| 1. |
- Baeten, Lander, et al.
(författare)
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Identifying the tree species compositions that maximize ecosystem functioning in European forests
- 2019
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 56:3, s. 733-744
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Tidskriftsartikel (refereegranskat)abstract
- 1. Forest ecosystem functioning generally benefits from higher tree species richness, but variation within richness levels is typically large. This is mostly due to the contrasting performances of communities with different compositions. Evidence-based understanding of composition effects on forest productivity, as well as on multiple other functions will enable forest managers to focus on the selection of species that maximize functioning, rather than on diversity per se.2. We used a dataset of 30 ecosystem functions measured in stands with different species richness and composition in six European forest types. First, we quantified whether the compositions that maximize annual above-ground wood production (productivity) generally also fulfil the multiple other ecosystem functions (multifunctionality). Then, we quantified the species identity effects and strength of interspecific interactions to identify the "best" and "worst" species composition for multifunctionality. Finally, we evaluated the real-world frequency of occurrence of best and worst mixtures, using harmonized data from multiple national forest inventories.3. The most productive tree species combinations also tended to express relatively high multifunctionality, although we found a relatively wide range of compositions with high- or low-average multifunctionality for the same level of productivity. Monocultures were distributed among the highest as well as the lowest performing compositions. The variation in functioning between compositions was generally driven by differences in the performance of the component species and, to a lesser extent, by particular interspecific interactions. Finally, we found that the most frequent species compositions in inventory data were monospecific stands and that the most common compositions showed below-average multifunctionality and productivity.4. Synthesis and applications. Species identity and composition effects are essential to the development of high-performing production systems, for instance in forestry and agriculture. They therefore deserve great attention in the analysis and design of functional biodiversity studies if the aim is to inform ecosystem management. A management focus on tree productivity does not necessarily trade-off against other ecosystem functions; high productivity and multifunctionality can be combined with an informed selection of tree species and species combinations.
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| 2. |
- Kärvemo, Simon, et al.
(författare)
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Forest restoration as a double-edged sword: the conflict between biodiversity conservation and pest control
- 2017
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 54, s. 1658-1668
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Tidskriftsartikel (refereegranskat)abstract
- 1. Forestry has markedly changed a large proportion of the world's boreal forests, often with negative effects on biodiversity. As a result, forest restoration is increasingly implemented to counteract the negative effects. However, restoration measures aimed at mimicking natural disturbance regimes could simultaneously increase the risk of unwanted negative effects, such as damage by forest pest species. This study compares the effect of two restoration methods (prescribed burning and gap-cutting), on both biodiversity conservation and pest control, to provide a basis for solutions to this potential conflict.2. Bark beetles are ideal for studying this conflict, as this group is both species-rich and contains notorious pest species. We conducted a unique, large-scale field experiment in which we compared the effect of two different restoration methods on the abundance, species richness and assemblage composition of bark beetles. In addition, we estimated uncontrolled tree mortality by the number of trees that died post-restoration.3. Beetles were divided in two groups, primary and secondary, the former with an ability to kill growing trees. Bark beetle diversity did not differ between treatment groups prior to restoration. However, after restoration, assemblage composition and primary bark beetle abundance differed between the treatments. Furthermore, species richness was higher in burned and gap-cut stands compared to reference stands4. The number of trees that died post-restoration was highest on burned sites, whereas no difference was found between gap-cut and reference stands. The number of dead trees was correlated with the number of primary beetles.5. Synthesis and applications. We demonstrate the potential for a conflict between forest restoration for biodiversity conservation and the potential risk for tree mortality caused by forest pests. This is likely to become a problem in many boreal forests; however, our results suggest that this conflict can be moderated by the choice of restoration method. The restoration method gap-cutting had a similar positive impact on bark beetle species richness as compared to the burning method, but did not as burning, increase tree mortality. Thus, in areas where there is an apparent risk for pest outbreaks, our data suggest that gap-cutting should be the chosen method to avoid an unwanted increase in tree mortality at the stand level.
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| 3. |
- Söderquist, Linus, et al.
