Growing development pressures and expectations that forest managers provide future wildlife habitat require better understanding of species' habitat needs, particularly food, cover, and space requirements, and an ability to spatially depict these needs. In forest management in Canada, the primary data used to identify and quantify wildlife habitat reside in remotely sensed forest resource inventories (FRI) that were originally developed to assess timber values for merchantable tree species. Although FRI- and field-based sampling do not always show strong agreement, research has shown that FRI can be informative for wildlife habitat assessments. However, much uncertainty remains when investigating forest characteristics that are not visible to the interpreters, such as sub-canopy features. Here, we used 152 plots in northwestern Ontario to compare the ability of field-based and remotely sensed forest inventories to predict Cladonia lichen cover, a primary winter food source for woodland caribou. The best model for field-based data, which included percentage of jack pine and black spruce in the tree canopy, tree height, stand age, soil moisture, and stem density, correctly predicted 92% of cases where Cladonia spp. were absent (n = 107 plots) and 62% of cases where they were present (i.e., cover >1%; n = 45 plots). FRI performed poorly by contrast, with corresponding percentages of 96 and 19%. FRI provide weak data support for differentiating winter forage availability for woodland caribou, an important habitat factor at the stand level. These findings have important implications for predictions of herd productivity, and suggest that improved remote-sensing capabilities are required in order to assess woodland caribou winter habitat.

Root-associated mycorrhizal fungi affect plant growth and resource allocation. Our major aim was to explore the plant-internal mechanisms behind the effects of mycorrhizal colonization on leaf chemistry of willow (Salix spp.). Combinations of 2 willow varieties (Loden, Tora) and 2 ectomycorrhizal fungal species (Hebeloma fastibile, Tricholoma cingulatum) were grown under controlled conditions. Host plant variety and fungal species effects on host resource allocation (biomass and leaf chemistry) varied in a complex way. Shoot biomass growth and allocation was mostly affected by host plant variety, whereas leaf and root biomass allocation were strongly affected by mycorrhizal treatment. Leaf biomass production was affected by willow variety, mycorrhizal treatment, and the interaction between them. The results indicate a strong effect of mycorrhizal colonization on host plant biomass allocation, which can mediate mycorrhizal effects on leaf chemistry. For example, leaf biomass allocation was inversely correlated with foliar concentrations of salicylic acid, suggesting a functional link between the two. However, the apparent complexity of the host plant variety-fungal species interaction makes any prediction of their possible outcome very difficult, especially in an ecological context. Still, fungal species identity seems to be more important for the responses of Salix to mycorrhizal colonization than the amount of fungal biomass.

Foraging theory suggests animals should prefer habitats with a greater density of prey, but few have investigated whether birds change foraging habitats according to short-term changes in prey abundance caused by weather. We studied a woodpecker, the northern flicker (Colaptes auratus), in which the diet is composed mainly of ants collected on the ground surface. We measured the surface density of the ant prey in 1-m² quadrats placed in 2 habitat types that had different thermal properties: open grassland and forest. The density of ants varied according to year of the study, habitat type, date during the summer, and time of day and was strongly associated with ambient temperature. In the shaded forest habitat, ant density increased linearly with air temperatures between 6 and 28 ^°C In contrast, the surface activity of ants in the open habitat exposed to sun began to decline once ground surface temperatures reached 26 ^°C Ant densities were higher in the open habitat than in the shade in relatively cold conditions but were higher in the shaded forest habitat when it was hot. Using radio telemetry, we recorded the habitat use of foraging flickers and found they shifted from foraging in the open when it was cold to foraging in shaded habitats when it was hot. Flickers tracked the density of their main prey on fine spatial and short temporal scales consistent with foraging theory.

Seedling emergence is a critical stage in the life cycle of annual plants, especially in arid and semiarid Mediterranean ecosystems characterized by high environmental unpredictability. We examined whether the timing of seedling emergence is related to plant survival and fitness for Anchusa littorea (Boraginaceae), an annual plant growing in a Mediterranean coastal sand dune ecosystem of southwest Sardinia (Italy). Seedling emergence, survival, and fruit set was monitored during 4 y (2008–2011) in 25 plots distributed in 2 contrasting microhabitats. Emergence concentrated in late winter (February–March), with few plants emerging thereafter. Early emergence time increased plant life length and fitness. Microhabitat conditions did not influence seedling emergence, although higher survival and fitness occurred in more favourable habitats. Our study enabled us to characterize the patterns of recruitment in A. littorea by analyzing the most critical stages in its life cycle.

Familiarity with its habitat is vital for any individual, enabling it to meet its requirements for food, shelter, and reproduction. The questions of how optimal habitat is found and is shared with a competitor species remain problematic for rodents. Study of the habitat preferences and selection of 2 murinae from the south of France, the short-tailed mouse Mus spretus and the wood mouse Apodemus sylvaticus, found a large overlap in habitat and only small differences in preferences. Although both species live in almost every garrigue habitat and are more abundant in transitory humandisturbed areas, A. sylvaticus was higher in abundance in holm oak coppices, while M. spretus was more abundant in low scrubland with shrub oaks or thorny broom thickets. The high level of habitat overlap resulted in many co-occurrences, with A. sylvaticus always more abundant than the short-tailed mouse. When wood mice were experimentally introduced as an attractor in a low-suitability habitat, they surprisingly attracted many short-tailed mice, but fewer wood mice than were attracted by bait-only traps. Encounters arranged in situ between the attractor and the attracted mice showed predominantly amicable or neutral behaviours and very few instances of agonistic behaviour. We hypothesize that the demographic dominance of wood mice and the abundance of resources during a large part of the year resulted in a non-competitive cohabitation, which may be beneficial to short-tailed mice using wood mice cues as “public information” indicating resource abundance.

