| 1. |
- Hasselquist, Eliza Maher, et al.
(författare)
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Microsite differentiation among conifer species during seedling establishment at alpine treeline
- 2006
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Ingår i: Ecoscience. - : Presses de L`Université Laval. - 1195-6860. ; 13:3, s. 334-341
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Tidskriftsartikel (refereegranskat)abstract
- Tree establishment is a potentially important factor affecting tree populations in alpine-treeline ecotones. Patterns of seedling establishment of Abies lasiocarpa, Pinus albicaulis, and Picea engelmannii were evaluated relative to neighbouring trees and herbs over two years and three treelines of the Rocky Mountains, USA. The greatest mortality rates were observed in seedlings that had just emerged from seed and were in their first year of growth and in seedlings that had the least amount of cover provided by trees or other landscape features that block exposure to the sky. Although herb cover promoted survivorship in microsites that were not near trees, no seedlings were detected at or above the upper limit of the treeline ecotone. Microsite tree cover was greatest for A. lasiocarpa and least for P. albicaulis seedlings, which matches predictions based on their relative photosynthetic tolerances to the bright sunlight and frequent frost that occur in exposed microsites. Interspecific differences in seedling requirements for neighbouring plant cover likely contribute to the apparent coexistence and possible interdependency of these conifers along a continuum of colonization and succession within treelines.
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| 2. |
- Karlsson, P. Staffan, et al.
(författare)
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Relationships between fruit production and branching in monocarpic shoot modules of Rhododendron lapponicum
- 2006
-
Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 13:3, s. 396-403
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Tidskriftsartikel (refereegranskat)abstract
- Rhododendron lapponicum is an ericaceous clonal dwarf shrub in which vegetative growth largely coincides with the formation of flowers and fruits. We used a flower-removal experiment and a descriptive data set to look for relationships and potential trade-offs between vegetative growth, i.e., branching, and fruit production in two contrasting subarctic populations (growing at low and high altitude). The two sites are similar in most respects and differ mainly in that the higher site has lower temperatures and a shorter growing season. We predicted that trade-offs between branching and fruit production would be less marked in a high-altitude population because at lower temperatures reproductive activities could be less resource dependent. At lower altitudes, where temperatures are higher, there would be competition for nutrients between fruiting and branching; hence, a trade-off between these two activities would be more obvious. In both populations about 80% of all new shoot modules were produced by reproductive shoot modules. We found evidence for a [linear] trade-off in the experimental study only, whereas the descriptive data set did not show any consistent indications of trade-offs between branch and fruit production. The high-altitude population showed several characteristics indicating that this population gave priority to vegetative growth over sexual reproduction. The data we present is a typical example of a case where co-variation in size and resource economy among modules masks potential trade-off patterns.
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| 3. |
- Niva, Mikael, et al.
(författare)
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Effects of light and water availability on shoot dynamics of the stoloniferous Linnaea borealis
- 2006
-
Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 13:3, s. 318-323
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Tidskriftsartikel (refereegranskat)abstract
- Many stoloniferous plant species have the ability to exploit resource-rich patches via plastic growth responses. The most efficient responses are shortened spacers and increased branching frequency. Here we experimentally investigate the ability of the stoloniferous plant Linnaea borealis to respond to patches of increased light intensity and reduced water availability in natural systems. The significance of contrasts between patches was also investigated. A three-level factorial design was used, with light, water availability, and site as the factors. Increased light intensity was achieved through mowing of the surrounding vegetation, and reduced water availability was achieved by placing wooden ledges under the stolons. The treatments were applied at three subarctic sites that differ in light conditions. Branching frequency, number of new meristems, average internode length, leaf area, and dry weight production were studied 14 months after the manipulations. Increased light intensity increased branching frequencies; the strongest effects were obtained at the site with a closed canopy. Average intemode length decreased 19% in response to increased light intensity. Root:shoot ratios decreased under increased light intensity and reduced water availability. A reduction in water availability alone did not affect any other investigated traits. We conclude that ramets of L. borealis are able to respond efficiently to small-scale variations in light intensity in natural systems, an ability of great importance for the performance of a prostrate species on shady forest floors.
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| 4. |
- Angelstam, Per, et al.
(författare)
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Gap analysis as a basis for strategic spatial planning of green infrastructure: a case study in the Ukrainian Carpathians
- 2017
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 24, s. 41-58
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Tidskriftsartikel (refereegranskat)abstract
- Increased demand for natural resources and economic transition threaten natural and biocultural capital and thus ecosystem services for human well-being. We applied an evidence-based approach to strategic planning of functional green infrastructure in a European biodiversity hotspot: the Ukrainian Carpathian Mountains. We (1) described how potential natural vegetation types have been transformed, (2) applied evidence-based critical thresholds for each potential natural vegetation land cover, (3) measured how much of the potential natural vegetation land covers are protected, and (4) estimated the area of cultural landscapes that emerged. While only 2% of lowland land cover types were left, 55% of mountain forests and 94% of alpine land covers remained. Many mountain forests were transformed to valuable cultural landscapes. Beech and oak forests covered 42% of the study area but at low levels of protection (< 5%). The highest protection level (12-17%) was in mixed beech-fir-spruce and in spruce forests. However, taking connectivity into account, only alpine land covers formed a functional habitat network. More areas need to be protected and planned to build a functional green infrastructure. Traditional village systems with biocultural values need support. We discuss how strategic analyses can encourage collaborative spatial planning and international development cooperation.
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| 5. |
- Asplund, Johan, et al.
(författare)
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Simulated nitrogen deposition influences gastropod grazing in lichens
- 2010
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Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 17:1, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- Lichens are often important photosynthetic organisms in oligotrophic environments where high-quality fodder plants are rare. A strong herbivore defence and/or low nutritional quality allows the accumulation of a high lichen biomass in such areas. However, it is not known how N deposition influences lichen palatability. This study analyzes possible changes in gastropod grazing preference after 3 months simulated N deposition on 3 foliose (Lobaria scrobiculata, Platismatia glauca, and Xanthoria aureola) and 1 pendulous lichen species (Alectoria sarmentosa). Lichens were daily irrigated in the field with rainwater containing 1.625 mM NH4NO3 from June to September, equivalent to a deposition of 50 kg N·ha-1·y-1. Irrigations applied at night, morning, or noon simulated different C-gain regimes. Afterwards in the lab, we offered 2 common lichen-feeding gastropods the choice between N-fertilized thalli and control thalli irrigated with artificial rainwater. The gastropods clearly preferred the unfertilized thalli of the 3 foliose species. For the pendulous A. sarmentosa, the gastropods preferred N-enriched thalli (irrigated at night) to controls. In conclusion, N-enrichment changes the palatability of lichens in species-specific ways.
