Skip to main content
Advanced Search

Filters: Tags: Diversity (X)

13 results (8ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
We examined the biogeography of aquatic and semiaquatic Heteroptera (ASH) in the Grand Canyon (GC) ecoregion (GCE) on and adjacent to the southern Colorado Plateau. We report 89 ASH taxa in 86 species, 37 genera, and 14 families in the GCE, including 54 ASH taxa detected within or on the rims of GC and its major tributaries, a fauna 3.8-fold greater than previously reported. We tested 2 groups of biogeographic hypotheses to account for this high level of diversity, demonstrating an underlying pattern of mixed biogeographic affinity and strong landform-climate effects. Equal numbers of ASH taxa were derived from allochthonous (neotropical and nearctic) sources and autochthonous (range-centered) sources. A negative...
While there has been extensive interest in understanding the relationship between diversity and invasibility of communities, most studies have only focused on one component of diversity: species richness. Although the number of species can affect community invasibility, other aspects of diversity, including species identity and community evenness, may be equally important. While several field studies have examined how invasibility varies with diversity by manipulating species identity or evenness, the results are often confounded by resource heterogeneity, site history, or disturbance. We designed a mesocosm experiment to examine explicitly the role of dominant species identity and evenness on the invasibility of...
Archived soil samples (1937-1999) and historic air quality data from the Los Angeles Basin were used for reconstructing the record of change between atmospheric NO(x) loads, soil delta(15)N values and the diversity of arbuscular mycorrhizae (AM), which are ubiquitous plant-fungus mutualists that control plant community productivity. A tripling of atmospheric NO(x) loads between 1937 and the 1970s was paralleled by soil nitrogen enrichment (delta(15)N = 3.18). From 1975 onwards, atmospheric NO(x) declined, but soils became nitrogen saturated (delta(15) N = -4 and NO(3)-nitrogen = 171mgkg(-1)). The shifts in the AM community followed 28 years of atmospheric nitrogen enrichment and coincided with the onset of soil...
thumbnail
The Wyoming Natural Diversity Database (WYNDD) maintains a computer database of the locations and biological characteristics of rare plants, rare animals, and important plant communities in Wyoming. The database is in a standard format used by the nationwide network of Natural Heritage programs. Location and biological information from the database is available to the public through data requests submitted to WYNDD.
thumbnail
This thematic map summarizes racial and ethnic diversity in the United States. The Diversity Index shows the likelihood that two persons chosen at random from the same area, belong to different race or ethnic groups. The index ranges from 0 (no diversity) to 100 (complete diversity). The diversity score for the entire United States in 2010 is 60. This data variable is included in Esri’s Updated Demographics (2010/2015). This thematic map summarizes racial and ethnic diversity in the United States. The Diversity Index shows the likelihood that two persons chosen at random from the same area, belong to different race or ethnic groups. The index ranges from 0 (no diversity) to 100 (complete diversity). The diversity...
Arbuscular mycorrhizal (AM) fungi form mutualistic symbioses with the root systems of most plant species. These mutualisms regulate nutrient exchange in the plant?soil interface and might influence the way in which plants respond to increasing atmospheric CO2. In other experiments, mycorrhizal responses to elevated CO2 have been variable, so in this study we test the hypothesis that different genera of AM fungi differ in their response, and in turn alter the plant's response, to elevated CO2. Four species from three genera of AM fungi were tested. Artemisia tridentata Nutt. seedlings were inoculated with either Glomus intraradices Schenck & Smith, Glomus etunicatum Becker & Gerdemann, Acaulospora sp. or Scutellospora...
Forty-nine vegetation transects were measured in 1997 and 1998 to determine the impact of grass seeding after the 1996 Dome Fire, which burned almost 6900 ha of ponderosa pine (Pinus ponderosa Lawson) forest in the Jemez Mountains of north-central New Mexico. High- and moderate-burned areas in Santa Fe National Forest were seeded with a mixture that included the exotic ryegrass (Lolium multiflorum Lam.). Adjacent burned areas of Bandelier National Monument were not seeded, and were used as a control in the post-seeding study. On the seeded plots, foliar cover of ryegrass declined from 1997 to 1998 due to self-inhibition and/or reduced precipitation from 1997 to 1998. Foliar cover and diversity of native forbs were...
