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Climate change represents a growing ecological challenge. The (sub) arctic and boreal regions of the world experience the most rapid warming, presenting an excellent model system for studying how climate change affects mammals. Moose (Alces alces) are a particularly relevant model species with their circumpolar range. Population declines across the southern edge of this range are linked to rising temperatures. Using a long-term dataset (1988–1997, 2017–2019), we examine the relative strength of direct (thermoregulatory costs) and indirect (food quality) pathways linking temperature, precipitation, and the quality of two important food items (birch and fireweed) to variation in moose calf mass in northern Sweden. The direct effects of temperature consistently showed stronger relationships to moose calf mass than did the indirect effects. The proportion of growing season days where the temperature exceeded a 20 °C threshold showed stronger direct negative relationships to moose calf mass than did mean temperature values. Finally, while annual forb (fireweed) quality was more strongly influenced by temperature and precipitation than were perennial (birch) leaves, this did not translate into a stronger relationship to moose calf weight. The only indirect path with supporting evidence suggested that mean growing season temperatures were positively associated with neutral detergent fiber, which was, in turn, negatively associated with calf mass. While indirect impacts of climate change deserve further investigation, it is important to recognize the large direct impacts of temperature on cold-adapted species.

In northern environments, the period of access to high-quality forage is limited, exerting strong selective pressure to optimize the timing of parturition. We analysed timing and variation in moose ( Alces alces ) parturition dates of 555 females at 18 study sites across 12° of latitude (56–68° N, 1350 km) in Sweden. We found evidence for a spatial match of parturition timing to vegetation onset, but no evidence that moose adjust parturition to vegetation onset in a given year. We found a breakpoint at 64° N. Despite adaptation across latitudes, temporal divergences occurred. Females below 64° N calved after vegetation onset and females above 64° N calved before. Here, parturition before vegetation onset might be a strategy to optimize forage utilization time with the very short growing season. Highly seasonal environments such as at higher latitudes may make it advantageous to adapt parturition towards long-term climatic patterns by matching the most favourable period. Given the direction of temporal divergence, our study suggests that climate change may have less of an impact on moose parturition at northern latitudes than southern latitudes.

A community or multi-species approach to wetland management may more likely satisfy the aims of the various interest groups. This chapter discusses an approach to wetland management and shows that techniques which simulate natural events can be employed to simultaneously satisfy many of the interests of these various groups. It emphasizes the dynamic and often cyclical nature of marshes as it pertains to management for wildlife. The flora and fauna of wetlands have been subjected to the natural fluctuations and perturbations over evolutionary time. Therefore, it seems likely that management procedures that closely mimic these natural events will result in typical marsh communities. The chapter argues that a community/multi-species approach to marsh management will both minimize conflicts between interest groups and maximize benefits for most plants and animals. Natural techniques are particularly appropriate for this community approach to management.

The co-evolved relationship between the chemical composition of plants and herbivory is fundamental in understanding diet selection of herbivores and their impacts on plants and ecosystems. However, the impact of plant secondary chemistry on mammalian herbivory is not fully understood. We investigated seasonal influences of phenolics with low molecular weight (e.g., flavonoids, salicylates) and plant morphology of the tea-leaved willow (Salix phylicifolia L.) on moose (Alces alces (L., 1758)) foraging. We analysed the relationship of different phenolic compounds in twigs and browsing in winter, and in leaves and the degree of leaf stripping in summer, and the role of plant morphology. In winter, higher concentrations of phenolics, e.g., myricetin-related compounds (belonging to the flavonoids), had a negative impact on herbivory by moose. This impact was not associated with a single compound but instead seemed to be more a result of synergistic or additive effects of different compounds. In contrast, the models for summer browsing showed a pronounced effect of plant morphology. Our analyses reveal differences in the relative importance of phenolics of low molecular weight and plant morphology on diet selection between seasons. These findings are relevant for understanding feeding decisions and mechanisms deterring mammalian herbivores known for shaping the vegetation on the ecosystem level.

Coniferous trees of different species, or of the same species growing at different locations, vary in the extent to which they are attacked by various herbivores and pathogens. Plant secondary metabolites might be a key to understanding some of this variation. At the site level, we investigated if there was an intra- or interspecies pattern for individual compounds (or for groups of compounds) and their relationship to indices of plant nitrogen and plant productivity. For example, do plants exhibit similar covariance in defence compounds when evaluated across a number of sites varying in productivity? Here, we concentrated on the phenolic profile of Pinus sylvestris, Picea abies, Juniperus communis and Pinus contorta. Our results indicate striking differences in secondary chemistry profiles of the twigs including needles of the trees and in the inter-relationships amongst individual compounds and groups of compounds. Flavonols occurred in high variety in P. sylvestris and were highly correlated with each other, differing from P. contorta. But the results of the factor analyses indicate an underlying pattern for flavonols of the coumaroyl type for P. contorta. In contrast, the compounds of the other tree species showed a low degree of inter-correlation. Co-occurring phenolics of different tree species were not correlated. Overall, our analysis of site indices indicated that plant productivity was not a useful predictor for the concentration of specific phenolics. The relationship amongst plant nitrogen and specific phenolics might be the result of two defence strategies (one related and the other not related to nitrogen content). This might enable the plant to shift its defences against attacks with a high degree of flexibility.

