Planting of non-native spruce in subarctic birch forests introduces new habitats that change the landscape mosaic and increase the extent of artificial edges. This may alter the spatio-temporal predator—prey dynamics. In this study, we focused on small- to medium-sized ground-dwelling prey species and their mammalian predators in winter. In a spatially extensive snow-tracking study over 3 winters (2003–2005), we explored the spatial distribution of species at 3 spatial scales ranging from forest stands to landscape mosaics. We documented scale- and time-dependent responses to spruce plantations for red fox, stoat, mountain hare, and voles, which were the dominant species in the study. However, the responses to spruce plantations were mostly inconsistent across scales. A small-scale affinity for plantation edges, largely consistent over time, was found for all species. By contrast, habitat selection for and against spruce plantations at stand scale alternated profoundly among the different years, although in qualitatively similar patterns among the dominant species, which suggests a common cause. At the landscape scale only red fox was negatively related to proportion of spruce plantations, while mountain hares exhibited annual shifts in occurrence relative to the amount of spruce. Predators and prey were spatially and temporally related at the 2 smallest scales (i.e., within and among forest stands) in a manner that may be explained by year- and standspecific snow conditions affecting the predator—prey interactions within the community.

How deterministic or stochastic is tree regeneration in a temperate forest? To answer this question, we analyzed the relative effects of abiotic and biotic factors on seed and seedling demography of tree species in an old-growth temperate forest, Ogawa Forest Reserve, Japan. The working hypothesis was that seed and seedling demography of trees would be controlled more deterministically in comparison with tropical forests and that the magnitude of deterministic effects of the abiotic and biotic factors would depend on regeneration traits relating to seed dispersal ability. We examined 5 abiotic factors (litter and humus cover, vegetation cover, light level, soil moisture, and relative elevation) and 2 species-specific biotic factors (distance from the nearest conspecific adult and density of conspecific seeds or seedlings) to quantify their contribution to the spatial variation in seedling emergence and survival for 18 principal tree species in the community. The results showed that conspecific seed density had a negative effect on seedling emergence for almost all species, as suggested by the Janzen—Connell model. On the other hand, various factors were detected for seedling survival of each species. We also found that regeneration traits relating to seed dispersal ability were significantly correlated with some of the abiotic factors. However, the 7 factors tested were less important than expected; seed and seedling demography appeared to be determined rather stochastically in this stable forest community. Even in a temperate forest, seed and seedling demography appeared to be rather stochastic, and niche partitioning among species during these stages was of limited importance.

Flies and beetles are 2 major functional invertebrate groups responsible for dung removal and nutrient cycling in many alpine pastures. In order to determine the effect of the 2 groups on dung removal rate, as well as the associated mechanisms, we conducted a two-factor, two-level factorial-designed experiment in an alpine meadow of eastern Qinghai-Tibetan Plateau. Four treatments were included: (A) flies excluded, beetles included; (B) beetles excluded, flies included; (C) both flies and beetles excluded; and (D) both flies and beetles included, each having 45 replicates of artificial dung pats (17 cm in diameter; ca. 248 g in dry weight). We examined dung quality, removal rates, and abundance and biomass of macro-soil faunas within the dung 9 times (5 replicates sampled each time) during the experimental period of 32 d. Both beetles and flies (maggots), as well as the interaction between the 2 groups, markedly affected the dung removal rates. The total dry weight loss of the dung during the experiment was 167.6 g and 127.5 g on average for the beetle and fly groups, respectively. The removal rate in terms of both dung weight and organic matter loss was significantly greater for the beetles than the flies, which was principally because the consumption rate was lower and the resident time was shorter for fly maggots than for the beetles. The coexistence of the 2 species increased dung removal synergistically on the first sampling day and additively between the 2^nd and the 5^th day. However, after the 8^th day of the experiment, the coexistence effect was negative, such that the dung loss of treatment D was comparable to treatment A but significantly greater than treatment B. The synergistic control might be due to the mediating effect of predator beetles on the relative abundance of coprophagous beetles and maggots, and the negative effect of the functional group diversity was because of the overwhelming competitive advantage of the beetles over fly maggots. In conclusion, although both fly and beetle species may significantly contribute to dung removal, the effect of the interaction between flies and beetles appears to depend on dung age (the sampling timing) in the alpine meadow.