(författare)
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Predicting heterosis and inbreeding depression from population size and density to inform management efforts
- 2020
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Ingår i: Journal of Applied Ecology. - : WILEY. - 0021-8901 .- 1365-2664. ; 57:8, s. 1459-1468
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Tidskriftsartikel (refereegranskat)abstract
- Effective population size should be positively related to census size and density, and it is expected to influence the strength of genetic drift, inbreeding and response to selection, and thus the distribution of the genetic load across populations. We examined whether census population size and density predict the strength of inbreeding depression, heterosis and population mean fitness at the seed stage in the terrestrial orchid Gymnadenia conopsea by conducting controlled crosses (self, outcross within and between populations) in 20 populations of varying size (7-30,000 individuals) and density (1-12.8 individuals/m(2)). In the largest population, we also examined how local density affects the occurrence of self-pollination with a pollen staining experiment. The majority of populations expressed strong inbreeding depression at the seed stage (mean delta ID: min-max = 0.26: -0.53 to 0.51), consistent with a mainly outcrossing mating system and substantial genetic load. The effect of between-population crosses varied from strong outbreeding depression to heterosis (mean delta OD: min-max = 0.05: -0.22 to 0.92), indicating varying influence of drift and selection among populations. Census population size did not significantly predict the strength of inbreeding depression, heterosis or population mean fitness. However, inbreeding depression was positively and heterosis negatively correlated with population density. The proportion of self-massulae deposition was three times higher in sparse patches compared to dense ones (41% vs. 14%). Combined effects of density-dependent pollinator behaviour and limited seed dispersal may cause stronger genetic sub-structuring in sparse populations and reduce the strength of the correlation between census and effective population size. The results point to the importance of considering population density in addition to size when evaluating the distribution of recessive deleterious alleles across populations. Synthesis and applications. Management plans for threatened species often involve crosses between populations to restore genetic variation, a process termed genetic rescue. This study indicates that such conservation efforts should be more successful if designed on the basis of population density in addition to population size, because we found population density predicted both the strength of heterosis and inbreeding depression across populations of Gymnadenia conopsea.
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| 4. |
- Avril, Alexis, et al.
(författare)
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Capturing individual-level parameters of influenza A virus dynamics in wild ducks using multistate models
- 2016
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 53:4, s. 1289-1297
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Tidskriftsartikel (refereegranskat)abstract
- Disease prevalence in wildlife is governed by epidemiological parameters (infection and recovery rates) and response to infection, both of which vary within and among individual hosts. Studies quantifying these individual-scale parameters and documenting their source of variation in wild hosts are fundamental for predicting disease dynamics. Such studies do not exist for the influenza A virus (IAV), despite its strong impact on the global economy and public health. Using capture-recaptures of 3500 individual mallards Anas platyrhynchos during seven migration seasons at a stopover site in southern Sweden, we provide the first empirical description of the individual-based mechanisms of IAV dynamics in a wild reservoir host. For most years, prevalence and risk of IAV infection peaked at a single time during the autumn migration season, but the timing, shape and intensity of the infection curve showed strong annual heterogeneity. In contrast, the seasonal pattern of recovery rate only varied in intensity across years. Adults and juveniles displayed similar seasonal patterns of infection and recovery each year. However, compared to adults, juveniles experienced twice the risk of becoming infected, whereas recovery rates were similar across age categories. Finally, we did not find evidence that infection influenced the timing of emigration.Synthesis and applications. Our study provides robust empirical estimates of epidemiological parameters for predicting influenza A virus (IAV) dynamics. However, the strong annual variation in infection curves makes forecasting difficult. Prevalence data can provide reliable surveillance indicators as long as they catch the variation in infection risk. However, individual-based monitoring of infection is required to verify this assumption in areas where surveillance occurs. In this context, monitoring of captive sentinel birds kept in close contact with wild birds is useful. The fact that infection does not impact the timing of migration underpins the potential for mallards to spread viruses rapidly over large geographical scales. Hence, we strongly encourage IAV surveillance with a multistate capture-recapture approach along the entire migratory flyway of mallards.
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| 5. |
- Granath, Gustaf, 1980-, et al.
