Recent spruce (Picea abies) treeline ecotonal progression since the late1980s in the Swedish Scandes-a repeat photographic narration and analysis

Leif Kullman *

Department of Ecology and Environmental Science, Umeå University, SE 901 87, Umeå, Sweden.
 
Research Article
International Journal of Science and Research Archive, 2021, 04(01), 067–085.
Article DOI: 10.30574/ijsra.2021.4.1.0189
 
Publication history: 
Received on 23 October 2021; revised on 25 November 2021; accepted on 27 November 2021
 
Abstract: 
This study reports a case of climate-mediated transformation and physiognomic progression of the Norway spruce (Picea abies) treeline ecotone since the mid-1990s in the Swedish Scandes. The methods include repeat photography and foliation estimates of old-established clonal spruces. An air and soil temperature nadir by the 1980s had caused extensive needle and shoot mortality, evident at the landscape-scale. Subsequent winter and summer temperature rises induced a striking canopy recovery, including densification and vertical growth. Release from low soil temperature stress appears as instrumental for canopy progression and shift from stunted growth to erect tree forms. Seed-based regeneration of new individuals has been virtually nil and the ecotone appears to be spatially stable. Ongoing ecotonal shifts has the character of growth form transformations in accordance with climatic conjunctures.
 
Keywords: 
Treeline ecotone; Picea abies; Phenotypic dynamics; Climate change; Swedish Scandes
 
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