The influence of induced host moisture stress on the growth and development of western spruce budworm and Armillaria ostoyae on grand fir seedlings

This greenhouse study evaluates the influence of separately and simultaneously imposed water stress, western spruce budworm (Choristorneura occidentalis Freeman) defoliation, and inoculation with the root pathogen, Armillaria ostoyae (Romagn.) Herink, on the growth and biochemical features of Abies .grandis (Dougl.) Lindi. Seedling biomass, plant moisture status, bud phenology, and allocation patterns of phenolics, carbohydrates, and key nutrients (nitrogen, phosphorus, potassium and sulfur) are reported. Hypotheses are developed and tested on the impacts of water-stress, defoliation, and root inoculation, on western spruce budworm growth and development, and Armillaria ostoyae-caused mortality and infection. Western spruce budworm larvae fed on water-stressed seedlings had higher survival rates, grew faster, and produced larger pupae than those fed on well-watered seedlings. There is no clear reason for the positive insect response, but changes in foliage nutrient patterns and phenolic chemistry are indicated. Insect caused defoliation has been earlier reported to enhance successful colonization of Armillaria spp. on deciduous trees in the forests of the northeastern United States. The positive response of the fungus was attributed to a weakened tree condition. Conversely, although this study conclusively found water-limited trees to have increased susceptibility to A. ostoyae, defoliation significantly lowered Armillaria-caused infection and mortality. The decline in infection success is attributed to defoliation-caused reduction in plant water stress and an alteration of root carbohydrate chemistry. One and/or two years of defoliation did not appear to weaken the physiological condition of seedlings. Conversely, water-stressed seedlings that were also defoliated produced more buds, had an earlier bud phenology, contained higher total reserve carbohydrates, and had little Armillaria-caused mortality. The study suggests that during drought, short-term defoliation may be beneficial to grand fir and its associated forest community. Also, the additive effects of simultaneously occurring A. ostoyae and western spruce budworm may not be as severe as conventionally believed. Ecological and forest management implications are explored

Qualitative Research Methods in the Living Lab: Reflecting upon a learning and teaching approach for promoting psychological literacy.

This report describes and reflects upon an approach to embedding psychological literacy within the core Research Methods curriculum in a small university in the United Kingdom. Psychology students were involved in the ‘Living Lab: Feeding the Campus’ project, an interdisciplinary network of students and staff aiming to find solutions for local issues of direct relevance to students’ lives. The Living Lab focused on understanding and improving the campus food system in the context of ecological justice. Undergraduate psychology students participated through the Qualitative Research Methods, a compulsory second-year module. Psychology students conducted interview studies related to food topics such as poverty, identities and culture, community gardens, waste, sustainable lifestyles, and activism. Students collected data on campus to examine food-related experiences within the university community. Findings are being used to inform changes in the university. In this report, we describe the first iteration of involving psychology students in the Living Lab. Our approach involved an authentic assessment, participation in events and fieldtrips and interdisciplinary collaboration. We combine insights from student feedback with staff reflections on its implementation and impact. Finally, we discuss the potential of using research methods modules as a way to facilitate psychological literacy

Contrasting distribution patterns of invasive and naturalized non-native species along environmental gradients in a semi-arid montane ecosystem

Questions: Mountain systems have high abiotic heterogeneity over local spatial scales, offering natural experiments for examining plant species invasions. We ask whether functional groupings explain non-native species spread into native vegetation and up elevation gradients.We examine whether non-native species distribution patterns are related to environmental variables after controlling for elevation and, thus, driven by niche processes. Location: TheWallowa Mountains, northeast Oregon, USA. Methods: We surveyed non-native plant species along three mountain roads and into the native habitat matrix to assess the extent of invasion success along distance from roadside and elevation gradients. We used GLM to predict single species occurrence probabilities, LMM to examine differences in distribution patterns among functional types, and pCCA to examine multivariate responses of the non-native community to ecological variables. Results: Probability of occurrence of the eight focal invasive species was not significantly related to distance from the road, but declined with elevation. Nonnative species with annual life history strategies were more restricted to lower elevations than perennial species. Non-native species considered invasive occurred at lower minimum elevations than naturalized species. Shifts in the species composition of the non-native plant community were related to changes in soil and climate variables. Conclusions: Our results suggest that invasive species have similar patterns of habitat associations and spread from roadsides to interior vegetation zones, whereas naturalized species partition environmental gradients in this semi-arid montane ecosystem. Furthermore, annual and invasive species groups occupy lower elevations and perennial and naturalized species groups have invaded further up the mountain roads and into the native vegetation. Thus, functional groupings may explain contrasting distribution patterns of non-native species and could be used to inform management strategies for non-native species.This is the publisher’s final pdf. The article is copyrighted by International Association for Vegetation Science and published by John Wiley & Sons, Ltd.. It can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291654-109XKeywords: Community assembly, Plant invasions, Elevation gradient, Species turnover, Disturbance, Non-native species, Habitat filtering, Functional group

