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- Skovsgaard, Jens Peter
(författare)
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Røn på Bornholm: en genetisk smeltedigel for tarmvridrøn, klipperøn, seljerøn, finsk røn og almindelig røn.
- 2013
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Ingår i: Skoven. - 0106-8539. ; 45, s. 296-299
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Bornholm is a Danish island located in the Baltic Sea between Sweden and Poland. The island covers an area of 588 km2. The soils are derived mainly from Holocene glacial till overlying Pre-cambric gneiss or granite and, at some places, Cambro-Silurian sandstone or shale. There are frequent outcrops of bedrock. There are five Sorbus species on Bornholm (Figure 2): wild service tree (Sorbus torminalis ( L.) Crantz), rock whitebeam (Sorbus rupicola (Syme) Hedl.), Swedish whitebeam (Sorbus intermedia (Ehrh.) Pers.), Swedish service tree (Sorbus hybrida L.), and rowan (Sorbus aucuparia L.) The botanical, genetic and ecological characteristics of each Sorbus species are briefly outlined. It is argued that wild service tree, Swedish whitebeam and rowan could play a larger role in silviculture. Rock whitebeam (due to its bushy growth) and Swedish service tree (due to its infrequent occurrence) are considered of little or no interest for silviculture. Wild service tree: A large share of Denmark's natural populations of wild service tree is found on Bornholm, primarily on inaccessible coastal cliffs, but also in the forest. On coastal cliffs wild service tree often only grows to the size of a bush or a small tree (Figure 1), while in the forest it can grow to timber dimensions (Figure 3). Although there are only few individuals in each population, they collectively represent an important genetic resource. It is suggested to establish a seed orchard based on locally collected scions and to install experiments comparing controlled-pollination offspring to offspring from, for example, the large autochthonous population in Ulvshale Forest on the Danish island of Møn or the superior German populations at Sailershausen. Swedish whitebeam: Swedish whitebeam is found almost exclusively in the open landscape, where it is frequently planted in hedgerows and as a solitary tree. It thrives particularly well on calcareous sites, but clearly has a much wider site potential (as witnessed by its growth when planted on other site types in northern Europe). Swedish whitebeam is healthy and wind firm, tolerates salt-spray deposition and is capable of producing a sizeable stem of timber quality (Figure 4). Due to the species' asexual reproduction through agamospermy or apomixis, offspring will inherit essential mother tree characteristics such as growth potential, stem form and health status. It is suggested that Swedish whitebeam should be tested for forestry use. Rowan: Rowan is one of the commonest tree species in many parts of Europe, including Bornholm. It is not dealt with specifically in this article, but it is suggested that the species should be considered given a more prominent role in forestry. Finally, it is pointed out that Bornholm deserves more attention in Sorbus research. The island's role as a genetic melting pot for Sorbus at species and genus level has not yet been explored. Due to its geographic isolation from other Sorbus populations Bornholm could be an interesting case-study, not only for research, but also for the development and testing of suitable management practices for conservation as well as for economic forestry.
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| 2. |
- Skovsgaard, Jens Peter
(författare)
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Røn på Bornholm: en botanisk og forvaltningsmæssig udfordring
- 2013
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Ingår i: Dansk dendrologisk årsskrift. - 0416-6906. ; 30, s. 6-25
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Der er fem naturligt forekommende rønnearter på Bornholm: almindelig røn, finsk røn, seljerøn, klipperøn og tarmvridrøn. Formålet med denne artikel er at gøre opmærksom på røns potentiale som skovtræ og på de udfordringer, der er med at forvalte den bornholmske genressource i røn. Der er røn overalt på Bornholm, på vanskeligt tilgængelige klipper langs kysten, ude i det åbne land og inde i skoven. Almindelig røn forekommer i næsten alle habitattyper på øen. Finsk røn, som er den sjældneste art, findes mest i klippeområder og kratskov. Seljerøn ses næsten udelukkende i det åbne land, hvor den ofte er plantet. Klipperøn er en udkantsart, som kun findes på skrænter og i klippeterræn. Tarmvridrøn forekommer både på eksponerede klipper, i krat og inde i skoven. Bortset fra almindelig røn er der ofte kun få individer i hver population, og populationerne er ofte adskilte uden umiddelbar biologisk forbindelse. Der tale om en vigtig genressource, både nationalt og internationalt. Røn på Bornholm kræver derfor særlig opmærksomhed i skovdriften og ved anden naturforvaltning. Tarmvridrøn og seljerøn har umiddelbart potentiale til skovdyrkning. Det skyldes især deres vækstpotentiale og muligheden for at opnå en for røn forholdsvis høj alder. Også almindelig røn, finsk røn og måske klipperøn kan under de rette omstændigheder være egnede til skovdyrkning.
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| 3. |
- Skovsgaard, Jens Peter
(författare)
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Afløvning af kirsebær
- 2013
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Ingår i: Skoven. - 0106-8539. ; 45, s. 430-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Many wild cherry trees in Denmark lost their foliage during the summer of 2013. Some appeared to be infected by cherry leaf spot (Blumeriella jaapii (Rehm) Arx), others by shothole blight (Stigmina carpophila ((Lév.) M.B. Ellis). Both fungi are generally harmless for cherry in the forest. Infected trees subsequently recover and should not be felled.
