Soil signals of key mechanisms driving greater protection of organic carbon under aspen compared to spruce forests in a North American montane ecosystem
Year: 2025
Type: article
Abstract: . Soil organic carbon (SOC) is often retained more effectively in aspen-dominated forests compared to coniferous forests in North America, yet the reasons why are unclear. A potential driver could be differences in SOC protection mechanisms. Over decades to centuries, chemical (e.g., mineral association) and physical (e.g., aggregation) processes can work to preserve SOC stocks, which can vary across cover types. To investigate this hypothesis, we evaluate controls on SOC concentrations in the Coal Creek watershed (CO, USA), a montane ecosystem dominated by quaking aspen and Engelmann spruce and underlain by granite and sandstone. We examined a combination of biological, chemical, physical, and environmental conditions to evaluate potential abiotic and biotic mechanisms of SOC preservation at multiple depths. As expected, we observed greater SOC under aspen compared to spruce. Growing season soil moisture, temperature, and CO2 and O2 varied with slope position and aspect, and thus forest cover type. Dissolved organic carbon (DOC) was lower under aspen compared to spruce. Exo-enzyme data indicate that aspen soil microbes exhibited greater effort to seek organically-bound resources; consistent with this, soil organic N exhibited higher δ15N values, hinting at a greater degree of organic matter processing. Finally, aspen roots exhibited greater root abundance, and aspen mineral soils revealed smaller mean aggregate diameters compared to conifer sites. Our data suggest enhanced biotic activities in aspen-dominated forest soils that promote both chemical and physical protection of SOC in aspen- relative to spruce-dominated forests, and associated limitations on DOC export.
Source: Biogeosciences
Institutions: Oregon State University, University of Kansas, Pennsylvania State University, Texas Tech University, The University of Sydney, University of California, Riverside, Lawrence Berkeley National Laboratory, Rocky Mountain Biological Laboratory, Institute of Arctic and Alpine Research, University of Colorado Boulder, Boise State University
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDG: Life on land
Open Access status: gold
Estimated APC paid: $1,628
Awards: G1202769797, G125460123, G1286236842, G1337544421, G1442032648, G1863003419, G223002938, ADVANCING A WATERSHED HYDRO-BIOGEOCHEMICAL THEORY: LINKING WATER TRAVEL TIME AND REACTION RATES UNDER CHANGING CLIMATE, G2506945562, G2510423872, G2630886286, G2820049545, G2988778103, G3083819904, G419881185, G4244316143, G42916606, G4501827968, G4886300740, G4956880362, G498139845, Collaborative Research: Network Cluster: Quantifying controls and feedbacks of dynamic storage on critical zone processes in western montane watersheds, G5373841109, Collaborative Research: How roots, regolith, rock and climate interact over decades to centuries - the R3-C Frontier, Collaborative Research: Network Cluster: Quantifying controls and feedbacks of dynamic storage on critical zone processes in western montane watersheds, G5653134238, Collaborative Research: How roots, regolith, rock and climate interact over decades to centuries — the R3-C Frontier., Collaborative Research: How roots, regolith, rock and climate interact over decades to centuries — the R3-C Frontier., G7560550554, G7787287669, G821644656, G8943285087, G969889393
OpenAlex ID: W4415604900