Grassland Response to Herbicides and Seeding of Native Grasses 6 Years Posttreatment

Herbicides are the primary method used to control exotic, invasive plants. This study evaluated restoration efforts applied to grasslands dominated by an invasive plant, sulfur cinquefoil, 6 yr after treatments. Of the five herbicides we evaluated, picloram continued to provide the best control of sulfur cinquefoil over 6 yr. We found the timing of picloram applications to be important to the native forb community. Plots with picloram applied in the fall had greater native forb cover. However, without the addition of native perennial grass seeds, the sites became dominated by exotic grasses. Seeding resulted in a 20% decrease in exotic grass cover. Successful establishment of native perennial grasses was not apparent until 6 yr after seeding. Our study found integrating herbicide application and the addition of native grass seed to be an effective grassland restoration strategy, at least in the case where livestock are excluded.This is the publisher’s final pdf. The published article is copyrighted by the Weed Science Society of America and can be found at: http://wssajournals.org/loi/ipsmKeywords: wildlife management., Potentilla recta L., rangeland, sulfur cinquefoilKeywords: wildlife management., Potentilla recta L., rangeland, sulfur cinquefoi

Ungulate Browsing Maintains Shrub Diversity in the Absence of Episodic Disturbance in Seasonally-Arid Conifer Forest

Ungulates exert a strong influence on the composition and diversity of vegetation communities. However, little is known about how ungulate browsing pressure interacts with episodic disturbances such as fire and stand thinning. We assessed shrub responses to variable browsing pressure by cattle and elk in fuels treated (mechanical removal of fuels followed by prescribed burning) and non-fuels treated forest sites in northeastern Oregon, US. Seven treatment paddocks were established at each site; three with cattle exclusion and low, moderate and high elk browsing pressure, three with elk exclusion and low, moderate and high cattle browsing pressure, and one with both cattle and elk exclusion. The height, cover and number of stems of each shrub species were recorded at multiple plots within each paddock at the time of establishment and six years later. Changes in shrub species composition over the six year period were explored using multivariate analyses. Generalized Linear Mixed Models were used to determine the effect of browsing pressure on the change in shrub diversity and evenness. Vegetation composition in un-browsed paddocks changed more strongly and in different trajectories than in browsed paddocks at sites that were not fuels treated. In fuels treated sites, changes in composition were minimal for un-browsed paddocks. Shrub diversity and evenness decreased strongly in un-browsed paddocks relative to paddocks with low, moderate and high browsing pressure at non-fuels treated sites, but not at fuels treated sites. These results suggest that in the combined absence of fire, mechanical thinning and ungulate browsing, shrub diversity is reduced due to increased dominance by certain shrub species which are otherwise suppressed by ungulates and/or fuels removal. Accordingly, ungulate browsing, even at low intensities, can be used to suppress dominant shrub species and maintain diversity in the absence of episodic disturbance events

Response of native versus exotic plant guilds to cattle and elk herbivory in forested rangeland

Questions: Are exotic plant species favoured by non-native ungulate herbivores and disadvantaged by native herbivores in forested rangelands? Do the impacts of ungulates on exotic vs native plants depend on forest management activities such as prescribed fire and stand thinning? Location: Northeastern Oregon, USA. Methods: We recorded changes in richness and cover of different exotic and native plant life forms in experimental plots that were grazed only by cattle (a non-native herbivore), only by elk (a native herbivore) or not grazed by any ungulate over a 7-yr period at both managed (recently burned and thinned) and unmanaged (where no fire and thinning has occurred in >40 yr) forest stands. Results: There was a general decrease in exotic plant species richness and cover across all treatments. However, the decrease in exotic richness, particularly of exotic annual forbs, was slightly lower in plots grazed by elk than in ungrazed plots at managed stands. Managed stands also displayed a larger increase in native annual forb richness and exotic graminoid richness, and a larger decrease in native perennial graminoid cover with cattle grazing than elk grazing. At unmanaged stands, cover of woody native plants such as shrubs, sub-shrubs and trees as well as native perennial forbs decreased or remained relatively constant with elk grazing while increasing strongly at plots that were ungrazed or grazed by cattle. Conclusions: Cattle and elk have variable effects on different plant guilds at managed vs unmanaged forest stands. Overall, cattle grazing tends to have a larger impact on herbaceous plant guilds at managed stands, while elk grazing tends to have a larger impact on woody plant guilds at unmanaged stands. However, in contrast to findings from other ecosystems, grazing only has a minor impact on exotic plant dynamics in our study area, and cattle grazing does not favour exotic plants any more than grazing by elk or ungulate exclusion.Keywords: Non-Native Species, Conditioned Correspondence Analysis, Conifer Forest Management, Grazing, Ungulates, Stand Thinning, Prescribed Burnin