Intensive forest management and fire protection programs have dramatically reduced the frequency of fires and this is believed to have negative effects on biodiversity. As a result, fire is used as a restoration tool to improve conditions for fire adapted/favoured species. The aim of our study was to determine how burning of clear-felled areas (i.e. those typical of real-world management in Fennoscandinavia) influenced beetle assemblages, and to identify taxonomic and functional groups and individual species that are favoured by burning as it is currently practiced. We studied five sites, each consisting of one burned and one unburned clear-cut. Beetles were collected in sixteen pitfall traps per site for three consecutive years. Regardless of whether beetles were divided into taxonomic or functional groups, abundance was generally higher on burned clear-cuts, with the exception of Staphylinidae which showed indications of an opposite response. The species assemblages differed significantly between burned and control clear-cuts in all years. The species contributing most to the difference included Corticaria ferruginea, Pterostichus adstrictus, Corticaria rubripes, Atomaria pulchra and Hylobius abietes (all more common on burned clear-cuts), and Drusilla canaliculata and Atomaria peltata (more common on controls). We also found a succession of species, i.e. Otiorhynchus nodosus and Anthicus ater became dominant species on burned clear-cuts the third year after burning whereas C. ferruginea and A. pulchra became scarce. In conclusion, clear-cut burning clearly changed the assemblage composition of beetles and seems to benefit at least some species associated with natural fires. Thus, although clear-cut burning cannot exactly emulate the effect of natural fires it could be used as a restoration tool for improving the quality of the matrix outside protected areas and in particular to create habitats for disturbance-associated species, including species associated with fire.

We determine if lacustrine salmonids show large-scale patterns of coexistence with the keystone predator northern pike ( Esox lucius ) and test an approach to predict fish communities using coexistence rules set in the context of three hierarchical filters that a species must pass to be present. The mutually exclusive species distribution patterns that we detected among 1029 lakes were repeatedly verified from results of whole-lake interventions with rotenone and introductions. Essentially, pike did not coexist with self-sustaining salmonid populations in lakes. High connectivity to pike (derived from maps) largely predicts the absence of lacustrine salmonids. Our analysis strongly suggests that pike prevented self-sustaining populations of brown trout ( Salmo trutta ), Arctic char ( Salvelinus alpinus ), and brook trout ( Salvelinus fontinalis ) in lakes. High connectivity to pike resulted in nonsalmonid lake fish communities, most often including both European perch ( Perca fluviatilis ) and roach ( Rutilus rutilus ). Our analysis suggests that if pike were not present in many boreal lakes where they now dwell, salmonid fish assemblages would prevail, a sharp contrast from the present pike-driven homogenized state with mainly nonsalmonid fish communities.

We analyse the selection of denning habitats by Scandinavian brown bears Ursus arctos and test if there are differences related to sex and age. At the landscape level, the vegetation types within a 500-m radius around 250 dens used during 1990–2000 in south-central Sweden were analysed using a Geographical Information System (GIS). Compositional analysis (CA) was used to test if bears selected or avoided certain habitat types for denning. There were relatively few differences in habitat selection among bears of differences age or sex. Overall, as a group the bears showed distinct preferences in selection of denning habitats; selecting for open canopy (Scots pine Pinus sylvestris) forests and habitats with moist soil with rich vegetation, before closed canopy (older Norway spruce Picea abies and Scots pine) forests, young forest and clear cuts, mountain coniferous forests and bogs. Denning bears avoided water, alpine mountain-birch forest, deciduous forest, peat, exposed bedrock and gravel pits. B...

We investigated the effects of snow and environmental variables on the depths to which moose sank in snow, and the extent to which moose followed in the tracks of other free-ranging moose in the mountains of the subarctic areas of northernmost Sweden. We tested a method to combine the variables that affect snow quality (e.g. density and hardness) into a single variable that is easier to measure in the field. We also studied the snow conditions in the summer and winter ranges of migrating moose. First, we performed correlation analyses that revealed that sinking depths of moose decreased with increasing snow quality, snow depth, altitude, and air temperature. Next, we next used the Akaike information criterion (AIC) to determine the best model of sinking depth, which indicated that the important variables were snow quality, altitude, and snow temperature. For trail-following behavior, the best model included air temperature only. Regarding seasonal ranges, winter ranges had considerably less snow than the summer ranges that these individual moose left, but snow quality did not differ. Overall, our new method to index snow quality (here, using a dynamometer to measure the force required to press a simulated moose foot down in the snow to the depth of a moose footprint) shows promise, and we suggest that future studies of ungulate winter ecology investigate it further.

Summary Modern forestry management has reduced the amount of dead wood in forest ecosystems and this has become a serious threat to flora and fauna. Efforts are therefore being made to reverse this trend but one problem is that we still lack detailed knowledge regarding the substrate requirements of many saproxylic species. In a field experiment, conducted in three forest types (forest reserve, mature managed forest and clear-cut), we evaluated the value, from a conservation perspective, of different substrate types (logs, snags and tops) of Norway Spruce, Picea abies, and if the quality of spruce logs as saproxylic habitats can be improved by simple log treatments (scorching and shading). We collected 9982 individuals representing 262 saproxylic beetle species in window traps. Both substrate type and, to a lesser extent, log treatment had a significant effect on the abundance and species richness of saproxylic beetles attracted to the different dead wood substrates. However, more importantly, the composition of the beetle assemblages differed significantly between both substrates and log treatments. Snags, logs and tops all attracted significantly different beetle assemblages and scorched logs differed from untreated control logs. Sixteen red listed species were trapped, with the highest number (11 species) being found on scorched logs. We found strong evidence that some species preferred a specific substrate type, mainly logs, in some cases treated logs (scorched or shaded), but not snags, the substrate commonly provided for conservation purposes on e.g. clear-cuts. This stresses the importance of conducting forestry in such a way that a multitude of both forest habitats and dead wood substrates are available continuously in the forest landscape to maintain biodiversity.

The presence and distribution of vertically-transmitted, asexual Neotyphodium/Epichloe endophytes in four species of widely distributed grasses, all members of the sub-family Pooideae, were determined at 57 spatially-distinct sites across Sweden in naturally-occurring grass populations. While these endophytes are well-studied in agricultural systems, much less is known about their abundance and distribution in non-agricultural systems at larger scales across landscapes. We used two screening methods to detect endophytes: 1) visual inspection of fixed, stained grass shoots, and 2) immunoblot cards with monoclonal antibodies specific for Neotyphodium/ Epichloe endophytes. Infection frequency (i.e. the proportion of individuals) varied widely among species and among sites, a finding common to most studies performed in non-agricultural ecosystems. Festuca rubra had the highest overall infection frequency (23% visual screening, 27% immunoblot screening), while Deschampsia flexuosa (4%) and Poa trivialis (4%) had low frequencies of infection. None of the sampled Agrostis capillaris populations were infected. In F. rubra, the within-site infection frequency varied from 0 to 100%. A significant altitudinal gradient was found for F. rubra, with the infection frequency of the vertically-transmitted endophyte Epichloe festucae decreasing with increasing altitude above sea level. The high variation across and within grass species at different geographical locations that ours and others' studies reveal, agree with suggestions that agronomic model systems cannot be readily extrapolated to understand the ecological role of endophytes in native grasses in the wild. Further investigation into the underlying cause of the observed altitudinal gradient is required to understand broader-scale patterns in the distribution of endophyte-infected grasses.