Light availability and herbivory are 2 major factors affecting the regeneration of woody species, and thus a better perception of how light and herbivory interact to shape the sapling performance of cohabitant tree species emerges as a key issue. The purpose of this work is to experimentally analyze the influence of light conditions on tree responses to browsing. We evaluated the responses to browsing (simulated by mechanical clipping of 50% of current-year shoots) of saplings from 2 deciduous (Acer opalus ssp. granatense and Quercus pyrenaica) and 2 evergreen (Quercus ilex and Pinus nigra ssp. salzmannii) late-successional tree species, measuring an array of morphological, physiological, and biochemical traits. The experiment was performed with saplings grown for 2 y under 3 experimental light environments emulating natural microhabitats: full (open microhabitats), 80% (below pioneer shrub canopy), and 13% (below tree canopy) sunlight. Clipping affected biomass distribution, growth, and sapling size, while only slight physiological and biochemical effects were detected. Species characteristics and the light environment in which saplings grow determine their capacity to recover biomass lost after herbivore damage. Black pine was found to be the least tolerant species to clipping, whereas the broadleaf species displayed greater recovery after clipping. Light scarcity increased the nutritional quality of plants and negatively affected herbivory tolerance of 3 of the 4 species.

The extent to which large carnivores compete with hunters for harvestable populations of wild ungulates is a topic of widespread controversy in many areas of the world where carnivore populations are recovering or are reintroduced. Theory predicts that predation impacts should vary with prey density and environmental conditions. To test this prediction, we analyzed trends in an index of population abundance of roe deer (Capreolus capreolus) over 9 y in 144 Norwegian municipalities. The municipalities span a wide range of landscapes and climatic conditions and were associated with a varying degree of Eurasian lynx (Lynx lynx) presence. There was a wide variation in trends of roe deer abundance (estimated long-term average λ ranging from 0.69 to 1.23) among municipalities. Roe deer population growth rates were lower in the municipalities with lynx and harsh climatic conditions than in municipalities with mild climatic conditions and/or without lynx. Thus, lynx presence appears to be having a negative impact on roe deer populations; this was especially evident in areas with unfavourable environmental conditions. Our finding that estimated long-term average values of λ were less than 1 in many municipalities indicates that roe deer populations in Norway may not be able to sustain current combined mortality from hunters and lynx, especially in marginal areas.

American marten (Martes americana) are typically associated with mature coniferous forests. Some recent results, however, suggest that marten habitat selection may also operate at a finer scale. We therefore described site characteristics of 24 martens that were radio-tracked and snow-tracked between August 2002 and March 2004. From these data we developed 2 resource selection functions, one for summer and the other for winter, using logistic regressions. In summer, selected sites were mainly characterized by abundant biomass of spruces and short (≤ 30 cm) herbaceous plants and low biomass of tall (> 30 cm) herbaceous plants. Other factors, such as increased coniferous canopy closure and amount of coarse woody debris (CWD) and reduced lateral cover (LC5) were included in the composite model. In winter, sites with closed coniferous canopy and LC5, high snow sinking depth, greater amounts of CWD, greater basal area, and greater tree density were more likely to be visited by marten. These variables may be related to 3 factors that play roles in marten ecology: prey abundance, protective cover, and thermoregulation. Our results also show that, unlike clear-cutting with protection of regeneration and soils (CPRS) and pre-commercial thinning (PCT), partial logging techniques (PL) could maintain, under certain conditions, the structural elements required by pine marten in a managed forest. These elements would favour prey abundance and detection, protective cover, and rest and thermoregulation sites.

Large, late-winter ptarmigan migrations heavily impact the shoot, plant, and patch architecture of shrubs that remain above the snow surface. Ptarmigan browsing on arctic shrubs was assessed in the vicinity of Toolik Lake, on the north side of the Brooks Range in Alaska. Data were collected in early May 2007, at maximum snow depth, after the bulk of the ptarmigan migration had passed through the area. In an area of tall shrubs, half of the buds on Salix alaxensis were browsed by ptarmigan. Three percent of the buds that were buried beneath the snow were browsed, 90% of the buds that were less than 30 cm above the maximum snow level were browsed, and 45% of the buds above that height were browsed. Ptarmigan browsing was found to be a major height limiter for tall shrubs, thereby controlling shrub architecture by brooming stems at the snow surface and inducing stump shoots. These results were qualitatively extrapolated by photographing shrub morphology over a region approximately 300 km wide across a series of north-flowing arctic rivers with headwaters in the Brooks Range. Ptarmigan “hedging” of shrub patches, and shrub growth under a warmer climate, are opposing forces mediated by snow distribution.

