Treesearch

We evaluated the effect of summer biogeography of migrant wood warblers (Parulidae) on their stopover abundance. To characterize abundance patterns, we used mist-net capture data from spring and fall migration in the Middle Rio Grande Valley, New Mexico, spring migration on the Gulf Coast of Louisiana, and fall migration on the Gulf Coast of Alabama. To describe the summer biogeography of 47 species of wood warblers, we used indices of their summer range size, their summer density, and distance between their summer ranges and our netting sites. Multiple linear regressions indicated that...

Ozone concentrations have been monitored at the Glacier Lakes Ecosystem Experiment Site (GLEES) in the Snowy Range of the Medicine Bow Mountains 55 km west of Laramie, Wyoming, USA. The site is located at 3,186 m elevation in a large subalpine meadow of a mature subalpine forest near timberline. Continuous ozone and meteorological monitoring are a part of the GLEES research to determine the effects of atmospheric deposition on alpine and subalpine ecosystems. Ozone monitoring has shown specific summer and winter diel ozone distribution patterns, typical of remote, rural, high elevation...

The restoration of natural fire to wilderness ecosystems poses a significant challenge to the federal land management agencies. The U.S. Department of the Interior, National Park Service and U.S. Department of Agriculture, Forest Service have conducted progressive prescribed natural fire (PNF) programs for more than two decades. The U.S. Department of the Interior, Bureau of Land Management has only recently approved the use of PNF in a few wilderness areas, whereas the U.S. Department of Interior, Fish and Wildlife Service has relied primarily on the use of management-ignited fires to...

With the increasing demand of people recreating in protected areas, managers around the world are asking questions about how to manage recreation use, whether to limit use, and if so, when to limit use. How do managers decide when recreation use is causing unacceptable resource damage and how to restrict use to limit damage? And how do they know whether restrictions that have been implemented are effective at meeting management goals? In the mid-1980s the Limits of Acceptable Change (LAC) process was formally defined to address these types of questions. Since then, wilderness managers in...

We used radiotelemetry to determine habitat use by flammulated owls (Otus flammeolus) during the breeding season on 452 ha of montane conifer forest in central Colorado in 1982-1983. Mean size and SD of home ranges was 11.1 +/- 1.9 ha (range = 8.5-12.5 ha, n = 4) in 1982 and 18.3 +/- 5.1 ha (range = 14.0-24.0 ha, n = 3) in 1983. Habitat use by nesting males was affected by distribution of old forests of ponderosa pine (Pinus ponderosa) mixed with Douglas-fir (Pseudotsuga menziesii), by topography, and by juxtaposition of home ranges of conspecifics. In spring, both new and returning owls...

Traditionally, state agencies in the United States have invested millions of dollars to collect information on fish populations. Management of fisheries resources often necessitates the sharing of this information across political boundaries. Federal agencies need to share information on fish populations across political boundaries to complete the congressional mandates of the Resource Planning Act (U.S. Forest Service) and Resource Conservation Act (Natural Resources Conservation Service). Further, these data are needed for other analyses such as proposed listings under the Endangered...

Understanding the relationship between animal community dynamics and landscape structure has become a priority for biodiversity conservation. In particular, predicting the effects of habitat destruction that confine species to networks of small patches is an important prerequisite to conservation plan development. Theoretical models that predict the occurrence of species in fragmented landscapes, and relationships between stability and diversity do exist. However, reliable empirical investigations of the dynamics of biodiversity have been prevented by differences in species detection...

Dynamic change - that is what we see in the establishment and development of western larch (Larix occidentalis) forests. Spawned by traumatic events such as fire, harvesting, or post- harvest treatments that prepare receptive seedbeds, larch regenerates promptly and more often than not, excessively over much of its natural range (Schmidt and others 1976).

Boreal forests, which are often undeveloped, are a major source of raw materials for many countries. They are circumpolar in extent and occupy a belt to a width of 1000 km in certain regions. Various conifer and hardwood species ranging from true firs to poplars grow in boreal forests. These species exhibit a wide range of shade tolerance and growth characteristics, and occupy different successional positions. The climate is subarctic, with short growing seasons, and the soils are shallow. Both wildfires and timber harvesting play an important role in shaping the structure and composition...

Infested and uninfested areas within Douglas fir, Pseudotsuga menziesii Mirb.. Franco, stands affected by the Douglas-fir beetle, Dendroctonus pseudotsugae Hopk. were sampled in the Colorado Front Range, CO. Classification tree models were built to predict probabilities of infestation. Regression trees and linear regression analysis were used to model amount of tree mortality in terms of basal area killed in infested stands. Classification trees had cross-validation estimates of classification accuracy ranging from 0.55 to 0.63. The data suggests that Douglas-fir beetle-attacked stands...