Several studies carried out in boreal forests have found significant edge effects in Scots pine although, none of them in southern Sweden. The aim of this study was to investigate edge effects in adjacent Scots pine stands and its influence on tree growth and field vegetation composition. This was carried out in 10 selected forest edges in southeastern Sweden. Results showed reduced number of stems, height, diameter and basal area growth among young trees in particular within 2 m from the forest edge. In the older stands number of stems, diameter and basal area growth increased within the first 2 m from the edge. Field vegetation inventory showed differences in composition in the adjacent stands. In the older stands lichens, lingonberry and blueberry were more frequent, while heather and grasses showed a higher appearance in young stands.

Summary  In the 1990s a new way of thinking about forestry started. One of the effects of the changing silvicultural practices was that the size of clearcuts became smaller. As the felling areas were reduced in size, the areas where young and older forest meet grew, with this also the occurrence of edge zones increased. An edge can be defined as an interface between different ecosystems, and a forest edge as an interface between forested and non-forested ecosystems, or between two forests of contrasting composition or structure. This edge results in a transition zone in which the adjacent contrasting ecosystems interact - the edge zone. In the edge zone - both abiotic and biotic - processes result in a detectable difference in composition, structure or function of the vegetation near the edge, as compared with the ecosystem on either side of the edge.  This study aimed to increase understanding of occurrence and types of edge zones and their composition on a property, their effect on tree growth, the species diversity of tree and field vegetation. The study was performed on a property of approximately 60 hectares located in southeastern Blekinge. The sampling procedure was based on four transects ranging from 527 to 860 meters in length, which were laid out in south-north direction over the property. Wherever the transect crossed a forest edge, a corridor perpendicular to the edge was laid out. In each corridor a measuring grid dividing the corridor in 10 distance classes of one meter, measured from the forest edge, was laid out. In each distance class tree species were determined, stems counted, and the following variables were measured per tree: height, distance from edge and the diameter at breast height. Data gathering on forest field vegetation was conducted in 1x1 meter plots laid out in the middle of the corridor. Within each sample area, the occurrence of species was noted according to field vegetation type index. For comparing the edge zones to the rest of the estate, reference plots were laid out along the transects between the forest edges. On the property of 60 hectares an estimated 4,2 hectares were influenced by edge effects. All edges were created by anthropogenic processes, there were forest edges with roads and edges created by forestry. Where thinning stands were bordering roads, growth was found to decrease closer to the road. In pre-commercial thinning stands bordering a road the opposite effect was visible. Where old and young productive forest stands bordered, on the young side there was an increase of both tree height as well as diameter further away from the edge. On the old side no edge effect on tree growth was seen. Herbaceous plants, mosses and lichens were more abundant close to the edge in both old and young stands. Borders with roads had the highest diversity of tree and plant species. The field vegetation was found to be more diverse and abundant closer to the edge. The edge zone showed to be of great importance for natural regeneration. In about half the corridors positive, negative or neutral edge effects were found on one or more of the variables: tree height, diameter, basal area, stems per hectare, plants per hectare. These effects were found up to eight meters into the stand. The inventory of tree species and field vegetation showed that different kinds of edge zones give rise to different species compositions. A higher diversity of tree species was found in the edge zone compared to the reference plots. One could use the edge zone for nature conservation purposes as these areas favor biological diversity and constitute interesting environments for species that would otherwise be at risk of being outcompeted in neighboring, more closed spruce forest stands. Keywords: tree growth, diversity, field vegetation, edge zones, edge effect

Det svenska skogsbruket har med fokus på beståndsvis avverkning och återbeskogning genererat ett mosaikartat landskap med en mängd väl avgränsande kantzoner mellan yngre och äldre bestånd, och att uppkomna förändringar hos växtmiljön i anslutning till dessa beståndsgränser kan påverka såväl tillväxt som artsammansättning har konstaterats i ett flertal tidigare studier. Men även om dessa studier påvisat förekomsten av kanteffekter har resultaten varierat utifrån geografiskt undersökningsområde och studerade trädslag. Tidigare studier har utifrån ett nordiskt perspektiv dessutom främst fokuserat på tillväxtförändringar hos tall i Finland och norra Sverige, vilket föranlett att denna studie valt att undersöka förekomst och omfattning av tillväxteffekter inom kantzoner belägna mellan angränsande äldre och yngre granbestånd i västra Götaland. Studien har genomförts genom att inom ett antal representativa objekt samla in data utifrån utlagda provyor i terrängen och undersökningen har avgränsats till att omfatta trädens höjd- och diametertillväxt samt markvegetationens artsammansättning. Vidare jämförelser har därefter gjorts utifrån avstånd från aktuell beståndsgräns, kantzonernas väderstreck i nordlig respektive sydlig riktning samt de yngre beståndens skötselhistorik i form av röjt eller oröjt. För att undersöka förekomsten av signifikanta skillnader mellan grupperna har insamlad data analyserats med hjälp av variansanalys (ANOVA) samt Tukey’s test för skillnader mellan medelvärden. Resultatet visade på signifikanta kanteffekter hos yngre granbestånd där tillväxtnedsättningarna var som tydligast närmast beståndsgränsen, oavsett väderstreck och tidigare skötselhistorik. Dessa tillväxtnedsättningar var dock mindre än de som tidigare konstaterats hos tall, och till skillnad från tidigare studier kunde inga tillväxteffekter konstateras hos angränsande äldre bestånd. Inga tydliga skillnader kunde heller konstateras utifrån kantzonernas väderstreck eller de yngre beståndens skötselhistorik. Markvegetationens artsammansättning uppvisade i sin tur en ökad förekomst av lavar och bärris intill beståndsgränserna. Bärris, lavar och ljung förekommer frekvent inom sydligt exponerade kantzoner medan smal- och bredbladigt gräs i sin tur uppvisade en ökad förekomst inom nordligt exponerade kantzoner. Utifrån dessa resultat skulle en tänkbar rekommendation inför kommande skogsbruksåtgärder och återbeskogning kunna vara att utifrån konstaterade tillväxtnedsättningar ej prioritera plantering av gran inom ett avstånd av 0-2,5 m från beståndsgräns angränsande mot äldre granbestånd. Därmed skulle kantzonen kunna nyttjas för naturvårdande ändamål då dessa områden gynnar den biologiska mångfalden och utgör intressanta miljöer för arter som annars skulle riskera att bli utkonkurrerade i angränsande mer slutna granskogsbestånd. / The aim of this study was to evaluate edge effects along forest edges between young and old Norway spruce stands in south-western Sweden, and examine its influence on tree growth and field vegetation. Comparison between distance from stand edge, exposure (north or south facing) and young forest clearing (cleared or not cleared) showed a reduced growth among young trees near the stand edge, mainly at a distance of 0-2,5 m. This edge effect occurred regardless of exposure or forest clearing history. On the other hand, in contrary to earlier studies, no positive growth effect was found in older stands adjacent to younger stands. Regarding edge effects found on field vegetation, blueberries, lingonberries and lichens showed an increased incidence adjacent to stand edges. Berries, lichens and heather showed an increased incidence at south facing edges while grass showed an increased incidence at north facing edges.