Impact of ungulate exclusion on understorey succession in relation to forest management in the Intermountain Western United States

QUESTIONS: Do successional trajectories in plant diversity, heterogeneity and dominance respond differently to ungulate exclusion in unmanaged forests vs managed forests that are thinned and burned? Is vegetation in recently thinned and burned stands more sensitive to changes in the grazing regime? LOCATION: Northeast OR, USA. METHODS: We evaluated changes in plant community composition, diversity, heterogeneity and dominance under herbivory by multiple ungulates (cattle, elk, deer) vs ungulate exclusion at sites where trees were recently thinned and a prescribed burn was applied (managed), and in sites that were not thinned or burned in over 40 yr (unmanaged). Plant species diversity was calculated with the Simpsons index and richness as the total number of plant species. We estimated changes in plant community heterogeneity using a measure of taxonomic dissimilarity. Plant dominance was measured as the relative evenness among different plant functional groups (annual and perennial forbs and graminoids, and shrubs, subshrubs and trees). RESULTS: As expected, managed sites displayed more early succession species, such as annual forbs and annual graminoids,while unmanaged sites were dominated by late-succession species such as shrubs, subshrubs and trees. Species richness, particularly of annuals, was strongly reduced when ungulates were excluded from managed sites, and to a lesser extent from unmanaged sites for some perennial plant species. Species diversity decreased to a slightly greater extent with ungulate exclusion at managed sites. Species dominance was not influenced by ungulate exclusion. The effect of ungulate exclusion on plant heterogeneity also depended on forest management. Heterogeneity increased at managed sites and decreased in unmanaged sites with ungulate exclusion. Overall, the change in vegetation composition over time increased with the exclusion of ungulates, particularly at managed sites. CONCLUSIONS: The strength and direction of specific vegetation and diversity responses to ungulate exclusion vary with forest management, and the influence of ungulate exclusion on plant succession is more pronounced in recently thinned and burned sites. Management of wild and domestic ungulates thus needs to account for forest management activities that alter vegetation seral stage and increase the sensitivity of vegetation to the ungulate grazing regime.Keywords: Grazing, Stand thinning, Cattle, Conifer forest, Elk and deer herbivory, Prescribed burning, Taxonomic dissimilarityKeywords: Grazing, Stand thinning, Cattle, Conifer forest, Elk and deer herbivory, Prescribed burning, Taxonomic dissimilarit

Non-Native Plant Invasion along Elevation and Canopy Closure Gradients in a Middle Rocky Mountain Ecosystem

Mountain environments are currently among the ecosystems least invaded by non-native species; however, mountains are increasingly under threat of non-native plant invasion. The slow pace of exotic plant invasions in mountain ecosystems is likely due to a combination of low anthropogenic disturbances, low propagule supply, and extreme/steep environmental gradients. The importance of any one of these factors is debated and likely ecosystem dependent.We evaluated the importance of various correlates of plant invasions in the Wallowa Mountain Range of northeastern Oregon and explored whether non-native species distributions differed from native species along an elevation gradient. Vascular plant communities were sampled in summer 2012 along three mountain roads. Transects (n = 20) were evenly stratified by elevation (~70 m intervals) along each road. Vascular plant species abundances and environmental parameters were measured. We used indicator species analysis to identify habitat affinities for non-native species. Plots were ordinated in species space, joint plots and non-parametric multiplicative regression were used to relate species and community variation to environmental variables. Nonnative species richness decreased continuously with increasing elevation. In contrast, native species richness displayed a unimodal distribution with maximum richness occurring at mid–elevations. Species composition was strongly related to elevation and canopy openness. Overlays of trait and environmental factors onto non-metric multidimensional ordinations identified the montane-subalpine community transition and over-story canopy closure exceeding 60% as potential barriers to non-native species establishment. Unlike native species, non-native species showed little evidence for high-elevation or closed-canopy specialization. These data suggest that non-native plants currently found in the Wallowa Mountains are dependent on open canopies and disturbance for establishment in low and mid elevations. Current management objectives including restoration to more open canopies in dry Rocky Mountain forests, may increase immigration pressure of non-native plants from lower elevations into the montane and subalpine zones

