The effects of two fuel reduction treatments on chaparral communities in southwest Oregon

Fuel reduction treatments are being applied to public lands, affecting significant acreage at considerable expense. This study compares the short term effects on a chaparral plant community of two different fuel reduction methods, brush mastication and "hand piling and burning" (HPB). Ceanothus cuneatus dominated the southwestern Oregon study sites where permanent paired plots were established on either side of treatment-control boundaries. Two years of sampling included a census of all vascular plant species within each plot and an abundance measure for each species. Species composition and abundance were analyzed using multivariate statistical techniques. Differences in species composition were detected for plots grouped by presence-absence of small Ceanothus, as well as plots grouped by abundance of mature Ceanothus. There were more Ceanothus seedlings in treatments than in controls. Abundance of all stages of Ceanothus was more reduced by the mastication treatment than the HPB treatment. The plot characteristic that had the most influence on species composition was the presence of a tree canopy which was positively correlated with abundance of perennial species. Both Ceanothus and oak canopy provided areas with higher abundance of natives and perennials compared to open areas that were dominated by exotic annual grasses. The effects of treatment were surprisingly small. Time passed since treatment, 1 yr or 2 yr, had a stronger effect on species composition than did the method of treatment. Species abundance and richness were greatest in the first year after treatment compared to the second year or to controls. In the mastication treatment, species abundance and richness were lower than in their controls in the second year after treatment. These measures were reduced in the second year HPB treatment plots compared to the first year, but were still higher than in controls. In general, fuel reduction treatments appeared to increase the abundance of annuals, forbs, exotics, introduced weeds, and special status plants (taxa monitored by the Bureau of Land Management) during the first two years after treatments. Special status plants did not appear to be negatively affected by treatment, but treatment areas excluded known sites of occurrence for these species so there was scant data. The HPB treatment had a greater effect on plant communities than the mastication treatment because of the inclusion of fire rings remaining after the burning of piles. In the second year after treatment, fire rings had a higher proportion of annuals, exotics, and introduced weeds than their surrounding HPB treatment plots. Ceanothus germination was stimulated in fire rings but also occurred in the majority of plots, whether treatment or control. Resprouting of cut Ceanothus stems was also common in both types of treated plots. Short term evidence suggests that the HPB treatment may lead to an increase in weedy and/or exotic species and the mastication treatment may reduce species diversity. The HPB treatment may increase species diversity by allowing fire-cued species to establish. When applied to limited areas, both treatments will increase the heterogeneity of the overall chaparral community in the absence of wildfire, which also increases heterogeneity

Root pathogen diversity and composition varies with climate in undisturbed grasslands, but less so in anthropogenically disturbed grasslands

Soil-borne pathogens structure plant communities, shaping their diversity, and through these effects may mediate plant responses to climate change and disturbance. Little is known, however, about the environmental determinants of plant pathogen communities. Therefore, we explored the impact of climate gradients and anthropogenic disturbance on root-associated pathogens in grasslands. We examined the community structure of two pathogenic groups—fungal pathogens and oomycetes—in undisturbed and anthropogenically disturbed grasslands across a natural precipitation and temperature gradient in the Midwestern USA. In undisturbed grasslands, precipitation and temperature gradients were important predictors of pathogen community richness and composition. Oomycete richness increased with precipitation, while fungal pathogen richness depended on an interaction of precipitation and temperature, with precipitation increasing richness most with higher temperatures. Disturbance altered plant pathogen composition and precipitation and temperature had a reduced effect on pathogen richness and composition in disturbed grasslands. Because pathogens can mediate plant community diversity and structure, the sensitivity of pathogens to disturbance and climate suggests that degradation of the pathogen community may mediate loss, or limit restoration of, native plant diversity in disturbed grasslands, and may modify plant community response to climate change

Conductivity of graphene: How to distinguish between samples with short and long range scatterers

Applying a quasiclassical equation to carriers in graphene we found a way how to distinguish between samples with the domination of short and long range scatterers from the conductivity measurements. The model proposed explains recent transport experiments with chemically doped as well as suspended graphene.Comment: 6 pages, 3 figures, some references have been corrected and revise

Coupled ecological and management connectivity across administrative boundaries in undeveloped landscapes

Human-induced ecological boundaries, or anthropogenic ecotones, may arise where administrative boundaries meet on undeveloped lands. Landscape-level ecological processes related to factors such as fire, invasive species, grazing, resource extraction, wildlife, and water may be affected due to unique management strategies adopted by each administrative unit. Over time, different management can result in discernible ecological differences (e.g., species composition or soil characteristics). Thus, fragmentation in the management landscape can correspond to ecological fragmentation. Different ecological patterns may emerge due to an increase in the number of management units in a region, or due to an increase in the number of different types of management units in the region. Temporal effects and collaboration history can also affect the emergence of ecotones. We use conceptual models to explore the relationship between these aspects of management fragmentation and the anthropogenic ecotones between management parcels. We then use examples of different management challenges to explore how anthropogenic ecotones can disrupt ecological flows. Our models suggest that cross-boundary collaboration that enhances management connectivity is likely essential to ecological connectivity in the face of environmental and social change

