| 1. |
- Andersson, K., et al.
(author)
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High-accuracy sampling of saproxylic diversity indicators at regional scales with pheromones : The case of Elater ferrugineus (Coleoptera, Elateridae)
- 2014
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In: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 171, s. 156-166
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Journal article (peer-reviewed)abstract
- The rare beetle Elater ferrugineus was sampled at 47 sites in the county of Östergötland, Sweden by means of pheromone-baited traps to assess its value as an indicator species for hollow oak stands rich in rare saproxylic beetle species. In addition, Osmoderma eremita was also sampled with pheromone baits. These data were then compared against species survey data collected at the same sites by pitfall and window traps. Both species co-occur with many Red Listed saproxylic beetles, with E. ferrugineus being a somewhat better indicator for the rarest species. The conservation value of a site (measured as Red List points or number of Red Listed species) increased with the number of specimens of E. ferrugineus and O. eremita caught. Accuracy of sampling by means of pheromone trapping turned out to be radically different for the two model species. E. ferrugineus traps put out during July obtained full accuracy after only 6. days, whereas O. eremita traps needed to be out from early July to mid-August in order to obtain full accuracy with one trap per site. By using E. ferrugineus, or preferably both species, as indicator species, accuracy would increase and costs decrease for saproxylic biodiversity sampling, monitoring and identification of hotspots. © 2014 Elsevier Ltd.
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| 2. |
- Andersson, Marie, et al.
(author)
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Low pre-death growth rates of oak (Quercus robur L.)-Is oak death a long-term process induced by dry years?
- 2011
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In: ANNALS OF FOREST SCIENCE. - : EDP Sciences. - 1286-4560 .- 1297-966X. ; 68:1, s. 159-168
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Journal article (peer-reviewed)abstract
- Background and purpose A complex interplay between biotic and abiotic factors is believed to be responsible for several oak declines in pedunculate oak (Quercus robur L.). This study aims to clarify the temporal process of oak declines, as well as identifying individual tree and environmental variables that affects growth rate and that may increase the risk of mortality. The study was performed in southern Sweden at three sites. Findings Cross-dating revealed that most trees had died during the last decade and that the growth rates of the dead oaks were affected long before death. Averaged growth chronologies of dead and control trees reaching 150 years back in time illustrated an excellent match up until around 1992, when a severe drought occurred after which the dead trees started to express reduced growth. Precipitation the previous year during August-September and during March-June this current year was of significant importance for oak growth. Site-specific results that showed that dead trees: included fewer small-sized trees, grew on non-clay soils, were more likely to have shelf fungus and cavities and were exposed to less sunshine. Conclusion The results support the theories that oak mortality is a long process that may be induced decades before the actual death.
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| 3. |
- Angelstam, Per, et al.
(author)
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Evidence-Based Knowledge Versus Negotiated Indicators for Assessment of Ecological Sustainability : The Swedish Forest Stewardship Council Standard as a Case Study
- 2013
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In: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 42:2, s. 229-240
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Journal article (peer-reviewed)abstract
- Assessing ecological sustainability involves monitoring of indicators and comparison of their states with performance targets that are deemed sustainable. First, a normative model was developed centered on evidence-based knowledge about (a) forest composition, structure, and function at multiple scales, and (b) performance targets derived by quantifying the habitat amount in naturally dynamic forests, and as required for presence of populations of specialized focal species. Second, we compared the Forest Stewardship Council (FSC) certification standards' ecological indicators from 1998 and 2010 in Sweden to the normative model using a Specific, Measurable, Accurate, Realistic, and Timebound (SMART) indicator approach. Indicator variables and targets for riparian and aquatic ecosystems were clearly under-represented compared to terrestrial ones. FSC's ecological indicators expanded over time from composition and structure towards function, and from finer to coarser spatial scales. However, SMART indicators were few. Moreover, they poorly reflected quantitative evidence-based knowledge, a consequence of the fact that forest certification mirrors the outcome of a complex social negotiation process.
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| 4. |
- Askling, John, et al.
(author)
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Ryggradslösa djur och planering av infrastruktur - dagfjärilar som landskapsekologiska verktyg och modellorganismer.
- 2006
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Reports (other academic/artistic)abstract
- Föreliggande rapport är slutrapporten inom projektet ”Landskapsekologiska effekter av vägar och järnvägar på ryggradslösa djur” som pågått 2001-2003. En övervägande majoritet av alla studier av vägars/järnvägars effekter på djur har tidigare gjorts på större däggdjur och fåglar, men även groddjur och smådäggdjur fanns relativt väl representerade. För ryggradslösa djur fanns dock få studier och kunskapen var dålig om effekterna på denna grupp som är den absolut artrikaste. Projektet har fokuserat på dagfjärilar och odlingslandskap. En av de bäst kända grupperna av ryggradslösa djur är dagfjärilar. Odlingslandskapet som de framförallt finns i är också ett intressant landskap gällande infrastrukturproblematik. Det här projektet ligger under paraplyprojektet EKLIPS (ekologisk infrastrukturplanering med fjärranalys). Målet med EKLIPS är att utveckla och förbättra trafikverkens hantering av natur- och kulturvärden i de olika delarna av planeringsprocessen.Projektet bestod av två delar: 1) att undersöka arealkrav på landskapsnivå hos en grupp ryggradslösa djur (dagfjärilar) för att i förlängningen kunna identifiera värdefulla odlingslandskap. 2) att studera den eventuella barriäreffekt en väg kan ha på flygande ryggradslösa djur. Även här är det dagfjärilar som studerats.De huvudsakliga slutsatserna av den här studien av dagfjärilar som verktyg i infrastrukturplanering är att:Dagfjärilar kan användas för att identifiera biologiskt rika odlingslandskap. Totalt undersöktes 62 områden och 12 170 individer av 57 fjärilsarter identifierades.Landskapet ska studeras i relativt stor skala. Den skala som påverkar fjärilssamhällets sammansättning handlar om kilometrar snarare än hundratals meter. Mängden hagmarker och lövskogar inom 500 m och 2000 m kunde inte förklara fjärilsfaunans sammansättning, däremot mängden inom 5000 m.Det finns kritiska tröskelvärden för mängden av habitat i landskapet och infrastruktur har troligen sin största negativa påverkan kring dessa värden. Tröskelvärdet för att ett artrikt område (>20 arter dagfjärilar) med >50% sannolikhet ska kunna finnas i ett område var i denna studie 570 ha (7,3%) hagmarker/lövskog inom en radie av 5000 m.Tröskelvärdena för enskilda arter varierade mellan 130-950 ha, det vill säga 1,6-12.1% av landskapet ska bestå av passande habitat.Indikatorarter kan användas för att identifiera rika landskap. Våra studier pekar på att flera arter och två artgrupper kan vara användbara. De två artgrupperna är pärlemorfjärilar och bastardsvärmare. Totalt 13 arter eller artgrupper påträffades främst i rika landskap, t ex skogsnätfjäril, vitgräsfjäril, midsommarblåvinge, brunfläckig pärlemorfjäril och silverstreckad pärlemorfjäril.Vägar kan fungera som barriärer för vissa arter. För två av arterna hade vägen en signifikant barriäreffekt. För luktgräsfjäril minskade flödet med 74% och för slåttergräsfjäril med 43%.Potentiellt rika landskap ska gå att identifiera från flygbilder och satellitdata utan att göra omfattande fältinventeringar i framtiden baserat på våra resultat. Fortfarande är dock resultaten för osäkra (ej upprepade i andra landskap) för att appliceras i större skala.När vägplaneringsprocessen kommit fram till vägutredningen kan indikatorarterna användas för att identifiera för artrikedomen viktiga områden och för att precisera målsättningarna för vilken naturhänsyn som skall tas i arbetet. Indikatorarterna kan också användas i uppföljningsarbete för att uppskatta om projektmålen uppnåtts.
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| 5. |
- Berg, Åke, et al.
