Conservation hatcheries are becoming a tool in rebuilding salmonid populations, but their contributions are strongly debated. Most studies focus on genetic, morphological, and behavioural, issues and less is known of the importance of infectious agents. The Living Gene Bank (LGB) program of the British Columbia Ministry of the Environment is a recent effort to restore collapsed steelhead trout (Oncorhynchus mykiss) populations on the east coast of Vancouver Island. Our study describes the change in macro- and microparasitic profiles of LGB-hatchery-produced juveniles after they leave the hatchery and enter the natural river environment and also compares them with a limited wild smolt sample. We found that the hatchery was successful in raising parr free of infectious agents, but once introduced into the river environment, the hatchery fish quickly took on a diverse profile of infectious agents. The high numbers of fish released from the hatchery and the existence of hatchery fish that stay in the river as residents increased the number of fish in the system with sub-clinical levels of infection. An ecological understanding of the role resident hatchery fish play in the spatial distribution of infectious agents as well as the temporal and seasonal variations in infectious agent prevalence and diversity will be important in determining the net effect of the LGB conservation hatchery on the wild population.

Nomenclature: Behnke, 1992.

Tree age and tree structure are important determinants for epiphytic lichen communities, affecting substrate stability, light availability, and propagule dispersal. However, little is known about the relative importance of these 2 factors on many species. This work aims to evaluate the importance of tree age and tree structure in explaining the within-stand frequency of the macrolichen Letharia vulpina. The study was carried out in 2 larch–stone pine forests in the Eastern Italian Alps. The frequency of Letharia was evaluated using a standard sampling method. To explain the within-stand frequency of Letharia, tree age and several variables related to tree structure were considered. Multiple ordinary least square regression was applied to clarify the influence of the set of variables. Several partial regressions were then computed to evaluate the relative importance of each significant predictor. The frequency of Letharia increases with increasing tree age, tree diameter, and first branch height. Tree age is the most important variable, accounting for one third of the total explained variation, although tree structure also has a significant effect on lichen frequency. Due to its dispersal limitations and old-tree dependence Letharia is proposed as a suitable indicator of forest continuity. The results may be of interest for conservation purposes, since the frequency of Letharia may be enhanced by protecting old trees.

Nomenclature: Nimis & Martellos, 2003.

One of the more common and dramatic patterns observed in species abundance and richness is that imposed by altitude. Many non-exclusive factors have been proposed to explain these altitudinal patterns, including climate, habitat structure, productivity, geographical factors, and historical factors. In this study, we investigated the altitudinal trend of beetle richness and diversity, trying to determine the factors affecting beetle diversity and composition along an altitudinal gradient on a high mountain of the Sierra Nevada National Park (Spain). Beetles were sampled every 15 d for 2 y using pitfall traps at 10 altitudinal sites located between 2000 and 3000 m asl. Against predictions, beetle diversity and the standardized richness indices were not correlated with altitude. Instead, lower richness and diversity values were found at middle altitude in the selected altitudinal range. Although a combination of biotic and abiotic factors satisfactorily explained these richness and diversity values, the main factor was plant diversity, which was correlated with all richness and diversity indices. A second factor was temperature; however, the interaction between beetle richness and temperature was evident only when the effect of plant diversity was removed. Multivariate analysis for species composition showed that 2 factors, plant diversity and shrub cover, explained more than 50% of the variance observed. In summary, our results suggest a strong dependence of beetle species on vegetation structure and diversity, although temperature appears to be a complementary factor determining beetle richness and diversity in the high mountains of the Sierra Nevada National Park.

Nomenclature: Fauna Europaea Web Service, 2004.

This study analyzes the effect of fire on the composition and abundance of ground beetles in Pinus nigra forests. We used pitfall traps to sample beetles in burned P. nigra forests in Catalonia (Spain). Since fire dramatically alters forest structure and composition and beetles follow vegetation changes, we expected drastic changes in beetle composition and abundance immediately after fire. Because P. nigra forests do not recover after fire, we also expected beetles in burned and unburned areas to differ along a chronosequence. Beetle abundance per plot increased in canopy-fire–burned areas, but per plot species richness, diversity, and dominance were not affected by fire. Species composition varied depending on fire intensity. Some species were associated with canopy fire and low vegetation cover. Other species were associated with shrub cover and time since fire. Finally, some species were not dependent on fire or vegetation cover. Beetle abundance in burned areas was independent of time since fire. This lack of medium-term convergence between burned and unburned P. nigra forests agrees with our second hypothesis. Given the increase in fire frequency and size in submediterranean areas and the observed slow recovery of beetle species, a decline in beetle diversity at a regional scale is expected.

