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The composition and structure of native riverine ecosystems are tightly linked to natural hydro- logic variability. By managing river flows for water supplies and power generation, water management agencies have inadvertently caused considerable degradation of riverine ecosystems and associated biodiver- sity. New approaches for meeting human needs for water while conserving the ecological integrity of riverine ecosystems are greatly needed. We describe an approach for identifying the natural flooding characteristics that must beprotected or restored to maintain riparian (floodplain) ecosystems along meandering rivers. We developed a computer model to simulate flood-driven changes in the relative abundance of riparian...
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FY2017There is an increasing concern and need for the conservation of springsnails and other endemic mollusks and for conservation of the unique spring and springbrook habitats on which they depend (Hershler et al 2014; Abele 2011). Nationwide, several of these species have been listed as endangered or threatened under provisions of the ESA; others are candidates for federal listing or are undergoing review by USFWS for possible future listing actions. These species can be particularly susceptible to localized threats and specific knowledge necessary for effective site-based conservation is often limited or lacking.Springsnail are particularly susceptible to extinction because the entire population of any single...
The razorback sucker, Xyrauchen texanus, in the middle Green River (U.S.A.) has been described as a static population consisting of old individuals that will eventually disappear through attrition. Capture data between 1980 and 1992 indicated a constant length frequency despite a slow but positive growth rate of individual fish. Abundance and survival estimates indicated that the population of razorback sucker in the middle Green River is precariously low but dynamic. Although high variation existed among survival estimates, no significant decrease in the population between 1982 and 1992 could be detected. The low level of recruitment occurring in the razorback sucker population of the middle Green River was related...
Population genetic structure of boreal toad (Bufo boreas boreas) in Utah: A basis for defining units of conservation, credited to Hogrefe, Todd C, published in 2001.
Given the steady accumulation of empirical studies documenting negative impacts of cattle grazing on diversity and abundance of plant and animal species in the arid southwestern United States (e.g., reviewed by Fleischner [1994] and Belsky et al. [1999] and recently by Walsberg [2005] and Bock et al. [2007] for Arizona), I was disappointed but not surprised by the following comment in arguably the premier scientific journal in conservation: “. . .over the next 50 years, we will need more ranches, not less� (White 2008: 1381). In spite of a wealth of empirical evidence, for many, the cattle industry has been “reconceived� (Brunson & Huntsinger 2008) as a relatively positive environmental force. I have detected...
The lower delta of the Colorado River has been severely affected by the upstream diversion of water for human use. No river water is officially appropriated to support delta wetlands, yet large marsh areas of conservation interest still exist below the agricultural fields in Mexico. These are supported by flood water, agricultural drainage water, municipal sewage effluent, and seawater in the intertidal zone. From 1973 to 1993 the area of freshwater and brackish marsh varied widely, from 5800 to 63,000 ha. A new opportunity exists to restore wetlands in the delta now that the upstream water impoundments on the Colorado River are filled and flood flows are once again being directed to the delta. But flood control...
We examined consensus-based management through the lens of the Colorado River Recovery Implementation Program, a consensus-based plan that attempts to develop the Colorado River's water while protecting its endangered fishes. Because this management model has been touted as a preferred substitute to government-imposed regulation, we analyzed the recovery implementation program to determine its strengths and weaknesses. By reviewing secondary information and interviewing members of the diverse groups involved in the program, we gathered detailed information about the program's history, implementation, and progress. Our investigation revealed that the recovery implementation program has allowed development of the...
Neither time nor resources exist to design conservation plans for every species, particularly for little-studied, noncharismatic,but ecologically important taxa that make up most of biodiversity. To explore the feasibility of basing conservation action on community-level biogeography, we sampled a montane insect community. We addressed three issues: (1) the appropriate scale for sampling insect communities; (2) the association of habitat specialization-perhaps a measure of extinction vulnerability-with other ecological or physical traits; and (3) the correlation of diversity across major insect groups. Using malaise traps in Gunnison County, Colorado, we captured 8847 Diptera (identified to family and morphospecies),...