(author)
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Power-line corridors as source habitat for butterflies in forest landscapes
- 2016
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In: Biological Conservation. - : ELSEVIER SCI LTD. - 0006-3207 .- 1873-2917. ; 201, s. 320-326
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Journal article (peer-reviewed)abstract
- Modern intensified agriculture has decreased farmland heterogeneity, which has led to strong negative effects on farmland biodiversity. However, partly forested landscapes seem to offer many alternative habitats for open habitat species such as butterflies, since modern forestry and development of infrastructure has created several new environments such as forest road verges and power-line corridors. The aim of the present study was to investigate the importance of power-line corridors (PLCs) as butterfly habitats by testing i) if species richness and abundance of butterflies in PLCs are affected by adjacent habitat composition (i.e. comparisons of PLCs with different adjacent habitats), ii) if PLCs act as source habitat through spill-over of individuals into adjacent forest roads and semi-natural pastures and iii) if species composition differs among the investigated habitat types. To investigate this we censured the butterfly fauna in 23 study landscapes in south-central Sweden. We found support for the hypothesis that PLCs may act as source habitats for butterflies in forest roads and pastures, since species richness and abundance were decreasing with increasing distance to PLC from 0 to 500 m. In addition, the species composition in forest roads and pastures close to and far from PLCs was similar, suggesting that this increase was not due to an increase of PLC specialists in the other two habitats. Thus, we have shown that PLCs in themselves are important butterfly habitats independently of adjacent habitat composition (adjacent mature forest, clear cuts or arable land), and they contribute to increased species richness and abundance of butterflies in surrounding areas over 10 times larger than their own width. (C) 2016 Elsevier Ltd. All rights reserved.
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| 6. |
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| 7. |
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| 8. |
- Bergman, Karl-Olof, et al.
(author)
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Butterflies in Swedish grasslands benefit from forest and respond to landscape composition at different spatial scales
- 2018
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In: Landscape Ecology. - : SPRINGER. - 0921-2973 .- 1572-9761. ; 33:12, s. 2189-2204
-
Journal article (peer-reviewed)abstract
- ContextLoss and fragmentation of semi-natural grasslands has critically affected many butterfly species in Europe. Habitat area and isolation can have strong effects on the local biodiversity but species may also be strongly affected by the surrounding matrix.ObjectivesWe explored how different land cover types in the landscape explained the occurrence of butterfly species in semi-natural grasslands.MethodsUsing data from 476 semi-natural grasslands in Sweden, we analysed the effect of matrix composition on species richness and occurrence. Additionally, we analysed at which spatial scales butterflies responded to matrix types (forests, semi-natural grasslands, arable land and water).ResultsForest cover showed the strongest positive effect on species richness, followed by semi-natural grasslands. Forest also had a positive effect on red-listed species at local scales. Responses to matrix composition were highly species-specific. The majority of the 30most common species showed strong positive responses to the amount of forest cover within 200-500m. There was a smaller group of species showing a positive response to arable land cover within 500-2000m. Thirteen species showed positive responses to the amount of semi-natural grasslands, generally at larger scales (10-30km).ConclusionsOur study showed that surrounding forest is beneficial for many grassland butterfly species and that forests might mitigate the negative effects of habitat loss caused by agricultural intensification. Also, semi-natural grasslands were an important factor for species richness at larger spatial scales, indicating that a landscape consisting mainly of supporting habitats (i.e. forests) are insufficient to sustain a rich butterfly fauna.
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| 9. |
- Bergman, Karl-Olof, et al.
(author)
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Clear-cuts are temporary habitats, not matrix, for endangered grassland burnet moths (Zygaena spp.)
- 2020
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In: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 24:2, s. 269-277
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Journal article (peer-reviewed)abstract
- Burnet moths (Zygaena spp.) are day-flying Lepidoptera considered indicative of species-rich grasslands. In the present study, our aim was to clarify whether clear-cuts are habitat, supporting habitat or matrix for three species of Zygaena. We did so by sampling these species with sex pheromones on 48 clear-cuts, varying in amount of host and nectar plants, in southern Sweden. To compare the efficiency of such sampling, we also conducted transect walks on these clearcuts. Overall, host-plants on clear-cuts best explained the abundance of Zygaena spp. recorded, better than nectar-plants or connectivity with nearby grasslands. These results indicate that clear-cuts with an abundance of host plants are used as a fully functional habitat, and not a supporting habitat in the sense of only providing nectar. There is no support in these results for considering clear-cuts as an inert matrix. With about half the work-effort, pheromone traps recorded 100 times more Zygaena spp. as transect walks. The poor correspondence between observations during transects walks and pheromone trap catches suggest Zygaena spp. being difficult to monitor by transect walks. In contrast to grasslands, clear-cuts are short-term in nature requiring repeated recolonization, indicating the importance of permanent grasslands. However, clear-cuts are important temporary insect habitats due to their great acreage, and suitable management can increase the time they remain a habitat.
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| 10. |
- Bergman, Karl-Olof, 1965-, et al.
(author)
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Distribution of occupied and vacant sites and migration of Lopinga achine (Nymphalidae : Satyrinae) in a fragmented landscape
- 2001
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In: Biological Conservation. - 0006-3207 .- 1873-2917. ; 102:2, s. 183-190
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Journal article (peer-reviewed)abstract
- The distribution of occupied and vacant sites and migration of the threatened butterfly Lopinga achine were studied in the province of ╓sterg÷tland, Sweden. The probability of occupation increased with increasing patch area and decreasing distance to the nearest occupied patch, presumably due to different probabilities of colonisation and survival of the populations inhabiting the patches. Probability of female emigration from and immigration to a patch increased with decreasing area. Middle-sized patches produced the largest number of female migrants, although the highest fraction was noted for the smallest patches, and the greatest number of females was marked in the largest patch. The fraction of resident females, but not males, increased with increasing area. The observed occupancy and migration pattern have important conservation implications: all but two populations comprising three or more individuals were within 740 m of the nearest neighbour, indicating the need for networks of suitable, closely situated patches. ⌐ 2001 Elsevier Science Ltd. All rights reserved.
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| 11. |
- Bergman, Karl-Olof, 1965-
(author)
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Ecology and conservation of the butterfly Lopinga achine
- 2000
-
Doctoral thesis (other academic/artistic)abstract
- The ecology of the red-listed butterfly Lopinga achine was studied in partly open woodlands in the province of Östergotland, Sweden. Detailed autoecological research is essential for successful conservation of a species, and the present investigation focused on the initial aspects of such work, namely, choice of host plant, habitat selection, and dispersal ability. The effects of patch area, isolation, and successional stages of studied sites were also examined.The results indicate that L. achine depends on a single host plant, Carex montana. The females preferred to oviposit near this sedge, and most of the larvae (> 80%) were found on C. montana in the field. Egg-laying females and larvae were restricted to C. montana growing in a narrow zone along the edges of glades. This restriction to forest edges is probably the cause for the dependence of L. achine on a restricted stage of canopy cover. More specifically, no L. achine occurred at sites with less than 60% canopy cover, and population densities decreased sharply with more than 90% cover. Eighty-six percent of the studied sites that were occupied are unmanaged, thus the most important aspect of long-term conservation of L. achine is probably the deterministic changes of its woodland habitat. If the sites remain unmanaged, the system of populations will most likely collapse within 20-40 years. Populations of both L. achine and C. montana increased in size at experimentally managed sites where new glades were created. However, an important prerequisite of successful restoration appears to be the presence of C. montana along the edges of new glades from the start, because the rate of C. montana colonisation was slow.Most of the populations (50 of 79) were small (< 500 adults; none larger than 4,500) and seemed to show synchronous interannual fluctuation. The probability that a patch would be occupied increased with increasing patch area and decreasing distance to the nearest occupied patch. This was presumably due to different probabilities of extinctions, colonisations, and survival of the inhabiting populations. All but two of the sites with ≥ 3 individuals were within 740 m of the nearest neighbour. Patch size is also a key factor for occurrence: compared to larger patches, small patches are more dependent on neighbour populations.The majority of the movements were small and within sites, although in many cases the distance to other sites was less than 100 m. Only 56 individuals (4.0% of those recaptured) moved between sites. It seems that habitat patches of L. achine should be less than 700 m from each other to ensure inter-population contact. Fifteen to 20 wellconnected populations have been stated as a lower limit for a viable metapopulation.Based on these criteria, there are two groups of viable populations in the studied area,and these two groups will be given priority in future conservation work.
