The Jena Diversity-Dynamic Global Vegetation Model (JeDi-DGVM):a diverse approach to representing terrestrial biogeography and biogeochemistry based on plant functional trade-offs

[摘要] Terrestrial biosphere modelstypically abstract theimmense diversity of vegetation forms and functioning intoa relatively small set of predefined semi-empirical plant functionaltypes (PFTs). There is growing evidence, however, from the fieldecology community as well as from modelling studies that current PFTschemes may not adequately represent the observed variations inplant functional traits and their effect on ecosystemfunctioning. In this paper, we introduce the Jena Diversity-Dynamic Global Vegetation Model(JeDi-DGVM) as a new approach to terrestrial biosphere modelling witha richer representation of functional diversity than traditionalmodelling approaches based on a small number of fixed PFTs.

JeDi-DGVM simulates the performance of a large number ofrandomly generated plant growth strategies, each defined bya set of 15 trait parameters which characterize various aspects ofplant functioning including carbon allocation, ecophysiology andphenology. Each trait parameter is involved in one or morefunctional trade-offs. These trade-offs ultimately determine whethera strategy is able to survive under the climatic conditions in a givenmodel grid cell and its performance relative to the other strategies. Thebiogeochemical fluxes and land surface properties of the individualstrategies are aggregated to the grid-cell scale using a mass-basedweighting scheme.

We evaluate the simulated global biogeochemical patternsagainst a variety of field and satellite-based observations following aprotocol established by the Carbon-Land Model Intercomparison Project. Theland surface fluxes and vegetation structural properties are reasonably wellsimulated by JeDi-DGVM, and compare favourably with other state-of-the-artglobal vegetation models. We also evaluate the simulated patterns offunctional diversity and the sensitivity of the JeDi-DGVM modelling approachto the number of sampled strategies. Altogether, the results demonstrate theparsimonious and flexible nature of a functional trade-off approach to globalvegetation modelling, i.e. it can provide more types of testable outputs thanstandard PFT-based approaches and with fewer inputs.

The approach implemented here in JeDi-DGVM sets the foundation for futureapplications that will explore the impacts of explicitly resolving diverseplant communities, allowing for a more flexible temporal and spatialrepresentation of the structure and function of the terrestrial biosphere.

[学科分类] 地球化学与岩石