, is an important weed of rangelands, agricultural crops and waste areas in North America. The literature is less extensive than for the closely related yellow toadflax (Linaria vulgaris Mill.). Introduced from Eurasia as an ornamental plant into North America by 1894, it became naturalized in seven Canadian provinces and all of the United States of America west of the 100th meridian except for New Mexico. In North America it ranges from ca. 35°to 56°N latitude and it grows from near sea level to altitudes up to ca. 2800 m. Production of up to one-half million seeds per plant and its long-lived perennial nature make the species highly competitive and able to invade cropland and even stands of native ungrazed vegetation. Linaria dalmatica is a hemicryptophyte with strong vegetative reproduction and dormant seeds. Growth of creeping roots after removal of aboveground plant parts limits the effectiveness of control treatments such as grazing, clipping, mowing or burning. Several herbicides control the species for the short term; the smooth and waxy leaf surfaces may hinder herbicide uptake. Experimental biological control with insects since the 1960s shows promise. La croissance des racines traçantes après l'enlèvement des parties aériennes restreint l'efficacité des mesures de lutte comme la pâture, le fauchage ou le brûlage. Quelques herbicides sont efficaces à court terme encore que la texture lisse et cireuse des surfaces foliaires puisse entraver l'absorption des produits chimiques. Les essais de lutte biologique par les insectes en cours depuis les années 1960, ont donné des résultats encourageants.

The Intermediate Disturbance Hypothesis states that the greatest species diversity occurs at intermediate levels of disturbance because species coexistence is maintained at a nonequilibrium state and no strong competitor can dominate completely. On the other hand, diversity of exotic species is expected to increase with the disturbance magnitude. These patterns were tested for in this study. The cover of all vascular plants, mosses, and lichens in 1 × 1 m plots across a range of disturbance levels was sampled in 11 remnant grasslands within the Aspen Parkland Ecoregion of central Alberta, western Canada. The Intermediate Disturbance Hypothesis was supported for small-scale within-patch diversity for total species richness and Simpson's diversity index. Lower species diversity was found in undisturbed and lightly grazed as well as in highly disturbed plots. Intermediate levels of disturbance had reduced dominance of Festuca hallii (Vasey) Piper and increased abundance of most other species; this gave the highest species diversity. The species richness and diversity of exotic plant species showed a significant positive relationship with the magnitude of the disturbance. Understanding relationships between disturbance and plant species diversity, especially exotic plants, can influence management decisions on what disturbance regime is conducive to maintaining natural plant communities.Key words: Intermediate Disturbance Hypothesis, diversity, exotic species, grassland.

Scientists increasingly acknowledge the influence that nonlethal effects of predation have on structuring wildlife-landscape interactions. In landscapes dominated by human activities, wildlife can respond to human disturbance in a similar fashion to the risk of predation. Further, the risk allocation hypothesis suggests that individuals respond most strongly to risk when it is spatially and temporally predictable. We predict that individuals in agriculturally dominated landscapes will respond to potential risk from humans during hunting season by shifting their behavior to avoid agricultural areas during the day, instead retreating to refuge habitat. We predict that this shift to more nocturnal behavior will be strongest for elk (Cervus elaphus) adult female-calf pairs and will be influenced by the level of moon illumination. Using motion-sensing cameras, we studied the response of elk moving between the Wainwright Dunes Ecological Reserve (a hunting refuge) and surrounding agriculturally dominated landscape in east-central Alberta, Canada, to human disturbance in relation to sunrise and sunset. Elk became increasingly nocturnal with the onset of hunting, leaving the refuge following sunset and returning to the refuge earlier before sunrise. Further, elk became increasingly nocturnal in response to greater levels of moon illumination. Lastly, we found that adult female-calf pairs perceived greater risks associated with diurnal activity and exhibited the most nocturnal behavior relative to other demographic classes. Our results suggest that ungulate management based on traditional hunting seasons and times may be problematic as it creates strong cues for resident elk, allowing them to minimize risk by avoiding risky places at risky times in accordance with the risk allocation hypothesis. Ó 2017 The Wildlife Society.

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Abstract. This paper describes the species composition of remnant grasslands in the aspen parkland region of Alberta and its relation to soil characteristics and small‐scale disturbance. Our findings are consistent with the centrifugal model of communities with Festuca hallii dominating undisturbed ‘core’ habitat and the composition of more ‘peripheral’ habitats varying in soil properties and in the magnitude of disturbance. Invasive non‐native species are not present in the core habitat and are present only in the disturbed sites, most abundantly in those with the highest soil nitrogen. The centrifugal model, as it applies to these remnant grasslands, differs from its previous application to wetlands and forests in that the core communities are not on the most fertile sites, but on the least disturbed. These findings have implications for the management of prairie remnants to exclude invasive exotic species.