How important is diversity for capturing environmental-change responses in ecosystem models?

[摘要] Marine ecosystem models used to investigate how global change affects oceanecosystems and their functioning typically omit pelagic plankton diversity.Diversity, however, may affect functions such as primary production and theirsensitivity to environmental changes. Here we use a global ocean ecosystemmodel that explicitly resolves phytoplankton diversity by defining subtypeswithin four phytoplankton functional types (PFTs). We investigate the model'sability to capture diversity effects on primary production underenvironmental change. An idealized scenario with a sudden reduction invertical mixing causes diversity and primary-production changes that turn outto be largely independent of the number of coexisting phytoplankton subtypes.The way diversity is represented in the model provides a small number ofniches with respect to nutrient use in accordance with the PFTs defined inthe model. Increasing the number of phytoplankton subtypes increases theresolution within the niches. Diversity effects such as niche complementarityoperate between, but not within PFTs, and are constrained by the variety oftraits and trade-offs resolved in the model. The number and nature of theniches formulated in the model, for example via trade-offs or different PFTs,thus determines the diversity effects on ecosystem functioning captured inocean ecosystem models.

[学科分类] 地球化学与岩石