Characteristics of dissolved organic matter and phenolic compounds in forest soils under silver birch (Betula pendula), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris)

Abstract

Summary The aim was to characterize dissolved organic matter in soils under different tree species. Molecular size distribution and chemical composition of dissolved organic carbon and nitrogen were determined in water extracts from humus layers and mineral soils taken from silver birch (Betula pendula Roth.), Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) stands. Concentrations of tannins and 15 phenolic acids in the humus layers were measured. Per unit of organic matter, the concentrations of dissolved organic C and N were larger in birch and spruce humus layers than in the pine humus layer. In the underlying mineral soil, the concentrations of dissolved organic C were similar at all sites, but the concentration of dissolved organic N was greater in spruce and pine soils than in birch soil. In all soils, the 10–100 kDa fraction was the most abundant molecular size group and hydrophobic acids the most abundant chemical group of dissolved organic C. In all humus layers, hydrophobic acids and hydrophilic bases were the major components of dissolved organic N. There were only minor differences in the concentrations of total tannins in the humus layers under different tree species. Small‐molecule tannins (about < 0.5 kDa) were most abundant in the birch humus, and large‐molecule tannins in the pine humus. Coniferous humus contained more ferulic and p‐coumaric acids than did the birch humus. The concentrations of 3,4 and 3,5‐dihydroxybenzoic acid, vanillic acid and 4‐hydroxybenzoic acid were similar in all soils.

Dissolved organic carbon and nitrogen leaching from Scots pine, Norway spruce and silver birch stands in southern Sweden

“…Other direct comparisons of tree species effects on DOC are scarce, especially when interested in spruce, pine and birch, more specifically. There are data from Finland comparing water extracts from the three species, indicating that there is less water soluble carbon leached from pine stands than from spruce and birch (Smolander and Kitunen, 2002;Suominen et al, 2003). In a recent study, Lindroos et al (2011) for birch, 550 mm for spruce and 690 mm for pine.…”

“…Numerous studies of DOC transport in soils under different tree species have been made, but there are only few systematic investigations of the effects of the three dominant Scandinavian tree species in the literature. In previous studies of effects of birch, spruce and pine in Finland (Kiikkilä et al 2006;Smolander and Kitunen, 2002;Suominen et al 2003), higher concentrations of water extractable organic matter (WEOM) per gram of carbon were found under birch and spruce than under pine in the O horizon, but no differences were found between tree species for mineral soil samples. It can however be questioned how representative those studies are for field conditions, as water extracts were used instead of soil water collected with lysimeters.…”

The phenolic compounds in Cladonia lichens are not antimicrobial in soils

“…The only published solubility of usnic acid in distilled water is provided by Dawson et al (1984), who report that the solubility in distilled water is about 3 ppm, although they do not indicate how this solution was obtained. Dawson et al (1984) also report Wndings of usnic acid in soil solution, but the analytical method they used meant that it was possible to mistake other phenolic compounds common to soil (e.g., Suominen et al 2003) for usnic acid. Second, we tested the assumption that lichen substances accumulate in the lichen necromass and soil beneath the lichens, but found the concentrations of secondary substances to be very low in the lichen necromass and negligible in the soil.…”

Links between plant community composition, soil organic matter quality and microbial communities in contrasting tundra habitats

“…The WSE fraction was further analysed for soluble N concentrations (FIA Tecator) and soluble phenolic concentrations. Phenolics were determined by the Folin-Ciocalteau method (Suominen et al 2003), using commercial tannic acid (Ph Eur. ; VWR BDH Prolabo) as a standard.…”