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| 6. |
- Brodin, Anders, et al.
(författare)
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Optimal energy allocation and behaviour in female raptorial birds during the nestling period
- 2003
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Ingår i: Écoscience. - : University Laval. - 1195-6860. ; 10:2, s. 140-150
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Tidskriftsartikel (refereegranskat)abstract
- In many raptors and owls the male is the main provider of food in the early phase of the nestling period while the female incubates the eggs and broods the young. In the nestling period the female often helps the male to feed the young, but the factors affecting whether and when she leaves the brood to hunt have not been investigated in detail. We present a dynamic state variable model that analyses female behaviour and fat storage dynamics over the nestling period. The results show that in the first half of the nestling period the female faces a conflict between the need to brood the young and the need to hunt to provision them with food. This conflict arises because the energy needs of the young peak early in the nestling period, at a time when they still cannot thermoregulate and therefore need brooding from the female. The most critical period is the second nestling week, when both female and nestling fat reserves will decrease to low levels. Large female fat reserves in the early nestling period provide a solution to this conflict and are essential for successful breeding. Stochasticity in male provisioning is thus not needed to explain why females should be fat when the eggs hatch. Under normal circumstances, the female broods during the first two weeks and leaves the young only if hunting is absolutely necessary. After the second week the energy requirements are relaxed, and whether the female assists the male in hunting or not depends on factors such as male hunting success, environmental stochasticity, and energy requirements of the young. Our model provides a framework for empirical investigations on female behaviour during breeding in raptors, owls, and other birds with marked division of labour.
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| 7. |
- Bruun, Hans Henrik, et al.
(författare)
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Recruitment advantage of large seeds is greater in shaded habitats
- 2008
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 15:4, s. 498-507
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Chiari, Stefano, et al.
(författare)
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Habitat of an endangered saproxylic beetle, Osmoderma eremita, in Mediterranean woodlands
- 2012
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 19, s. 299-307
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Tidskriftsartikel (refereegranskat)abstract
- The habitat of Osmoderma eremita, a European endangered beetle species restricted to tree cavities, was examined in central Italy, at the southernmost limit of its distributional range. The occurrence of adults, larvae, and fragments was investigated in 170 and 151 living hollow trees by pitfall trapping and sampling of wood mould (i.e., loose material) in the hollow, respectively. Overall, O. eremita was present in 22% of the trees, which belonged to 4 different tree species (Ostrya carpinifolia, Quercus suber, Acer obtusatum, and Quercus pubescens). The frequency of presence was higher in cavities with more than 4 L of wood mould, in cavities with dry or half-moist wood mould rather than wet wood mould, and with wood mould with low soil contamination. A comparison with northern regions indicated that the warmer macro-climatic conditions in the south make the species independent of a warm microclimate. As most of the hollow trees contain only a small amount of wood mould (<4 L), the habitat quality is generally poorer than in oak pastures studied in northern Europe.
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| 9. |
- Dahlberg, Anders, et al.
(författare)
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Effects of ecological continuity on species richness and composition in forests and woodlands: A review
- 2014
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 21, s. 34-45
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Forskningsöversikt (refereegranskat)abstract
- Forests and woodlands with a long, uninterrupted presence (continuity) are often associated with high biodiversity and many habitat specialist species. But the mechanisms by which, and the scales in time and space at which, populations are dependent on continuity remain debated. We examine the spatial and temporal scales at which occurrences of plants, fungi, and invertebrates are affected by continuity and consider whether they are restricted by time for colonization (continuity per se) or by habitat formation times. We give improved definitions of landscape and local levels of continuity anti evaluate the empirical literature with respect to these. By critically examining the reported effects of continuity on the occurrence of species in forests and woodlands, we explore the mechanisms behind the patterns at local and landscape scales. We conclude that many species are dispersal-limited in the current fragmented landscapes and occur mainly in landscapes with surplus continuity, meaning that the availability of habitats was greater in the past than it is currently. Our review indicates that local continuity per se is important at least for many forest herbs and for certain species of epiphytic lichens, insects, and land snails, but to a lesser extent for fungi. Several studies show that landscape-level continuity affects the current occurrence of species, in particular for vascular plants, but also for particular lichen, bryophyte, and invertebrate species. For continuity-dependent species, a successful conservation strategy should include both extending the period of habitat duration in relict patches and promoting habitat formation in the immediate surroundings of potential source patches. Conservation strategies need to acknowledge the continuity dependence of many species. Research on how to shorten habitat formation times by forest restoration is an urgent priority.
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| 10. |
- Forsum, A., et al.
(författare)
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Nitrogen uptake by Hylocomium splendens during snowmelt in a boreal forest
- 2008
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Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 15:3, s. 315-319
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Tidskriftsartikel (refereegranskat)abstract
- In most boreal regions snow composes a large portion of the annual precipitation. Although many boreal forest floor bryophytes depend largely on precipitation for their nitrogen (N) supply, bryophyte uptake of snow N little explored. We studied chemical forms of plant-accessible N in snowmelt, as well as the temporal dynamics of their release. In conjuction we performed a N uptake experiment using the common boreal bryophyte Hylocomium splendens. the results demonstrated that the snowmelt N pool was dominated by NO3 (86%), followed by NH4+ (11%) and amino acid N (3%), in total providing ca 0.3 kg N.ha(-1) to the forest floor vegetation. Hylocomium splendens was able to access both inorganic and organic N-15 labelled N forms (NO3-, NH4+, and glycine) applied in situ to the snow covering the moss prior to snowmelt. Across all the N forms H. splendens took up ca 24% of the snow-deposited N. Nitrate uptake exceeded that of glycine, while NH4+ uptake was intermediate, reflecting the ambient distribution of the snowmelt N pool between plant-accessible N forms.
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| 11. |
- Fransson, Petra, et al.