Nomenclature: Bolós et al., 1990; Museo Nacional Ciencias Naturales (CSIC), 1997–2008.

Several species of trout have been introduced into most wetlands within the mountain and foothill regions of southwestern Alberta, Canada. In this study, we used standard survey methods to evaluate the distribution of long-toed salamander (Ambystoma macrodactylum) larvae relative to introduced trout within 27 low-elevation wetlands and 30 high-elevation wetlands in Waterton Lakes National Park and the adjacent Castle Special Management Area. Results provided indirect evidence of salamander displacement by trout. At high elevations, salamander larvae were not detected in any of the sites that contained trout. The complete allotopy between trout and long-toed salamanders within high-elevation sites supports previous studies completed within the core of this species' range, further documenting the widespread negative impacts of introduced trout on native amphibians in upper basins. Similarly, salamander larvae were present in each of the low-elevation wetlands that lacked trout; they co-occurred in only 4 of 27 low-elevation wetlands. Allotopy within lower elevation sites is particularly important from a conservation perspective because, relative to populations in high-elevation wetlands, these populations tend to contain individuals with rapid growth and high dispersal rates.

Nomenclature: Nelson & Paetz, 1992; Corkran & Thoms, 2006.

Vegetation succession in mires is rather well identified using the paleoecological approach. Recently, the ecological succession concept has been extended to ecosystem functions, e.g., carbon dioxide (CO₂) dynamics. Although a strong link between mire vegetation and carbon dynamics is well acknowledged, the successional changes in mire ecosystem functions have remained practically unstudied, especially under the same climatic control. To study the patterns and dynamics of CO₂ exchange during mire succession, we measured CO₂ exchange and vegetation dynamics over 2 growing seasons along a mire chronosequence on the land uplift coast of the Bay of Bothnia in western Finland. The study showed a decrease in photosynthesis during mire succession that was linked to compositional change in vegetation, i.e., replacement of sedge and herb dominance with the dominance of dwarf shrubs and Sphagna. Similarly, the study revealed decreased variation in gross photosynthesis (P_G) and ecosystem respiration (R_E) over a growing season, which resulted in lower levels of seasonal CO₂ dynamics at older stages. The observed successional trend in phenology and CO₂ dynamics was largely a consequence of the gradual decrease in the abundance of plant groups with efficient photosynthesis and green area production.

Nomenclature: Hämet-Ahti et al., 1998.

Temperature is often an important determinant of species presence and activity patterns, but observations of temperature at fine resolution and broad extents—scales relevant to individual organisms—are rare. We analyzed how biotic and abiotic variables influence ground surface temperature (GST) using high-resolution thermal data for a 1900-ha area of forest and field near Wasaga Beach, Ontario, Canada. Temperature was recorded at 2-h intervals from May to October, 2004 and 2005, from data loggers approximately 300 m apart. At the same sites, we recorded overstory and understory vegetation, elevation, and distances to the nearest road and urban infrastructure. Correspondence Analysis (CA) indicated that thermal conditions varied most strongly seasonally and diurnally. Canonical Correspondence Analysis (CCA) pinpointed which biotic and abiotic variables were related to surface temperature. Canopy cover and leaf litter cover were positively related to cool sites during both cool and warm periods. Sites close to urban areas and roads were warmer than those further away from these features. As thermally variable environments affect the physiology, behaviour, and ecology of ectothermic species, determination of variables that affect GST provides a more comprehensive depiction of habitat for these species.

The effects of cold stratification on seed germination of 58 species from a Mediterranean area in central–eastern Spain were studied. The area is subject to fires and has a very continental climate, with long winters (187 frost days during the year). Differences in germination among species taking into account their phylogeny were studied by dividing them according to their life form (chamaephytes, hemicryptophytes), post-fire regeneration strategy (non-sprouters, sprouters), and geographical distribution range (Iberian Peninsula endemics, Mediterranean, widely distributed species). Treated seeds were stratified at 5 °C for 4 weeks, then incubated, along with the control seeds, at 15 °C for 6 weeks. Most species were not affected by cold stratification, and in the cases where they were, germination was generally lower after stratification, not higher. In general, germination percentages were low, which shows that stratification by itself was not able to break seed dormancy. Functional groups differing in their post-fire regenerative strategy or distribution range showed differing responses. Sprouters and endemic species from the Iberian Peninsula were negatively affected by stratification treatment. This is interpreted as a mechanism to stop germination after winter, preventing plants from late germination in spring, which would leave them facing summer drought without a deeply developed root system.

Nomenclature: Bolòs & Vigo, 1984–2001.

