1,588 research outputs found

    Barbaetis: A New Genus of Eastern Nearctic Mayflies (Ephemeroptera: Baetidae)

    Get PDF
    The new genus Barbaetis Waltz and McCafferty, and new species Barbaetis benfieldi Kennedy are described from larvae collected from the New River, Virginia. Barbaetis is easily told from Baetis by the presence of procoxal osmobranchia. Cladistics of B. benfieldi, related Pseudocloeon species, and the lutheri and pavidus complexes of Baetis are presented and indicate the need for further taxonomic revision. The habitat of B. benfieldi is described in terms of several ecological parameters. The new species demonstrates a univoltine life history with postembryonic development restricted to a short springtime period

    Aurora Volume 04

    Get PDF
    College formerly located at Olivet, Illinois and known as Olivet University, 1912-1923 ; Olivet College, 1923-1939 ; Olivet Nazarene College, 1940-1986 ; Olivet Nazarene University, 1986-https://digitalcommons.olivet.edu/arch_yrbks/1003/thumbnail.jp

    New Synonomy in \u3ci\u3eHypogastrura\u3c/i\u3e (Collembola: Hypogastruridae)

    Get PDF
    (excerpt) In the course of faunistic studies of Indiana Collembola, seasonal occurrences of the two species Hypogastrura packardi (Folsom), 1902 and H. notha (MacNamara), 1922 were found to exhibit seasonal dimorphism and population dynamics similar to those patterns observed in cyclomorphic species previously reported in literature (Leinaas 1981 a,b)

    Internal transport barriers in the National Spherical Torus Experiment

    Get PDF
    In the National Spherical Torus Experiment [M. Ono , Nucl. Fusion 41, 1435 (2001)], internal transport barriers (ITBs) are observed in reversed (negative) shear discharges where diffusivities for electron and ion thermal channels and momentum are reduced. While neutral beam heating can produce ITBs in both electron and ion channels, high harmonic fast wave heating can also produce electron ITBs (e-ITBs) under reversed magnetic shear conditions without momentum input. Interestingly, the location of the e-ITB does not necessarily match that of the ion ITB (i-ITB). The e-ITB location correlates best with the magnetic shear minima location determined by motional Stark effect constrained equilibria, whereas the i-ITB location better correlates with the location of maximum ExB shearing rate. Measured electron temperature gradients in the e-ITB can exceed critical gradients for the onset of electron thermal gradient microinstabilities calculated by linear gyrokinetic codes. A high-k microwave scattering diagnostic shows locally reduced density fluctuations at wave numbers characteristic of electron turbulence for discharges with strongly negative magnetic shear versus weakly negative or positive magnetic shear. Reductions in fluctuation amplitude are found to be correlated with the local value of magnetic shear. These results are consistent with nonlinear gyrokinetic simulations predicting a reduction in electron turbulence under negative magnetic shear conditions despite exceeding critical gradients.X1128sciescopu

    Seeding versus natural regeneration: a comparison of vegetation change following thinning and burning in ponderosa pine

    Get PDF
    The decision whether to seed with native species following restoration treatments should be based on existing vegetation, species present in or absent from the soil seed bank, past management history, microclimate conditions and soils. We installed three permanent monitoring plots in two areas (total 18.6 ha) at Mt. Trumbull, AZ. Trees were thinned and the sites burned in 1996 and 1997. A 5 ha area was seeded with native shrub, grass and forb species; the remaining 13.6 ha were unseeded. Pretreatment species richness ranged from none to five species per plot. We recorded 13 graminoid and eight shrub species in the seeded area, and four graminoid and four shrub species in the unseeded area. The greatest increase in species richness in both seeded and unseeded plots occurred approximately 1.8 years posttreatment. Perennial native species dominated plant cover by 2.8 years, although annual native forbs dominate the soil seed bank. Perennial grasses are nearly absent from the seed bank. The seeded area had the highest diversity, but it also had twice as many nonnative species (14 versus 7 in the unseeded plots). By August 1999, maximum species richness reached 51 species on the seeded plot. Of these species, 80 percent were native. Although seeding increases diversity, it may also have the long-term tradeoff of introducing new genotypes and species, both native and nonnative

    Changes in ponderosa pine forests of the Mt. Trumbull Wilderness

    Get PDF
    Ponderosa pine forests in the Mt. Trumbull Wilderness on the Arizona Strip have become dense with young trees and highly susceptible to catastrophic wildfire due to exclusion of the natural frequent-fire regime. As part of a broader regional ecological restoration study, the Mt. Trumbull Wilderness was sampled for fire scarred trees, vegetation, and fuels in 1997 and 1999. Reconstructed fire histories show that fires recurred about every 4.4 years prior to settlement, with larger fires burning every 9.5 years. Frequent fires ceased after 1863 in the Mt. Trumbull Wilderness, coincident with the time of Euro-American settlement around 1870, beginning a fire-free period that has lasted up to the present except for a few small fires and a larger 1989 wildfire. Current forests are dense, averaging approximately 1,200 trees/ha, and dominated by small trees. Throughout the wilderness, tree canopy cover averages over 65(percent) and tree basal area is high, 35- 36 m2/ha. Understory plant cover is about 20(percent) and understory species diversity averages 11.4 species/sample plot. Living and dead fuels, including plants, woody debris, and the forest floor, will easily support high-intensity wildfires. In contrast, the presettlement forest was relatively open, with tree density of approximately 62 trees/ha and basal area averaging 8.9 m2/ha, dominated by large ponderosa pine trees. In ecological terms, prospects are good for restoring the Mt. Trumbull Wilderness to emulate the ecological structure and fire disturbance regime of the presettlement reference condition. The current forest condition is perhaps least affected by recent degradation of any site in the Uinkaret Mountains. However, ecological information is only one component contributing to the debate over appropriate management values and practices in wilderness areas on public lands
    corecore