Holocene climatic change and tree-line response in Leirdalen, central Jotunheimen, south central Norway

The provisional results of pollen analysis of a small mire (Leirdalen 5) provide evidence for long-term changes in forest composition and extent at and around the present day altitudinal tree-line in Leirdalen valley, south central Norway. Following deglaciation c. 10,115cal.yrbp, dense pine forest migrated into the area c. 9785cal.yrbp, replacing vegetation dominated formerly by birch. The pollen evidence suggests that Pinus sylvestris then expanded significantly in response to a warmer climate with summer temperatures ca. 1.5-2.0oC higher than present. This climatic optimum was probably interrupted by climatic deterioration c. 8380cal.yrbp (the Finse event), that caused woodland around Leirdalen 5 to retreat to lower altitudes. A sudden shift from dense pine forest to birch woodland with Pinus sylvestris and Alnus in conjunction with the development of a sub-alpine Betula belt is postulated to have occurred c. 6870cal.yrbp Since c. 4850cal.yrbp a general decrease in woodland extent due to further climatic deterioration and increased human impact is evident.

tree-line, sub-alpine birch belt, climatic optimum, norway, finse event

10.1016/S0034-6667(01)00081-1

0034-6667

119-137

Barnett, Catherine

9b12df98-005b-4aa5-a9d9-3aa0b2c7b398

Dumayne-Peaty, Lisa

8cf0713e-65f7-4291-b2e5-7c50e0d995e7

Matthews, John A.

46fc2234-b5aa-45bc-aaa2-016d2369628e

October 2001

Barnett, Catherine

9b12df98-005b-4aa5-a9d9-3aa0b2c7b398

Dumayne-Peaty, Lisa

8cf0713e-65f7-4291-b2e5-7c50e0d995e7

Matthews, John A.

46fc2234-b5aa-45bc-aaa2-016d2369628e

Barnett, Catherine, Dumayne-Peaty, Lisa and Matthews, John A. (2001) Holocene climatic change and tree-line response in Leirdalen, central Jotunheimen, south central Norway. Review of Palaeobotany and Palynology, 117 (1), 119-137. (doi:10.1016/S0034-6667(01)00081-1).

Record type: Article

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Published date: October 2001

Additional Information: Based on original PhD data illustrating significant shifts in Holocene tree-line altitude, the paper provides the first palynological evidence for the 8,200 cal. year BP event in the area. Valuable advances are also made regarding the sub-alpine birch belt debate, of benefit to the Scandinavian palaeoecological community.

Keywords: tree-line, sub-alpine birch belt, climatic optimum, norway, finse event