(författare)
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Host plant-ectomycorrhizal fungus combination drives resource allocation in willow: Evidence for complex species interaction from a simple experiment
- 2013
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 20, s. 112-121
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Tidskriftsartikel (refereegranskat)abstract
- Root-associated mycorrhizal fungi affect plant growth and resource allocation. Our major aim was to explore the plant-internal mechanisms behind the effects of mycorrhizal colonization on leaf chemistry of willow (Salix spp.). Combinations of 2 willow varieties (Loden, Tora) and 2 ectomycorrhizal fungal species (Hebeloma fastibile, Tricholoma cingulatum) were grown under controlled conditions. Host plant variety and fungal species effects on host resource allocation (biomass and leaf chemistry) varied in a complex way. Shoot biomass growth and allocation was mostly affected by host plant variety, whereas leaf and root biomass allocation were strongly affected by mycorrhizal treatment. Leaf biomass production was affected by willow variety, mycorrhizal treatment, and the interaction between them. The results indicate a strong effect of mycorrhizal colonization on host plant biomass allocation, which can mediate mycorrhizal effects on leaf chemistry. For example, leaf biomass allocation was inversely correlated with foliar concentrations of salicylic acid, suggesting a functional link between the two. However, the apparent complexity of the host plant variety-fungal species interaction makes any prediction of their possible outcome very difficult, especially in an ecological context. Still, fungal species identity seems to be more important for the responses of Salix to mycorrhizal colonization than the amount of fungal biomass.
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| 12. |
- Graae, Bente J., et al.
(författare)
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Germination requirements and seed mass of slow- and fast-colonizing temperate forest herbs along a latitudinal gradient
- 2009
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 16:2, s. 248-257
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Tidskriftsartikel (refereegranskat)abstract
- Predictions on displacement of suitable habitats due to climate change suggest that plant species with poor colonization ability may be unable to move fast enough to match forecasted climate-induced changes in habitat distribution. However, studies on early Holocene plant migration show fast migration of many plant species that are poor colonizers today We hypothesize that warmer temperatures during the early Holocene yielded higher seed quality, contributing to explaining the fast migration. We studied how the 3 seed quality variables, seed mass, germinability, and requirements for break of seed dormancy, vary for seeds of 11 forest herb species with varying colonization capacity collected along a 1400-km latitudinal gradient. Within species, seed mass showed a positive correlation with latitude, whereas germinability was more positively correlated with temperature (growing degree hours obtained at time of seed collection). Only slow-colonizing species increased germinability with temperature, whereas only fast-colonizing species increased germinability with latitude. These interactions were only detectable when analyzing germinability of the seeds, even though this trait and seed mass were correlated. The requirement for dormancy break did not correlate with latitude or temperature. The results indicate that seed development of slow colonizers may be favoured by a warmer climate, which in turn may be important for their migration capacity.
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| 13. |
- Hambäck, Peter A., et al.
(författare)
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Plant trait-mediated interactions between early and late herbivores on common figwort (Scrophularia nodosa) and effects on plant seed set
- 2011
-
Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 18:4, s. 375-381
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Tidskriftsartikel (refereegranskat)abstract
- This study examined the interactive effects of early and late season herbivory on the growth and reproductive output of figwort (Scrophularia nodosa). The early season herbivore is a pentatomid bug that feeds on and kills the apical meristem, while the late season herbivores are 2 weevil species and a sawfly that all feed on leaves and flowers. The direct effect of early season meristem damage on plant reproduction was quite limited, although meristem damage did cause increased branching. This change in plant morphology may entail that early season herbivores have profound indirect effects on plant reproduction by affecting the abundance of and damage caused by late season herbivores. Comparisons of plants with and without early season meristem damage, natural and artificial, also suggest that plants with meristem damage are significantly shorter throughout most of the summer and receive less damage late in season. However, the reduced damage translated to increased flowering but not to increased fruit production, suggesting that the plants were able to compensate for late season damage. In the end, and despite damage, figwort was well able to tolerate the observed meristem and leaf damage.
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| 14. |
- Jakobsson, Anna, et al.
(författare)
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Competition for pollinators between invasive and native plants : Effects of spatial scale of investigation (note)
- 2009
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Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 16:1, s. 138-141
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Tidskriftsartikel (refereegranskat)abstract
- In this study we show that spatial scale of investigation affects the estimated strength of competition for pollinators between an invasive and a native plant species. The effect of the invasive herb Oxalis pes-caprae on pollinator visits to the native herb Diplotaxis erucoides was studied when the invader was (1) totally present, (2) present on a large scale (of hectares) but absent on a small scale (of square metres), and (3) totally absent. No difference in number of pollinator visits to D. erucoides was found between treatment 1 and 3, i.e., between total presence and total absence of the invader. However, when the invader was removed in the small scale while still remaining in the large scale, a higher number of visits to the native was recorded. Our study thus shows the importance of incorporating multiple spatial scales to allow for investigation of hierarchical effects on competition for pollinators, and it suggests that small-scale studies of effects of invasive plants on pollinator visitation might risk overstating negative effects of the invader.
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| 15. |
- Jurczyk, M., et al.
(författare)
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Utilization of prey-rich patches leads to reproductive advantages for clustered individuals of a web-building spider
- 2012
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 19:2, s. 170-176
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Tidskriftsartikel (refereegranskat)abstract
- The ideal free distribution (IFD) model predicts that consumers match the distribution of resources across habitat patches and that this association should lead to equal individual fitness among individuals in a population. Here we studied to what extent predators utilize different prey groups and if the resulting spatial patterns relate to the reproductive success of individuals in a population of a web-building spider species (Phylloneta impressa, Theridiidae). Web-building spiders, their prey remains, egg sacs, and spiderlings were collected in a wheat field, and coordinates of web sites were recorded for spatial point pattern analysis using pair and mark correlation functions. Spiders were aggregated in the study area, but only post-reproductive females were aggregated over the full range of spatial scales. Web-owners in clusters caught a higher proportion of hemipteran prey than expected by the mean, suggesting that the availability of this prey type contributed to the clustering of individuals and the higher reproductive success of females in clusters. However, 2 abundant prey groups (Syrphidae and Hymenoptera) were not more common than expected by the mean at any distance, and another prey group (Elateridae) was even less common in webs close to each other. At least 2 prey groups (Hemiptera and Elateridae) showed deviations from the assumption of the IFD model that predators in clusters should have similar prey capture success compared to predators that are not located in clusters. Both prey groups include many cereal pest species, and our results suggest that spatially explicit information about prey utilization and predator fitness may contribute to a better understanding of the role of natural enemies in biological control.