Epichloe festucae, a common fungal symbiont of the genus Festuca (family Poaceae), can provide its host plant with protection against herbivores. However, infection might also be associated with a cost to its host plant. We examined the distribution of Epichloe festucae infection in natural populations of three fescue grasses, Festuca rubra, F. ovina and F. vivipara, on mountains in northern Sweden to determine whether infection frequency varied with reindeer Rangifertarandus grazing pressure and altitude. Two differently-scaled approaches were used: 1) infection frequency was measured at a local scale along ten elevational transects within a ca 400 km2 area and 2) infection frequency was measured on a regional scale along elevational transects on 17 mountains classified as having a history of high or low reindeer grazing pressure. Mean infection frequencies in F. rubra were 10% (vegetative tillers at a local scale), and 23% (flowering culms at a regional scale), and in F. ovina they were 13% (local scale) and 15% (regional scale). Endophyte infection frequency in F. vivipara, was, on average, 12% (local scale) and 37% (regional scale). In F. rubra, infection decreased significantly with increasing altitude at both the local and regional scale, and was positively correlated with grazing pressure. In F. ovina, an opposite trend was found at the regional scale: infection frequency increased significantly with increasing altitude, while no discernible distribution pattern was observed at the local scale. No elevational trends were observed in infection of F. vivipara. These patterns in the distribution of endophyte-infected grasses in non-agricultural ecosystems may be explained by both biotic (grazing) and abiotic factors (altitude). Differences in ecology and life history of the studied grass species may also be of importance for the different results observed among species.

Predatory beetles are important natural enemies of early successional cambium feeding beetles and knowledge about their ecology is of paramount importance for biological control and sustainable forest management. We used a large-scale experiment including 3 stand types (clear-cut, mature managed and old-growth stand) and 6 dead wood substrates (burned, shaded, white rot inoculated, brown rot inoculated, untreated control logs and created snags) to test substrate preferences of 10 common predatory beetle species. We collected insects in eclector traps and measured dead wood availability within 100 m from the experimental logs at each site. We also tested the relationships between predators and prey at the trap level. Stand type was important for all predators; Nudobius lentus and Ampedus tristis were more abundant on clear-cuts while Phloeonomus sjoebergi, Quedius plagiatus, Epuraea boreella, Epuraea pygmaea, Epuraea angustula, Rhizophagus dispar and Epuraea laeviscula were more abundant in mature managed and old-growth stands. Snags differed most from the control logs supporting significantly more E. boreella and E. angustula and significantly less P. sjoebergi, E. pygmaea, A. tristis and R. dispar. Prey abundance proved to be more important than dead wood availability at the stand level for most species, although the response varied among species. At the trap level, the abundances of P. sjoebergi, E. laeviscula and Q. plagiatus were correlated with the abundances of their known prey species. P. sjoebergi, E. boreella, E. pygmaea, R. dispar and N. lentus were correlated with total bark beetle abundance suggesting that many predators might be less specific in their choice of prey than previously thought. The variable response of the 10 examined predatory beetles at different levels of scale suggests complex relationships with their prey and environment. The conservation of this group of beetles is important both to achieve environmental goals but also for biological control of potential pest species. Thus, conservation oriented measures needs to be performed aiming at improving both substrate and stand qualities.

Different functional groups of beetles are likely to exhibit different responses to forest management and it is essential that we gain knowledge on these responses to understand and minimize the negative impacts of forestry in boreal ecosystems. In a large-scale manipulative experiment in nine sites (including 27 stands) in northern Sweden, we tested how saproxylic beetles, fire-favoured beetles and functional groups of beetles were affected by log treatment (shaded, burnt and fungi inoculated logs) and stand type (clear-cuts, mature managed and old-growth stands). All sites included one clear-cut, one mature managed stand and one old-growth stand, which give in total 27 stands. Fresh logs were placed out in the stands and exposed to different treatments. Insects were caught in eclector traps attached to the experimental logs. Log treatment, stand type and their interactions affected abundance, species richness and assemblages of saproxylic beetles, fire-favoured beetles and functional groups of beetles. Cambium consumers were less abundant on burnt logs compared with control logs. Furthermore, the assemblage composition differed between burnt logs and control logs for fire-favoured species and cambium consumers. On the clear-cuts burnt logs hosted lower abundance of all saproxylic beetles and fire-favoured species. For predators, the assemblage composition differed between burnt logs and control logs on clear-cuts. Shaded logs hosted lower abundance of wood borers compared to control logs. Shaded logs also supported different assemblages of saproxylic beetles and predators compared with the control logs on clear cuts. The effect of stand type was stronger than the effect of log treatment and for most of the examined groups; the clear-cuts differed from the mature managed and old-growth stands, while few differences was detected between mature managed and old-growth stands. The results indicate that in an area with intense forestry, both old-growth forest reserves and the creation of suitable substrates in managed forests are needed to conserve functionally intact beetle assemblages.

