Effects of bedrock type and soil chemistry on the fine roots of European beech – A study on the belowground plasticity of trees.

• Fine root biomass totals are much larger in deep soils compared to shallow soils. • We did not observe a clear relation between fine root biomass and soil base richness. • Root morphology was only slightly effected by soil chemistry. • On-site root morphological differences are bigger than among-site variation. We studied the fine root system of Fagus sylvatica in six mature stands on different bedrock down to the rock surface (or to 2 m) to investigate whether (1) the stand total of fine root biomass (FRB) increases, while the fine root live:dead ratio decreases, with decreasing soil base richness, (2) specific root area (SRA) and root tip frequency increase with a decrease in base richness, and (3) FRB is related to profile depth. The three beech stands on deep soil (>2 m profile depth) had on average by 38% larger FRB totals than the stands on shallow soil (60–80 cm), suggesting that limited root space is an important determinant of fine root system size in F. sylvatica. Despite large variation among sites, soil chemistry influenced root morphology only little: fine root diameter depended on soil C/N ratio and root tip frequency on base saturation in a few soil horizons. Much larger morphological differences were found between topsoil and subsoil roots within a profile. We conclude that the fine root system of F. sylvatica varies under similar climatic conditions remarkably little between base-poor and base-rich sites, in contrast to the pronounced topsoil-subsoil differences in root morphology and fine root density. [ABSTRACT FROM AUTHOR]