Many species of plants and animals associated with grasslands are rare or declining due to habitat loss and degradation. Although grassland plants and insects evolved in the context of both grazing and fire, the appropriate use of grazing and fire has been debated among those concerned with protecting insect communities. We established an experiment to test insect responses to three grassland management treatments: (1) patch‐burn graze (burning of spatially distinct patches and free access by cattle), (2) graze‐and‐burn (burning of entire tract with free access by cattle), and (3) burn‐only. Because we expected that land‐use legacies could also affect insect abundance and diversity, we evaluated effects of time since fire, grazing history, remnant history (remnant or reconstructed grassland) and pre‐treatment vegetation characteristics, which were assumed to be a legacy of prior land‐use. Butterflies (Lepidoptera), ants (Hymenoptera: Formicidae), and leaf beetles (Coleoptera: Chrysomelidae) were surveyed for three years to compare their responses to each of these treatments as measured by abundance, richness and species diversity. Each of these taxa is relatively diverse and was expected to have the potential to have strong negative responses to grazing and burning, but we predicted more positive responses to patch‐burn grazing. Our results showed that land‐use legacies affected insect abundance, richness and diversity, but treatments did not. Ant abundance was lower in tracts with a history of heavy grazing. Ant species richness was positively associated with pre‐treatment time since fire and vegetation height and negatively associated with pre‐treatment proportion native plant cover. Butterfly abundance was positively associated with pre‐treatment litter cover. Leaf beetle diversity was positively associated with pre‐treatment native plant cover, and leaf beetle abundance was negatively associated with time since fire. Our results indicate that land‐use legacies can exert more influence on grassland insect community composition than current management, but the particular aspects of these land‐use legacies that are important vary across insect taxa. The implications of these finding are that (1) land‐use legacies should garner more attention in grassland management and (2) conservation of grassland insect communities will be improved by taxon‐specific analysis of land‐use legacy variables.
In the BATHOLITHSonland seismic project, a refraction – wide-angle reflection survey was shot in 2009 across the Coast Mountains and Interior Plateau of central British Columbia. Part of the seismic profile crossed the Nechako Basin, a Jurassic–Cretaceous basin with potential for hydrocarbons within sedimentary strata that underlies widespread volcanic rocks. Along this 205 km-long line segment, eight large explosive shots were fired into 980 seismometers. Forward and inverse modelling of the traveltime data were conducted with two independent methods: ray-tracing based modelling of first and secondary arrivals, and a higher resolution wavefront-based first-arrival seismic tomography. Material with velocities less than 5.0 km/s is interpreted as sedimentary rocks of the Nechako Basin, while velocities from 5.0–6.0 km/s may correspond to interlayered sedimentary and volcanic rocks. The greatest thickness of sedimentary rocks in the basin is found in the central 110 km of the profile. Two sub-basins were identified in this region, with widths of 20–50 km and maximum sedimentary depths of 2.5 and 3.3 km. Such features are well-defined in the velocity model, since resolution tests indicate that features with widths greater than ∼13 km are reliable. Beneath the sedimentary rocks, seismic velocities increase more slowly with depth — from 6.0 km/s just below the basin to 6.3 km/s at ∼17 km in depth, and then to 6.8–7.0 km/s at the base of the crust. The Moho is found at a depth of 33.5–35 km beneath the profile, and mantle velocities are high at 8.05–8.10 km/s.
Despite the growing body of research concerning victimization and mental health among college populations around the world, there remains a need for additional studies that emphasize the role that victimization has on mental health. This study builds on previous research by analyzing the relationship between mental distress and victimization status in Spanish college students ( n = 828, 490 women and 338 men). Using online surveys, we examined the prevalence rates of seven types of victimization (threats, insults, online slander, theft, physical abuse, sexual harassment, and sexual abuse) and three mental health disorders (stress, anxiety, and depression, as measured by the DASS-21 [Depression Anxiety Stress Scale-21]) among students at two universities in southeastern Spain. According to their victimization experiences during the 12 months prior to the interviews, participants were classified into three victimization status groups: nonvictims (42.3%), single-type victims (23.3%), and polyvictims (34.4%). Except for threat and physical abuse, women reported significantly higher rates than men for each type of victimization and were classified more often as polyvictims. MANCOVA showed significant associations between polyvictimization and all three indicators of mental distress after controlling for sex. Interestingly, there were no differences between single-type victims and nonvictims in their self-reported levels of anxiety, stress, and depression. Female students reported a higher prevalence of severe and extremely severe levels of anxiety and stress than did their male counterparts. This study highlights the fact that a nontrivial proportion of college students experience mental distress, reinforces the existing link between polyvictimization and mental health disorders, and stresses the importance of violence awareness and prevention activities targeting this population.
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