Improving the representation of roots in terrestrial models

• Published in: Ecological modelling 2014-11, Vol.291 (C), p.193-204
• Main Authors: Smithwick, Erica A.H., Lucash, Melissa S., McCormack, M. Luke, Sivandran, Gajan
• Format: Article
• Language: English
• Subjects: Allocation; Animal, plant and microbial ecology; Biological and medical sciences; Carbon; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Methods and techniques (sampling, tagging, trapping, modelling...); Modeling; Parameterization; Roots; Turnover
• ISSN: 0304-3800; 1872-7026
• DOI: 10.1016/j.ecolmodel.2014.07.023

•Root modeling is limited by data, terminology, and conceptual frameworks.•We review the key root processes of interest to field ecologists and modelers.•We suggest five emerging themes: size, allocation, turnover, biomass, and uptake.•Improvement in root modeling will aid predictions of ecosystem resilience. Root biomass, root production and lifespan, and root-mycorrhizal interactions govern soil carbon fluxes and resource uptake and are critical components of terrestrial models. However, limitations in data and confusions over terminology, together with a strong dependence on a small set of conceptual frameworks, have limited the exploration of root function in terrestrial models. We review the key root processes of interest to both field ecologists and modelers including root classification, production, turnover, biomass, resource uptake, and depth distribution to ask (1) what are contemporary approaches for modeling roots in terrestrial models? and (2) can these approaches be improved via recent advancements in field research methods? We isolate several emerging themes that are ready for collaboration among field scientists and modelers: (1) alternatives to size-class based root classifications based on function and the inclusion of fungal symbioses, (2) dynamic root allocation and phenology as a function of root environment, rather than leaf demand alone, (3) improved understanding of the treatment of root turnover in models, including the role of root tissue chemistry on root lifespan, (4) better estimates of root stocks across sites and species to parameterize or validate models, and (5) dynamic interplay among rooting depth, resource availability and resource uptake. Greater attention to model parameterization and structural representation of roots will lead to greater appreciation for belowground processes in terrestrial models and improve estimates of ecosystem resilience to global change drivers.