Temperature Sensitivity of Soil Respiration in Two Temperate Forest Ecosystems: The Synthesis of a 24-Year Continuous Observation

Abstract

Soil respiration (SR) is one of the largest fluxes in the global carbon cycle. The temperature sensitivity of SR (often termed as Q10) is a principal parameter for evaluating the feedback intensity between soil carbon efflux and global warming. The present study aimed to estimate the seasonal and interannual dynamics of the temperature sensitivity of SR based on a long-term 24-year series of measurements in two temperate forest ecosystems in European Russia. The study was conducted in a mature mixed forest with sandy Entic Podzol and in a secondary deciduous forest with loamy Haplic Luvisol. The SR rate was measured continuously from December 1997 to November 2021 at 7–10-day intervals using the closed chamber method. Sandy Entic Podzol demonstrated a higher temperature sensitivity of SR in comparison with loamy Entic Luvisol. The Q10 values for both soils in dry years were 1.3–1.4 times lower than they were in the years with normal levels of humidity. For both types of soil, we observed a significant positive correlation between the Q10 values and wetness indexes. The interannual variability of Q10 values for SR in forest soils was 18%–40% depending on the calculation approach and levels of aridity/humidity over the growing season. The heterogeneous Q10 values should be integrated into SR and C balance models for better predictions.

Carbon emission by soil respiration in a deciduous forest on the southern border of the taiga (Tatarstan, Russia)

“…According to the results of [16] topsoil moisture, the precipitation during the preceding period is also recognized as significant, which my provide clues that local spatial moisture E3S Web of Conferences 463, 02020 (2023) EESTE2023 https://doi.org/10.1051/e3sconf/202346302020 heterogeneity resulting from past rains may have been a factor leading to significant heterogeneity in June carbon dioxide emissions measured in "Carbon-Povolzhie" polygon. The study [19] for mixed and broad-leaved forests on the border of the southern taiga and the zone of broad-leaved forests also supports the version of higher humidity at the moments of the highest carbon dioxide emission, reporting 1.3-1.4 times less carbon dioxide in the drier years. Also [29] showed for cool temperate deciduous broad-leaved (Quercus and Betula dominated) forest that rainfall events significantly increased soil CO 2 emission.…”

“…The works on greenhouse gas emissions conducted in forest ecosystems of the European part of Russia cover the northern taiga zone and soddy-podzolic soils in coniferous-deciduous forests [11][12], coniferous forest of middle [13][14] and southern taiga zones [15][16][17][18], mixed forests of southern taiga [19][20].…”

Soil Temperature, Organic-Carbon Storage, and Water-Holding Ability Should Be Accounted for the Empirical Soil Respiration Model Selection in Two Forest Ecosystems

“…Selyaninov hydrothermal coefficient-HTC ∑ 𝑃 / ∑ 𝑇 /10 , when T > 10 °C (HTC6-8-summer period, June to August months) [53]; • Wetness Indexes-WI 𝑙𝑔 ∑ 𝑃 / ∑ 𝑇 (WI5-8 and WI5-9 for May to August and May to September periods, respectively) [53].…”