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Conservation prioritization usually focuses on conservation of rare species or biodiversity, rather than ecological processes. This is partially due to a lack of informative indicators of ecosystem function. Biological soil crusts (BSCs) trap and retain soil and water resources in arid ecosystems and function as major carbon and nitrogen fixers; thus, they may be informative indicators of ecosystem function. We created spatial models of multiple indicators of the diversity and function of BSCs (species richness, evenness, functional diversity, functional redundancy, number of rare species, number of habitat specialists, nitrogen and carbon fixation indices, soil stabilization, and surface roughening) for the 800,000-ha...
In the U.S. National Biological Service's gap analysis, potential distributions of terrestrial vertebrate species are based on the synthesis of wildlife habitat relation data and then modeled using a vegetation cover map derived from Landsat Thematic Mapper imagery. Using long-term species lists from eight National Parks in Utah, we evaluated the adequacy of the wildlife habitat relations data generated by gap analysis in predicting species distributions at landscape scales. Omission and commission error rates were estimated for major taxonomic groups and for each national park. Depending on the taxonomic group, omission error ranged from 0 to 25%, whereas commission error ranged from 4 to 33%. Error rates were...
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FY2017There is an increasing concern and need for the conservation of springsnails and other endemic mollusks and for conservation of the unique spring and springbrook habitats on which they depend (Hershler et al 2014; Abele 2011). Nationwide, several of these species have been listed as endangered or threatened under provisions of the ESA; others are candidates for federal listing or are undergoing review by USFWS for possible future listing actions. These species can be particularly susceptible to localized threats and specific knowledge necessary for effective site-based conservation is often limited or lacking.Springsnail are particularly susceptible to extinction because the entire population of any single...
This cooperative effort by USDA Forest Service Research and the National Forest System assesses the state of knowledge related to the conservation status of four forest carnivores in the western United States: American marten, fisher, lynx, and wolverine. The conservation assessment reviews the biology and ecology of these species. It also discusses management considerations stemming from what is known and identifies information needed. Overall, we found huge knowledge gaps that make it difficult to evaluate the species' conservation status. In the western United States, the forest carnivores in this assessment are limited to boreal forest ecosystems. These forests are characterized by extensive landscapes with...
Survival or extinction of an endangered species is inherently stochastic. We develop statistical methods for estimating quantities related to growth rates and extinction probabilities from time series data on the abundance of a single population. The statistical methods are based on a stochastic model of exponential growth arising from the biological theory of age or stagestructured populations. The model incorporates the socalled environmental type of stochastic fluctuations and yields a lognormal probability distribution of population abundance. Calculation of maximum likelihood estimates of the two unknown parameters in this model reduces to performing a simple linear regression. We describe techniques for rigorously...
The Mexican Spotted Owl (Strix occidentalis lucida) is a threatened subspecies of the southwestern United States and northern Mexico. Although threatened, little is known about its population status. We studied the demography of the Mexican Spotted Owl in one study area in Arizona and one in New Mexico from 1991 to 1997. We estimated annual survival rates (phi), fecundity rates (b), and abundance (N) to test the hypothesis that population trends were stationary Although annual fecundity rates ((b) over bar = 0.494 for Arizona and 0.380 for New Mexico) and annual juvenile survival rates ( = 0.179 for Arizona and 0.109 for New Mexico) differed in magnitude between the study areas, they exhibited similar temporal patterns....
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FY2017There is an increasing concern and need for the conservation of springsnails and other endemic mollusks and for conservation of the unique spring and springbrook habitats on which they depend (Hershler et al 2014; Abele 2011). Nationwide, several of these species have been listed as endangered or threatened under provisions of the ESA; others are candidates for federal listing or are undergoing review by USFWS for possible future listing actions. These species can be particularly susceptible to localized threats and specific knowledge necessary for effective site-based conservation is often limited or lacking.Springsnail are particularly susceptible to extinction because the entire population of any single...
