Mammalian herbivory shapes intraspecific trait responses to warmer climate and nutrient enrichment

• Published in: Global Change Biology
• Main Authors: Jessen, Maria-Theresa, Kaarlejärvi, Elina, Olofsson, Johan, Eskelinen, Anu
• Other Authors: Organismal and Evolutionary Biology Research Programme, Research Centre for Ecological Change
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: anthropogenic change; climate warming; grazing; herbivory; intraspecific trait plasticity; nutrient addition; open-top chamber; plant performance; reindeer; trait-environment relationship; PLANT FUNCTIONAL TRAITS; PHENOTYPIC PLASTICITY; COMMUNITY RESPONSES; SPECIES RICHNESS; GLOBAL CHANGE; LEAF TRAITS; NITROGEN; TUNDRA; VEGETATION; TOLERANCE; 1181 Ecology; evolutionary biology; Tundra
• Online Access: http://hdl.handle.net/10138/326714

Variation in intraspecific traits is one important mechanism that can allow plant species to respond to global changes. Understanding plant trait responses to environmental changes such as grazing patterns, nutrient enrichment and climate warming is, thus, essential for predicting the composition of future plant communities. We measured traits of eight common tundra species in a fully factorial field experiment with mammalian herbivore exclusion, fertilization, and passive warming, and assessed how trait responsiveness to the treatments was associated with abundance changes in those treatments. Herbivory exhibited the strongest impact on traits. Exclusion of herbivores increased vegetative plant height by 50% and specific leaf area (SLA) by 19%, and decreased foliar C:N by 11%; fertilization and warming also increased height and SLA but to a smaller extent. Herbivory also modulated intraspecific height, SLA and foliar C:N responses to fertilization and warming, and these interactions were species-specific. Furthermore, herbivory affected how trait change translated into relative abundance change: increased height under warming and fertilization was more positively related to abundance change inside fences than in grazed plots. Our findings highlight the key role of mammalian herbivory when assessing intraspecific trait change in tundra and its consequences for plant performance under global changes. Peer reviewed