(författare)
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Trade-offs in berry production and biodiversity under prescribed burning and retention regimes in boreal forests
- 2018
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 55:4, s. 1658-1667
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Green tree retention and prescribed burning are the practices used to mitigate negative effects of boreal forestry. Beside their effects on biodiversity, these practices should also promote non-timber forest products (NTFPs). We assessed: (1) how prescribed burning and tree retention influence NTFPs by examining the production of bilberry, Vaccinium myrtillus and cowberry, Vaccinium vitis-idaea; (2) if there are synergies or trade-offs in the delivery of these NTFPs in relation to the delivery of species richness, focusing on five groups of forest-dwelling species. We used a long-term experiment located in eastern Finland, with three different harvesting treatments: clear-cut logging, logging with retention patches and unlogged, which were combined with or without prescribed burning. Eleven years after the treatment application, we scored plant cover and berry production in different microhabitats within these treatments, while species richness data for five species groups (ground layer lichens and bryophytes, vascular plants, saproxylic beetles, pollinators?here bees and hoverflies) were collected at the stand level. Logging favoured cowberry production, particularly for plants growing in the vicinity of stumps. Logging was detrimental for cover and berry production of bilberry. Retention mitigated these negative effects slightly, but cover and berry production were still substantially lower compared to unlogged forests. Prescribed burning increased the cowberry production in retention patches and in unlogged forest. Bilberry production decreased with burning, except in unlogged forest where the effect was neutral. No single management treatment simultaneously favoured all values?NTFPs and richness?and trade-offs among values were common. Only bilberry production and beetle diversity were higher under retention forestry, or in unlogged stands, compared to logged stands. Prescribed burning favoured many values when performed in combination with retention forestry, or in unlogged stands, but different treatment combinations favoured different species groups. Synthesis and applications. Our results demonstrate that widely applied conservation practices in managed boreal forests are unlikely to benefit all ecosystem values everywhere. If high multifunctionality is desired, managing at a landscape scale, countering the local trade-offs among values, may be more appropriate than the stand-scale conservation practices commonly practiced today.
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| 6. |
- Sundström, L. Fredrik, et al.
(författare)
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Growth-enhanced coho salmon invading other salmon species populations : effects on early survival and growth
- 2014
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 51:1, s. 82-89
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Tidskriftsartikel (refereegranskat)abstract
- The first genetically modified (GM) fish intended for human consumption has recently stimulated significant scientific discussion and regulatory scrutiny regarding food safety and environmental risks. Currently, no experiments with transgenic fish have been performed in nature, yet such data are needed to facilitate predictions of ecological consequences should engineered fish escape to the natural environment. To address this limitation, we conducted experiments under natural conditions but within a contained environment to assess the impact of invasion of growth-enhanced GM coho salmon Oncorhynchus kisutch (Walbaum) on survival and growth of three naturally cohabitating fishes: Chinook salmon O.tshawytscha (Walbaum), steelhead trout O.mykiss (Walbaum) and conspecific wild-type coho salmon. We found that the impact of stream-reared GM coho salmon on invaded specimens was similar to the impact of non-GM coho salmon. However, GM fish significantly reduced survival and growth of the invaded populations if they were first allowed to grow larger under hatchery conditions before being released.Synthesis and applications. Our results show that the ecological impact of fish genetically modified (GM) for rapid growth on closely related fish species may not be high in stream environments, unless these fish are first reared under culture conditions where they are able to realize their genetic growth potential. As such, first generation escapes of GM fish into the natural environment should be a main concern in the short term, whereas later generations, which are more similar to naturally occurring genotypes, are expected to have significantly weaker effects but which could persist for longer periods. Our results show that the ecological impact of fish genetically modified (GM) for rapid growth on closely related fish species may not be high in stream environments, unless these fish are first reared under culture conditions where they are able to realize their genetic growth potential. As such, first generation escapes of GM fish into the natural environment should be a main concern in the short term, whereas later generations, which are more similar to naturally occurring genotypes, are expected to have significantly weaker effects but which could persist for longer periods.
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| 7. |
- Breed, Martin F., 1981-, et al.
(författare)
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Clarifying climate change adaptation responses for scattered trees in modified landscapes
- 2011
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 48:3, s. 637-641
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Tidskriftsartikel (refereegranskat)abstract
- 1. Many studies have investigated adaptation to climate change. However, the term ‘adaptation’ has been used ambiguously and sometimes included parts of both classic evolutionary processes and conservation planning measures (i.e. human-mediated adaptation).2. To reduce ambiguity, we define three classes of evolutionary processes involved in adaptation – migrational, novel-variant and plasticity. Migrational adaptation describes the process of redistribution of standing genetic variation among populations. Novel-variant adaptation describes the increase in frequency of beneficial, new genetic variants. Plasticity adaptation refers to adaptive plastic responses of organisms to environmental stressors. Quite separately, human-mediated adaptation aims to maintain these evolutionary processes.3. Whilst the role of scattered trees in migrational adaptation of fauna may have been neglected in the past, their capacity to assist migrational adaptation of trees has been previously documented. However, their role in novel-variant and plasticity adaptation is generally unrecognised, and warrants further attention.4. Synthesis and applications. By defining different aspects of adaptation carefully, we show that scattered trees should not be cleared since they may facilitate gene flow across fragmented landscapes. However, they should be avoided as dominant seed sources since their stock may be of poor quality.
