Divergent roles of herbivory in eutrophying forests

Josiane Segar , Henrique Pereira , Lander Baeten (1) , Markus Bernhardt-Römermann (2) , Pieter de Frenne (1) , Néstor Fernández (3) , Frank Gilliam , Jonathan Lenoir (4) , Adrienne Ortmann-Ajkai (5) , Kris Verheyen (6) , Donald Waller (7) , Balázs Teleki (8) , Jörg Brunet , Markéta Chudomelová (9, 10) , Guillaume Decocq (4) , Thomas Dirnböck (11) , Radim Hédl (9, 12) , Thilo Heinken (13) , Bogdan Jaroszewicz (14) , Martin Kopecký (15, 16) , Martin Macek , František Máliš , Tobias Naaf , Anna Orczewska , Kamila Reczynska , Wolfgang Schmidt , Jan Šebesta , Alina Stachurska-Swakoń , Tibor Standovár , Krzysztof Swierkosz , Ondřej Vild , Monika Wulf , Ingmar Staude

1 UGENT - Universiteit Gent = Ghent University
2 Institute of Ecology and Evolution, Friedrich Schiller University Jena, Jena, Germany
3 German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig
4 EDYSAN - Ecologie et Dynamique des Systèmes Anthropisés - UMR CNRS 7058
5 University of Pecs
6 UCPH - University of Copenhagen = Københavns Universitet
7 University of Wisconsin-Madison
8 University of Debrecen Egyetem [Debrecen]
9 CAS - Czech Academy of Sciences [Prague]
10 MUNI - Masaryk University [Brno]
11 Umweltbundesamt GmbH = Environment Agency Austria
12 Palacky University Olomouc
13 University of Potsdam = Universität Potsdam
14 UW - University of Warsaw
15 IB / CAS - Institute of Botany of the Czech Academy of Sciences
16 CZU - Czech University of Life Sciences Prague

Ungulate populations are increasing across Europe with important implications for forest plant communities. Concurrently, atmospheric nitrogen (N) deposition continues to eutrophicate forests, threatening many rare, often more nutrient-efficient, plant species. These pressures may critically interact to shape biodiversity as in grassland and tundra systems, yet any potential interactions in forests remain poorly understood. Here, we combined vegetation resurveys from 52 sites across 13 European countries to test how changes in ungulate herbivory and eutrophication drive long-term changes in forest understorey communities. Increases in herbivory were associated with elevated temporal species turnover, however, identities of winner and loser species depended on N levels. Under low levels of N-deposition, herbivory favored threatened and small-ranged species while reducing the proportion of non-native and nutrient-demanding species. Yet all these trends were reversed under high levels of N-deposition. Herbivores also reduced shrub cover, likely exacerbating N effects by increasing light levels in the understorey. Eutrophication levels may therefore determine whether herbivory acts as a catalyst for the “N time bomb” or as a conservation tool in temperate forests.

Domaines: Ecologie, Environnement

Josiane Segar, Henrique Pereira, Lander Baeten, Markus Bernhardt-Römermann, Pieter de Frenne, et al.. Divergent roles of herbivory in eutrophying forests. Nature Communications, 2022, 13 (1), pp.7837. ⟨10.1038/s41467-022-35282-6⟩. ⟨hal-03915578⟩