title: Far from Naturalness: How Much Does Spatial Ecological Structure of European Tree Assemblages Depart from Potential Natural Vegetation?
abstract: Contemporaneous plant communities may retain a mark of past disturbances in their ecological patterns. However, unraveling the history of disturbance on natural systems at a large scale is often unfeasible, due to the complexity of the factors involved and lack of historical data. Here we aim at demonstrating how comparing observed spatial structure of tree assemblages with that expected in a hypothetical, undisturbed scenario can shed light on how natural European forests are. Borrowing an analytical approach developed in the field of network analysis, we assessed how much the observed ecological patterns of nestedness (i.e. positive co-occurrence), segregation (i.e. negative co-occurrence), and modularity in tree assemblages deviate from randomness, and from those projected by Potential Natural Vegetation (PNV) geobotanical expert assessments. We found clear evidence that European forests are far from a natural condition, showing only moderate signals (especially at higher latitudes) of the ecological spatial structure typical of undisturbed vegetation (i.e. nestedness). Our results highlight how taking into account spatial structure along with diversity can be a fundamental tool to address this problem and assess the degree of naturalness in species assemblages.
authors.affiliation: European Commission, Joint Research Centre, Directorate D - Sustainable Resources - Bio-Economy Unit, Ispra (VA), Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Strona
authors.affiliation: European Commission, Joint Research Centre, Directorate D - Sustainable Resources - Bio-Economy Unit, Ispra (VA), Italy.
authors.forename: Achille
authors.initials: A
authors.lastname: Mauri
authors.affiliation: Department of Biology, Texas State University, San Marcos, United States of America.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Veech
authors.affiliation: European Commission, Joint Research Centre, Directorate D - Sustainable Resources - Bio-Economy Unit, Ispra (VA), Italy.
authors.forename: Günther
authors.initials: G
authors.lastname: Seufert
authors.affiliation: European Commission, Joint Research Centre, Directorate D - Sustainable Resources - Bio-Economy Unit, Ispra (VA), Italy.
authors.forename: Jesus
authors.initials: J
authors.lastname: San-Miguel Ayanz
authors.affiliation: Department of Life, Health & Environmental Sciences, University of L'Aquila, L'Aquila, Italy.|CE3C - Centre for Ecology, Evolution and Environmental Changes / Azorean Biodiversity Group and Universidade dos Açores - Departamento de Ciências Agrárias, Angra do Heroísmo, Açores, Portugal.
authors.forename: Simone
authors.initials: S
authors.lastname: Fattorini
mesh_terms: D019985:Benchmarking; D004463:Ecology; D005060:Europe; D065928:Forests; D014197:Trees / Q000254:growth & development*