Contrasting responses after fires of the source components of soil respiration and ecosystem respiration

Abstract

Wildfire is an important ecological disturbance that can have cascading effects on ecosystem carbon (C) fluxes. Ecosystem respiration (ER) and soil respiration (SR) account for two of the largest terrestrial C fluxes to the atmosphere, and they play critical roles in regulating C–climate feedbacks. Here, the responses of ER, SR and their source components to experimental burning in a meadow grassland on the Tibetan Plateau were investigated. Fire treatment increased ER by 9% but decreased SR by 15%. The contrasting post‐fire responses of SR and ER can be explained by the behaviour of their source components; that is, fire increased aboveground plant respiration (Ragb) by 37%, but decreased heterotrophic respiration (HR) by 21%. Increases in ER and Ragb were mainly related to enhanced plant productivity, whereas smaller SR and HR were associated with reductions in microbial biomass and soil moisture. Accounting for the responses of ER, SR and their intrinsic components has advanced our understanding of how fire affects ecosystem C fluxes. Highlights Fire treatment increased ecosystem respiration (ER) and aboveground plant respiration. Fire treatment decreased soil respiration (SR) and heterotrophic respiration (HR). Increases in ER and aboveground plant respiration were related to plant productivity. Reductions in SR and HR were caused by the suppressed microbial activity.

Satellite-detected large CO2 release in southwestern North America during the 2020–2021 drought and associated wildfires

“…During compound drought and fire events, there are evidence to support the occurrence of such phenomenon. The larger inhibition in Reco than in GPP could be explained by suppressed microbial soil respiration, which has also been found in previous studies in the post-drought and post-fire periods (Selsted et al 2012, Kopittke et al 2014, Chen et al 2019, Huang et al 2021. Further evidence, especially from intensive in-situ measurements, is critically needed to confirm this finding.…”

Soil carbon flux research in the Asian region: Review and future perspectives

“…Globally, approximately half the average annual flux of 2.0 Pg C yr -1 has been emitted due to fires in forest ecosystems between 1997 and 2009; 20 of these fires were from deforestation and tropical forest fires, 16 from woodland fires, and 15 from mostly extra-tropical forest fires 2001 -2009 van der Werf et al, 2010 . Although most fires in ecosystems are set by humans, a complex interaction between climate, ecosystem processes, and human activities determines fire-driven C emissions from burned areas van der Werf et al, 2010 . In tropical peatlands of Southeast Asia such as the Indonesian lowlands and Peninsular Malaysia, there are substantial fire-driven C losses in the global terrestrial C cycle Herawati and Santoso, 2011;Smith et al, 2018;Kumar et al, 2020 . For examples, the R s from burned peat surfaces increased 46 over the first nine months following a fire in the Kalimantan tropical peatland forest Astiani et al, 2018 , and a ground fire significantly stimulated R s by 17.5 for a mixed forest of sub-tropical-temperate transition zones in central China Hu et al, 2020 . Although the humid climate typical of the Asian monsoon region is relatively free from wildfire when compared to drier ecosystems in other arid or boreal ecosystems, the frequency, intensity, and size of wildfires have been increasing and is expected to increase rapidly in future given the increase in lightning strikes and seasonally extreme droughts associated with global warming Hu et al, 2017;Chen et al, 2019;Song et al, 2019. Sun et al 2014 investigated the effect of fire disturbance on R s in birch and larch forests in China, and Hu et al 2017 examined the effects of fire severity on R s in larch forests to better estimate R s in boreal ecosystems; they found that wildfires decreased R s mainly due to decreased autotrophic respiration.…”

“…Sun et al 2014 investigated the effect of fire disturbance on R s in birch and larch forests in China, and Hu et al 2017 examined the effects of fire severity on R s in larch forests to better estimate R s in boreal ecosystems; they found that wildfires decreased R s mainly due to decreased autotrophic respiration. Experimental burning studies in the temperate forests of northern Japan and a Tibetan meadow grassland in China, have demonstrated that the artificial fire significantly decreases R s due to reductions in root activity, litter layer, microbial biomass and soil moisture Kim, 2013;Chen et al, 2019. Song et al 2019 found that wildfires in a montane coniferous forest decreased R s largely from the reduction in R r leading to an increase in the R h to R s ratio.…”

Soil respiration and controls in warmer winter: A snow manipulation study in postfire and undisturbed black pine forests

“…However, reported observations on the effects of fire on R s rates are not consistent, with some authors reporting an increase in R s due to enhanced heterotrophic respiration rates (Hu et al, 2021;Wang, Chen, et al, 2021;Wang, Yao, et al, 2021) while others reporting a decrease due to suppressed microbial activities and reduced microbial biomass (Chen et al, 2019;Hu et al, 2023). Kong et al (2019) reported no R s changes regardless of fire intensity.…”