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| 12. |
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| 13. |
- Bergman, Karl-Olof, 1965-
(author)
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Host plant choice, habitat selection, dispersal ability and population structure of a threatened butterfly, Lopinga achine
- 1998
-
Licentiate thesis (other academic/artistic)abstract
- Host plant choice, habitat selection and dispersal ability of the red-listed butterfly Lopinga achine were studied in partly open woodland in the province of Östergötland. Females preferred to oviposit near Carex montana, although they did not attach their eggs to any plant. Carex montana was also generally preferred by the larvae in laboratory experiments among plant species available in the field. Most of the larvae found in the field (>80%), were found on C. montana. Hence, C. montana seems to be a keystone resource for the studied populations of L. achine.Egg-laying females and larvae were found be restricted to a narrow zone along the edges of glades under a tree and bush canopy even though C. montana occurs outside this zone. This restriction to edges may be ascribed to two factors: First, egg survival was much higher at forest edges, being 48% compared with 12 and 14% in the sun of the open glades and in the shade, respectively. Second, host plant abundance in the shade under the tree and bush canopy is highest near the edge of the glades. Management to maintain glades and suitable edges is probably necessary for the long-term conservation of L. achine.Because of the recent fragmentation of its habitat, the dispersal ability of L. achine was considered important for its long-term survival. Of the 4546 individuals marked during three years, 1387 were recaptured at least once. Only 56 individuals (4,0% of the recaptured ones) were shown to have moved between populations. The mean distance between successive recaptures of the females varied between 94 and 116 meters and that of the males between 45 and 54 meters under the three years of study, and the maximum distance between any points of capture/recapture for an individual was 670 meters for one male. Movements of marked specimens between sites indicated that woods or forest edges enhance dispersal. Fewer butterflies moved between sites over open field than through woods or along edges. More females than males moved between sites and this difference increased with increasing age from three days until about ten days. Approximately 13% of the females 7-8 days old were shown to move to a new population. At this age, they had approximately 25 eggs left to lay, 15 - 20% of their total egg production. The mark -recapture results suggests that to maintain exchange between patches of L. achine they should not be farther apart than 300-800 metres depending of the matrix between patches.This study has identified the host plant, clarified habitat requirements and it has quantified movements of L. achine in Östergötland, the first necessary steps for a successful long -term conservation strategy of L. achine.
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| 14. |
- Bergman, Karl-Olof, et al.
(author)
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How much and at what scale? Multiscale analyses as decision support for conservation of saproxylic oak beetles
- 2012
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In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 265, s. 133-141
-
Journal article (peer-reviewed)abstract
- A key aspect for understanding species distributions is how they respond to habitat factors at different spatial scales. In this study we used a dataset mapping 33,000 large/hollow oaks, habitat for a guild of saproxylic beetles specialised on oaks at an extent of 10,000 km2. A total of 16 oak-dependent saproxylic species, out of 35, showed a clear relationship with substrate density at scales ranging from 52 m to ⩾5200 m. The characteristic scale of response for species richness of oak specialist species was 2284 m. At this scale, there was a tendency for richness to plateau at about 0.15 oaks ha−1, in which case about 250 hollow or large (circumference 310 cm) oaks would be needed in an area of 1600 ha to ensure a rich saproxylic oak fauna. The main general conclusions were: (i) a multi-scale approach is especially valuable to identify the characteristic scale of response; and that assuming a joint, single scale for all species may result in very poor decision support. (ii) The variation in species’ responses to substrate density at different scales means that habitat loss and fragmentation as well as management and restoration may have very different effects upon different species. (iii) Some species respond both to local and landscape scales, indicating that species occurrences in fragmented oak landscapes are affected both by short-term dynamics of the beetles and long term dynamics of the oak substrate. (iv) Maps, useful as decision support, can be constructed based on resource availability (in our case oak density) and characteristic scales.
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| 15. |
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| 16. |
- Bergman, Karl-Olof, et al.
(author)
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Importance of scale and density of hollow oaks for saproxylic oak beetles
-
Other publication (other academic/artistic)abstract
- One of the key aspects in conservation management and in understanding species distributions is how they respond to habitat factors at different scales. Old-growth deciduous forests is severely fragmented in Europe and the most important substrates for saproxylic beetles in this habitat is hollow veteran trees. In this study, we used an extensive field survey data, mapping all large and/or hollow oaks (ca 33,000) in an area of 10,000 km² in south-eastern Sweden. With beetle occurrence data from 38 sites we did a multi-scale analysis of how different beetle species responded to oak density. A total of 16 species responded significant to substrate density from 52 m to 5200 m showing that conclusions made from data measured on a single scale may lead to wrong conclusions. We hypothesized that larger species should respond to larger scales and that both local and landscape scales should be important for several species. We found no evidence for that larger species responded to substrate density at larger scales. However, several species as e.g. Tenebrio opacus, responded to oak density at both small a scale (92 m) and a large scale (859 m). The reason for the importance of two scales is probably that several processes are acting on different time scales and therefore over different spatial scales. Individual oaks may act as static patches in the short term and the small-scale response may reflect the scale of metapopulation dynamics. However, as changes in the densities of old oaks over larger landscapes over several centuries occurs, long-term substrate dynamics are expected to act over larger areas, reflecting the larger scale. The variation in species response to substrate density at different scales means that habitat loss and fragmentation will have different effects upon different species.
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| 17. |
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| 18. |
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| 19. |
- Bergman, Karl-Olof, 1965-, et al.
(author)
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Population structure and movements of a threatened butterfly (Lopinga achine) in a fragmented landscape in Sweden
- 2002
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In: Biological Conservation. - 0006-3207 .- 1873-2917. ; 108:3, s. 361-369
-
Journal article (peer-reviewed)abstract
- The red-listed butterfly Lopinga achine was studied by mark-recapture methods in southern Sweden for three seasons. We examined movement within and between populations and egg production in relation to age. The majority of the movements were small with mean movements between recaptures of 45-54 m for males and 94-116 m for females. There were few movements between sites, 20 of 996 recaptured males moved and 36 of 391 recaptured females, even though the distance to other sites was in many cases < 100 m. The distance moved and the number of females moving between sites increased with increasing age. On average, a female that moves does so after laying two-thirds of its eggs in its natal site. It is therefore important to take account of the proportion of reproductive effort involved in dispersal when estimating colonisation ability. The males did not move more with increasing age. Female behaviour can be seen as a "spread-the-risk" strategy, an adaptation to the successional habitat of L. achine, whose natal site sooner or later will deteriorate. Butterflies like L. achine living in successional habitats may exhibit mobility that is intermediate between butterflies living in ephemeral habitats (very mobile) and in long-lived habitats (sedentary). ⌐ 2002 Elsevier Science Ltd. All rights reserved.
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| 20. |
- Bergman, Karl-Olof, 1965-, et al.
(author)
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Population viability analysis of the butterfly Lopinga achine in a changing landscape in Sweden
- 2004
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In: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 27:1, s. 49-58
-
Journal article (peer-reviewed)abstract
- Metapopulation theory has generally focused only on the stochastic turn-over rate among populations and assumed that the number and location of suitable habitat patches will remain constant through time. This study combines in a PVA both the deterministic landscape dynamics and the stochastic colonisations and extinctions of populations for the butterfly Lopinga achine in Sweden. With data on occupancy pattern and the rate of habitat change, we built a simulation model and examined five different scenarios with different assumptions of landscape changes for L. achine. If no landscape changes would be expected, around 80 populations are predicted to persist during the next 100 yr. Adding the knowledge that many of the sites are unmanaged and that the host plant will slowly deteriorate as canopies close over, and adding environmental variation and synchrony, showed that the number of populations will decrease to around of 4.3 and 2.8 respectively, with an extinction risk of 34% - quite different from the first scenario based only on the metapopulation model. This study has shown the importance of incorporating both deterministic and stochastic events when making a reliable population viability analysis. Even though one can not expect that the long-term predictions of either occupied patches or extinction risks will be accurate quantitatively, the qualitative implications are correct. The extinction risk will be high if grazing is not applied to more patches than is the case today. The simulations indicate that an absolute minimum of 10-30 top-ranked patches needs to be managed for the persistence of the metapopulation of L. achine in the long term. The same problem of abandoned and overgrowing habitats affects many other threatened species in the European landscape and a similar approach could also be applied to them.