The use of saproxylic beetle community as a metric to evaluate nature conservation measures in forests requires efficient methods. We first compare traditional bark sieving to a potential improvement (extracting beetles from whole bark with Tullgren funnels) to determine the most efficient. Secondly we compare this most efficient bark sampling to eclector and window traps. At the species, family, and functional group levels, we consider species richness, abundance and practical aspects. Traditional bark sieving missed >50% of the individual beetles compared to whole bark sampling so we recommend the latter. Window traps caught large numbers of mobile saproxylic beetles, but a high proportion of non-saproxylics results in high sorting cost; bark sampling and eclector traps had a high proportion of saproxylics and obligate saproxylics. Compared to bark sampling, eclector traps are non-destructive, and monitor the whole saproxylic assemblage (i.e. also beetles inside the wood). Overall, window traps are useful because they capture saproxylic beetles attracted to dead wood and sample the local species pool, whereas eclector traps capture the saproxylics that actually emerge from a particular piece of dead wood, and thus are suited to detailed studies. Overall, we suggest that a combination of these two best methods is highly complementary.

Traits such as poor dispersal ability and high habitat specificity are thought to predispose some species to a greater risk of extinction than others. Habitat preferences and morphological features associated with dispersal ability were compared between red-listed species and common congenerics co-occurring in boreal forests in northern Sweden. Measurements of body size, wing loading and wing aspect ratio were used to compare dispersal abilities, while catches from experimental treatments of dead wood were used to compare habitat preferences. We also compared how restricted red-listed species were to particular sites or habitats relative to common species. The red-listed Epuraea longipennis was longer and wider, while Epuraea. deubeli weighed less than common Epuraea species. In contrast to expectations, these red-listed species had a larger wing area (relative to their body mass) and thus a lower wing-loading than congeneric species, suggesting superior dispersal abilities. The red-listed Tachinus elegans possessed intermediate morphological characteristics, compared with common congenerics. However, the relationships between the risk of extinction in fragmented habitats and size and dispersal ability are likely to be scale-dependent, so intermediate or superior dispersal abilities may increase extinction risk at some scales. Red-listed species were not found in fewer sites or habitat types than congenerics so were not more likely to be habitat specialists. However, some red-listed species preferred deeply shaded and Fomitopsis pinicola-inoculated logs, relative to congenerics, suggesting that specificity to these particular microhabitats may be connected with extinction risk.

Summary 1Standard visual screening methods for determining the qualitative and quantitative presence of fungal endophytes are too time-consuming for large-scale ecological studies. 2We investigated whether commercially available immunoblot kits, using monoclonal antibody techniques and designed for rapid-screening of the presence of Neotyphodium endophytes in fresh samples of the pasture grasses Festuca arundinacea and Lolium perenne, could be used for Neotyphodium detection using other grasses and preserved samples. We also determined whether immunoblot kits could provide quantitative information about the amount of Neotyphodium in the grass. 3The kits accurately detected endophyte presence in F. rubra, F. ovina, F. pratensis and F. altaica, in both preserved samples (dried and fixed), including 12-year-old stored, dried samples of F. rubra. 4Endophytes were detected in 7-day-old seedlings of Lolium perenne, 3 days (30%) earlier than previously recognized. 5The intensity of the coloured tissue prints on scanned immunoblot cards was significantly positively correlated with hyphal density, demonstrating a previously unrecognized accurate quantitative application. 6These findings greatly reduce logistical barriers to large-scale field research into the broader ecological significance of Neotyphodium in temperate and arctic grasses in non-agricultural ecosystems (particularly in remote areas) and suggest potential for estimating historical infection rates using stored and herbarium specimens.

New conservation-oriented forestry aims to maintain intact populations of forest organisms by improving the conservation value of managed forests and providing protected areas. We tested the conservation value of treatments of dead wood for assemblages of early successional saproxylic beetles. In nine areas in northern Sweden, we selected one clear-cut, one mature managed forest and one reserve. In 2001–2002, we placed three blocks of spruce logs, each containing control, burned and shaded logs and a high stump (“snag”) at each site. Saproxylic beetles emerging from the dead wood were collected using emergence traps and beetles flying close to it were collected using flight-intercept traps. After one year of exposure, assemblage composition was examined, with respect to nutritionally-defined functional groups, red-listed species and fire-favoured species. Experimental snags were most complementary to control logs, supporting different assemblages of cambium consumers and fungivores and supporting more red-listed individuals. Burned logs supported depauperate assemblages, particularly with respect to cambium consumers, while shading of logs affected assemblages of fungivores, but only on clear-cuts. Despite containing less dead wood, managed forests provided valuable habitat, supporting similar assemblages of saproxylic beetles to reserves. Most functional groups were less abundant on clear-cuts than in older forests, but fire-favoured species were more common on clear-cuts, suggesting that clear-cuts may support assemblages of species associated with natural disturbances, if suitable substrates are available. Utilization of logs by saproxylic beetles changes over time, so long-term monitoring of our experimental logs will determine their lifetime conservation value.

Many species of Scolytinae are pests in boreal forests, so factors that affect their abundance are of great interest to forestry. Using emergence and window traps we examined the effects of stand type and substrate characteristics on the abundance of spruce-infesting Scolytinae in northern Sweden. Several species of Scolytinae (Crypturgus subcribrosus, Hylastes cunicularius, Hylurgops palliatus, Pityogenes chalcographus, Polygraphus punctifrons) were captured in greater numbers on snags than on untreated logs. Log exposure also had a significant effect on some species, H. palliatus and Trypodendron lineatum were more abundant in window traps on artificially shaded logs than on naturally shaded or untreated logs. Significantly fewer Dryocoetes autographus, H. palliatus,Hylurgops glabratus, andH. cunicularius were captured on burned logs than on untreated logs. Stand type clearly affected several species, P. chalcographus emerged in greater numbers on clearcuts than in mature managed and old-growth stands, and D. autographus,H. glabratus, and T. lineatum showed the opposite pattern. Historical records suggest that pest outbreaks are rare in northern Sweden; however, improved knowledge of the habitat preferences of potential pest species in this region will allow us to take the necessary precautions against outbreaks, whilst leaving sufficient dead wood to support intact saproxylic assemblages.

