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Evenness mediates the global relationship between forest productivity and richness / Iris Hordijk in Journal of ecology, vol inconnu (2023)  

Public [article]  inJournal of ecology > vol inconnu (2023) Titre : Evenness mediates the global relationship between forest productivity and richness Type de document : Article/Communication Auteurs : Iris Hordijk, Auteur ; Daniel S. Maynard, Auteur ; et al., Auteur ; Olivier Bouriaud , Auteur Année de publication : 2023 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] forêt [Termes IGN] futaie irrégulière [Termes IGN] futaie régulière [Termes IGN] productivité biologique [Termes IGN] richesse floristique [Vedettes matières IGN] Foresterie Résumé : (auteur) 1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions. Numéro de notice : A2023-093 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : 10.1111/1365-2745.14098 Date de publication en ligne : 02/05/2023 En ligne : https://doi.org/10.1111/1365-2745.14098 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103184 [article]

Drivers and implications of dominant and rare tree species in global forests / Iris Hordijk (2021)  

Public Titre : Drivers and implications of dominant and rare tree species in global forests Type de document : Thèse/HDR Auteurs : Iris Hordijk, Auteur Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Année de publication : 2021 Note générale : bibliographie Thesis submitted to attain the degree of Doctor of Sciences of ETH Zurich Langues : Anglais (eng) Descripteur : [Termes IGN] âge du peuplement forestier [Termes IGN] biodiversité végétale [Termes IGN] biome [Termes IGN] écosystème forestier [Termes IGN] espèce végétale [Termes IGN] extinction (biologie) [Termes IGN] forêt boréale [Termes IGN] forêt tempérée [Termes IGN] forêt tropicale [Termes IGN] habitat (nature) [Termes IGN] peuplement forestier [Termes IGN] plante menacée [Termes IGN] productivité biologique [Termes IGN] richesse floristique [Termes IGN] service écosystémique [Vedettes matières IGN] Inventaire forestier Index. décimale : THESE Thèses et HDR Résumé : (auteur) Forests provide crucial ecosystem functions and services for the earth system and humanity. Due to ongoing deforestation and forest degradation, these ecosystems are increasingly fragmented and disturbed, significantly changing tree species composition within the forest. Most plant communities are comprised of a few dominant species that are numerically abundant, and many rare species, each of which exist at low abundance. Given their differences in abundance and characteristics, the loss of dominant and rare species have distinct impacts on ecosystem functioning. Decreasing abundances of dominant species typically have larger immediate impacts on overall ecosystem processes (e.g. productivity), while a decline in abundance of rare species can lead to the loss of key functions and overall multifunctionality, and can ultimately drive species extinctions. Despite their unique role in the ecosystem, it remains unclear what drives species to become dominant or rare, how threatened locally dominant and rare species are, and what the effect of species abundance on ecosystem function is across large environmental gradients in our global forests. The aim of this thesis is to explore the drivers of tree species abundance, and evaluate the effect of relative tree species abundance on forest productivity. Specifically, the three chapters of this thesis aimed to identify at a global scale the 1) patterns, drivers, and threats to dominant and rare tree species, 2) differences in trait values and trait diversity that differentiate the functional contributions of dominant and rare tree species, and 3) how evenness (the relative species abundances in the community) mediates the relationship between tree species richness and forest productivity in forests. In this thesis I answered these research questions by analyzing a global dataset of forest composition, which enabled me to describe broad-scale ecological patterns and to test general ecological laws. Note de contenu : General introduction 1- Patterns, drivers and threats to dominant and rare tree species worldwide 2- Trait diversity of dominant and rare tree species in global forests: a habitat filtering perspective 3- Evenness mediates the global relationship between forest productivity and richness Synthesis Numéro de notice : 28690 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Thèse étrangère Note de thèse : PhD Thesis : Sciences : ETH Zurich 2021 DOI : sans En ligne : https://www.research-collection.ethz.ch/handle/20.500.11850/520710 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100131