Root respiration and biomass responses to experimental soil warming vary with root diameter and soil depth

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College of Forest Resources and Environmental Science


Aims: Respiration of sugar maple (Acer saccharum) surface fine roots has been shown to partially acclimate to experimentally increased soil temperature. In this study, we assessed how larger roots and roots at deeper depths responded to experimental warming. Methods: We quantified specific root respiration and root biomass for three different diameter classes (< 1, 1–2, and 2–10 mm) from three soil depths (0–10, 10–30, and 30–50 cm) in a sugar maple forest that had received a factorial combination of increased soil temperature (4 to 5 °C above ambient) and supplemental precipitation for three growing seasons. Results: Partial temperature acclimation occurred for respiration of fine-roots (< 1 mm) at 0–10 cm, limiting the increase to 30% above that for roots in the control treatment. In contrast, there was no evidence for acclimation of fine-roots at deeper depths, where soil warming caused respiration to more than double. There was evidence of acclimation for 1–2 mm roots at the 0–10 cm depth (20% reduction in respiration at an 18 °C reference temperature) but not for the larger diameter roots at any of the three soil depths. Root biomass was not altered by soil warming or moisture addition. Conclusions: Despite partial thermal acclimation in surface fine-root respiration, soil warming caused an overall 41% increase in the C flux to the atmosphere from respiration of roots in the upper 30 cm of soil, from 21.3 to 30.1 μmol m−2 s−1, potentially reducing C availability for biomass production.

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© 2020, Springer Nature Switzerland AG. Publisher’s version of record: https://doi.org/10.1007/s11104-020-04540-1

Publication Title

Plant and Soil