The habitat requirements and effects of forest management on insects belonging to higher trophic levels are relatively unknown in forest ecosystems. We tested the effect of forest successional stage and dead wood characteristics on the saproxylic parasitoid ( Hymenoptera , Ichneumonoidea ) assemblage in boreal spruce-dominated forests in northern Sweden. Within each of nine areas, we selected three sites with different management histories: (1) a clear-cut (2) a mature managed forest and (3) an old-growth forest. Parasitoids were collected in 2003 using eclector traps mounted on fresh logs, which were either untreated (control), burned, inoculated with fungi, or naturally shaded, and on artificially-created snags. Both forest type and dead wood characteristics had a significant effect on parasitoid assemblages. Grouped idiobionts and some species, such as Bracon obscurator and Ontsira antica , preferred clear-cuts, while others, such as Cosmophorus regius (Hym., Braconidae) and other koinobionts, were associated with older successional forest stages. No single dead wood substrate was sufficient to support the entire community of parasitoids in any forest type, even when the regular host was present. In particular, snags hosted a different assemblage of species from other types of dead wood, with parasitoids of Tetropium spp. such as Rhimphoctona spp. (Hym., Ichneumonidae) and Helconidea dentator (Hym., Braconidae) being abundant. These results indicate that a diversity of dead wood habitats is necessary to support complete assemblages of beetle-associated parasitoids from early successional stages of dead wood and that parasitoids may be more sensitive to habitat change than their hosts.

Intensive forestry practises in the Swedish landscape have led to the loss and fragmentation of stable old-growth habitats. We investigated relationships between landscape composition at multiple scales and the composition of saproxylic beetle assemblages in nine clear-cut, mature managed and old-growth spruce-dominated forest stands in the central boreal zone of Sweden. We set out fresh spruce and birch logs and created spruce snags in 2001–2002 to experimentally test the effects of coarse woody debris (CWD) type and forest management on the composition of early and late successional, and red-listed saproxylic beetle assemblages. We examined effects of CWD availability at 100 m, and landscape composition at 1 and 10 km on saproxylic beetle abundances. Additionally, we tested whether assemblage similarity decreased with increasing distance between sites. We collected beetles from the experimental logs using eclector and window traps in four periods during 2003. CWD was measured and landscape composition data was obtained from maps of remotely sensed data. The composition of saproxylic beetles differed among different CWD substrates and between clear-cuts and the older stand types, however differences between mature managed and old-growth forests were significant only for red-listed species. Assemblage similarities for red-listed species on clear-cuts were more different at greater distances apart, indicating that they have more localised distributions. CWD availability within 100 m of the study sites was rarely important in determining the abundance of species, suggesting that early successional saproxylic beetles can disperse further than this distance. At a larger scale, a large area of suitable stand types within both 1 and 10 km resulted in greater abundances in the study sites for several common and habitat-specific species. The availability of suitable habitat at scales of 1–10 km is thus likely to be important in the survival of many saproxylic species in forestry-fragmented areas.

We investigated the selection criteria of moose, Alces alces (L., 1758), feeding on two willow species, Salix phylicifolia L. and Salix myrsinifolia Salisb., and whether these willows respond chemically. We correlated winter twig browsing with the concentrations of primary and secondary plant compounds in twigs and new leaves. Furthermore, we investigated 12 specific phenolics in twigs of S. phylicifolia. During winter, moose browsed twigs with low concentrations of phenolic compounds. Additionally, we found significant negative correlations between browsing and the concentration of 7 of the 12 specific phenolic compounds in S. phylicifolia. Most importantly, even though ours was a field study and had many potential sources of variation, a multivariate analysis revealed that these specific phenolics predicted 47% of the variation in moose browsing. The two willows reacted in different chemical ways to moose browsing, but both showed signs of defensive response in early spring and compensation growth in summer. Our data demonstrate the importance of plant secondary chemicals for feeding behaviour of moose and underline the importance of working at a species level in studies of plant–animal interactions, especially with the chemically heterogeneous willows.

Forest management practices have led to a reduction in the volume and a change in the composition of coarse woody debris (CWD) in many forest types. This study compared CWD volume and composition in reserves and two types of managed forest in the central boreal zone of Sweden. Ten areas were surveyed, each containing clear-cut, mature managed and old-growth stands, to determine the volume of standing and lying CWD in terms of species composition, decay class and size class. Volumes of CWD on clear-cuts and in mature managed forests were high compared with previous studies. Old-growth forests (72.6 m3 ha−1) contained a greater volume of CWD than mature managed forests (23.3 m3 ha−1) and clear-cuts (13.6 m3 ha−1). Differences were greatest for the larger size classes and intermediate decay stages. Despite stand ages being up to 144 years, CWD volume and composition in managed forests was more similar to clear-cuts than to old-growth forests.

The mechanistic foraging models introduced by Spalinger and Hobbs in 1992 have been very influential in studies of herbivory at a variety of scales. However, almost no field study has evaluated whether the assumption regarding invariability of parameters with time holds for large herbivores with long foraging bouts, and most studies have obtained the model parameters from very short trials. We used free-ranging moose, Alces alces (L., 1758), to test this assumption of invariability and to compare intake calculated by the Spalinger–Hobbs model using parameters obtained from 10-min trials with intake calculated using data obtained from entire bouts. Our results revealed that the invariance assumption was not fully met: moose increased bite and chew rates and took smaller bites the longer a bite or chew sequence lasted, which resulted in declining intake rates. As a result, the original model misestimated intake by more than double for mountain birch (Betula pubescens ssp. czerepanovii (Orlova) Hämet-Ahti) and by up to 23% for willow (Salix spp.). Compared with data from entire foraging bouts, parameters derived from only the first 10 min of a bout overestimated intake of mountain birch by 31% and underestimated intake of willow by up to 24%. Our results suggest that for herbivores with long foraging bouts, one could modify the model to allow some parameters to vary with time but, more simply, one should parameterize the model using data from entire foraging bouts.