Placement of seeds in favourable microsites by inhumation in ant nests is considered a principal advantage of myrmecochory. However, nest chambers may be too deep to allow seedling emergence. In this case, successful germination requires secondary transport of seeds to shallower sites. Little is known about the architecture of nests of seed-dispersing ants and the locations within nests to which seeds are initially transported. These data are essential to assess the importance of secondary transport for germination success of seeds. We studied dispersal of Manihot esculenta subsp. flabellifolia seeds by Ectatomma brunneum ants in French Guianan savannas. We followed movements of seeds within nests by offering marked diaspores to foraging workers, observing transport into the nest, then excavating to determine locations of marked seeds. In 4 nests, chambers ranged from 2 to 40 cm deep. Because elaiosomes are fed to brood, Manihot diaspores were initially transported to deep chambers, where brood was concentrated. Recovered diaspores had been carried to chambers 14–40 cm deep, all deeper than the maximum burial depth for emergence (≈ 13.8 cm) predicted from the mass (≈ 0.13 g) of Manihot seeds. Nest architecture thus makes secondary vertical transport of seeds crucial for dispersal success of this species. Failure of secondary transport may be an underestimated mortality factor in myrmecochorous plants.

Environmental stochasticity and density-dependence can have critical synergetic effects on population dynamics, especially when dealing with threatened species. In this study, we examine the effects of these interactions on the dynamics of a vulnerable bird species, the Dalmatian pelican (Pelicanus crispus). We conducted demographic analysis and population dynamics modelling of the Amvrakikos pelican population (western Greece) based on a 20-y dataset. Results indicated that annual juvenile survival probability is low (mean = 0.65) and varies according to both negative (regulation) and positive (Allee effect) density-dependent processes. In contrast, adult survival is relatively high (mean = 0.95) and less variable. Deterministic and stochastic population dynamics models based on means, inter-annual variances, and covariances between vital rates revealed that the population is increasing deterministically. Simulations of the extinction risk for the study population and also for various population sizes revealed that short-term extinction risk remains extremely low, even for very small populations of the species. However, when we considered the possibility of rare catastrophic events and their interactions with density-dependence patterns, the projected extinction risk increased dramatically, especially for small populations. Given that many European Dalmatian pelican populations are small, most of them could be at risk for local extinction. Our results illustrate the critical and general importance of considering interactions between all potential factors of extinction in population viability assessments.

Flooding boreal forest ecosystems for hydroelectric power generation may release substantial amounts of carbon (C) to the atmosphere, contributing to global warming. The objectives of this study were to evaluate CO₂ and CH₄ production rates using spring/fall (14 °C) and summer (21 °C) temperatures under non-flooded and flooded conditions. Incubation temperatures represented the mean annual air temperature in May and September (14 °C), and in July (21 °C). Greenhouse gas production rates were quantified using laboratory incubations of 2 contrasting soil types (Humo-Ferric Podzol [very dry, mineral] and a Histic Folisol [moist, organic]) collected at the Experimental Lakes Area in northwestern Ontario, Canada. The mean production rate of CO₂ and CH₄ in the headspace of the incubation jars was significantly influenced by temperature, flooding and soil type. Results showed that the mean CO₂ (65 [Podzol]; 43 [Folisol]) and CH₄ (0.06 [Podzol]; 0.06 [Folisol]) production rates (µg·g^-1·d^-1) were significantly higher (P < 0.05) at 21 °C and in flooded treatments from both soil types. The greatest CO₂ and CH₄ production rates (µg·^-1·d^-1) occurred from the Folisol (110 [CO₂]; 0.03 [CH₄]) and the L and FH horizons of the Podzol (250 [CO₂]; 0.05 [CH₄]). Q₁₀ values showed that decomposition of soil organic matter was more temperature dependent in non-flooded treatments, with values ranging from 1.57 to 5.03, than in flooded treatments (1.31 to 3.58). The greatest loss of soil organic carbon relative to the original C content (g·m^-2) occurred in the Ah horizon of the Podzol in non-flooded (0.01% [14 °C]; 0.02% [21°C]) and flooded (0.02% [14 °C]; 0.03% [21 °C]) treatments and at both temperatures. Information presented in this paper helps to evaluate how 2 contrasting soil types (Podzol and Folisol) responded to flooding and provided further insight into the dynamics of greenhouse gas (GHG) production rates as a result of hydroelectric reservoir creation. This will aid in future planning, construction, and management of hydroelectric reservoirs to help minimize GHG emissions and boreal forest disturbance.