some species. South of the glaciers, winters were warmer and summers cooler than at present. Snakelike reptiles, leaping frogs, and turtle "tanks" are favored adaptive types in uniform dense grassland. A typical fauna consists of about 10-15 species, mostly snakes. Special habitat components, such as streams and ponds, bare ground, sand, trees, prairie dog towns, and rocky outcrops, add distinct suites...

Of the bat research that has been conducted in the Southwestern states, few studies have addressed species inhabiting grasslands and the potential effects of management activities on these populations. Up to 17 bat species may be found regularly or occasionally in Southwestern grasslands or short-grass prairie. Main habitat requirements of grassland-dwelling bats are suitable roosts, water, and food. Livestock grazing, fire suppression, mining, bridge construction, agriculture, and urbanization affect the quality, quantity, and distribution of these resources. Effects of activities may not...

We analyzed trends of sparrows and towhees captured in fall at the Rio Grande Nature Center, Albuquerque, New Mexico from 1985 to 1994. Species were grouped into three breeding-habitat classes: grassland and shrubsteppe, riparian and deciduous vegetation, and upland forests, woodlands, and edges. Spearman's rank correlations were used to determine whether population trends were similar within and among species groups. We found that steep fluctuations in captures of many species masked population increases or decreases over time. Eight of nineteen (42%) correlations of pairs of species were...

Management of a 775-km2, privately-owned ranch in northeastern Utah exemplifies a progressive approach to utilizing domestic livestock and wild ungulates, elk (Cervus elaphus), mule deer (Odocoileus hemionus), and pronghorn (Antilocapra americana), for economic return while maintaining or enhancing land health. The management program on the Deseret Ranch includes the use of a multiple-herbivore grazing system in balance with the available forage and native wildlife in a sagebrush (Artemisia spp.)-grass ecosystem.

This publication is the result of a half-day symposium, "Ecology, management, and sustainability of western grassland ecosystems," held at The Wildlife Society’s First Annual Technical Conference, September 22-26, 1994 in Albuquerque, NM. The symposium was sponsored by The Wildlife Society's Working Group on Sustainable Use of Ecosystem Resources and was organized by members Deborah Finch, Gale Wolters, and Bertie Weddell. The scope of this working group is the assembly, study, and transfer of information pertaining to the conservation of wildlife through sustainable uses of ecosystem...

Retrospective examination of cutover forests enables the development of models that predict regeneration success as a function of plot conditions and time since disturbance. The modeling process uses a two-state system. In the first state, all plots are analyzed to predict the probability of stocking (at least one established seedling on the plot). In the second state, only stocked plots are analyzed to predict seedling density, species composition, and seedling heights. Outcomes are predicted on a plot basis; therefore, the model is sensitive to variation within the stand. Predictions are...