Using growth of different tissues in Acacia tortilis as a model, we tested current hypotheses on how nutrients affect mechanical plant defence. In a greenhouse experiment we applied a balanced commercial fertiliser (NPK) at three treatment levels to juvenile potted Acacias. As expected, plants increased in size with nutrient addition. More importantly, however, the relative mass of long spines increased significantly more than other structural components (leaves and twigs). This effect is not predicted by current nutrient availability hypotheses, which suggest either equal or proportionally lower investment in mechanical defence with increasing nutrient availability. Our results suggest that investment in spine size is nutrient limited in Acacia tortilis. It is commonly observed that the risk of damage by herbivores is highest on plants growing in nutrient-rich soils. If spines act as an effective form of anti-herbivore protection, then these plants might be expected to increase their production of physical defences (long spines) under such circumstances. Plants growing under higher nutrient conditions might therefore invest more in constitutive defences. These changes in allocation pattern are consistent with the increase in production of long spines, which are also induced by browsing.

Food-plant and foraging-site selection by semidomesticated female reindeer (Rangifer tarandus tarandus L.) was studied to shed light on the searching and foraging behaviour of this herbivore. The aims of the study were (i) to determine the role of food biomass and (or) plant nitrogen content in feeding-site selection and (ii) to analyse the extent to which movement patterns of reindeer are related to availability of food resources using several models of searching behaviour (fractal analysis, correlated random walks, and Lévy flights). The study was conducted in summer 1999 in a mountainous area of northern Sweden. Reindeer selected different plant communities during this period and changed search pattern in late summer. We found that reindeer selected feeding sites with higher green biomass of Betula spp. and Salix spp. However, there was no sharp threshold for foraging as suggested by some models. Contrary to qualitative predictions of optimal-foraging theory, we found no selection of feeding sites on the basis of the nitrogen content of food. The changed search pattern in late summer and the discrepancy between reindeer foraging paths and a correlated random walk model suggests that reindeer were responding to their environment by changing their searching behaviour.

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the e...

A general prediction for aging placental mammals is that they should show a decline in reproductive value, and reproductive effort is therefore predicted to increase with age. To test this, we monitored known-age radio-collared females of a large ungulate, the moose (Alces alces), in a Swedish population. Female moose showed senescence in reproduction (i.e., litter size) from about 12 yr of age. Further evidence of senescence was a decrease in parental care during summer (expressed as increased offspring mortality) with the mother's age. Moreover, aging females facing a declining reproductive value increased their reproductive effort by giving birth to heavier offspring regardless of litter size. A logistic regression model showed that older moose have to give birth to heavier offspring to achieve the same offspring summer survival as that for offspring of younger mothers. This suggests that females increase their reproductive effort (by increasing offspring mass) as they get older. Furthermore, the rather intense harvest in our population may select for an increased reproductive effort in terms of litter size, which furthermore may select for an earlier onset of senescence in reproductive characters and mortality.

We studied seasonal migration of individually radio-collared moose Alces alces in a partially migrant population in northern Sweden. First, to investigate habitat selection at the level of individuals, we examined use vs availability of habitat characteristics within seasonal ranges. Second, to investigate what habitat characteristics migrants use to select these seasonal ranges, we contrasted the characteristics of summer and winter ranges of individual migrants. Third, to investigate why some moose migrate whereas others do not, we contrasted the snow conditions and the composition of the vegetation in the seasonal ranges of 36 migrant and 30 resident moose. At the level of habitat selection within a range, moose selected areas which had less mire, clear-cut and field habitats, as well as less snow. At the level of the entire range, migrants and residents had rather similar range compositions and differed only in migrants having less field habitats in their winter ranges; the proportion of Scots pine Pinus sylvestris stands, Norway spruce Picea abies stands, mire, deciduous, and clear-cut forest habitats did not differ, nor was there a difference in snow depth. Similarly, within the group of migrants, we detected no differences in habitat composition or snow depth between the summer ranges they just left, and the winter ranges they moved to. Snow quality (as indexed by the depths to which moose sank) did not differ between the two seasonal ranges of migrants, but calves sank less deeply in ranges of migrants than in ranges of residents, suggesting that snow quality may play a role in the selection of ranges by moose or their decision to migrate/remain resident. Thus, habitat composition and snow depth were important at lower levels of habitat selection, but differences among home ranges were not dramatic. The observation that snow quality differed significantly between ranges of residents and migrants suggests that future studies of migration might profitably investigate snow quality.

We investigated habitat selection by grey seals, Halichoerus grypus, around haulouts in the Baltic Sea. Home ranges (95% fixed kernel) varied in size from 1088 to 6400 km2. Observed habitat use was tested against the circular home range predicted from a simple central-place model. The overlap between the home ranges predicted by this simple model and actually exhibited by the seals was 51 m deep. Ten of the 11 seals used areas within a 50-km radius around the haulout site for more than 75% of the time. Thus, in spite of their mobility and the availability of many islands, seals usually remained in the vicinity of a specific haulout site for extended periods. The seals did not use the habitat around the haulout site as predicted by the simple central-place model, but selected habitat according to bathymetric characteristics (e.g., water depth). Detection of these relatively small but heavily used home ranges around haulout sites may be of assistance in management plans in order to reduce the growing number of seal-fisheries conflicts.

Summary 1. Herbivores make decisions at different spatial levels in response to food plant quality and quantity. Although experiments have examined the responses of herbivores at lower levels, few have examined how herbivores respond to such variation at the stand level. We assessed the response of a herbivore community in a boreal forest to manipulations of food resources at the stand level by performing a large replicated experiment where we fertilized young forest stands and then followed their use by herbivores during the subsequent year. 2. We used stands at 25 sites in an area 35 × 45 km. At each site we had one fertilized plot, a close control (100 m away) and a distant control (300 m away), all 50 × 50 m. 3. Before the growing season we fertilized treatment plots with calcium–ammonium–nitrate at 600 kg ha−1 (200 kg N ha−1). Fertilization significantly improved browse quality (nitrogen concentration) in both downy birch Betula pubescens and Scots pine Pinus sylvestris. Furthermore, the amount of browse significantly increased for birch, and Scots pine showed a similar trend. 4. Considering the animal community as a whole, we found that 10 of 13 animal species/groups made more tracks during winter in fertilized than in control plots. The total number of tracks was greater in fertilized plots, followed by close and then distant controls. 5. In the summer following fertilization, moose Alces alces strongly selected fertilized plots over controls. Furthermore, during the following winter moose again selected fertilized plots over controls. Hares Lepus timidus similarly left more pellets in the fertilized plots. Other mammals used the fertilized and the close controls similarly, and both were used more than distant controls. The number of grouse pellets did not differ among the treatments, although they followed a similar trend. 6. Several lines of evidence suggest that moose browsed fertilized plots more. Although not statistically significant, both heavy and light browsing were more common in fertilized than in control plots. Trees with the top shoot removed, or with bark stripped from the stem, did not differ significantly, but once again fertilized plots were browsed more than controls. 7. Our results are discussed in light of understanding both how herbivores in general respond to changes in food quality and quantity, and if fertilization may be a useful tool in modern forestry to manage herbivores. 8. Fertilization might be useful as a tool to alter the location of herbivore feeding, but buffer strips around any fertilized areas appear necessary, and other potential environmental effects should be evaluated.

