title: Decoupled diversity dynamics in green and brown webs during primary succession in a saltmarsh.
abstract: Terrestrial ecosystems are characterized by a strong functional connection between the green (plant-herbivore-based) and brown (detritus-detritivore-based) parts of the food web, which both develop over successional time. However, the interlinked changes in green and brown food web diversity patterns in relation to key ecosystem processes are rarely studied. Here, we demonstrate changes in species richness, diversity and evenness over a wide range of invertebrate green and brown trophic groups during 100 years of primary succession in a saltmarsh ecosystem, using a well-calibrated chronosequence. We contrast two hypotheses on the relationship between green and brown food web diversity across succession: (i) 'coupled diversity hypothesis', which predicts that all trophic groups covary similarly with the main drivers of successional ecosystem assembly vs. (ii) the 'decoupled diversity hypothesis', where green and brown trophic groups diversity respond to different drivers during succession. We found that, while species richness for plants and invertebrate herbivores (green web groups) both peaked at intermediate productivity and successional age, the diversity of macrodetritivores, microarthropod microbivores and secondary consumers (brown web groups) continuously increased towards the latest successional stages. These results suggest that green web trophic groups are mainly driven by vegetation parameters, such as the amount of bare soil, vegetation biomass production and vegetation height, while brown web trophic groups are mostly driven by the production and standing stock of dead organic material and soil development. Our results show that plant diversity cannot simply be used as a proxy for the diversity of all other species groups that drive ecosystem functioning, as brown and green diversity components in our ecosystem responded differently to successional gradients.
authors.affiliation: Institute for Environmental Science, University of Leiden, 2333 CC, Leiden, The Netherlands.|Soil and Ecosystem Ecology Group, University of Manchester, Michael Smith Building, Oxford Road, M13 9PT, Manchester, UK.|Community and Conservation Ecology, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Schrama
authors.affiliation: Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013, Bern, Switzerland.|Senckenberg Gesellschaft für Naturforschung, Biodiversity and Climate Research Centre BIK-F, Senckenberganlage 25, 60325, Frankfurt, Germany.
authors.forename: Fons
authors.initials: F
authors.lastname: van der Plas
authors.affiliation: Community and Conservation Ecology, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands.|Section Animal Ecology, Department of Ecological Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
authors.forename: Matty P
authors.initials: MP
authors.lastname: Berg
authors.affiliation: Community and Conservation Ecology, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands.
authors.forename: Han
authors.initials: H
authors.lastname: Olff
mesh_terms: D000818:Animals; D044822:Biodiversity; D020387:Food Chain; D007448:Invertebrates / Q000502:physiology*; D009426:Netherlands; D018521:Plant Physiological Phenomena; D011157:Population Dynamics; D013997:Time Factors; D053833:Wetlands
keywords: brown web; chronosequence; ecosystem assembly rules; ecosystem functioning; food web; green web; saltmarsh; succession