Hieracium (Asteraceae) of sub-alpine Dalarna, Sweden, revisited: decline in species richness attributable to both forestry and overgrowth

• Published in: Nordic Journal of Botany
• Main Authors: Tyler, Torbjörn, Bertilsson, Per-Anders
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2009
• Subjects: Botany; taiga
• Online Access: https://lup.lub.lu.se/record/1489446; https://doi.org/10.1111/j.1756-1051.2009.00392.x

The Hieracium flora of westernmost Dalarna, comprising the southern fringe of the Scandes alps (central Scandinavia), is extremely rich in species. The area is dominated by species-poor coniferous sub-alpine and taiga forest, but within this matrix there are small and isolated sites with high species richness of both Hieracium and other plants. Both steep mountain slopes with outcrops of base-rich bedrock and moving ground water, and old seasonal or permanant human settlements constitute such biodiversity hotspots. However, today the former are threatened by modern forestry practices and/or exploitation for winter tourism and the latter are commonly abandoned and subjected to severe overgrowth or dramatically changed land-use. The area was thorougly surveyed in 1897-1921. In 2007, the same region and partly the same sites, were revisited. In 1897-1921, 15 Hieracium species were on average recorded from each site, but when the same sites were revisited in 2007 significantly fewer, only about 6 (40%) species per site, were refound. As far as the total species pool of the study area is concerned, it consisted of 168 species in 1897-1921, whereof only 117 (67%) were found in 2007. This remarkable reduction in species richness at both the local and the regional scale is attributable to both modern forestry practices and to the cessation of traditional agricultural practices like hay-making on semi-natural grasslands and extensive cattle-grazing in the forests. It is concluded that to reduce the on-going severe loss of biodiversity in the sub-alpine and taiga regions, conservation efforts in these areas ought to be enhanced and concentrated not only on saving what still remains of old-growth forest but also on managing remnants of grasslands and formerly grazed or mowed open forests around former settlements.