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| 16. |
- Kindberg, Jonas
(författare)
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Behavioral reactions of brown bears to approaching humans in Fennoscandia
- 2019
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 26, s. 23-33
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Tidskriftsartikel (refereegranskat)abstract
- Human disturbance causes behavioral responses in wildlife, including large carnivores. Previous research in Scandinavia has documented that brown bears (Ursus arctos) show a variety of behavioral reactions to different human activities. We investigated how proximity to human settlements and roads, as proxies of human influence, affected brown bears' reactions to encountering humans. We analyzed experimental approaches to GPS collared bears, 18 males and 23 single females, in Sweden (n = 148 approaches) and Finland (n = 33), conducted between 2004 and 2012. The bears in Finland inhabited areas with higher human density compared to Sweden. However, the proportion of bears staying or moving when approached and the flight initiation distances were similar in both countries. In Sweden, the flight responses were not dependent on human densities or roads inside the bears' home ranges or the distances from the bears to roads and settlements. Brown bears in Fennoscandia live in areas with relatively low human population densities, but in many areas with high forestry road densities. Our results show that bears' flight reactions were consistent between areas, which is an important message for management, reinforcing previous studies that have documented human avoidance by bears at different spatial and temporal scales.
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| 17. |
- Lundgren, Andreas, et al.
(författare)
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Wild boar (Sus scrofa) has minor effects on soil nutrient and carbon dynamics
- 2023
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Ingår i: Ecoscience. - 1195-6860 .- 2376-7626. ; 30, s. 84-96
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Tidskriftsartikel (refereegranskat)abstract
- Wild boar populations have increased worldwide, but the consequences of their disturbances on boreal forest ecosystems are largely unknown. We investigated how wild boars affect soil processes in a Swedish boreal forest. We estimated effects on ecosystem functioning using phospholipid fatty acid analyses (PLFA) to characterise microbial groups, and by measuring soil respiration, soil carbon (C), nitrogen (N) and phosphorus (P) concentrations, as well as the availability of NO3- and NH4+. We compared samples collected inside wild boar enclosures with adjacent reference areas without wild boar disturbance. We found no difference in soil microbial composition, except for a consistently higher fungi:bacteria ratio in the enclosures. These results are contrary to our hypothesis that rooting raises nitrogen levels, which in turn result in more bacteria. Soil nutrient levels showed inconsistent patterns, suggesting that substrate changes - as opposed to nutrient changes - stimulated fungal growth. Soil respiration was lower in the enclosures, contradicting earlier findings suggesting increased soil CO2 emissions from wild boar rooting. Overall, our study suggests that increased wild boar abundance has a minor impact on soil processes in boreal forests. Future studies should determine if the modest impacts remain across time and boreal forests.
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| 18. |
- Lundgren, Andreas, et al.
(författare)
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Wild boar (Sus scrofa) has minor effects on soil nutrient and carbon dynamics
- 2023
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Ingår i: Ecoscience. - : Taylor & Francis. - 1195-6860 .- 2376-7626. ; 30:2, s. 84-96
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Tidskriftsartikel (refereegranskat)abstract
- Wild boar populations have increased worldwide, but the consequences of their disturbances on boreal forest ecosystems are largely unknown. We investigated how wild boars affect soil processes in a Swedish boreal forest. We estimated effects on ecosystem functioning using phospholipid fatty acid analyses (PLFA) to characterise microbial groups, and by measuring soil respiration, soil carbon (C), nitrogen (N) and phosphorus (P) concentrations, as well as the availability of NO3- and NH4+. We compared samples collected inside wild boar enclosures with adjacent reference areas without wild boar disturbance. We found no difference in soil microbial composition, except for a consistently higher fungi:bacteria ratio in the enclosures. These results are contrary to our hypothesis that rooting raises nitrogen levels, which in turn result in more bacteria. Soil nutrient levels showed inconsistent patterns, suggesting that substrate changes - as opposed to nutrient changes - stimulated fungal growth. Soil respiration was lower in the enclosures, contradicting earlier findings suggesting increased soil CO2 emissions from wild boar rooting. Overall, our study suggests that increased wild boar abundance has a minor impact on soil processes in boreal forests. Future studies should determine if the modest impacts remain across time and boreal forests.
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| 19. |
- Lönnberg, Karin, 1975-, et al.
(författare)
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Seed size and recruitment patterns in a gradient from grassland to forest
- 2012
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Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 19:2, s. 140-147
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Tidskriftsartikel (refereegranskat)abstract
- Seedlings germinating from large seeds are known to endure hazards such as shading, competition, and litter coverage better than seedlings germinating from small seeds. However, few studies have assessed the relationships between seed size and recruitment comparing plant communities with different structures in order to establish the conditions under which a seed-size advantage prevails. Here, seeds from 20 species varying in seed size from 0.05 to 17.8 mg were sown in 6 different vegetation types, representing a gradient from open grassland to closed canopy coniferous forest. We hypothesized that the effect of seed size on recruitment is generally positive, but that there is a stronger positive effect of seed size in closed than in open communities. Our results provided only limited support for this hypothesis. Firstly, the results varied between years, suggesting that any seed size advantage may depend on factors varying on an annual basis. Secondly, although there were trends of significantly positive relationships between seed size and seedling emergence, seedling survival, and recruitment success, particularly in relatively more closed vegetation types, the strongest positive effects of seed size were found in intermediate (semi-open) habitats along the gradient. We conclude that the filtering of species into the investigated communities is only weakly related to seed size, and that several factors other than canopy probably influence the link between seed size and recruitment.
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| 20. |
- Ranius, Thomas, et al.