Quantifying ecological variation across jurisdictional boundaries in a management mosaic landscape

Context Large landscapes exhibit natural heterogeneity. Land management can impose additional variation, altering ecosystem patterns. Habitat characteristics may reflect these management factors, potentially resulting in habitat differences that manifest along jurisdictional boundaries. Objectives We characterized the patchwork of habitats across a case study landscape, the Grand Canyon Protected Area-Centered Ecosystem. We asked: how do ecological conditions vary across different types of jurisdictional boundaries on public lands? We hypothesized that differences in fire and grazing, because they respond to differences in management over time, contribute to ecological differences by jurisdiction. Methods We collected plot-scale vegetation and soils data along boundaries between public lands units surrounding the Grand Canyon. We compared locations across boundaries of units managed differently, accounting for vegetation type and elevation differences that pre-date management unit designations. We used generalized mixed effects models to evaluate differences in disturbance and ecology across boundaries. Results Jurisdictions varied in evidence of grazing and fire. After accounting for these differences, some measured vegetation and soil properties also differed among jurisdictions. The greatest differences were between US Forest Service wilderness and Bureau of Land Management units. For most measured variables, US Forest Service non-wilderness units and National Park Service units were intermediate. Conclusions In this study, several ecological properties tracked jurisdictional boundaries, forming a predictable patchwork of habitats. These patterns likely reflect site differences that pre-date jurisdictions as well as those resulting from different management histories. Understanding how ecosystem differences manifest at jurisdictional boundaries can inform resource management, conservation, and cross-boundary collaborations

Superconductivity coexisting with phase-separated static magnetic order in (Ba,K)Fe2_{2}As2_{2}, (Sr,Na)Fe2_{2}As2_{2} and CaFe2_{2}As2_{2}

The recent discovery and subsequent developments of FeAs-based superconductors have presented novel challenges and opportunities in the quest for superconducting mechanisms in correlated-electron systems. Central issues of ongoing studies include interplay between superconductivity and magnetism as well as the nature of the pairing symmetry reflected in the superconducting energy gap. In the cuprate and RE(O,F)FeAs (RE = rare earth) systems, the superconducting phase appears without being accompanied by static magnetic order, except for narrow phase-separated regions at the border of phase boundaries. By muon spin relaxation measurements on single crystal specimens, here we show that superconductivity in the AFe$_{2}$As$_{2}$ (A = Ca,Ba,Sr) systems, in both the cases of composition and pressure tunings, coexists with a strong static magnetic order in a partial volume fraction. The superfluid response from the remaining paramagnetic volume fraction of (Ba$_{0.5}$K$_{0.5}$)Fe$_{2}$As$_{2}$ exhibits a nearly linear variation in T at low temperatures, suggesting an anisotropic energy gap with line nodes and/or multi-gap effects.Comment: 14 pages 7 figures (4 for main text and 3 for on-line supplementary documents

The effect of electro-hydrodynamic shockwaves on the quality of striploin and brisket beef muscles during long-term storage

Shockwaves generate instantaneous high pressures, which could affect meat shelf-life or quality. This study assessed microbiological counts, pH, drip, cook and moisture loss and texture of striploin (longissimus lumborum) and brisket (pectoralis profundus) treated with electrical shockwave (25 kV, 8 pulses) and subsequently stored (−0.5 °C) for 0, 4, 8, 12, 16 and 20 weeks. Shockwave did not affect total viable counts (p>0.05), with all samples considered microbiologically acceptable (0.05). Shockwave × storage time increased moisture losses in striploin (p<0.01) and brisket (p<0.01) at week 0 but this decreased over subsequent storage weeks. Shockwave technology did not affect meat shelf-life and has potential for beef tenderisation

Vibrational Enhancement of the Effective Donor - Acceptor Coupling

The paper deals with a simple three sites model for charge transfer phenomena in an one-dimensional donor (D) - bridge (B) - acceptor (A) system coupled with vibrational dynamics of the B site. It is found that in a certain range of parameters the vibrational coupling leads to an enhancement of the effective donor - acceptor electronic coupling as a result of the formation of the polaron on the B site. This enhancement of the charge transfer efficiency is maximum at the resonance, where the effective energy of the fluctuating B site coincides with the donor (acceptor) energy.Comment: 5 pages, 3 figure