title: The muddle of ages, turnover, transit, and residence times in the carbon cycle.
abstract: Comparisons among ecosystem models or ecosystem dynamics along environmental gradients commonly rely on metrics that integrate different processes into a useful diagnostic. Terms such as age, turnover, residence, and transit times are often used for this purpose; however, these terms are variably defined in the literature and in many cases, calculations ignore assumptions implicit in their formulas. The aim of this opinion piece was i) to make evident these discrepancies and the incorrect use of formulas, ii) highlight recent results that simplify calculations and may help to avoid confusion, and iii) propose the adoption of simple and less ambiguous terms.
authors.affiliation: Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Carlos A
authors.identifier: 0000-0003-0009-4169
authors.initials: CA
authors.lastname: Sierra
authors.affiliation: Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Müller
authors.affiliation: Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Holger
authors.identifier: 0000-0002-8239-1601
authors.initials: H
authors.lastname: Metzler
authors.affiliation: Department of Physical Geography, Stockholm University, Stockholm, Sweden.|Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden.
authors.forename: Stefano
authors.identifier: 0000-0002-5960-5712
authors.initials: S
authors.lastname: Manzoni
authors.affiliation: Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Trumbore
mesh_terms: D002244:Carbon; D057486:Carbon Cycle; D017753:Ecosystem; D004777:Environment
chemical_list: D002244:Carbon
keywords: carbon cycle models; carbon fluxes; carbon stocks; compartment models; dynamical systems; model diagnostics; radiocarbon; reservoir theory