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| 21. |
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| 22. |
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| 23. |
- Blixt, Torbjörn, et al.
(author)
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Clear-cuts in production forests: From matrix to neo-habitat forbutterflies
- 2015
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In: Acta Oecologica. - : Elsevier. - 1146-609X .- 1873-6238. ; 69, s. 71-77
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Journal article (peer-reviewed)abstract
- Butterfly conservation in Europe is mainly focused on well-defined grassland habitat patches. Such anapproach ignores the impact of the surrounding landscape, which may contain complementary resourcesand facilitate dispersal. Here, we investigated butterfly species richness and abundance in a habitatnormally regarded as unsuitable matrix: production forestry clear-cuts. Butterflies were recorded in 48clear-cuts in southern Sweden differing with regards to the time since clear-cutting and land-use history(meadow or forest based on historical maps from the 1870s). All clear-cuts had been managed as productionforests for at least 80e120 years. A total of 39 species were found in clear-cuts of both land-usehistories, but clear-cuts with a history as meadow had on average 34% higher species richness and 19%higher abundance than did clear-cuts with a history as forest. No effect of the time since clear-cuttingwas found, irrespective of land-use history, which was likely due to the narrow timespan sampled (<8years). The absence of temporal effect suggests that clear-cuts may provide butterflies with valuableresources for 10e15 years. Assuming a 100 year forest rotational cycle, this means that 10e15% of thetotal forested area are made up by clear-cuts valuable to butterflies, which corresponds to an area aboutfour times as large as that of species-rich semi-natural grasslands. The study illustrates the importance ofconsidering land-use legacies in ecological research and question the landscape-ecological view thatclear-cuts make up an unsuitable matrix for butterflies. Moreover, forest conservation management withspecial attention to land-use history may increase the quality of the landscape, thus facilitating butterflymetapopulation persistence. Given their large area and assets of nectar and host plant resources, clearcutsmust be considered as a butterfly habitat in its own right. Being a man-made environment withshort history, we might call it a neo-habitat.
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| 24. |
- Burman, Joseph, et al.
(author)
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Revealing hidden species distribution with pheromones: the caseof Synanthedon vespiformis (Lepidoptera: Sesiidae) in Sweden
- 2016
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In: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 20:1, s. 11-21
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Journal article (peer-reviewed)abstract
- Synanthedon vespiformis L. (Lepidoptera:Sesiidae) is considered a rare insect in Sweden, discoveredin 1860, with only a few observations recorded until a sexpheromone attractant became available recently. This studydetails a national survey conducted using pheromones as asampling method for this species. Through pheromonetrapping we captured 439 specimens in Southern Sweden at77 sites, almost tripling the number of previously reportedrecords for this species. The results suggest that S. vespiformisis truly a rare species with a genuinely scattereddistribution, but can be locally abundant. Habitat analyseswere conducted in order to test the relationship betweenhabitat quality and the number of individuals caught. InSweden, S. vespiformis is thought to be associated with oakhosts, but our attempts to predict its occurrence by theabundance of oaks yielded no significant relationships. Wetherefore suggest that sampling bias and limited knowledgeon distribution may have led to the assumption that thisspecies is primarily reliant on oaks in the northern part ofits range, whereas it may in fact be polyphagous, similar toS. vespiformis found as an agricultural pest in Central andSouthern Europe. We conclude that pheromones canmassively enhance sampling potential for this and otherrare lepidopteran species. Large-scale pheromone-basedsurveys provide a snapshot of true presences and absencesacross a considerable part of a species national distributionrange, and thus for the first time provide a viable means ofsystematically assessing changes in distribution over timewith high spatiotemporal resolution.
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| 25. |
- Carlsson, Staffan, et al.
(author)
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Boxing for biodiversity: evaluation of an artificiallycreated decaying wood habitat
- 2016
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In: Biodiversity and Conservation. - : Springer Science+Business Media B.V.. - 0960-3115 .- 1572-9710. ; 25:2, s. 393-405
-
Journal article (peer-reviewed)abstract
- Many saproxylic species are threatened in Europe because of habitat decline.Hollow trees represent an important habitat for saproxylic species. Artificial habitats mayneed to be created to maintain or increase the amount of habitat due to natural habitat decline.This study investigated the extent to which saproxylic beetles use artificial habitats in woodenboxes. The boxes were placed at various distances (0–1800 m) from known biodiversityhotspots with hollow oaks and studied over 10 years. Boxes were mainly filled with oak sawdust, oak leaves, hay and lucerne flour. In total, 2170 specimens of 91 saproxylic beetlespecies were sampled in 43 boxes. The abundance of species associated with tree hollows,wood rot and animal nests increased from the fourth to the final year, but species richnessdeclined for all groups. This study shows that wooden boxes can function as saproxylicspecies habitats. The artificial habitats developed into a more hollow-like environment duringthe decade long experiment with fewer but more abundant tree hollow specialists.
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- Hambäck, Peter, et al.
(author)
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Allometric density responses in butterflies : the response to small and large patches by small and large species
- 2010
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In: Ecography. - : Blackwell. - 0906-7590 .- 1600-0587. ; 33:6, s. 1149-1156
-
Journal article (peer-reviewed)abstract
- Species are differentially affected by habitat fragmentation as a consequence of differences in mobility, area requirements, use of the matrix, and responses to edges. A quantitative understanding of these differences is essential not only for conservation biology but also for basic ecological theory. Here, we examine density responses by butterflies to patch size and use a quantitative theory on the scaling of population density with patch size to interpret results. Theory suggests that the density distribution of mobile species along a patch size gradient should depend on the scaling of net migration rates, whereas the density distribution of less mobile species should depend more on local growth. Using data from 11 localities in three European countries, we calculated the slope in the relationship between patch size and population density. These slopes were evaluated in relation to butterfly traits and matrix composition. As estimates of butterfly mobility we used both wing span and expert mobility rankings. The slope of the density–area relationship changed as predicted with wing span and the association of species to grasslands. Large and highly mobile species had a negative slope, similarly for grassland specialists and generalist species, and the slope matched quantitative predictions based on the scaling of net migration rates. Small and less mobile grassland specialists had a slope that was less negative than the slope of large and mobile grassland specialists, whereas the slope did not change with size for generalist species. These analyses suggest that the variability in response among butterfly species to patch size could be explained by accounting for body size/mobility and habitat associations among species. A caveat is that edge effects are not explicitly included in the model analysis, and future research should aim to combine area and edge effects in a common theoretical framework.
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| 30. |
- Ibbe, Mathias, et al.
(author)
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History matters: impact of historical land use on butterfly diversity in clear-cuts in a boreal landscape
- 2011
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In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 261:11, s. 1885-1891
-
Journal article (peer-reviewed)abstract
- In Swedish boreal landscapes, the loss of species-rich semi-natural grasslands is largely due to a longhistory of agricultural abandonment. Large areas historically managed as meadows have become matureconiferous forest. This study focused on the potential biological legacy following a long period of grasslandabandonment. The butterfly fauna in clear-cuts which was historically meadows and abandoned longenough to allow a generation of conifers to mature (70–90 years) was compared with clear-cuts whichwere historically coniferous forest. The results showed that clear-cuts historically managed as meadowswere: (i) much richer in individuals, (ii) more species-rich, and (iii) contained many more grasslandspecialists than clear-cuts with a history as forest, with many of these species threatened in other partsof Europe.The results from our study demonstrate for the first time, to our knowledge, that the legacy of historicalland-use in remnant plant communities can affect butterfly diversity in clear-cuts and hence the largescaledynamics over a timescale of a full tree rotation. The results of this study have implications for forestmanagement practices. Replanting clear-cuts on land that was previously meadows with deciduous treesor allowing the forest to regenerate naturally instead of planting conifers would make it possible topreserve a greater diversity of habitats for butterflies and other organisms.