Long snowy winters combined with a short growing season make boreal forests an unproductive environment that challenges black bears (Ursus americanus). We used resource selection functions (based on GPS telemetry of 16 bears), diet analysis, surveys of plant phenology, and vegetation inventories to study adaptations of black bears to boreal forest. Because plants are heavily favoured in bear diets, we expected diet composition to reflect their temporal availability. We anticipated that bears would make choices among land cover types and specific topographic conditions in order to select plants that would fulfil their energetic demands throughout the active period. We also predicted that bears would select habitats modified by insect outbreaks or forest harvesting because these disturbances likely increase resource availability. We found supporting evidence for all of our predictions. (1) Bear diet was closely linked to plant availability. (2) Bears made seasonal altitudinal movements and selected sites according to solar irradiation, tracking the availability of the most digestible plants. Accordingly, bears relied on high-altitude graminoids in spring, a variety of fleshy fruits in summer, and mainly Sorbus americana berries in autumn. (3) Land covers resulting from clearcutting and insect outbreaks increased resource availability for bears and were preferred from summer to autumn. In our study area, black bears are considered predators of a threatened caribou (Rangifer tarandus) population. Even so, we did not find any caribou remains in bear scats. However, our results show that forestry practices, such as clearcutting near the caribou range, could contribute to increased bear presence and thus increase the probability of predation.

Nomenclature: Wilson & Reeder, 1993; Marie-Victorin, 1995.

Large seeds are assumed to have higher probability of successful recruitment than small seeds. This is because larger seeds give rise to larger seedlings and larger seedlings better withstand environmental hazards like deep shade and drought. Biotic and abiotic limitations to seedling growth and survival, and conversely availability of safe sites for recruitment, vary along environmental gradients and between habitat types. Thus, the value to plant species of possessing large seeds may differ between plant communities. We analyzed the relationship between seed mass and per-seed recruitment success (seedlings established per number of seeds produced) along an environmental gradient from open grassland to closed-canopy forest using data collected by Uuno Perttula in southern Finland in 1934. We found that larger seeds have greater recruitment success relative to smaller seeds in all investigated communities. However, the recruitment success of large seeds relative to small seeds strongly increased from grassland and open forest to closed-canopy forest. Of the measured environmental variables, canopy closure most strongly explained this increase. This indicates a strong direct effect of deep shade on seedling survival in natural plant communities. Additional explanatory power was associated with soil moisture. Litter cover, moss cover, and soil pH did not contribute to explaining the variation in relative recruitment success of larger seeds. Thus, the advantage of large seeds in recruitment success is pronounced in deeply shaded forest but may be insignificant in open vegetation.

Nomenclature: Tutin et al., 1964–1980.

Resource-rich restoration sites are prone to invasion by aggressive plants that prevent community recovery. Reducing light by sowing non-persistent cover crops and immobilizing nitrogen by amending soils with sawdust, however, may prevent this scenario in restored sedge meadows by limiting Phalaris arundinacea (reed canarygrass) invasions. To determine the usefulness of these resource-reducing methods, a perennial target community and Phalaris were sown with a high-diversity cover crop, a low-diversity cover crop, or no cover crop in plots with or without sawdust under controlled hydrological conditions. Aboveground biomass was measured after two growing seasons, and light and soil nitrogen were measured throughout the study. Only high-diversity cover crops reduced light, and in doing so they decreased target community and Phalaris establishment by 73% and 68%, respectively, resulting in a Phalaris-dominated community. Despite only reducing nitrogen over the short term, amending soils with sawdust decreased Phalaris establishment by 56% without hindering target community establishment, resulting in a graminoid-rich community similar to natural sedge meadows. The target community, however, reduced both light and nitrogen, and in doing so decreased Phalaris establishment by 78% and 67% in plots with and without sawdust, respectively. Our results show that rapidly establishing a perennial plant community may be more important than reducing initial resource availability when trying to limit invasions of resource-rich restorations.

Nomenclature: Gleason & Cronquist, 1991.

The effect of high fire frequency on the species composition of Mediterranean-type plant communities is reported on the basis of shrubland stands located in Catalonia (Spain) that have experienced from 1 to 5 fires over the last 31 years. We focused on changes in the abundance of species, grouped according to post-fire regenerative traits (resprouting and seed germination) and life form (shrubs, herbaceous graminoids, and herbaceous non-graminoids). High fire frequency was related to a low abundance of obligate resprouter and obligate seeder shrubs. In the latter group, Cistus sp. disappeared in stands with high fire frequency and showed a maximum abundance in stands with low fire frequency. The abundance of facultative resprouter shrubs did not change with fire frequency. This group thus became dominant in the shrub layer at high fire frequency due to the low abundance of obligate resprouter and obligate seeder shrubs. These changes in the abundance of shrub species involve changes in the patterns of relative dominance of regenerative syndromes, in line with fire frequency. An examination of life forms revealed that the abundance of herbaceous non-graminoids and herbaceous graminoids was higher in stands with high fire frequency and the graminoid Brachypodium retusum was dominant at all fire frequencies. These results suggest a loss in the resilience of shrubs after frequent fires, leading to a simplification of vegetation structure, with a shift from shrubland to grassland-type communities, thereby probably enhancing a potential positive herb–fire feedback.