Urbanization is a major cause of ecosystem change, and arthropods are a principal component of grassland ecosystems, which are often found in human-dominated landscapes. Although higher trophic level arthropods have been expected to be the most sensitive to urbanization, researchers are debating whether this is the case. We compared the guild structure of grassland arthropod food webs along an urban—rural gradient in the Tokyo metropolitan area, the largest metropolitan area in the world. Arthropod communities were sampled, and guild types were classified by body size and food habit. The guild structure of arthropod food webs was compared among various types of grasslands, and the effects on the guild structure of the surrounding landscape and local vegetation were analyzed. The arthropod guild structure varied along the urban—rural gradient. Large carnivores were abundant in semi-natural grassland ecosystems in the traditional rural landscape, which was at one end of the studied urban—rural gradient. In contrast, small carnivores, omnivores, and detritivores were abundant in the artificial grassland ecosystems of the urban landscape at the other end of the gradient. Because very large carnivores are vulnerable to urbanization activities, rural landscapes rich in these species should be conserved.

Spontaneous populations of saltcedars are widely distributed in Argentina. The invasive behaviour of the genus has been documented in the USA, Mexico, and Australia, where its presence is associated with significant changes in ecosystem functioning and the structure of natural communities. Previous to this work there were no studies assessing the potential of saltcedars as drivers of ecological change in Argentina. The aim of this work was to assess the potential distribution of saltcedars in the country in order to provide useful information for designing management strategies to reduce the impacts associated with their invasion. Known occurrences of the genus in Argentina were used to predict its potential distribution by applying different distribution models using both presence/absence and presence-only data. The DOMAIN model was the model that performed best once sensitivity and omission errors were taken into account. Our results indicate the severity of the problem of saltcedar in Argentina, with more than three quarters of the total arid and semiarid area vulnerable to invasion. Our results also highlight the need to include information about the status of populations when selecting training points for the development of distribution models.

Most plants that are dispersed by seed-caching animals are large, woody trees that produce large, nutritious nuts. But a few species dispersed in this way are relatively small shrubs or perennial herbs. Wild peony (Paeonia brownii) is a perennial herb in western North America that is dispersed by seed-caching rodents such as chipmunks (Tamias sp.), deer mice (Peromyscus mamculatus), and pocket mice (Perognathus parvus). These rodents harvest seeds from the dehiscent, pendant pods and transport them short distances (most <20 m) and cache 1 or a few seeds from 0 to 15 mm deep in soil. Unrecovered seeds germinate in the spring. Unlike most nuts, peony seeds are not highly preferred food items; they are rich in carbohydrates and low in lipids and protein. Rodents remove peony seeds slowly compared to Jeffrey pine (Pinus jeffreyi) seeds, which are highly preferred by rodents and dispersed in the same manner. The low preference for peony seeds may benefit the plants: peony seeds are slow to be harvested and cached, but also slow to be removed from caches and eaten. Small herbaceous plants cannot produce large crops of large, attractive seeds to satiate potential seed dispersers, as do most nut-bearing trees, so producing low-preference food items probably helps these types of plants to ensure that some of the seeds survive to germinate.

In boreal mixedwood stands dominated by trembling aspen (Populus tremuloides), forest tent caterpillar (Malacosoma disstria, FTC) outbreaks are recurrent events whose effects on stand dynamics are poorly documented. To describe and characterize the effects of FTC outbreaks, we assessed canopy opening, gap size, and understory tree recruitment in 12 stands dominated by trembling aspen that had experienced different levels of defoliation (in terms of severity and duration) during the last outbreak in northwestern Quebec (1999–2002). The study showed a significant increase in canopy opening and gap size with defoliation intensity. Furthermore, the proportion of large gaps and aspen mortality increased with defoliation intensity. Balsam fir (Abies balsamea) regeneration benefited from changes in canopy structure caused by the FTC, while aspen did not. Forest succession in mixedwood stands that had been defoliated for 1 y was not profoundly affected, while multiple years of defoliation likely caused more rapid canopy transition from aspen to fir. By creating a variety of gaps, FTC outbreaks modify stand structure in ways that differ from succession to coniferous dominance controlled by single-stem exclusion.

Montane riparian forests exhibit a higher diversity of tree species than adjacent stands. This pattern is thought to be generated by the unique disturbance regime of riparian forests, including canopy gap formation and fluvial disturbance (e.g., transport of boulder/gravel sediments), which provides a variety of habitat conditions for regeneration (habitat niche segregation). Although segregation of micro-environmental conditions for seedling establishment has been confirmed, habitat segregation for saplings remains untested. Thus, to determine if the composition and structure of the riparian sapling community is influenced by canopy and fluvial disturbances, we sampled 11 canopy-gap sites and 3 fluvial boulder-deposit sites, as well as beneath-canopy sites that had not been disturbed recently, in a temperate mixed-species deciduous forest. We analyzed the distribution patterns of saplings for 31 canopy and subcanopy species. Saplings were found mainly on the disturbed sites compared with the beneath-canopy sites. A comparison of relative densities for 13 major species in gaps versus on fluvial deposits revealed that 5 species were biased significantly to gaps and 4 species to fluvial deposits. Cluster analysis detected 4 species groups with different light requirements. These results suggest riparian habitat partitioning between species through differentiated preferences for the disturbance type × light requirement combination.