Northern prairie wetlands play a vital role in the life cycle of a wide array of bird species. Prairie wetlands used by birds span the entire range from shallow ephemeral ponds inundated for short periods each spring to large permanent water bodies that seldom, if ever, go dry. The objective of this study was to determine the response of blackbirds, waterfowl, and American Coots to changes in habitat structure induced by water level fluctuations in prairie wetlands. The study was conducted on a series of experimental marshes within the Delta Marsh in southern Manitoba, Canada. Water levels were adjusted following a predetermined schedule to simulate the wet–dry cycle of prairie marshes. Aerial photographs were taken annually, and habitats were characterized using Geographic Information System (GIS) techniques. Weekly avian censuses were related to habitat features using Principal Components Analysis (PCA) procedures. Yellow-headed Blackbirds selected shallowly flooded habitats with a mixture of open water...

To compare the effects of two tree harvesting methods (clear-cutting and single tree selection felling), spring-occurring ground beetles (Carabidae) were studied by pitfall trapping in northern Sweden. Species abundance, total abundance and Hill's diversity indices were used to compare the ground beetle community in clear-cuts to selectively-logged and to uncut control forests. In addition, to highlight the importance of site replication when evaluating a spatially-variable ecosystem like the boreal forest, we consider how our conclusions might have differed with and without site replication. Results from the two analyses differed considerably, highlighting the importance of site replication in studies offorestry effects in order to increase confidence in the conclusions. Overall, no significant harvest effects were found on the ground beetle community except for a significantly higher abundance of the open habitat species P. assimilis in clear-cuts than in uncut control forests. Our results thus do not support suggestions of an increase in diversity following clear-cutting, but are consistent with previous findings regarding increased abundances of open habitat species and no changes in abundance of forest generalists in clear-cuts. In general, the carabid community in the selection loggings resembled that in the uncut control forest, indicating a low effect of this harvesting method. Based on our analysis, we suggest that future studies of forestry impacts on invertebrates attempt to increase the number of sites evaluated rather than increase the number of samples from a given area.

To investigate the effects of commercial forestry on canopy-living invertebrates in the boreal forest, we sampled branches in northern Sweden for invertebrates and lichens from paired natural spruce Picea abies forests and adjacent managed forests that were selectively logged. The study was conducted during late winter, when invertebrate abundance is lowest, and when small differences may be critical to foraging birds. Natural forests had significantly greater invertebrate diversity than managed forests and nearly five times as many invertebrates per branch. The number of large invertebrates (> 2·5 mm, the minimum prey size for foraging passerine birds) was consistently higher in natural forests, with spiders (Araneae), Lepidoptera and Diptera larvae dominating. The number and biomass of invertebrates were related to the abundance of lichens even after controlling for sampling location and branch size. Other studies have implicated forestry in the decline of non-migratory passerine birds in northern Europe through the destruction and fragmentation of forests, but our study indicates that it may also reduce foraging habitat quality through a reduction in lichen abundance.

Restoration of habitats is critically important in preventing full realization of the extinction debt owed as a result of anthropogenic habitat destruction. Although much emphasis has been placed on macrohabitats, suitable microhabitats are also vital for the survival of most species. The aim of this large-scale field experiment was to evaluate the relative importance of manipulated microhabitats, i.e., dead wood substrates of spruce (snags, and logs that were burned, inoculated with wood fungi or shaded) and macrohabitats, i.e., stand types (clear-cuts, mature managed forests, and forest reserves) for species richness, abundance and assemblage composition of all saproxylic and red-listed saproxylic beetles. Beetles were collected in emergence traps in 30 forest stands in 2001, 2003, 2004 and 2006. More individuals emerged from snags and untreated logs than from burned and shaded logs, but species richness did not differ among substrates. Assemblage composition differed among substrates for both all saproxylics and red-listed saproxylic species, mainly attributed to different assemblage composition on snags. This suggests that the practise of leaving snags for conservation purposes should be complemented with log supplementation. Clear-cuts supported fewer species and different assemblages from mature managed forests and reserves. Neither abundance, nor species richness or assemblage composition differed between reserves and mature managed forests. This suggests that managed stands subjected to selective cutting, not clear-felling, maintain sufficient old growth characteristics and continuity to maintain more or less intact assemblages of saproxylic beetles. Thus, alternative management methods, e.g., continuity forestry should be considered for some of these stands to maintain continuity and conservation values. Furthermore, the significantly higher estimated abundance per ha of red-listed beetles in reserves underlines the importance of reserves for maintaining viable populations of rare red-listed species and as source areas for saproxylic species in boreal forest landscapes.