Effects of ungulate herbivory on aspen, cottonwood, and willow development under forest fuels treatment regimes

Herbivory by domestic and wild ungulates can dramatically affect vegetation structure, composition and dynamics in nearly every terrestrial ecosystem of the world. These effects are of particular concern in forests of western North America, where intensive herbivory by native and domestic ungulates has the potential to substantially reduce or eliminate deciduous, highly palatable species of aspen (Populus tremuloides), cottonwood (Populus trichocarpa), and willow (Salix spp.). In turn, differential herbivory pressure may favor greater establishment of unpalatable conifers that serve as ladder fuels for stand-replacing fires. The resulting high fuel loads often require silvicultural fuels reductions to mitigate fire risk, which in turn may facilitate additional recruitment of deciduous species but also additional herbivory pressure. Potential interactions of ungulate herbivory with episodic disturbances of silviculture, fire, and other land uses are not well documented, but are thought to operate synergistically to affect forest dynamics. We evaluated individual and joint effects of ungulate herbivory and fuels reduction treatments in grand fir (Abies grandis) and Douglas-fir (Psuedotsuga menziezii) forests that dominate large areas of interior western North America. We applied fuels reduction treatments of mechanical thinning and prescribed fire and then evaluated the responses of aspen, cottonwood, and willow species to these treatments (N = 3) versus areas of no treatment (N = 3), and to exclusion from ungulate herbivory versus areas subjected to extant herbivory by free-ranging cattle (Bos taurus), elk (Cervus elaphus), and mule deer (Odocoileus hemionus). Densities of deciduous species were >4 times higher in response to fuels reduction treatments (84.4 individuals/ha) compared to areas of no treatment (19.7 individuals/ha). Additionally, when ungulates were excluded from fuels treated sites, the density of cottonwood was >5 times higher (122.5 individuals/ha) than fuels treated sites subjected to extant herbivory (24.3 individuals/ha). Similarly, densities of Populus spp. and Salix spp. were >3 times higher (211.6 individuals/ha) on fuels treated sites excluded from ungulate herbivory versus fuels treated sites subjected to extant herbivory (66.1 stems/ha). Deciduous species subjected to extant ungulate herbivory also were significantly lower in height, canopy surface area, and canopy volume than the same species inside the ungulate exclosures. Recruitment and long-term survival of aspen, cottonwood, and willow species in coniferous forests of interior western North America require a combination of episodic disturbances such as silviculture and fire to facilitate deciduous plant recruitment, followed by reductions in grazing pressure by domestic and wild ungulates during the time intervals between episodic disturbances to facilitate plant establishment, growth and survival.This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/forest-ecology-and-management/Keywords: Chronic disturbances, Fire, Grazing, Ungulates, Fuels reduction, Forest dynamic

Pharmacological Alterations of Anxious Behaviour in Mice Depending on Both Strain and the Behavioural Situation

A previous study comparing non-emotive mice from the strain C57BL/6/ByJ with ABP/Le mice showed ABP/Le to be more anxious in an open-field situation. In the present study, several compounds affecting anxiety were assayed on ABP/Le and C57BL/6/ByJ mice using three behavioural models of anxiety: the elevated plus-maze, the light-dark discrimination test and the free exploratory paradigm. The compounds used were the full benzodiazepine receptor agonist, chlordiazepoxide, and the antagonist, flumazenil, the GABAA antagonist, bicuculline, the full 5-HT1A agonist 8-OH-DPAT, and the mixed 5-HT1A/5-HT1B agonist, RU 24969. Results showed the effect of the compounds to be dependent on both the strain and the behavioural task. Several compounds found to be anxiolytic in ABP/Le mice had an anxiogenic effect on C57BL/6/ByJ mice. More behavioural changes were observed for ABP/Le in the elevated plus-maze, but the clearest findings for C57BL/6/ByJ mice were observed in the light-dark discrimination apparatus. These data demonstrate that anxious behaviour is a complex phenomenon which cannot be described by a single behavioural task nor by the action of a single compound