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Importance of soil calcium for composition of understory vegetation in boreal forests of Finnish Lapland

Author:
Närhi, Paavo, Middleton, Maarit, Gustavsson, Nils, Hyvönen, Eija, Sutinen, Marja-Liisa, Sutinen, Raimo
Source:
Biogeochemistry 2011 v.102 no.1-3 pp. 239-249
ISSN:
0168-2563
Subject:
Geranium, Rubus, aluminum, biogeochemistry, boreal forests, botanical composition, calcium, carbon nitrogen ratio, edaphic factors, electrical conductivity, magnesium, mineral soils, pH, risk, sulfur, understory, water content, zinc, Finland, Lapland
Abstract:
To focus conservation efforts into forest areas with high biodiversity, more information is needed about soil-vegetation dependencies in Finnish Lapland. We studied understory vegetation and soil variables along a transect across a felsic-mafic lithological sequence in central Finnish Lapland. At 119 northern boreal forest sites, coverages of understory vegetation, several mineral soil chemical elements, soil electrical conductivity, pH, and dielectric permittivity, as a measure of soil volumetric water content, were measured. We found that soil Ca concentration and Ca:Al ratio were the main variables determining vegetation composition and diversity. Ca-rich soils were characterised by high electrical conductivity, pH, and Mg concentration, and by low concentration of Al, S, Zn, and low C:N ratio. Soil Ca concentration is a diagnostic measure of plant diversity as concentration higher than 100 mg kg⁻¹ resulted in a considerable increase in plant diversity. Sites with Ca concentration this high were rare, and probably important in maintaining high biodiversity. The median soil Ca:Al ratio was only 0.02, suggesting, according to general theory, a considerable risk for aluminium stress. We found Geranium sylvaticum and Rubus saxatilis to be good indicators for Ca-rich regimes and high plant diversity.
Agid:
2313055