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| 4. |
- Skovsgaard, Jens Peter
(författare)
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Store tarmvridrøn. Verdens tykkeste tarmvridrøn står i Danmark
- 2013
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Ingår i: Skoven. - 0106-8539. ; 45, s. 451-455
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- The thickest wild service tree in the world The world's thickest wild service tree is located in Moesgaard Park south of Aarhus, Denmark (Figure 1). In 2013 the stem diameter at breast height (dbh) was 148 cm (circumference = 464 cm) and total tree height was 24 m. The stem forks at a height of 2 m above ground, but this does not influence the stem diameter at 1.30 m. The crown diameter was between 21.6 and 26.4 m. The health condition of the tree was excellent, but with some top dieback. The origin and age of the tree remain unknown, but based on archival studies and growth estimates derived from past measurements of stem diameter (Table 1) we believe it was planted sometime between 1783 and 1808, resulting in an estimated age of between 205 and 230 years. In 2009 we collected fruits, extracted seeds (1.53 seeds per fruit, average weight = 0.03775 g per seed) and had them sown. Germination was successful, but the seedlings appeared to originate from hybridization (based on poor growth and odd foliage) and most of them eventually died. The second thickest wild service tree in Denmark The second thickest wild service tree in Denmark is located in the Arboretum at Charlottenlund north of Copenhagen (Figure 2). The tree originates from the Mediterranean region and was planted in 1851. In 2013, at an age of 162-165 years, dbh was 82 cm, height was almost 22 m and the tree was still in good health. The stem has had an average growth rate of 1.56-1.59 cm per year on circumference, or 0.5 cm per year on dbh. Large wild service trees in the forest The largest wild service trees in the forests of Denmark can be found in Døndalen Forest on the island of Bornholm (Skoven 2013/6-7) and in Ulvshale Forest on the island of Møn (Skoven 2013/1). Both locations host trees with a dbh up to 36 cm and a height up to 17.5 m (one tree has been measured at over 20 m). Elsewhere in Europe wild service tree in forest settings may reach stem diameters of more than 70 cm (Figure 3). Based on past measurements the growth rate of the largest wild service trees in the unmanaged Ulvshale Forest was estimated at 1.8-4.4 mm per year during 2002-12. Large wild service trees in other countries A wild service tree on Parsonage Farm 15 km northeast of Hastings in Great Britain and one at Thenneberg 45 km southwest of Vienna in Austria had stem diameters similar to that of the large tree at Moesgaard in Denmark, but both collapsed some years ago. A wild service tree in a field near Mayerling 35 km southwest of Vienna is now believed to be the second thickest in the world, with a dbh of approximately 15 cm less than that of the Moesgaard tree. Below this are a number of trees with stem diameters of 100-120 cm, many of which are located in Austria (Figure 4). Conclusion The large wild service tree in Moesgaard Park has been known for decades as one of the thickest in the world and now is clearly the outright champion. The tree at Charlottenlund is probably the second thickest in Denmark. The ages of the trees as well as their growth performance and good health indicate the potential of wild service tree in Denmark and that the species is suited for use in silviculture. The growth rates indicate that a target dbh of 50 cm is suitable for silviculture in Denmark.
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| 5. |
- de Fine Licht, Henrik Hjarvard
(författare)
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Aggression og slaegtsskab hos myrer
- 2011
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Ingår i: Kaskelot. - 0106-0023. ; :187, s. 18-19
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 8. |
- Eriksen, Bente, 1960
(författare)
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Clementin eller mandarin?
- 2010
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Ingår i: Kaskelot. - 0106-0023. ; 184, s. 30-35
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Supermarkedets hylder bugner af citrusfrugter. De findes i farver fra grønne til gule og orange og i størrelser fra fugleæg til håndbolde. Hvis du er forvirret over alle sorter og navne, er det ikke så mærkeligt. Men i virkeligheden har vi kun at gøre med få vilde arter. Resten af vores citrusfrugter er med enkelte undtagelser opstået dom krydsninger mellem dem.
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| 9. |
- Bruun, Hans Henrik
(författare)
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Om flydeevnen hos frugter af Ræve-Star (Carex vulpina) og skovengenes forsvinden i Danmark
- 2009
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Ingår i: Flora og Fauna. - 0015-3818. ; 114:3-4, s. 73-76
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- The buoyancy of fruits (nutlets in utricles) of the marsh-inhabiting True Fox Sedge (Carex vulpina) was tested experimentally in stagnant water. Only 16 % of the seeds had sunk when the experiment was terminated after 284 days. Seeds did not germinate while floating, but remained fully viable (average 76 % germination for both floating and sunken seeds). For comparison, fruits of the grassland species Small-fruited Prickly-sedge (Carex muricata ssp. pairae) were treated similarly. Most of those seeds had sunk after three days, with only 4 % still floating after 115 days. The results suggest that regional dynamics of Carex vulpina may be dependent on regular flooding of its habitats; and that the strong restrictions on natural meadow hydrology – by forestry and agriculture – is one reason for the rarity of the species.
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| 10. |
- Bygebjerg, Rune, et al.
(författare)
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En population af snudebillen Brachyderes lusitanicus (Fabricius, 1781) fundet i Danmark. (Coleoptera: Curculionidae)
- 2006
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Ingår i: Entomologiske Meddelelser. - 0013-8851. ; 74, s. 147-150
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Tidskriftsartikel (refereegranskat)abstract
- The weevil Brachyderes lusitanicus (F.) is recorded for the first time from Denmark. In 2006 a population was found at Flyvesandet, Agernæs on the north coast of Fyn. The first Danish specimen was a found on the same locality in september 2000, but this has only recently been indetified correct. The second specimen was found in november 2005. Inspired by this finding the site has been visited by several entomologists in 2006, and the species seems to be vel established. Imagines of B. lusitanicus have been observed in copula both in spring and autumn.
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