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| 31. |
- Jansson, Nicklas, 1967-, et al.
(author)
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An indicator system for identification of sites of high conservation value for saproxylic oak (Quercus spp.) beetles in southern Sweden
- 2009
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In: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 13:4, s. 399-412
-
Journal article (peer-reviewed)abstract
- The saproxylic beetle fauna on old oaks was sampled in four regions of southern Sweden using two methods: window and pitfall trapping. The aim was to test a way of finding indicator species which can be used to identify sites with high species number or that scored high on a conservation priority species index, based on occurrence of red-listed species. From 92 sites surveyed, in total 164 species of saproxylic beetles were identified. Different sets of indicator species were selected based upon 22 sites from a centrally located region. Predictions of species number and the index for 30 other sites from the same province were made. The correlation between observed and predicted species number and the index increased with increasing number of indicators. When comparing different treatment of species indata, the explanatory power of predictions was strongest for presence/absence data. Indicator sets of species effectively caught with pitfall traps gave overall the best predictions of both species number and the index. Predictions of species number and the index worked well within the same regions but gave varied result for the three other regions which shows that transferability of indicators between regions may be doubtful.
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| 32. |
- Jansson, Nicklas, 1967-
(author)
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Habitat requirements and preservation of the beetle assemblages associated with hollow oaks
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- One of the most endangered assemblages of species in Europe is saproxylic beetles associated with old trees. To be able to conserve these species there is a need of developing methods to survey the fauna and to evaluate the conservation value of different oak habitats, develop instruments for landscape planning and detailed knowledge of species habitat requirements. The results are based on a data set from window and pit-fall trapping of saproxylic beetles at 94 different sites spread over four regions in southern Sweden. Additionally, 48 wooden boxes with artificial wood mould, consisting mainly of oak saw dust and oak leaves and some varying additional substrates, were studied for three years at three of the sites and their vicinities.A comparison of three methods to assess species richness and composition of the saproxylic beetle fauna in standing hollow oaks showed that all trapping methods were effective in detecting species, but as they partially target different assemblages of species it is profitable to combine the methods. Window traps gave most species but wood mould sampling is the cheapest method to sample the fauna. It was possible to predict the conservation value individual oak patches with sets of indicator species of saproxylic beetles with regard to number of species or presence of conservation priority species. Indicator sets of species effectively caught with pitfall traps gave the overall best predictions. When comparing different treatment of species indata, the explanatory power of predictions was strongest for presence/absence data. Predictions of species number and an index worked well within the same regions but gave varied result for three other regions, which shows that transferability of indicators between regions may be doubtful. Species richness was greatest in stands with large, free-standing trees. Among individual trees, large girth as well as low canopy cover, increased frequency of occurrence for several species. Forest regrowth was found to be detrimental for many beetle species. An evaluation of to what extent artificial habitats, mimicking the conditions in hollow oaks, can be exploited by saproxylic beetles showed that nearly 70% of the species found in hollow oaks was found in artificial wood mould boxes. A dead hen added to the artificial wood mould gave a higher number of beetle specimens. The number of species associated with tree hollows in oak decreased with distance from sites with hollow oaks.An analysis of species assemblages at 38 sites and positions of 33 000 large/hollow oaks showed that different beetle species dependent on a single substrate, hollow oaks, responded to different scales. The total species richness responded to a scale of 859 m and the characteristic scale of response for single species varied between 52 m and 5284 m. Several species were sensitive both to smaller and larger scales.As most sites with endangered beetles living in old oaks are small and isolated, ongoing management directed to keep old oaks free standing and sun exposed and to ensure the recruitment of young oaks, and the restoration of abandoned pasture woodlands should have a high priority in nature conservation. Artificial habitats may in critical areas be created to fill gaps in old oak habitat for parts of the species assemblage. To preserve the saproxylic beetle fauna dependent on old oaks, it is important to retain and create suitable habitats both in local stands and at the landscape level, from single hectares up to hundreds of hectares depending on the species. In some landscape, creations of new oak areas in the fragmented landscape are crucial for long-term survival of sensitive species.
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| 33. |
- Johansson, Victor, et al.
(author)
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Oviposition preferences and larval survival of the marsh fritillary butterfly : The adverse impact of grazing
- 2024
-
In: Insect Conservation and Diversity. - : John Wiley & Sons. - 1752-458X .- 1752-4598.
-
Journal article (peer-reviewed)abstract
- Species-rich semi-natural grasslands have been lost during the last century due to agricultural intensification. This has had large negative consequences for many specialised species, including grassland butterflies. To prevent further loss, management regimes in the remaining grasslands must maintain habitat quality over time, and we therefore need to understand the habitat preferences of specialised species and how different management regimes affect their survival. We studied the egg-laying preferences of the threatened marsh fritillary butterfly in relation to host plant properties, microclimate and management (grazing) on Gotland, Sweden. Moreover, we followed the survival of eggs and larvae from 27 egg batches during a period of 8 months (from June 2020 to March 2021) in grazed and ungrazed areas. We found 92 egg batches in total and the average number of eggs was 184.5. Egg-laying probability increased with increasing host plant size and abundance, and environmental variables associated with a warm microclimate (low grass cover, low vegetation height and south-facing edges). The 27 egg batches that were followed over time had on average 203 eggs in June. Roughly 28% of the eggs developed into larvae, and about 17% of these survived over the entire study period, resulting in an overall 4.7% survival. Egg survival was higher in ungrazed habitats compared with grazed; in March (post-hibernation), there were almost nine times more eggs in ungrazed habitats. This study highlights the complex habitat ecology of specialised butterflies and underscores the detrimental impact of intense grazing, advocating for rotational grazing or mowing regimes. We study oviposition preferences and survival of both eggs and larvae (post-hibernation) for the marsh fritillary, in relation to host plant availability, microclimate conditions and grazing management Egg-laying probability increased with increasing host plant size and abundance, and environmental variables associated with a warm microclimate (low grass cover, low vegetation height and south-facing edges) Egg survival was clearly higher in ungrazed habitats compared with grazed; in March (post-hibernation), there were almost nine times more eggs in ungrazed habitats. image
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| 34. |
- Johansson, Victor, et al.
(author)
-
Tree and site quality preferences of six epiphytic lichens growing on oaks in southeastern Sweden
- 2009
-
In: Annales Botanici Fennici. - Helsinki : Finnish Zoological and Botanical Publishing Board. - 0003-3847 .- 1797-2442. ; 46:6, s. 496-506
-
Journal article (peer-reviewed)abstract
- Oaks (Quercus robur) can reach a considerable age, which makes them an important substrate for many epiphytic lichens, including several red-listed species. We studied the importance of tree size and other environmental factors for the occurrence of six epiphytic lichens at two sites, in southeastern Sweden, differing in quality as judged by tree size distribution and number of old trees. The effects of tree circumference, light availability, trunk inclination and site were analysed. Results showed that different lichen species responded differently to these factors, but, overall, tree size was most important for lichen occurrence. Five species showed a positive relation to tree size, but the 50% probability of occurrence was reached at different tree sizes among these species and there were also site differences. This study shows that the maintenance of old trees is crucial for several lichen species, which highlights the importance of long-term management plans.
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| 35. |
- Jonason, Dennis, et al.