(författare)
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A comparison of methods for estimating the age of hollow oaks
- 2009
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 16, s. 167-174
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Tidskriftsartikel (refereegranskat)abstract
- We examined 6 direct (i.e., based on tree ring counts) and 2 indirect (i.e., based on correlations between age and tree characteristics) methods to estimate the age of hollow trees. The errors associated with methods were compared by simulating rotten centres of different sizes (diameter: 5-82 cm) in tree ring cores from sound old oaks (Quercus robur) (diameter: 17-129 cm) collected from pastures in southeast Sweden. The lowest error (mean deviation: 15%) was obtained using tree ring data from the sampled hollow trees in combination with a function based on the growth pattern of sound trees. Indirect methods resulted in moderate errors (mean deviation was 23% and 26% for a function with bark crevice depth and with tree diameter, respectively). Because rotten centres often develop asymmetrically, we found it desirable to take a minimum of 2 cores from each hollow tree, from different cardinal directions. Trunks with a high probability of having a rotten centre could be identified before coring, as the width of the rotten centre increased with increasing bark crevice depth, with increasing size of any entrance hole, and with decreasing distance between the lowest entrance hole and the ground.
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| 21. |
- Ranius, Thomas, et al.
(författare)
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How frequent is metapopulation structure among butterflies in grasslands? Occurrence patterns in a forest-dominated landscape in southern Sweden
- 2011
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 18:2, s. 138-144
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Tidskriftsartikel (refereegranskat)abstract
- We determined the proportion of butterfly species that occur as metapopulations with grasslands as the only habitat. We counted all butterflies in 19 semi-natural grassland patches in a forest-dominated landscape in southern Sweden over a 5-y period. Seven of the 44 butterfly species observed exhibited a metapopulation structure. The other species either use grassland mainly for adult feeding but not for breeding (8 species), breed both in grassland and in surrounding habitat types (19 species), or are grassland specialists but their colonization-extinction dynamics are probably not significant, since they were present in nearly all (> 80%) patches (10 species). Occupancy was generally higher in larger patches, and tended to increase with patch connectivity. Among grassland specialists and habitat generalists, the connectivity measure tended to explain more of the variation in occupancy if the shortest dispersal paths avoiding routes over water were considered rather than a measure based on the Euclidian distance between patches. This indicates that lakes, even when they are just a few hundred metres wide, can act as barriers to dispersal for butterflies. We conclude that for many butterflies that occur in semi-natural grasslands in forest-dominated landscapes, intervening habitats are important as breeding sites or as dispersal barriers.
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| 22. |
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| 23. |
- Subramanian, Narayanan, et al.
(författare)
-
Impacts of climate change, weather extremes and alternative strategies in managed forests
- 2019
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Ingår i: Ecoscience. - : Taylor & Francis. - 1195-6860 .- 2376-7626. ; 26:1, s. 53-70
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Tidskriftsartikel (refereegranskat)abstract
- The growth rate of most tree species in boreal forests will increase with changing climate. This increase is counterbalanced by an increased risk of damage due to extreme weather events. It is believed that the risk of storm damage will increase over time, especially if forests continue to be managed as they are today. In this study, a new landscape-level hybrid forest growth model 3PG-Heureka was developed and simulations were performed to predict the damage caused by storm events in Kronoberg county, over a period of 91 years (2010-2100) with different alternative management regimes under various climatic scenarios (historic, RCP4.5 and RCP8.5). The results indicate that damage caused by storm events could drastically reduce the annual volume increment and annual net revenue obtained from forest landscapes if current forest management regimes are used. These problems can be reduced by adopting alternative management strategies involving avoiding thinning, shorter rotation periods and planting alternative tree species. Alternative management strategies could potentially improve annual volume increments and net revenue obtained while reducing storm-felling. Planting Scots pine instead of Norway spruce across the landscape to minimize storm damage is predicted to be less effective than reducing rotation periods.
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| 24. |
- Tesson, Sylvie V M, et al.
(författare)
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Integrating microorganism and macroorganism dispersal: modes, techniques and challenges with particular focus on co-dispersal
- 2015
-
Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 22:2-4, s. 109-124
-
Tidskriftsartikel (refereegranskat)abstract
- Whatever their size and the ecosystem they live in, all organisms may disperse at some stage of their life cycle. Dispersal dynamics are to a varying extent dependent on organismal size, life history, ecological niche, survival capacities and phylogeny. Moves towards a synthesis in dispersal ecology have focused primarily on vertebrates and higher plants, yet recent studies suggest that the dispersal of microorganisms and macroorganisms has much more in common than previously assumed. The dispersal of one organism enables co-dispersal for many others, smaller in size. There is an increasing need for a more integrated approach to study dispersal within the context of organismal interactions and their environments. Such an approach is facilitated by recent developments of powerful indirect techniques that enable tracking of microorganisms and macroorganisms over multiple spatial and temporal scales. Likewise, dispersal modelling and theoretical models of the consequences of dispersal can inspire empirical studies across the entire size spectrum. Simultaneously studying the relationships between dispersal of microorganisms and macroorganisms, and accounting for dispersal through time and space, will allow us to better understand the functioning and dynamics of communities and ecosystems, and to make better predictions of future dispersal patterns, changes in biodiversity and connectivity.
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| 25. |
- Törnblom, Johan, et al.
(författare)
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Prioritizing dam removal and stream restoration using critical habitat patch threshold for brown trout (Salmo trutta L.): a catchment case study from Sweden
- 2017
-
Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 24, s. 157-166
-
Tidskriftsartikel (refereegranskat)abstract
- Catchments form an important terrestrial-aquatic habitat complex for biodiversity conservation and human well-being. Riparian and stream components are debated about how much habitat need to be maintained or restored in rivers subject to habitat degradation and fragmentation. Using brown trout as a focal species we tested the hypothesis that presence of suitable habitat in lotic stream sections can be predicted using habitat modelling. We modelled brown trout habitat at the catchment scale in terms of quality, size, juxtaposition of stream segments using digital elevation data, and presence of dams. The habitat models were validated against presence-absence data for local brown trout populations. A self-reproducing brown trout population was defined as having three year-classes. We identified the required minimum length (270 m) of a lotic stream section hosting a local brown trout population, corresponding to 3500 m(2). Adjacent areas of lotic stream habitat between dams had a significant positive effect on brown trout presence. The abundance of brown trout was significantly positively correlated to habitat quality, and negatively to hydropower water regulation. Critical habitat loss thresholds can be used for gap analysis regarding selection of dams to be removed and where restoration measures will be most effective in a catchment.
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| 26. |
- Johansson, Per, et al.
