Functional variability in specific root respiration translates to autotrophic differences in soil respiration in a temperate deciduous forest

• Published in: Geoderma 2023-04, Vol.432 (1), p.116414, Article 116414
• Main Authors: Aaron Hogan, J., Labbé, Jessy L., Carrell, Alyssa A., Franklin, Jennifer, Hoyt, Kevin P., Valverde-Barrantes, Oscar J., Baraloto, Christopher, Warren, Jeffrey M.
• Format: Article
• Language: English
• Subjects: Belowground physiology; ENVIRONMENTAL SCIENCES; Root functional traits; Soil fungi and bacteria; soil microbial 83 nitrogen; Soil microbial nitrogen; Temperate forest; ZeroTol
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2023.116414

[Display omitted] •Root-system specific respiration rates (Rr) are related to root functional traits.•Rr relates positively to root N content, diameter, and specific root area.•A new method to measure root and soil respiration in situ was developed and used.•Autotrophic soil respiration increased with SRL, tip abundance, and RTD. CO2 release from forest soils (Rs) is a prominent flux in the global carbon cycle. Rs is derived from roots (autotrophic respiration, Ra) and microbial (heterotrophic) respiration and is highly dynamic, as it depends on edaphic and environmental conditions as well as root functional traits and microbial community composition. It is unclear how root functional traits affect root and microbial respiration rates; however, their consideration may help parse out the relative contributions of root and microbial respiration to Rs. At a temperate forest site, root systems of 3–4 functional root orders and their surrounding surface soil were carefully excavated and placed into custom trays designed to repeatedly measure Rs in situ on eight temperate tree species that varied in their root functional strategies and mycorrhizal affinity. Rs was measured bi-weekly to monthly for nearly one year using a custom chamber attached to a gas exchange system. Rs varied over time, ranging from 0.3 to 12 µmol m−2 s−1. Comparable root systems of the same species were excised from the soil and specific root respiration rates (Rr) were measured. Rr ranged from 2.5 to 9.0 nmol g−1 s−1 and was negatively correlated with root tissue density and positively related to root tissue nitrogen concentration. Using Rr to estimate Ra, we estimate that Ra accounts for