(author)
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Land-use history exerts long-term effects on the clear-cut flora in boreonemoral Sweden
- 2016
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In: Applied Vegetation Science. - : WILEY-BLACKWELL. - 1402-2001 .- 1654-109X. ; 19:4, s. 634-643
-
Journal article (peer-reviewed)abstract
- QuestionsCan signs of 19th century grassland management, which can be observed in the flora immediately (2-4yrs) after clear-cutting in boreonemoral Sweden, still remain 4yrs later? Do the effects from the time since clear-cutting differ between forest and grassland plant species? LocationProvince of ostergotland, southern Sweden. MethodsTwelve contemporary clear-cut areas that were once meadows and 12 that were once forests were selected using land-use maps from the 1870s. Grasses and herbaceous plants were surveyed twice, once in 2009 and once in 2013 (2-4 and 6-8yrs after clear-cutting, respectively). Plant presence was recorded within 100 circular sample plots (radius 1m) placed evenly throughout each respective clear-cut area along transects spaced 25-m apart. The number of sample plots in which a species was present was taken as a measure of that species frequency. Random effects meta-analysis, odds ratios and ANCOVA were used to analyse species responses to clear-cutting over time. ResultsA total of 170 plant species were found in the study, of which 33 were classified as grassland indicator species and 31 as plants primarily confined to forests. Clear-cut areas with a history as meadowland had, on average, up to 64% higher total species richness and 110% more grassland indicator species than did clear-cut areas with a history as forest. The time since clear-cutting had no effect on total species richness. However, the odds of finding a grassland indicator species decreased with the time since clear-cutting, whereas the odds of finding a forest species increased. ConclusionsWe concluded that land-use history plays an important role in explaining the flora found in Swedish clear-cuts, and that its effects on species richness remain for a minimum of 8yrs after harvest (conservative estimate). This phenomenon highlights the importance of acknowledging land-use legacies in ecological research and conservation. Future studies should investigate various options for the promotion of grassland plants in clear-cuts with a history of grassland management while also acknowledging the potential conflicts between conservation and production. The results may pertain to other countries with similar land-use histories.
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| 36. |
- Jonason, Dennis, et al.
(author)
-
Monitoring of butterflies within a landscape context in south-eastern Sweden
- 2010
-
In: JOURNAL FOR NATURE CONSERVATION. - : Elsevier Science B.V., Amsterdam. - 1617-1381. ; 18:1, s. 22-33
-
Journal article (peer-reviewed)abstract
- Monitoring of butterflies is often directed only towards grassland fauna. Species associated with other habitats, as well as the impact of the surrounding landscape, are often neglected. The aim with this study was, in contrast, to perform and evaluate a landscape-based monitoring method for butterflies in diverse habitats and more specifically to (i) evaluate the impact of environmental variables on butterfly abundance; (ii) compare the distribution of butterflies in different habitats; and (iii) analyse data from the study with the aim of improving the method. Eight randomly placed study sites (750 m x 750 m) located in south-eastern Sweden were used. The vegetation composition (tree cover, percentage of coniferous and deciduous forest, shrubs, dry, mesic, damp and wet land) inside the squares was analysed using aerial photos and habitats along transects were categorised in the field. The butterfly composition varied depending on the landscape composition. Tree cover had the largest impact on butterfly abundance with a negative relationship between abundance and increasing tree cover. The most species-rich habitats were other grasslands (abandoned fields and fallows), clear-cuts, semi-natural grasslands, and bogs, each habitat also harbouring unique species. Clear-cut was the habitat harbouring the highest abundance and other grasslands the highest diversity of butterflies. Semi-natural grasslands, where the nationally based monitoring of butterflies in Sweden currently is being performed, constitutes andlt;1% of the total land area in Sweden, indicating a current bias in monitoring directed towards only a part of the species pool. The landscape-based form of monitoring presented here can, if performed regularly, increase our knowledge of how structural changes of landscape affect butterflies and thereby improve conservation efforts.
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| 37. |
- Jonason, Dennis, et al.
(author)
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Vegetation in clear-cuts depends on previous land use : a century-old grassland legacy
- 2014
-
In: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 4:22, s. 4287-4295
-
Journal article (peer-reviewed)abstract
- Plant species richness in central and northern European seminatural grasslandsis often more closely linked to past than present habitat configuration, which isindicative of an extinction debt. In this study, we investigate whether signs ofhistorical grassland management can be found in clear-cuts after at least80 years as coniferous production forest by comparing floras between clear-cutswith a history as meadow and as forest in the 1870s in Sweden. Study sites wereselected using old land-use maps and data on present-day clear-cuts. Speciestraits reflecting high capacities for dispersal and persistence were used toexplain any possible links between the plants and the historical land use. Clearcutsthat were formerly meadow had, on average, 36% higher species richnessand 35% higher richness of grassland indicator species, as well as a larger overallseed mass and lower anemochory, compared to clear-cuts with history asforest. We suggest that the plants in former meadows never disappeared afterafforestation but survived as remnant populations. Many contemporary forestsin Sweden were managed as grasslands in the 1800s. As conservation of remaininggrassland fragments will not be enough to reduce the existing extinctiondebts of the flora, these young forests offer opportunities for grassland restorationat large scales. Our study supports the concept of remnant populationsand highlights the importance of considering historical land use for understandingthe distribution of grassland plant species in fragmented landscapes, aswell as for policy-making and conservation.
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| 38. |
- Lindström, Tom, et al.
(author)
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A spectral and Bayesian approach for analysis of fluctuations and synchrony in ecological datasets
- 2012
-
In: Methods in Ecology and Evolution. - : Wiley-Blackwell. - 2041-210X. ; 3:6, s. 1019-1027
-
Journal article (peer-reviewed)abstract
- Autocorrelation within ecological time series and synchrony between them may provide insight into the main drivers of observed dynamics. We here present methods that analyse autocorrelation and synchrony in ecological datasets using a spectral approach combined with Bayesian inference. To exemplify, we implement the method on dendrochronological data of the pedunculate oak (Quercus robur). The data consist of 110 years of growth of 10 live trees and seven trees that died during a synchronized oak death in Sweden in c. 2002-2007. We find that the highest posterior density is found for a noise colour of tree growth of gamma approximate to 0.95 (i.e. pink noise) with little difference between trees, suggesting climatic variation as a driving factor. This is further supported by the presence of synchrony, which we estimate based on phase-shift analysis. We conclude that the synchrony is time-scale dependent with higher synchrony at larger time-scales. We further show that there is no difference between the growth patterns of the alive and dead tree groups. This suggests that the trees were driven by the same factors prior to the synchronized death. We argue that this method is a promising approach for linking theoretical models with empirical data.
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| 39. |
- Lättman, Håkan, et al.
(author)
-
Biodiversity in the wake of urban sprawl : loss among epiphytic lichens on large oaks
-
Other publication (other academic/artistic)abstract
- Biodiversity often suffers from urbanisation. In the present study, we focused on how the age of urbanisation affects the richness of 17 epiphytic lichens species and their cover on large oaks, with a minimum spacing of 250 m, in urban environments in the city of Linköping (100,000 inhabitants), SE Sweden. We also surveyed trees in adjacent rural areas, selected to have similar distributions of tree trunk circumference and oak density within 300 m. Lichen richness and cover were significantly lower on urban trees compared to rural trees. Furthermore, richness and cover decreased with the length of time that urban trees had been surrounded by houses. Roughly one species is lost every 30 years. Most of the species that were analysed demonstrated a drop in occurrence with respect to the duration of housing development. The reduction in the probability of occurrence varied from 60% (Calicium viride, Evernia prunastri), 80% (Chrysotrix candelaris) to 90% (Ramalina spp.) during the 160-year period of urbanisation considered. Therefore, even if valuable trees survive over the course of development, their lichen flora are likely to become depleted over time.
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| 40. |
- Lättman, Håkan, et al.
(author)
-
Biodiversity in the wake of urban sprawl : loss among epiphytic lichens on large oaks
-
Other publication (other academic/artistic)abstract
- Biodiversity often suffers from urbanisation. In the present study, we focused on how the age of urbanisation affects the richness of 17 epiphytic lichens species and their cover on large oaks, with a minimum spacing of 250 m, in urban environments in the city of Linköping (100,000 inhabitants), SE Sweden. We also surveyed trees in adjacent rural areas, selected to have similar distributions of tree trunk circumference and oak density within 300 m. Lichen richness and cover were significantly lower on urban trees compared to rural trees. Furthermore, richness and cover decreased with the length of time that urban trees had been surrounded by houses. Roughly one species is lost every 30 years. Most of the species that were analysed demonstrated a drop in occurrence with respect to the duration of housing development. The reduction in the probability of occurrence varied from 60% (Calicium viride, Evernia prunastri), 80% (Chrysotrix candelaris) to 90% (Ramalina spp.) during the 160-year period of urbanisation considered. Therefore, even if valuable trees survive over the course of development, their lichen flora are likely to become depleted over time.