(författare)
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Tree age relationships with epiphytic lichen diversity and lichen life history traits on ash in southern Sweden
- 2007
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Ingår i: Ecoscience. - 1195-6860. ; 14:1, s. 81-91
-
Tidskriftsartikel (refereegranskat)abstract
- We examined the influence of tree- and stand-level conditions on lichen diversity on 143 ash trees, varying in age from 11 to 140+ y, in 5 deciduous stands in southern Sweden. The number of lichen species per tree varied from 2 to 30 and was primarily explained by tree trunk diameter and to a lesser extent by tree age, crown cover, lichen cover, and stand identity. The positive relationship between species richness and lichen cover seems compatible with a random placement of species and suggests that similar factors affect both lichen growth and establishment. Species richness did not increase on trees above 65 y of age, while species composition changed with tree age. Together with the positive linear effect of trunk diameter, these results suggest a slight overall positive effect of area, but that species richness over time depends more on species turnover. In addition, we examined if lichens occurring on trees of different ages differed in life history traits, e.g., spore size, thallus height, and pH preference. The results indicate that lichens that most frequently occurred on old trees had larger spores and thicker thalli than other species, suggesting that lichen species' response to tree age can be understood to some extent from their life history traits. However, in this respect lichen ecology is still in its infancy.
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| 27. |
- Olofsson, Johan, et al.
(författare)
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Gray-sided voles increase the susceptibility of northern willow, Salix glauca, to invertebrate herbivory
- 2007
-
Ingår i: Ecoscience. - 1195-6860. ; 14:1, s. 48-54
-
Tidskriftsartikel (refereegranskat)abstract
- The relationships between grey-sided vole (Clethrionomys rufocanus) densities, levels of invertebrate herbivory on Northern willow (Salix glauca) leaves, and chemical quality of the willows was studied on 8 islands and 2 mainland sites with contrasting vole densities in northernmost Norway. These variables were measured at each of the study sites to determine the degree and nature of the effects of browsing-induced alterations in plant quality on subsequent invertebrate herbivory. The level of invertebrate herbivory was positively correlated with vole density, as were the number of leaves per shoot, leaf size, and leaf nitrogen content, while leaf C/N ratios were negatively correlated with vole density. The level of herbivory increased from > 1% on the vole-free island to < 4% on the island with the highest vole density. The plant character that explained most of the variance in the level of invertebrate herbivory was leaf size. Since the vole densities have been altered by human intervention and their numbers are largely governed by predation rather than food quality, the positive correlation between vole densities and level of invertebrate herbivory is probably due to a facilitative effect of voles on invertebrate herbivores, mediated through changes in plant chemistry. We suggest that voles affect susceptibility of willows to invertebrate herbivory both directly by winter browsing and indirectly by reducing the abundance of competing plants.
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| 28. |
- Öster, Mathias, et al.
(författare)
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Sex ratio mediated pollen limitation in the dioecious herb Antennaria dioica
- 2007
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Ingår i: Ecoscience. - 1195-6860. ; 14:3, s. 387-398
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Tidskriftsartikel (refereegranskat)abstract
- We examined how population structure affects seed set and recruitment in the dioecious plant Antennaria dioica, which is a declining species inhabiting semi-natural grasslands in Sweden. Flowering and sex ratio in A. dioica were studied over 4 y at a local (1.2 km2) scale and over 1 y at a regional (742 km2) scale in southern Sweden. Antennaria dioica was also hand-pollinated during 2y to examine whether sex ratios, male abundance, and distance to nearest male influence the degree of pollen limitation. Seed-sowing experiments were conducted to assess whether recruitment is limited by seed or microsite availability. There was a considerable spatio-temporal variation in both flowering and sex ratios. The regional scale survey showed that patch size and number of patches per site were positively correlated, and small patches of A.dioica tended to have biased sex ratios. Experimental hand-pollinations showed that the degree of pollen limitation increased with increasingly female-biased sex ratios in the closest vicinity of the experimental plants. Thus, even though A. dioica is pollinated by many different insects, a fragmented population structure has a large influence on reproductive performance of A. dioica. The seed-sowing experiments showed that recruitment is limited by a combination of seed and microsite availability. It is therefore plausible that reduced seed production due to pollen limitation translates into reduced recruitment. The results from the local and the regional scale indicate that a large fraction of local patches and populations of A. dioica have decreased sexual reproduction. The conclusion is that A. dioica is likely to be particularly sensitive to habitat fragmentation.
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| 29. |
- Bergvall, Ulrika A, et al.
(författare)
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The effect of spatial scale on plant associational defences against mammalian herbivores
- 2008
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Ingår i: Ecoscience. - 1195-6860. ; 15, s. 343-348
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Tidskriftsartikel (refereegranskat)abstract
- Intraspecific variation in plant toxins at different spatial scales can influence foraging decisions by wild herbivores. In order to investigate plant associational defences in relation to spatial scale, we performed an experiment with fallow deer encountering 2 patches of low- and high-tannin hazel branches. One patch was good, consisting of 7 low- and I high-tannin branch, and the other bad, with low- and 7 high-tannin branches. We kept the between-patch spatial scale constant and varied the within-patch spatial scale: the branches in a patch were either spread out or close together in a bundle. When the low-tannin branches were spread out, the deer showed a clear preference for low_tannin branches both patches and consumed similar amounts from low-tannin branches in the good and the bad patch, which means that there was no associational defence. In contrast, when the branches instead were together in a bundle, within-patch selectivity decreased and between-patch selectivity increased, and the low-tannin branches in the bad patch were less eaten than the low-tannin branches in the good patch, which corresponds to associational defence. We conclude that small inter-plant distances can be crucial for the operation of plant associational defences
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| 30. |
- Brodin, Anders, et al.