In western North America, quaking aspen (Populus tremuloides) is the most common hardwood in montane landscapes. Fire suppression, grazing and wildlife management practices, and climate patterns of the past century are all potential threats to aspen coverage in this region. If aspen-dependent species are losing habitat, this raises concerns about their long-term viability. Though lichens have a rich history as air pollution indicators, we believe that they may also be useful as a metric of community diversity associated with habitat change. We established 47 plots in the Bear River Range of northern Utah and southern Idaho to evaluate the effects of forest succession on epiphytic macrolichen communities. Plots were...
thumbnail
The information and data presented herein serve as the supplement to the report, “Spatial Integration of Biological and Social Objectives to Identify Priority Landscapes for Waterfowl Habitat Conservation”. The purpose of this supplemental material is to encourage exploration of the methods used to develop the spatially explicit products presented in the report. The in depth step-by-step methodology is complemented with a geodatabase to facilitate future refinement of the model as new information becomes available in the future. To repeat the process of developing the spatially explicit products (or to create other composite spatial products by varying objectives and weights), follow the methodology described in...
Categories: Data; Types: Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: Agriculture, American Black Duck, Biological Objectives, Black Ducks, Breeding Waterfowl, All tags...
A new avian richness evaluation method (AREM) was developed and tested for assessing lowland wetland and riparian habitats of the Colorado Plateau. AREM rapidly scores habitats for avian richness from simple observations of habitat characteristics. AREM's predictions were compared with original field data from 76 sites on the Colorado Plateau during the breeding season. Species predictions and detections were highly indicative of the breeding avifauna in regional wetlands studied. AREM has implications for use in mitigation calculations, detection of impaired wetland quality, selection of appropriate indicator species, targeting habitat enhancements, wildlife-based classification of wetland habitats, and assisting...
The frequency and intensity of hurricanes are increasing globally, and anthropogenic modifications in cities have created systems that may be particularly vulnerable to their negative effects. Organisms living in cities are exposed to variable levels of chronic environmental stress. However, whether chronic stress ameliorates or exacerbates the negative effects of hurricanes remains an open question. Here, we consider two hypotheses about the simultaneous consequences of acute disturbances from hurricanes and chronic stress from urbanization for the structure of urban arthropod communities. The tipping point hypothesis posits that organisms living in high stress habitats are less resilient than those in low stress...
After a long period in which fuel loads were sparse, fire recently has occurred with high frequency in the ungrazed riparian zone of the Upper San Pedro River in southern Arizona’s Chihuahuan Desert. We studied four accidental fires that occurred during 1994–2003 (two in different years at the same site). Woody vegetation was contrasted between three burned sites and matched spatial controls, and before and after the most recent fire. Herbaceous vegetation was sampled in multiple years producing a chronosequence of time since fire (from 4 months to 8 years). Riparian fire was associated with reductions in woody plant species diversity and canopy cover. In contrast, fire caused a short-term (2 year) pulse of...
Aim: North America harbours the most diverse freshwater mussel fauna on Earth. This fauna has high endemism at the continental scale and within individual river systems. Previous faunal classifications for North America were based on intuitive, subjective assessments of species distributions, primarily the occurrence of endemic species, and do not portray continent-wide patterns of faunal similarity. The aim of this study is to provide an analytical portrayal of patterns of mussel diversity in a hierarchical framework that informs the biogeographical history of the fauna. Published in Journal of Biogeography, volume 37, issue 1, on pages 12 - 26, in 2010.
    map background search result map search result map Wyoming Natural Diversity Database (WYNDD) USA Diversity Index Spatial Integration of Biological and Social Objectives to Identify Priority Landscapes for Waterfowl Habitat Conservation Wyoming Natural Diversity Database (WYNDD) Spatial Integration of Biological and Social Objectives to Identify Priority Landscapes for Waterfowl Habitat Conservation USA Diversity Index