Influences of temperature and moisture on abiotic and biotic soil CO2 emission from a subtropical forest

Xiaomei Chen,Zhanying Xu,Muying Liu,Hui Wei

doi:10.1186/s13021-021-00181-8

Abstract

BackgroundSoil CO2 efflux is considered to mainly derive from biotic activities, while potential contribution of abiotic processes has been mostly neglected especially in productive ecosystems with highly active soil biota. We collected a subtropical forest soil to sterilize for incubation under different temperature (20 and 30 °C) and moisture regimes (30%, 60 and 90% of water holding capacity), aiming to quantify contribution of abiotic and biotic soil CO2 emission under changing environment scenarios.Main findings:Results showed that abiotic processes accounted for a considerable proportion (15.6−60.0%) of CO2 emission in such a biologically active soil under different temperature and moisture conditions, and the abiotic soil CO2 emission was very likely to derive from degradation of soil organic carbon via thermal degradation and oxidation of reactive oxygen species. Furthermore, compared with biotically driving decomposition processes, abiotic soil CO2 emission was less sensitive to changes in temperature and moisture, causing reductions in proportion of the abiotic to total soil CO2 emission as temperature and moisture increased.ConclusionsThese observations highlight that abiotic soil CO2 emission is unneglectable even in productive ecosystems with high biological activities, and different responses of the abiotic and biotic processes to environmental changes could increase the uncertainty in predicting carbon cycling.

Highlights

Soil Carbon dioxide (CO2) efflux is considered to mainly derive from biotic activities, while potential contribution of abiotic processes has been mostly neglected especially in productive ecosystems with highly active soil biota
These observations highlight that abiotic soil CO2 emission is unneglectable even in productive ecosystems with high biological activities, and different responses of the abiotic and biotic processes to environmental changes could increase the uncertainty in predicting carbon cycling
We observed that Rsoil ranged from 0.061 ± 0.0069 to 0.25 ± 0.027 mg kg− 1 soil day− 1 under different combinations of temperature and moisture regimes, and increasing temperature or moisture significantly or tended to promote Rsoil in this study (Fig. 1A). It is not surprising because such positive relationships in a certain temperature or moisture range have been frequently reported for soil CO2 emission, the range may be variable depending on soil type and properties [15, 16, 19]

Summary

Introduction

Soil CO2 efflux is considered to mainly derive from biotic activities, while potential contribution of abiotic processes has been mostly neglected especially in productive ecosystems with highly active soil biota. In addition to microbial driven SOC decomposition, diverse abiotic pathways, such as photodegradation, thermal degradation, oxidation of reactive oxidative species (ROSs), extracellular oxidative metabolism, and inorganic chemistry reactions, may contribute to C O2 emission from the soil (Rsoil) and produce soil abiotic CO2 emission (Rabiotic) [7, 8] These abiotic C decomposition pathways have been recognized especially in litter decomposition studies, because a considerable number of studies have reported photodegradation of litter under different conditions [9,10,11]. In those biologically active ecosystems, contribution of the abiotic to total soil C O2 emission is assumed tiny and often overlooked, recent studies highlighted the importance of nonmicrobial CO2 emission and possible production pathways in the soil [7, 8]

Methods

Results

Conclusion