Holocene tree-line dynamics and inferred climatic changes in the Abisko area, northern Sweden, based on macrofossil and pollen records

被引:120
作者
Barnekow, L [1 ]
机构
[1] Lund Univ, Dept Quaternary Geol, S-22363 Lund, Sweden
关键词
climatic changes; tree-line variations; forest history; terrestrial macrofossils; pollen; Holocene; Sweden;
D O I
10.1191/095968399676322637
中图分类号
P9 [自然地理学];
学科分类号
0705 ; 070501 ;
摘要
Lake-sediment records of pollen and macroscopic plant remains of terrestrial origin provide evidence of long-term changes in forest composition close to the altitudinal tree-line in the Abisko area, northernmost Sweden. A dominance of mountain birch (Betula pubescens Ehrh. ssp. tortuosa (Ledeb.) Nyman) with a field-layer of ferns, grasses and sedges suggests that an oceanic climate with relatively high precipitation existed during the early Holocene. Macrofossils of mountain birch were found 300-400 m above the present tree-line which corresponds to a 1.5-2 degrees C higher summer temperature than at present. Scots Pine (Pinus sylvestris) was present to some extent at altitudes above its present limit during the early Holocene. A pronounced expansion of pine took place above its present limit around 6300 cal. BP (5500 BP). This is interpreted as a result of successively drier and more continental climatic conditions. A decreased abundance of pine from c. 5200 cal. BP (4700 BP), followed by a gradual retraction of the upper limit of pine during the later part of the Holocene, can be attributed mainly to long-term changes in solar radiation. A decline in the upper limit of pine of c. 175 m since 4500 cal. BP (4000 BP) is believed to represent a decrease in growing-season temperature of c. 1.5 degrees C.
引用
收藏
页码:253 / 265
页数:13
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