Work

Functional responses of understory vegetation to ungulate exclusion in temperate forest ecosystems—a comparative trait-based approach

Year: 2026

Type: article

Abstract: Key message An extensive exclosure-control experiment examining functional responses of forest understory vegetation revealed that ungulate exclusion favored plant traits associated with herbivory vulnerability and competitive ability, while ungulate access promoted rather disturbance-indicating communities with more acquisitive, fast-growing characteristics. This functional ecology perspective on plant-herbivore-interactions offers novel insights for both forest management and biodiversity conservation. Context Wild ungulates significantly impact temperate forest understory dynamics by affecting plant composition, diversity, and structure through their foraging strategies and movement behaviors, and can thus trigger cascading effects on ecosystem functioning. However, the functional responses of plant communities to ungulate impact remain poorly understood. Aims We aimed (i) to test how ungulates affect plant community traits and (ii) to identify indicator species along gradients of ungulate influence (approximated as browsing percentage of woody species) and light availability (approximated as canopy coverage) during vegetation dynamics (2016–2023). Methods Based on an extensive vegetation survey dataset of 248 paired ungulate exclosures (fenced) and control plots (unfenced), which were examined in 2016 and 2023, we assessed species-specific and functional responses of understory vegetation to ungulate exclusion via a trait-based approach, applying different plant community-weighting methods (i.e., presence/absence vs. coverage data). Results In ungulate exclosures, disturbance indicator values decreased more than in unfenced controls, indicating understory recovery from browsing, grazing, and trampling. Exclosures exhibited greater reductions in specific leaf area and ruderal species proportions, but larger increases in seed mass, plant height, and forest species proportions, reflecting a shift toward traits associated with herbivory susceptibility and competitive ability. Conversely, ungulate access promoted communities with more acquisitive, fast-growing traits. Presence/absence data proved more sensitive in detecting community trait shifts than cover-weighted analyses, as dominant species may have masked changes among less abundant species. Indicator species analysis along environmental gradients revealed that ungulate feeding preferences and light availability jointly shape understory dynamics and plant–herbivore interactions. Conclusion Our findings highlight ungulates as important drivers of forest understory dynamics and underline the importance of using multiple methods to accurately assess functional responses of plant communities to herbivory.

Source: Annals of Forest Science

DOI: 10.1186/s13595-026-01364-4

Authors: Alexander Seliger, Jan Zäh, Steffi Heinrichs, Christian Ammer, Torsten Vor

Institutions: University of Applied Sciences and Arts Hildesheim/Holzminden/Göttingen, Rottenburg University of Applied Forest Sciences, University of Göttingen

Language: English

Topic: Ecology and Vegetation Dynamics Studies

Subfield: Nature and Landscape Conservation

Field: Environmental Science

Domain: Physical Sciences

SDG: Life on land

Open Access status: gold

Estimated APC paid: $2,390