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| 8. |
- Dannewitz, Johan, et al.
(författare)
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Reproductive success of hatchery produced and wild born brown trout Salmo trutta in an experimental stream
- 2004
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 41:2, s. 355-364
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Tidskriftsartikel (refereegranskat)abstract
- 1.Although releases of hatchery-produced salmonids to support conspecific wildpopulations have increased dramatically during recent decades, little information isavailable about the performance in the wild of hatchery fish and their offspring.Important factors determining the success and genetic outcomes of supportive breedingprogrammes include (i) the relative reproductive success of released hatchery fish in thewild, and (ii) the extent to which the propagation affects the variance in reproductivesuccess in the population as a whole.2.We performed two field experiments on brown troutSalmo truttafrom the RiverDalälven in Sweden, where we examined reproductive success in an experimental stream.In experiment 1 we compared reproductive success between trout from a seventhgenerationhatchery stock of native origin and wild-born trout from the river. In experiment2, we compared reproductive success between seventh-generation hatchery troutand hatchery-reared trout derived from wild-born parents. Individual reproductivesuccess, based on the number of offspring assigned using microsatellite markers, wasassessed on three occasions after reproduction: immediately after hatching and after thefirst and second growth seasons.3.In experiment 1 there were no significant differences in reproductive success betweenseventh-generation hatchery trout and wild-born trout. In experiment 2, males from wildbornparents were more successful than males from the seventh-generation hatcherystock, but this difference was not observed among females.4.There was some evidence for a positive association between body size and reproductivesuccess among females but not males. For males, the number of mates was significantlyassociated with reproductive success, but this relationship was not evident among females.5.The variance in reproductive success was pronounced in both experiments, yieldingestimates of the ratio between the genetically effective size and the census size of ourexperimental populations ranging from 0·12 to 0·59.6.Synthesis and applications. Our results suggest that the reproductive success in thewild of hatchery-produced and wild-born trout with a common genetic backgroundmay be rather similar. These findings, in combination with the pronounced variancein reproductive success observed among breeders, indicate that supportive breedingcan be managed to increase not only the census but also the genetically effective sizeof small, endangered salmonid populations. However, to minimize negative effects ofhatchery selection, it is important to give priority to the restoration of natural habitatsand thereby increase the reproductive output from individuals in the wild.
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| 9. |
- Löbel, Swantje, et al.
(författare)
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Epiphytic bryophytes near forest edges and on retention trees : reduced growth and reproduction especially in old-growth-forest indicator species
- 2012
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 49:6, s. 1334-1343
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Tidskriftsartikel (refereegranskat)abstract
- Epiphytes are an important component in many forest ecosystems. The proportion of threatened epiphyte species is high, and the impact of clearcuts on key demographic processes via edge-influence is still poorly understood. There are few studies on epiphyte growth, and even less is known about how reproduction is affected by proximity to forest edges. For retention trees, demographic studies are even scarcer.Based on the results from a 6-month transplant experiment and a 3-year study of natural colonies, we modelled growth and reproduction of epiphytic bryophytes used as indicators of old-growth forests and widespread epiphytes in relation to distance from the forest edge. We also modelled growth and reproduction on retention trees within the clearcut. Species responses were linked to variation in canopy openness.Unlike the widespread species, the old-growth-forest indicators grew exponentially with distance from the edge, and this response was more pronounced at the south-east than north-west forest edge. In one red-listed species, reproduction was thoroughly inhibited near the edge, whereas the reproductive rate of the widespread species tended to increase. However, the widespread species also showed reduced shoot lengths on the retention trees.Reduced growth and inhibited reproduction of sensitive epiphytes near edges decrease the number of dispersing diaspores and may, in combination with lower local connectivity and increased tree fall rates close to edges, increase the risk of metapopulation extinction.Synthesis and applications. Two general management implications for boreal forests are drawn. First, retention trees may not have the capacity to act as a ‘lifeboat’ for epiphytic bryophytes and support their populations during the regeneration phase. Second, the creation of buffer zones is a useful conservation strategy for bryophytes. The exact width of zones depends on the forest structure and should be orientated in relation to the requirements of the most sensitive species. For the rather dense experimental forest, a width of at least 30 m was required for the south-facing buffer, whereas for the north-facing buffer 10 m was sufficient.
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| 10. |
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