Sustained large stimulation of soil heterotrophic respiration rate and its temperature sensitivity by soil warming in a cool-temperate forested peatland

Abstract

A B S T R A C T We conducted a soil warming experiment in a cool-temperate forested peatland in northern Japan during the snow-free seasons of 2007Á2011, to determine whether the soil warming would change the heterotrophic respiration rate and its temperature sensitivity. We elevated the soil temperature by 38C at 5-cm depth by using overhead infrared heaters and continuously measured hourly soil CO 2 fluxes with a 15-channel automated chamber system. The 15 chambers were divided into three groups each with five replications for the control, unwarmed-trenched and warmed-trenched treatments. Soil warming enhanced heterotrophic respiration by 82% (mean of four seasons (2008Á2011) observation9SD, 6.8492.22 mmol C m (2 s (1 ) as compared to the unwarmed-trenched treatment (3.7690.98 mmol C m (2 s (1 ). The sustained enhancement of heterotrophic respiration with soil warming suggests that global warming will accelerate the loss of carbon substantially more from forested peatlands than from other upland forest soils. Soil warming likewise enhanced temperature sensitivity slightly (Q 10 , 3.190.08 and 3.390.06 in the four-season average in unwarmed-and warmedtrenched treatments, respectively), and significant effect was observed in 2009 (pB0.001) and 2010 (pB0.01). However, there was no significant difference in the basal respiration rate at 108C (R 10 , 2.290.52 and 2.891.2 mmol C m (2 s (1 ) between treatments, although the values tended to be high by warming throughout the study period. These results suggest that global warming will enhance not only the heterotrophic respiration rate itself but also its Q 10 in forests with high substrate availability and without severe water stress, and predictions for such ecosystems obtained by using models assuming no change in Q 10 are likely to underestimate the carbon release from the soil to the atmosphere in a future warmer environment.

Long‐Term Stimulatory Warming Effect on Soil Heterotrophic Respiration in a Cool‐Temperate Broad‐Leaved Deciduous Forest in Northern Japan

“…When considering forest soils in Japan, Morisada et al () demonstrated that the mean SOC density of the upper 30 cm forest soil layer was 9.0 kg C m −2 and was about 70% higher than the global average. Previous soil warming studies in the forests of Japan by Aguilos et al () and Teramoto et al () also suggested the possible contribution of high carbon substrate availability for sustaining the stimulatory soil warming effect on R h during five to six years of warming treatments. SOC density at our study site was 11.49 kg C m −2 in the upper 30 cm and slightly higher than that estimated by Morisada et al ().…”

“…For example, among the 49 soil warming experiments synthesized by Crowther et al (), only two sites (a grassland and a cropland) were in the Asia‐Pacific region (in China). Recently, soil warming experiments extending over around five‐year periods in the Asian monsoon region have detected no decreasing trend in the stimulatory warming effect, possibly due to substrate depletion or acclimation (Aguilos et al, ; Teramoto et al, ; Wu et al, ). Thus, the response of R h to long‐term warming in the Asian monsoon region might differ to those in Europe and North America.…”

Carbon budgets in fertile silver birch (Betula pendula Roth) chronosequence stands

“…Climate change scenarios predict an increase in air temperature (by 2.3-4.5 C) in Baltic region (Kont et al, 2003) and soil warming experiments have showed significant enhancement of R s and R h (Bronson et al, 2008;Schindlbacher et al, 2009;Aguilos et al, 2013). Moreover, Aguilos et al (2013) reported enhanced temperature sensitivity of R h in soil warming experiment in cool-temperate forested peatland.…”

“…Moreover, Aguilos et al (2013) reported enhanced temperature sensitivity of R h in soil warming experiment in cool-temperate forested peatland. However, some warming studies report either decrease or no significant change in Q 10 values (Bronson et al, 2008;Niinistö et al, 2004).…”

Comparison of litter-bag and chamber methods for measuring CO₂ emissions from leaf litter decomposition in a temperate forest

“…A test of linearity was applied to control the quality of dC/dt following Aguilos et al 2013 . Simultaneously, soil temperature T s at a depth of 5 cm and volumetric soil water content SWC of the top layer of 5 cm were measured respectively at each plot with a thermocouple probe MHP; Omega Engineering, Stamford, CT, USA and a soil moisture sensor SM150; Delta-T Devices Ltd., Cambridge, UK .…”