Will heterotrophic soil respiration be more sensitive to warming than autotrophic respiration in subtropical forests?

Abstract

Understanding the responses of heterotrophic (Rh) and autotrophic (Ra) components of soil respiration (Rs) to warming is important in evaluating and modelling the effects of changes in climate on soil carbon (C) cycling in terrestrial ecosystems. We used a mesocosm system with buried heating cables (5°C warming) to investigate the responses of Rs, Rh and Ra to warming in a subtropical forest in southern China. Soil CO2 effluxes were measured with a portable automatic soil CO2 flux system from March 2014 to July 2015. We found that warming increased mean Rs and Rh from 788 to 1036 g C m−2 year−1 (+31%) and from 512 to 707 g C m−2 year−1 (+38%), respectively. There was no difference in Ra between the warming treatment and the control. The lack of response of Ra to warming was probably because the fine root biomass did not change with warming treatment. Soil warming also increased available dissolved organic carbon, microbial biomass carbon, actinomycetal biomass and arbuscular mycorrhizal biomass. Our results suggest that Rh might be more sensitive to climate warming than Ra, and future climate warming could increase soil C loss from increased Rh in subtropical forest ecosystems. Highlights A field warming experiment with partitioning of soil respiration in a humid subtropical forest. Warming increased Rs and Rh without significantly altering soil microbial substrate availability. Heterotrophic respiration appeared more sensitive to warming than autotrophic respiration. Warming increased Actinomycetes bacteria and Arbuscular mycorrhizal fungi.

Carbon Cycles of Forest Ecosystems in a Typical Climate Transition Zone under Future Climate Change: A Case Study of Shaanxi Province, China

“…At present, many studies have shown that future climate change will promote soil heterotrophic respiration [37,38]. The results of this study showed that future climate change under three RCP scenarios had a positive effect on forest soil heterotrophic respiration in arid and humid regions, which is consistent with previous studies.…”

Unaltered soil microbial community composition, but decreased metabolic activity in a semiarid grassland after two years of passive experimental warming

“…Studies over the past decades have shown that the warming response of microbial respiration is highly variable. Previous studies showed that warming could stimulate microbial respiration due to increased microbial biomass C (Liu et al., 2019), soil nutrient availability (Ali et al., 2018), root exudates (Li et al., 2013), enzymatic activity (Bragazza et al., 2012; Li et al., 2017), or plant production (Euskirchen et al., 2009). Some other studies showed opposite results; that is, microbial respiration inhibited by warming, which resulted from decreased soil water availability (Fang et al., 2018; Liu et al., 2009), labile C (Li et al., 2019), microbial biomass C (Chen, et al., 2016), or enzymatic activity (Garcia‐Palacios et al., 2018).…”

Warming Alters Plant Chemical and Nutrient Compositions by Affecting Metabolites in Cunninghamia lanceolata (Lamb.) Hook

“…In total, 40 one-year-old C. lanceolata seedlings were selected from a local nursery; the seedlings were uniform in plant height and basal diameter. The average height and basal diameter of seedlings were 25.7 ± 2.5 cm and 3.4 ± 0.4 mm, respectively [34].…”

“…The different results demonstrated that seasonal changes significantly affect the antioxidant system [28]. This could be largely related to the significant changes in temperature and precipitation [34]. It has been reported that plants exposed to moisture stress increase antioxidant activities in response to oxidative stress [28].…”

“…Warming treatments were administered continuously using heating cables (TXLP/1, Nexans, Norway) buried at a soil depth of 10 cm, and at intervals of 20 cm. The outputs of the heaters were set at 17 W m −1 at 230 V, which resulted in a 5 • C temperature increase [34]. In total, the design consisted of ten plots (2 m × 2 m) with five replicates of each temperature treatment.…”