Roads are believed to be a major contributing factor to the ongoing spread of exotic plants. We examined the effect of road improvement and environmental variables on exotic and native plant diversity in roadside verges and adjacent semiarid grassland, shrubland, and woodland communities of southern Utah ( U.S.A. ). We measured the cover of exotic and native species in roadside verges and both the richness and cover of exotic and native species in adjacent interior communities ( 50 m beyond the edge of the road cut ) along 42 roads stratified by level of road improvement ( paved, improved surface, graded, and four-wheel-drive track ). In roadside verges along paved roads, the cover of Bromus tectorum was three times...
In the U.S. National Biological Service's gap analysis, potential distributions of terrestrial vertebrate species are based on the synthesis of wildlife habitat relation data and then modeled using a vegetation cover map derived from Landsat Thematic Mapper imagery. Using long-term species lists from eight National Parks in Utah, we evaluated the adequacy of the wildlife habitat relations data generated by gap analysis in predicting species distributions at landscape scales. Omission and commission error rates were estimated for major taxonomic groups and for each national park. Depending on the taxonomic group, omission error ranged from 0 to 25%, whereas commission error ranged from 4 to 33%. Error rates were...
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Livestock grazing is the most ubiquitous land use in western North America, yet it rarely has been studied in a controlled manner because of the lack of large areas free of grazing. We compared the ecological effects of three grazing treatments—long-term protection, short-term protection, and currently grazed—at Chaco Culture National Historic Park in northern New Mexico. Chaco has a long history of human habitation and is now one of the largest grazing exclosures in the American West. We studied the effects of livestock grazing on the cover of plants, soil crusts, and plant species richness at six sites with different potential natural vegetation. Species richness was higher under long-term protection than under...
The Whooping Crane (Grus americana) is an endangered bird that suffered a severe population bottleneck; only 14 adults survived in 1938. We assessed the genetic effect of this human-caused bottleneck by sequencing 314 base pairs (bp) of the mitochondrial DNA control region from cranes that lived before, during and after this bottleneck. The maximum length of DNA amplifiable from museum specimens was negatively correlated with age, and only 10 of 153 specimens yielded the entire 314 bp sequence. Six haplotypes were present among the prebottleneck individuals sequenced, and only one of these persists in the modern population. The most common modern haplotype was in low frequency in the prebottleneck population, which...
: The Colorado River of the United States and Mexico is extensively dammed and diverted; only a fraction of its previous flow still reaches its estuary. How has the lack of freshwater inflow affected the estuary's biota? Because no prediversion studies are available for comparison, we examined the composition and geochemistry of subfossil shells dating from before the Colorado's diversion. The bivalve mollusc Mulinia coloradoensis was once the most abundant species of clam inhabiting the Colorado Delta. Today, however, only a small population survives near the mouth of the river. The relative abundance of empty shells of this species decreases with increasing distance from the mouth of the Colorado River, indicating...


map background search result map search result map Prioritizing Conservation Effort through the Use of Biological Soil Crusts as Ecosystem Function Indicators in an Arid Region Effects of Historic Livestock Grazing on Vegetation at Chaco Culture National Historic Park, New Mexico Development of a Regional Springsnail Conservation Strategy Development of a Regional Springsnail Conservation Strategy Development of a Regional Springsnail Conservation Strategy Effects of Historic Livestock Grazing on Vegetation at Chaco Culture National Historic Park, New Mexico Prioritizing Conservation Effort through the Use of Biological Soil Crusts as Ecosystem Function Indicators in an Arid Region Development of a Regional Springsnail Conservation Strategy Development of a Regional Springsnail Conservation Strategy Development of a Regional Springsnail Conservation Strategy