Species belonging to higher trophic levels are particularly vulnerable to habitat loss and consequential host population declines, but detection of effects depends on observation scale. We investigated the effects of habitat and host availability at multiple scales on parasitoids of early successional saproxylic beetles in middle boreal Sweden, where forestry has led to habitat fragmentation and coarse woody debris (CWD) loss. Parasitoid wasps and beetle hosts were collected from nine locations, each containing three spruce-dominated stand types (clear-cut, mature managed and unmanaged stands), using emergence traps on experimental CWD. We measured local CWD volumes and determined the availability of forests of a suitable age within the landscape. We tested parasitoid responses to stand type, CWD volume, abundance of known and probable hosts and longitude. Additionally, we tested whether parasitoids responded to the area of habitat of a suitable age within radii from 0.2 to 10 km. Stand type appeared in best-fit models for all common species, suggesting that wasps respond strongly to habitat at local scales. Longitude (largely climate) featured commonly, but CWD volume was never significant. Host abundance appeared in best-fit models for three of five common species, proving significant only for Bracon obscurator, the abundance of which correlated with that of Orthotomicus laricis at both trap and site levels. Rhimphoctona spp. also correlated significantly with its known host Tetropium castaneum at the trap level. B. obscurator responded to habitat area at scales of 0.6–1 km and Cosmophorus regius responded at radii greater than 7 km, while the larger species did not respond strongly to habitat area. The role of habitat area at greater scales thus varied greatly amongst species, but our data suggest that dispersal of these common early successional species may not be strongly restricted at the current scale of fragmentation of their boreal habitats.

An omnivore is an animal with morphological and physiological adaptations that enable it to exist on plant and animal foods (Westoby 1978), although at any given time the diet of an individual may not be mixed. Canvasback ducks (Aythya valisineria) are omnivores that dive and search for prey by using tactile cues. Few investigators have studied tactile predators (see Elner and Hughes 1978, Hughes 1979); fewer still have studied the foraging strategies of omnivores.

We tested whether altitude increased environmental heterogeneity in moose (Alces alces) populations on the landscape scale. Dressed mass from moose calves collected during 10 consecutive years was related to local climate information from 26 different weather stations (located from 7 to 525 m above sea level). Two hypotheses were contrasted: (1) Are moose offspring from higher altitudes heavier because of increased forage quality with increasing altitude? or (2) Are moose offspring from lower altitudes heavier because the growing season is longer there so that the time moose calves can grow is extended at these lower altitudes? During October (when moose calves stop growing), both sexes showed a significant negative relationship with altitude. The dressed body mass of female calves was more affected by increased altitude (-1.2 kg per 100 m increase in altitude) than males (-0.8 kg per 100 m). The mass of both sexes was positively related to the length of the growing season (i.e., days >6 °C). Female mass showed significant cohort effects during 4 of the 10 years investigated (range -6.3 to 3.4 kg), whereas males showed cohort effects during 2 years (-3.7 to 3.5 kg). We conclude that the annual variation in the length of the growing season together with year-specific effects may introduce considerable spatial and temporal variation in moose population dynamics mediated via offspring body mass. We suggest that this impact on population dynamics may be most pronounced at higher altitudes. Our analysis further suggests that a permanent factor (altitude) may interact with random variations (weather) to influence the length of the growing season and thus complicate the management of moose populations by creating cohorts composed of females of unequal quality. We suggest that managers be alert for sudden changes in ungulate recruitment due to unusually weak or strong cohorts reaching reproductive age.

A13STRACT.-Digestibility data generally are analyzed as ratio variables, but to be useful this method requires that animals consume large quantities of food. If little is eaten, as may occur with novel or unpalatable foods, apparent digestibility estimates can be seriously biased and statistical analyses may suffer from very low power to detect digestibility differences among foods. Moreover, ratio variables are undesirable for statistical analyses. We suggest that for many wildlife studies, true digestibility estimated from regression analysis is preferable to apparent digestibility estimated from ratio variables. True and apparent digestibilities were determined from the same data set. The regression method for estimating true digestibility was more applicable to wildlife species, provided greater statistical power, and avoided the unreliability of ratio variables used to estimate apparent digestibility. The advantages of the regression method are illustrated using data on digestibility of three woody forage species eaten by beavers (Castor canadensis).

I developed an individually-based non-linear programming model of prey selection to examine diet selection by omnivorous canvasback ducks (Aythya valisineria) in a complex foraging environment that approximates the problem of diet selection faced in real-world conditions. The model incorporated prey depletion, feeding rates and digestion rates, and predicted the energy-maximizing diet for each of 10 individuals choosing among 4 different prey (plant tubers, insect larvae, and 2 kinds of seeds). Feeding trials yielded estimates of the rate of prey digestion and energetic value. I observed underwater foraging in a 2 × 2 × 5 m aquarium to estimate feeding rates and diving times on these 4 prey

Interactive-image mnemonics were used by college age men and women to learn the meanings of German words. One experimental treatment provided ready-made interactive pictures and the other a procedure by which Ss could generate their own mental mnemonic pictures. The two control treatments included a repetition group and one which received no prescribed learning strategy. The two experimental groups remembered approximately twice as many words as either of the control groups, both on an immediate recall test and a delayed-retention test two weeks later. Data from self-reports suggested that over 75 per cent of the words which were remembered by Ss across all treatment conditions (including the control groups) were learned by elaborative strategies. These results suggest that the use of elaborative devices, either spontaneously or by design, is a natural and effective way for Ss to approach this kind of task.

Moose (Alces alces L.) prefer to browse Pinus sylvestris over other coniferous trees. One reason for this preference might be due to differences in the chemical composition of various coniferous plants, and/or differences in digestibility. We evaluated the in-sacco digestibility of P. sylvestris, Pinus contorta and Picea abies using a fistulated cow (Bos taurus). Additionally, we determined the chemical profile of the different plant species (with emphasis on specific phenolics) and we modified the concentration of the individual phenolic (+)catechin in plant material of P. sylvestris to test the influence of this particular phenolic on digestibility in vitro (IVDMD). The in-sacco experiment revealed the highest digestibility of dry matter, and neutral detergent fibre for P. sylvestris. In addition, the concentration of nitrogen was significantly higher, and the concentrations of total phenolics and condensed tannins were significantly lower in P. sylvestris than in the other species. Individual phenolics showed high variation but were low in P. sylvestris, whereas P. contorta and P. abies had at least one species-specific phenolic compound of high concentration each. We found no changes in the digestibility of samples in which we experimentally elevated (+)catechin content.