(författare)
-
Optimal energy allocation and behaviour in female raptorial birds during the nestling period
- 2003
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Ingår i: Ecoscience. - : University Laval. - 1195-6860. ; 10:2, s. 140-150
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Tidskriftsartikel (refereegranskat)abstract
- In many raptors and owls the male is the main provider of food in the early phase of the nestling period while the female incubates the eggs and broods the young. In the nestling period the female often helps the male to feed the young, but the factors affecting whether and when she leaves the brood to hunt have not been investigated in detail. We present a dynamic state variable model that analyses female behaviour and fat storage dynamics over the nestling period. The results show that in the first half of the nestling period the female faces a conflict between the need to brood the young and the need to hunt to provision them with food. This conflict arises because the energy needs of the young peak early in the nestling period, at a time when they still cannot thermoregulate and therefore need brooding from the female. The most critical period is the second nestling week, when both female and nestling fat reserves will decrease to low levels. Large female fat reserves in the early nestling period provide a solution to this conflict and are essential for successful breeding. Stochasticity in male provisioning is thus not needed to explain why females should be fat when the eggs hatch. Under normal circumstances, the female broods during the first two weeks and leaves the young only if hunting is absolutely necessary. After the second week the energy requirements are relaxed, and whether the female assists the male in hunting or not depends on factors such as male hunting success, environmental stochasticity, and energy requirements of the young. Our model provides a framework for empirical investigations on female behaviour during breeding in raptors, owls, and other birds with marked division of labour.
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| 31. |
- Bruun, Hans Henrik
(författare)
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Metacommunities: Spatial Dynamics and Ecological Communities
- 2006
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Ingår i: Écoscience. - 1195-6860. ; 13:4, s. 563-564
-
Forskningsöversikt (övrigt vetenskapligt/konstnärligt)abstract
- Assembly and dynamics in multispecies communities have long attracted the interest of ecologists. Yet, the subject has been studied from two separate paradigmatic angles. One line of thinking has focussed on local communities and competitive exclusion in situations when species’ niches overlap too much (limiting similarity), and on mechanisms that could prevent competitive exclusion and thus ensure coexistence of species at equilibrium (first and foremost niche differentiation). The other line of thinking has focussed on a regional (mainland) impact on the assembly of local communities (islands), while assuming no interactions among species and effectively no differences between them in terms of traits either. Robert MacArthur was extremely influential in the development of both paradigms during the sixties and seventies of the former century, an apparent schizophrenia that was later called ‘MacArthur’s paradox’ by Thomas Schoener. Now, in the edited volume Metacommunities, a group of ecologists has as set the laudable goal to reconcile these two apparently non-overlapping perspectives and formulate a new general theory for community ecology at a hierarchy of scales. The book makes a tiger leap forward in developing a truly unified community ecology.
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| 32. |
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| 33. |
- Frost, Ingela, et al.
(författare)
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Spatial pattern and size distribution of the animal-dispersed tree Quercus robur in two spruce-dominated forests
- 2000
-
Ingår i: Ecoscience. - 1195-6860. ; 7:1, s. 38-44
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the degree to which the spatial distribution of oaks (Quercus robur L.) was related to habitat conditions, as reflected by vegetation type and structural features presumed to attract animal dispersers (trails, community borders). We hypothesized that the distribution pattern of oaks, with their potential to establish in many habitats, depends on the behaviour of the dispersing animals to a greater extent than micro-habitat conditions. One 100 m x 100 m plot was surveyed in each of two coniferous forests in east-central Sweden. No adult oak trees grew in the forests; all oaks were considered as dispersed into the plots by animals. We tested whether oak distribution was clumped with spatial autocorrelation analyses and whether oak distribution was related to vegetation type, species composition, tree cover, distance to nearest fertile oak tree, or distance to animal trails. Our study showed that oak trees were also spatially aggregated in a small-scale context. The spatial distribution of seedlings and older trees were associated with species richness and tree cover but not with any specific vegetation type, even though fewer oaks than expected grew in spruce forest habitats. Furthermore, we found that oak trees were associated with trails. There were differences in oak distribution between the two study sites in total number of oaks, the number of first-year seedlings, caches, and oak occurrence in relation to species richness and distance to nearest fertile oak. Seed-dispersing animals seem to be of importance for oak distribution even though animal activities seem to differ between sites.
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| 34. |
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| 35. |
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| 36. |
- Jönsson, Ingemar
(författare)
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Life history consequences of fixed costs of reproduction
- 2000
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Ingår i: Écoscience. - 1195-6860. ; 7:4, s. 423-427
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Tidskriftsartikel (refereegranskat)abstract
- The distinction between fixed and variable factors of production and their corresponding costs has: long played a fundamental role in economic theory. However, in analyses of life history evolution a distinction between fixed and variable costs of reproduction has not been made. In this paper. I discuss these concepts and analyze some effects of fixed costs of reproduction on reproductive decisions. While some fitness functions do not allow fixed costs of reproduction to affect optimal reproductive effort, others do. Increasing fixed costs reduces total fitness and increases the level of investment required to obtain a reproductive profit. Increased fixed costs may also narrow the parameter space of reproductive effort for positive profit. These results are discussed in the perspectives of age at maturity and the evolution of semelparity.
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| 37. |
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| 38. |
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| 39. |
- Karlsson, Staffan, et al.
(författare)
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Seasonal variation in 15-N natural abundance in subarctic plants of different life-forms
- 2000
-
Ingår i: Ecoscience. - 1195-6860. ; 7:3, s. 365-369
-
Tidskriftsartikel (refereegranskat)abstract
- Plants can be expected to utilize different sources of nitrogen with different proportions of 15N at different times of the year. It was hypothesized that this may be reflected in a seasonal variation in the natural abundance of plant 15N, and that this pattern would vary among life-forms or species. To test this hypothesis, we studied the δ15N of eight different life-forms, selecting two representatives from each of four categories (woody deciduous, woody evergreen, graminoid, and cryptogam life-forms) at two locations in N. Sweden having different levels of precipitation, over a six-month period. Sampling was conducted in mid-winter, during snowmelt in May, after leaf emergence, in mid-August, and in September. The sampled species showed a highly significant seasonal pattern in the natural abundance of 15N. Within each species and site, the δ15N showed a difference on average of 3.6% (range from 2.1 to 5.3%) between minimum and maximum over the sampling period. In most cases δ15N was highest in mid-winter and lowest at the start of the growing season. Most species studied showed some common trends: (i) a decline in δ15N from mid-winter to pre-snowmelt (May); (ii) an increase from snowmelt to mid-June (mainly in plants sampled at one site); and (iii) a late-season decline in δ15N (August to September). Life-forms differed from each other in terms of their pattern of seasonal variation (harvest×life-form interaction) and between sites (site×life-form interaction). Thus, the outcome of comparisons of natural δ15N within and among species or sites depends on the time of year of sampling.
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| 40. |
- Karlsson, Staffan, et al.
