Palaeolimnological and sedimentary responses to Holocene forest retreat in the Scandes Mountains, west-central Sweden

• Main Author: Göran Possnert
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: Tundra
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.548.2669; http://www.science.uwaterloo.ca/~twdedwar/reprints-pdf/2004-holocene-hammarlund-et-al.pdf

Abstract: A suite of analyses was performed on sediments accumulated during the last 10 700 years in Lake Spåime, a small, hydrologically open water body in the modern alpine tundra zone of the Scandes Moun-tains, west-central Sweden. The study aimed to evaluate (1) the nature of climate changes that forced the late-Holocene lowering of altitudinal tree limit in the region, the timing of which is known from prior stu-dies based on radiocarbon dating of subfossil wood, and (2) the impact of these vegetational changes on an aquatic ecosystem. Arboreal pollen and plant macrofossil data confirm the persistence of trees in the lake catchment at least from c. 9700 cal. BP until c. 3700 cal. BP. Although growing-season temperature is com-monly believed to be the dominant factor driving boreal forest tree-limit variations in the region, a chir-onomid-based reconstruction of mean July air temperature suggests that local deforestation during the late Holocene was not accompanied by a significant cooling. The tree-limit retreat was more likely caused by increasing effective moisture and declining length of the growing season. The ecohydrological response of Lake Spåime to this combination of climate and vegetational changes included a decline in primary pro-ductivity, as indicated by an abrupt decrease in sediment organic matter content, while associated