Holocene vegetational and limnological changes in the Fennoscandian tree-line area as documented by pollen and diatom records from Lake Tsuolbmajavri, Finland
H. Seppa et J. Weckstrom, Holocene vegetational and limnological changes in the Fennoscandian tree-line area as documented by pollen and diatom records from Lake Tsuolbmajavri, Finland, ECOSCIENCE, 6(4), 1999, pp. 621-635
A 291 cm sediment core was taken from Lake Tsuolbmajavri in the Finnish tre
e-line area. The core was dated by means of 14 AMS C-14-dates. Pollen data
indicate that during the early-Holocene the catchment was characterized by
birch forest. Gradual expansion of pine started at 9200 cal BP. Pine reache
d its maximum occurrence at 7200-6000 cal BP and pine tree-line retreated f
rom the area at 4600 cal BP. During the late Holocene, the cooler and moist
er climate led to increasing peatland development in the catchment. The inf
luence of vegetation dynamics on the limnology of the lake was investigated
by means of diatom-stratigraphical data. The increasing total organic carb
on (TOC) concentration, water color, and decreasing pH from 8500 cal BP to
6000 cal BP reflect the gradual development of forest and more humic soil.
The disappearance of pine caused a slight rise in pH and a decrease of TOC
and water color values. At 3000 cal BP, TOC concentrations and water color
started to increase again. This change is synchronous with the rise of Spha
gnum spore influx values and may reflect the impact of peatland expansion o
n lake water quality. The results suggest that the catchment vegetation pat
terns, mainly tree-line dynamics and peatland distribution, have influenced
the limnological features of Lake Tsuolbmajavri.