| 1. |
- Askling, John, et al.
(författare)
-
Ryggradslösa djur och planering av infrastruktur - dagfjärilar som landskapsekologiska verktyg och modellorganismer.
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)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.
|
|
| 2. |
|
|
| 3. |
- Bergman, Karl-Olof, 1965-, et al.
(författare)
-
Distribution of occupied and vacant sites and migration of Lopinga achine (Nymphalidae : Satyrinae) in a fragmented landscape
- 2001
-
Ingår i: Biological Conservation. - 0006-3207 .- 1873-2917. ; 102:2, s. 183-190
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 4. |
- Bergman, Karl-Olof, 1965-
(författare)
-
Ecology and conservation of the butterfly Lopinga achine
- 2000
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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.
|
|
| 5. |
|
|
| 6. |
- Bergman, Karl-Olof, 1965-
(författare)
-
Host plant choice, habitat selection, dispersal ability and population structure of a threatened butterfly, Lopinga achine
- 1998
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)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.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Bergman, Karl-Olof, 1965-, et al.
(författare)
-
Population structure and movements of a threatened butterfly (Lopinga achine) in a fragmented landscape in Sweden
- 2002
-
Ingår i: Biological Conservation. - 0006-3207 .- 1873-2917. ; 108:3, s. 361-369
-
Tidskriftsartikel (refereegranskat)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.
|
|
