Tree species effects on coupled cycles of carbon, nitrogen, and acidity in mineral soils at a common garden experiment

• Published in: Biogeochemistry 2012-11, Vol.111 (1/3), p.601-614
• Main Authors: Mueller, Kevin E., Eissenstat, David M., Hobbie, Sarah E., Oleksyn, Jacek, Jagodzinski, Andrzej M., Reich, Peter B., Chadwick, Oliver A., Chorover, Jon
• Format: Article
• Language: English
• Subjects: Acid soils; Acidification; Acidity; Aluminum; Animal and plant ecology; Animal, plant and microbial ecology; Biochemistry; Biogeochemical cycles; Biogeochemistry; Biogeosciences; Biological and medical sciences; Calcium; Carbon cycle; Cation exchange; Cations; Clay soils; Dominant species; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Ecosystems; Environmental Chemistry; Exact sciences and technology; Forest soils; Fundamental and applied biological sciences. Psychology; Geochemistry; Leaf litter; Leaves; Life Sciences; Mineral soils; Monoculture; Nitrification; Nitrogen; Nutrient concentrations; Organic matter; Organic soils; Plant roots; Plant species; Sand soils; Soil acidification; Soil acidity; Soil and rock geochemistry; Soil horizons; Soil organic matter; Soil pH; Soil plant interactions; Soil properties; Soil solution; Soil stabilization; Soils; Surficial geology; Synecology; Terrestrial ecosystems; Trees
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-011-9695-7

Forest biogeochemical cycles are shaped by effects of dominant tree species on soils, but the underlying mechanisms are not well understood. We investigated effects of temperate tree species on interactions among carbon (C), nitrogen (N), and acidity in mineral soils from an experiment with replicated monocultures of 14 tree species. To identify how trees affected these soil properties, we evaluated correlations among species-level characteristics (e.g. nutrient concentrations in leaf litter, wood, and roots), stand-level properties (e.g. nutrient fluxes through leaf litterfall, nutrient pools in stemwood), and components of soil C, N, and cation cycles. Total extractable acidity (aciditytot) was correlated positively with mineral soil C stocks (R2 = 0.72, P < 0.001), such that a nearly two-fold increase in aciditytot was associated with a more than two-fold increase of organic C. We attribute this correlation to effects of tree species on soil acidification and subsequent mineral weathering reactions, which make hydrolyzing cations available for stabilization of soil organic matter. The effects of tree species on soil acidity were better understood by measuring multiple components of soil acidity, including pH, the abundance of hydrolyzing cations in soil solutions and on cation exchange sites, and aciditytot. Soil pH and aciditytot were correlated with proton-producing components of the soil N cycle (e.g. nitrification), which were positively correlated with species-level variability in fine root N concentrations. Soluble components of soil acidity, such as aluminum in saturated paste extracts, were more strongly related to plant traits associated with calcium cycling, including leaf and root calcium concentrations. Our results suggest conceptual models of plant impacts on soil biogeochemistry should be revised to account for underappreciated plant traits and biogeochemical processes.