Nomenclature: Bolós et al., 1990.

Our principal objective was to document dominant plant composition and the species frequency pattern in a plant community type, longleaf pine savanna, known for its extraordinary number of vascular plant species. We also tested whether an important habitat factor, soil moisture, affected the resulting patterns, and whether the patterns were scale-dependent. We began with a collection of 120 sample plots (1- × 1-m) in a wet coastal plain savanna. These plots contained 126 plant species. The 3 dominant species by cover were Rhynchospora gracilenta (15.37%), Schizachyrium tenerum (13.36%), and Scleria pauciflora (10.07%). The species frequency distribution was a skewed unimodal pattern with most species occurring infrequently, in less than 10% of the plots. There was no evidence for bimodality. To test whether soil moisture affected species frequency patterns, we sorted the plots into 2 groups: 60 representing wetter conditions and 60 representing drier conditions. Measured by percent cover, the dominants in the wetter plots were R. gracilenta, Dichanthelium scabriusculum, and S. pauciflora, whereas in the drier area they were S. tenerum, Ilex glabra, and D. dichotomum. The species frequency pattern was similar for both wet and dry plots (χ²= 8.97, P> 0.05). To explore possible effects of sample area on this pattern, we sampled a further 75 plots in a larger tract of similar habitat in De Soto National Forest, using 4 sample areas of 0.1, 1, 10, and 100 m². Again, the species frequency distributions all had a skewed unimodal pattern. These patterns are consistent with other studies of savannas but do not appear consistent with the bimodal patterns reported from some grasslands. Further studies of frequency will determine the degree of generality of such patterns and their relationship to mechanistic processes in plant communities.

Nomenclature: Kartesz, 1994.

The effects of invasive earthworms on decomposition are little known, and the controls of their effect on decomposition may be different than those of microbes. Sugar maple–dominated forests previously devoid of earthworms in the western Great Lakes region (USA) exhibit different degrees of earthworm invasion, presenting a natural experiment to study its effects on litter decomposition. We hypothesized that litter decomposition would depend on the degree of earthworm invasion, the presence or absence of worms of differing sizes, and initial litter chemistry. We established an experiment using fine- and coarse-mesh litterbags (to allow access by different-sized worms) to study decomposition of 3 different litters in mixture under different degrees of earthworm invasion in 12 Minnesota sites. The effect of earthworm invasion degree on litter decomposition varied by identity of the litter, mesh size, and time of litter collection. Decomposition of Quercus rubra, the litter with the lowest initial calcium concentration and highest lignin:nitrogen, was not significantly influenced by earthworm invasion degree. In contrast, decomposition of Tilia americana, the litter with the highest calcium concentration and lowest lignin:nitrogen, was fastest in coarse-mesh litterbags. After 15 months the mass of the highest-quality litters was highest in the fine-mesh bags of heavily invaded plots, suggesting that microbially mediated decomposition slowed where earthworms had removed the forest floor.

Nomenclature: Gleason & Cronquist, 1991; Reynolds, 1977; Sims & Gerard, 1999.

Petrels are a group of seabirds that undertake an exodus from their breeding colony just prior to egg-laying, purportedly to allow the female to acquire nutrients for egg synthesis from the local environment. We studied seasonal nutrient dynamics and at-nest behaviour of northern fulmars (Fulmarus glacialis), a petrel found in the Canadian High Arctic, to evaluate the importance of pre-laying nutrient reserves to annual breeding in this species. Females and males carried 35–50% more fat when they first arrived at the colony than when they returned from their pre-laying exodus to lay their egg or initiate incubation. Fulmars spent approximately 70% of their time at the nest engaged in energetically expensive behaviours (pair-bonding, digging out and defending their nest site) during the brief period from colony arrival to departure on their pre-laying exodus. In contrast, 70% of their time at the nest was spent resting during incubation. Both nutrient reserves and behavioural data suggest that High Arctic fulmars require large endogenous reserves prior to egg-laying to fuel their energetically costly activities during the arrival-to-exodus period.

Nomenclature: Hatch & Nettleship, 1998.