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| 41. |
- Lättman, Håkan, et al.
(author)
-
Decline in lichen biodiversity on oak trunks due to urbanization
- 2014
-
In: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 32:4, s. 518-528
-
Journal article (other academic/artistic)abstract
- Biodiversity often suffers from urbanization. In the present study, we focused on how the duration of urbanization affects the richness of 17 epiphytic lichen species and their cover on large oaks in urban environments in a city of 100 000 inhabitants in southeast Sweden. We also surveyed trees in adjacent rural areas, selected to have similar distributions of tree trunk circumference and surrounding oak density (within 300 m). Lichen richness and cover were lower on urban trees compared to rural trees. Furthermore, richness and cover decreased with the length of time that urban trees had been surrounded by houses. Most of the species that were analysed demonstrated a decline in occurrence with respect to the duration of housing development. The reduction in the probability of occurrence varied from 60% (Calicium viride, Evernia prunastri), 80% (Chrysothrix candelaris) to 90% (Ramalina spp.) during the considered 160-year period of urbanization. Therefore, even if valuable trees survive over the course of development, their lichen biota is likely to become depleted over time. © 2014 The Authors.
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| 42. |
- Lögdberg, Frida, 1975-
(author)
-
Population dynamics in variable environments – impacts of noise colour and synchrony
- 2012
-
Doctoral thesis (other academic/artistic)abstract
- Environmental variation is an essential part of population dynamics, and two characteristics of such variation—variance and the temporal autocorrelation termed ‘noise colour’—are essential for determining the persistence of a population. In addition, the spatial correlation of local environmental variation between habitat patches (i.e., synchrony) is equally important in subdivided populations connected via dispersal. The research underlying this thesis explored the effects of noise colour and synchrony on population dynamics. The dynamics were studied primarily in single-species models with fast or slow population responses to environmental changes, and several-species systems (i.e., food webs) with different stability properties were also considered. Populations were spatially subdivided with local dynamics in discrete patches, and patch positions were modelled either implicitly or explicitly, with different landscape configurations in the latter case.It has previously been shown that the effect of increased environmental redness on extinction risk in nonspatial models depends on population responsiveness, seen as increased and decreased risks for fast and slow responding populations, respectively. Here, increased redness of noise decreased the extinction risk for fast-responding populations (in accordance with non-spatial studies) in a simple implicit landscape model (Papers I and II). Slow-responding populations in some cases showed a raised extinction risk for intermediate noise colour values (Paper I), which does not agree with earlier results. However, increasing the spatial complexity evened out the differences that were caused by responsiveness (Papers III and IV). Thus, in general, the explicit landscape models displayed a decrease in extinction risk with increasing environmental redness regardless of whether the populations were fast or slow in responding to environmental variation.Still, fast and slow responsiveness of populations differed in relation to the following: overall levels of extinction risk (Papers I, III, and IV), synchrony of population variations (Paper II), colour of population variations (Paper II), and response to landscape structure (Papers III and IV). For fast-responding populations, the degree of synchrony of population variations was similar to the synchrony of environmental noise (Paper II). Local populations of a model organism that responded slowly to environmental variation were more synchronized than the environmental variation itself, and the largest shift between the environment and the populations was seen for intermediate red noise colours (Paper II). This indicated that dispersal-induced population synchrony could be enhanced by reddened noise.Landscape configuration proved to be important for the general levels of extinction risk. This effect was most pronounced for fast-responding populations (Papers III and IV) and became even more distinct when distance-dependent synchrony was added between the environmental variations (Paper IV). Adding explicit landscapes led to an decrease in the differences between fast- and slow-responding populations, when considering the influence of noise colour on extinction risk. Also, landscape configuration affected the importance of degree of synchrony through its impact on distances between patches, which resulted in configurations where extinction risk depended solely on noise colour. The effects on stability exerted by populations embedded in food webs were investigated in an implicit landscape model (Paper V). Three types of food webs with different properties of inherent stability all showed a decrease in stability at increased environmental variance and increased redness of environmental variation.In conclusion, the single-species models showed that the survival conditions of populations that were near extinction were improved by all of the following: decreased synchrony, reddening of noise, and aggregation of patches. The results of the web simulations indicate that we need better understanding of how findings obtained using single-species models can be used to reveal the effects of noise colour on species communities. From a management perspective, altering landscape structure may compensate for increased extinction risks caused by changed noise colour of environmental variation, which is a predicted outcome of climate change.
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| 43. |
- Marini, Lorenzo, et al.
(author)
-
Contrasting effects of habitat area and connectivity on evenness of pollinator communities
- 2014
-
In: Ecography. - : Wiley. - 1600-0587 .- 0906-7590. ; 37:6, s. 544-551
-
Journal article (peer-reviewed)abstract
- Losses of both habitat area and connectivity have been identified as important drivers of species richness declines, but little theoretical and empirical work exists that addresses the effect of fragmentation on relative commonness of highly mobile species such as pollinating insects. With a large dataset of wild bee and butterfly abundances collected across Europe, we first tested the effect of habitat area and connectivity on evenness in pollinator communities using a large array of indexes that give different weight to dominance and rarity. Second, we tested if traits related to mobility and diet breadth could explain the observed evenness patterns. We found a clear negative effect of area and a weaker, but positive effect of connectivity on evenness. Communities in small habitat fragments were mainly composed of mobile and generalist species. The higher evenness in small fragments could thereby be generated by highly mobile species that maintain local populations with frequent inter-fragment movements. Trait analysis suggested an increasing importance of dispersal over local recruitment, as we move from large to small fragments and from less to more connected fragments. Species richness and evenness were negatively correlated indicating that the two variables responded differently to habitat area and connectivity, although the mechanisms underlying the observed patterns are difficult to isolate. Even though habitat area and connectivity often decrease simultaneously due to habitat fragmentation, an interesting practical implication of the contrasting effect of the two variables is that the resulting community composition will depend on the relative strength of these two processes.
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| 44. |
- Milberg, Per, et al.
(author)
-
A burning desire for smoke? Sampling insects favoured by forestfire in the absence of fire
- 2015
-
In: Journal of Insect Conservation. - : Springer. - 1366-638X .- 1572-9753. ; 19:1, s. 55-65
-
Journal article (peer-reviewed)abstract
- Fire-favoured insects are difficult to sampleexcept opportunistically after forest fires. Here, we tested ifsmoke from a small fire could be an efficient way to samplesuch insects. Insects were sampled over ca. 10 h hours, byhand-picking and netting on screens put up around the fire.Two specimens of the rare and redlisted Hormopeza spp.(Diptera, Empididae) were caught. Large numbers([20,000) of Microsania spp. (Diptera, Platypezidae) werecaught, but none in the absence of smoke. The numbers ofMicrosania spp. clearly peaked in late afternoon, and ashort sampling period would be sufficient if targeting onlythis taxon. Of the almost 200 species of Coleoptera, 17 %were considered as fire-favoured, contributing 9 % of thespecimens, suggesting low efficiency of the method for thisgroup. Using 23 sites differing in fire history, catches ofMicrosania spp. were unaffected by numbers and area offorest fire (preceding 5 years and within 10 km radius overthe sampling sites). In contrast, there was a weak trend forthe proportion of fire-favoured Coleoptera to increase withincreasing number of fires. To conclude, smoke as producedin our study can clearly attract fire-favoured Diptera,but smoke had only a weak effect on fire-favoured Coleopterain the study area. It is still likely that selectivelypicking specimens of species attracted to smoke is a morecost-efficient method than using, e.g., Malaise traps thatcatch indiscriminately.
