Soil fauna: key to new carbon models

• Published in: Soil Vol. 2; no. 4; pp. 565 - 582
• Main Authors: Filser, Juliane, Faber, Jack H, Tiunov, Alexei V, Brussaard, Lijbert, Frouz, Jan, De Deyn, Gerlinde, Uvarov, Alexei V, Berg, Matty P, Lavelle, Patrick, Loreau, Michel, Wall, Diana H, Querner, Pascal, Eijsackers, Herman, Jiménez, Juan José
• Format: Journal Article
• Language: English
• Published: Göttingen Copernicus GmbH 01.01.2016; European Geosciences Union (EGU); Copernicus Publications
• Subjects: Alterra - Animal ecology; Alterra - Dierecologie; Animal Ecology; Animals; Aquatic insects; Biodegradation; Biodiversity; Bioturbation; Bodembiologie; Bodembiologie en biologische bodemkwaliteit; Carbon; Carbon cycle; Carbon sequestration; Chair Soil Biology and Biological Soil Quality; Climate change; Climate change mitigation; CS Wetenschappelijke Adviesraad; Decomposition; Dierecologie; Dynamics; Ecosystem management; Ecosystem services; Environmental Sciences; Fauna; Fertility; Field tests; Greenhouse effect; Greenhouse gases; Heterogeneity; Hydraulic properties; Invertebrates; Land degradation; Leerstoelgroep Bodembiologie en biologische Bodemkwaliteit; Life Sciences; Literature reviews; Microorganisms; Modelling; Molecular structure; NMR; Nuclear magnetic resonance; Nutrient availability; Organic matter; Organic soils; Particle size; PE&RC; Plant growth; Prediction models; Residues; Soil; Soil Biology; Soil Biology and Biological Soil Quality; Soil chemistry; Soil dynamics; Soil fauna; Soil fertility; Soil microorganisms; Soil organic matter; Soils; Wetenschappelijke Adviesraad; carbon models; Soil fauna
• ISSN: 2199-398X; 2199-3971; 2199-398X; 2199-3971
• DOI: 10.5194/soil-2-565-2016

Soil organic matter (SOM) is key to maintaining soil fertility, mitigating climate change, combatting land degradation, and conserving above- and below-ground biodiversity and associated soil processes and ecosystem services. In order to derive management options for maintaining these essential services provided by soils, policy makers depend on robust, predictive models identifying key drivers of SOM dynamics. Existing SOM models and suggested guidelines for future SOM modelling are defined mostly in terms of plant residue quality and input and microbial decomposition, overlooking the significant regulation provided by soil fauna. The fauna controls almost any aspect of organic matter turnover, foremost by regulating the activity and functional composition of soil microorganisms and their physical–chemical connectivity with soil organic matter. We demonstrate a very strong impact of soil animals on carbon turnover, increasing or decreasing it by several dozen percent, sometimes even turning C sinks into C sources or vice versa. This is demonstrated not only for earthworms and other larger invertebrates but also for smaller fauna such as Collembola. We suggest that inclusion of soil animal activities (plant residue consumption and bioturbation altering the formation, depth, hydraulic properties and physical heterogeneity of soils) can fundamentally affect the predictive outcome of SOM models. Understanding direct and indirect impacts of soil fauna on nutrient availability, carbon sequestration, greenhouse gas emissions and plant growth is key to the understanding of SOM dynamics in the context of global carbon cycling models. We argue that explicit consideration of soil fauna is essential to make realistic modelling predictions on SOM dynamics and to detect expected non-linear responses of SOM dynamics to global change. We present a decision framework, to be further developed through the activities of KEYSOM, a European COST Action, for when mechanistic SOM models include soil fauna. The research activities of KEYSOM, such as field experiments and literature reviews, together with dialogue between empiricists and modellers, will inform how this is to be done.