(författare)
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Seedling growth characteristics in three birches originating from different environments
- 2000
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Ingår i: Ecoscience. - 1195-6860. ; 7:1, s. 80-85
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Tidskriftsartikel (refereegranskat)abstract
- The mountain birch (Betula pubescens ssp. czerepanovii) is considered to have originated through introgressive hybridization between B. pubescens and B. nana. It is intermediate between the putative parent species in terms of growth form and distribution. Consequently, we hypothesized that the mountain birch should have growth characteristics intermediate between the other two birch forms. This hypothesis was tested in an experiment using first-year seedlings. Only in three out of 15 characteristics studied were mountain birch characteristics clearly intermediate between B. pubescens and B. nana. In some cases the mountain birch was most similar to B. pubescens, while in others it resembled B. nana most closely. In certain other respects, B. pubescens and B. nana were more similar to each other than to mountain birch. In three measures of plant productivity, i.e. , relative growth rate, leaf area productivity, and plant nitrogen productivity, mountain birch showed the highest values. Cluster analyses of thirteen growth-related characteristics indicate that at a low fertilizer supply, B. pubescens and B. nana are more similar to each other than to the mountain birch. At a high fertilizer supply, mountain birch was more similar to B. pubescens. The results indicate that the growth characteristics of mountain birch seedlings are not inherited from its two ?parent? species in any simple way.
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| 41. |
- Merila, J, et al.
(författare)
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Adaptive phenotypic plasticity in timing of metamorphosis in the common frog Rana temporaria
- 2000
-
Ingår i: ECOSCIENCE. - : UNIVERSITE LAVAL. - 1195-6860. ; 7:1, s. 18-24
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Tidskriftsartikel (refereegranskat)abstract
- Unpredictable environments are expected to select for adaptive plasticity in traits enabling adjustment of phenotype to prevailing environmental conditions. Common frogs (Rana temporaria) breed frequently in ponds, which dry up before the aquatic larvae h
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| 42. |
- Nordin, A, et al.
(författare)
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Amino acid accumulation and growth of Sphagnum under different levels of N deposition
- 2000
-
Ingår i: Ecoscience. - 1195-6860. ; 7:4, s. 474-480
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) is a critical nutrient for Sphagnum mosses dominating mire ecosystems. We simulated N deposition by adding doses of NH4NO3 (0, 1, 3, 5 and 10 g m-2 yr-1) to two Swedish mires with different levels of background atmospheric N deposition, i.e., on Luttumyren in central Sweden 0.3-0.4 g N m-2 yr-1 and 0.7-1.1 g N m-2 yr-1 on Åkhultmyren in south Sweden. After two years of NH4NO3 additions, free amino acid concentrations of S. fuscum, S. magellanicum and S. rubellum from the two mires were analyzed and length growth of the mosses were measured. N additions increased amino acid concentrations in Sphagnum capitula, whereas it decreased Sphagnum length growth. In general, we found that when Sphagnum amino acid N concentrations exceeded 2.0 mg amino acid N g-1 dry mass, Sphagnum length growth was reduced. The decreased growth did not explain the variation in amino acid concentrations. Hence, increased Sphagnum N assimilation in N treated plots was most likely the factor causing tissue amino acid concentrations to increase. Significant differences among control plots between the two mires in Sphagnum total amino acid N concentrations did not occur. Total amino acid N concentrations of Sphagnum are thus not sensitive enough to reflect differences in N deposition rates when they are below 1.0 g m-2 yr-1.
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| 43. |
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| 44. |
- Sjogren-Gulve, P
(författare)
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Spatial movement patterns in frogs: Differences between three Rana species
- 1998
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Ingår i: ECOSCIENCE. - : UNIVERSITE LAVAL. - 1195-6860. ; 5:2, s. 148-155
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Using drift fences, the spatial movement patterns of the pool frog (Rana lessonae Camerano), the moor frog (R arvalis Nilsson) and the common frog (R, temporaria L.)were studied with respect to orientation and vegetation at two common breeding pond at 60
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| 45. |
- Sjogren-Gulve, P
(författare)
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Spatial movement patterns in frogs: Target-oriented dispersal in the pool frog, Rana lessonae
- 1998
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Ingår i: ECOSCIENCE. - : UNIVERSITE LAVAL. - 1195-6860. ; 5:1, s. 31-38
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The spatial movement pattern of pool Frogs (Rana lessonae Camerano) was studied at two breeding ponds surrounded by drift fences at 60 degrees N in Sweden. Fence traps were classified according to (i) surrounding vegetation, or (ii) whether they were situ
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| 46. |
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| 47. |
- Uller, Tobias, 1977, et al.
(författare)
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Ectoparasite susceptibility in lizards from populations sympatric and allopatric with ticks
- 2004
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Ingår i: Ecoscience. - 1195-6860. ; 11:4, s. 428-432
-
Tidskriftsartikel (refereegranskat)abstract
- Theory suggests that host-parasite interaction should lead to local adaptation of parasites to their hosts and vice versa. The degree of local adaptation depends on, for example, migration, relative generation time of host and parasite, and the number of host species. Furthermore, in any coevolutionary process, local adaptation of one species is dependent on the evolution of sympatric and allopatric populations of the other species, and the degree of gene flow. The tick Ixodes ricinus is a generalist tick feeding on hosts of a variety of taxa. We contrasted populations of common lizards (Lacerta vivipara) differing in their evolutionary history of exposure to ticks. Juvenile lizards were raised in a common garden experiment. We monitored growth rate, physiological performance, and aspects of immune function in tick-exposed and control offspring. There were no differences in response to tick infestation between host populations, with both sympatric and allopatric hosts showing impaired growth and endurance under parasite exposure. Ticks were marginally more engorged on allopatric hosts (P = 0.06); hence, our results do not support the hypothesis of local adaptation of parasites.
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| 48. |
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| 49. |
- Weih, M, et al.
(författare)
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Intra-specific variation in nitrogen economy among three mountain birch provenances
- 1998
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Ingår i: ECOSCIENCE. - : UNIVERSITE LAVAL. - 1195-6860. ; 5:1, s. 108-116
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Intra-specific relationships between growth traits and nitrogen economy were studied for seedlings of mountain birch (Betula pubescens ssp. totuosa) originating from three climatically different regions within the northern forest margin in subarctic Fenno
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