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| 45. |
- Milberg, Per, et al.
(author)
-
Assemblages of flower-visiting insects in clear-cuts are rich and dynamic
- 2021
-
In: European Journal of Entomology. - : Akademie Ved Ceske Republiky Entomologicky Ustav,Czech Academy of Sciences, Institute of Entomology. - 1210-5759 .- 1802-8829. ; 118, s. 182-191
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Journal article (peer-reviewed)abstract
- Clear-cuts in production forests provide an open, sunny environment, with an abundance of nectar, as well as exposed soil and woody debris. This makes them a potential habitat for several groups of insects that typically use open habitats like grassland, including those species that visit flowers. In the current study, we used colour pan traps to catch flower-visiting species. Study sites were selected according to age (2-8 yrs since clear-cut) and land-use history (forest or meadow 150 yrs ago). We caught and identified solitary bees (395 specimens belonging to 59 species), social bees (831/16), other Hymenoptera (367/66), Syrphidae (256/31), and beetles (Lepturinae & Cetoniinae; 11,409/12). Age of the clear-cut strongly affected species composition as well as several groups and species, with most species caught mainly in the younger clear-cuts. Flower abundance statistically affected several groups and species, but inferring causation is difficult due to the flower-richness bias in pan trap catches. Bare soil and woody debris were important for the insect assemblage sampled, while bare rock was not. Although the majority of the insects caught were forest species, about one third of the species were associated with open, agricultural sites and hence seem to be able to locate and exploit resources in clear-cuts.
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| 46. |
- Milberg, Per, 1959-, et al.
(author)
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Assemblages of flower-visiting insects in clear-cuts are rich and dynamic
- 2021
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Other publicationabstract
- Clear-cuts in production forests provide an open, sunny environment, with an abundance of nectar, as well as exposed soil and woody debris. This makes them a potential habitat for several groups of insects that typically use open habitats like grassland, including those species that visit flowers. In the current study, we used colour pan traps to catch flower-visiting species. Study sites were selected according to age (2-8 yrs since clear-cut) and land-use history (forest or meadow 150 yrs ago). We caught and identified solitary bees (395 specimens belonging to 59 species), social bees (831/16), other Hymenoptera (367/66), Syrphidae (256/31), and beetles (Lepturinae & Cetoniinae; 11,409/12). Age of the clear-cut strongly affected species composition as well as several of the groups and species, with most species caught mainly in the younger clear-cuts. Flower abundance statistically affected several groups and species, but such effects are potentially suspect due to the flower-richness bias in pan trap catches. Bare soil and woody debris seemed irrelevant were important for the insect assemblage sampled, while bare rock sometimes positively affected flower-visiting insectswas not. Although the majority of the insects caught were forest species, about one third of the species were associated with open, agricultural sites and hence seem to be able to locate and exploit resources in clear-cuts.
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| 47. |
- Milberg, Per, et al.
(author)
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Assemblages of saproxylic beetles on large downed trunks of oak
- 2016
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In: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 6:6, s. 1614-1625
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Journal article (peer-reviewed)abstract
- Old living oaks (Quercus robur) are known as a very species-rich habitat for saproxylic beetles, but it is less clear to what extent such veteran trees differ from an even rarer feature: downed trunks of large oaks. In this study, we set out to sample this habitat, using window traps, with two aims: (1) to describe the variation of assemblages among downed trunks of different type and (2) to compare beetles on downed oaks with data from veteran standing trees. The results showed that trunk volume and sun exposure better explained assemblages as well as species numbers on downed trunks than did decay stage. Furthermore, species classified as facultative saproxylic species showed weak or no differentiation among downed trunks. Species with different feeding habits showed no apparent differentiation among downed trunks. Furthermore, species composition on dead, downed oak trunks differed sharply from that of living, veteran oaks. Wood or bark feeders were more common on veterans than downed trunks, but there was no difference for those species feeding on fungi or those feeding on insects and their remains. In conclusion, for a successful conservation of the saproxylic beetle fauna it is important to keep downed oak trunks, and particularly large ones, in forest and pastures as they constitute a saproxylic habitat that differs from that of living trees.
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| 48. |
- Milberg, Per, et al.
(author)
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Evidence-based conservation - a brief introduction [Evidensbaserad naturvård - Nytt begrepp och ny färdriktning?]
- 2010
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In: Svensk Botanisk Tidskrift. - : Btj Tryck Ab, Lund. - 0039-646X. ; 104:1, s. 18-22
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Journal article (peer-reviewed)abstract
- This article briefly describes the success of the knowledge-transfer reform within medicine known as evidence-based medicine. In this field, the idea is that any decision about an intervention, or lack thereof, should be based on the best available knowledge. The current move towards a similar reform within nature conservation is reviewed, and its differences with medicine discussed. If "evidencebased conservation" is broadly accepted among researchers, practitioners and NGOs, it might lead to a more consistent protocol for reporting case studies trying interventions and, in the long run, a more efficient use of limited resources for conservation.
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| 49. |
- Milberg, Per, et al.
(author)
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Flower abundance and vegetation height as predictors fornectar-feeding insect occurrence in Swedish semi-natural grasslands
- 2016
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In: Agriculture, Ecosystems & Environment. - : Elsevier. - 0167-8809 .- 1873-2305. ; 230, s. 47-54
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Journal article (peer-reviewed)abstract
- With steadily shrinking areas of species-rich semi-natural grasslands in Europe, the management of theremaining fragments becomes ever more crucial for the preservation of key elements of biodiversity inthe agricultural landscape. Detailed knowledge about species-wise, as well as group-wise, relationshipscan provide guidelines for conservation management and a basis for predictions about differentmanagement scenarios. In the present study, we related the occurrence of species of bumblebees (N = 12),butterflies (31) and day-flying moths (4) and their total richness in 424 sites in southern Sweden to threegrass sward attributes, (i)flower abundance, (ii) height of the grass sward and (iii) within-site variation inheight of vegetation. The abundance of nectar-bearingflowers proved overall the best predictor ofrichness and in most of the occurrence-based species-wise models. However, both high grass swardheight and high variation in grass sward height contributed significantly to species richness andoccurrence of individual species. There was a tendency for bumblebees to respond less positively toflower abundance and vegetation height than butterflies and moths. One expectation was that grasslandspecialists, red-listed species, or species decreasing in other part of Europe, would be more responsive totall vegetation orflower abundance but there was no support for this in the data. Hence, managementstrategies that promote common species will also benefit all, or most of, the rare ones as well.
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| 50. |
- Milberg, Per, et al.
(author)
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Is spring burning a viable management tool for species-rich grasslands?
- 2014
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In: Applied Vegetation Science. - : Wiley-Blackwell. - 1402-2001 .- 1654-109X. ; 17:3, s. 429-441
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Journal article (peer-reviewed)abstract
- QuestionThe management of species-rich semi-natural grasslands, a fragmented and threatened vegetation type in Europe, involves costs. Mowing is expensive and grazing can be difficult to achieve and maintain for logistical reasons. Is annual spring burning, which is potentially cheaper than mowing and grazing, a viable management tool for species-rich grasslands?LocationLong-term field trials in 11 grasslands in southern Sweden.MethodsWe calculated the odds for a species being an indicator of good management, an indicator of poor management, or an indicator of nitrogen influence in spring-burned plots, grazed plots and annually mowed plots. Odds ratios contrasting spring-burned plots with grazed plots and spring-burned plots with mowed plots were subjected to meta-analyses in which we compared the odds ratios after 1, 8 and 14 spring burns. For a single trial, we also analysed data after 1, 8, 14, 28 and 39 spring burns.ResultsCompared with mowed and grazed plots, the odds of the four different indicators of good management decreased in spring-burned plots, while the odds for the two indicators of poor management increased. There was no trend in the two indicators of excess nitrogen. Therefore, the conservation value of vegetation in spring-burned plots becomes reduced over time relative to traditional management.ConclusionsSpring burning is not an appropriate long-term management method if the aim is to maintain the conservation value of the vegetation in traditionally managed semi-natural grasslands.
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