Herbivore and pathogen effects on tree growth are additive, but mediated by tree diversity and plant traits. Issue 18 (11th August 2017)

• Record Type: Journal Article
• Authors: Schuldt, Andreas; Hönig, Lydia; Li, Ying; Fichtner, Andreas; Härdtle, Werner; von Oheimb, Goddert; Welk, Erik; Bruelheide, Helge
• Is Part Of: Ecology and evolution. Volume 7:Issue 18(2017:Oct.)
• Page Start: 7462
• Page End: 7474
• Publication Date: 2017-08-11
• Subjects: BEF‐China -- biodiversity and ecosystem functioning -- climatic niche -- functional traits -- fungal pathogens -- plant–herbivore interactions; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.3292
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Herbivores and fungal pathogens are key drivers of plant community composition and functioning. The effects of herbivores and pathogens are mediated by the diversity and functional characteristics of their host plants. However, the combined effects of herbivory and pathogen damage, and their consequences for plant performance, have not yet been addressed in the context of biodiversity–ecosystem functioning research. We analyzed the relationships between herbivory, fungal pathogen damage and their effects on tree growth in a large‐scale forest‐biodiversity experiment. Moreover, we tested whether variation in leaf trait and climatic niche characteristics among tree species influenced these relationships. We found significant positive effects of herbivory on pathogen damage, and vice versa. These effects were attenuated by tree species richness—because herbivory increased and pathogen damage decreased with increasing richness—and were most pronounced for species with soft leaves and narrow climatic niches. However, herbivory and pathogens had contrasting, independent effects on tree growth, with pathogens decreasing and herbivory increasing growth. The positive herbivory effects indicate that trees might be able to (over‐)compensate for local damage at the level of the whole tree. Nevertheless, we found a dependence of these effects on richness, leaf traits and climatic niche characteristics of the tree species. This could mean that the ability for compensation is influenced by both biodiversity loss and tree species identity—including effects of larger‐scale climatic adaptations that have been rarely considered in this context. Our results suggest that herbivory and pathogens have additive but contrasting effects on tree growth. Considering effects of both herbivory and pathogens may thus help to better understand the net effects of damage on tree performance in communities differing in diversity. Moreover, our study shows how species richness and species characteristics (leaf traits and climatic niches) can modify tree growth responses to leaf damage under real‐world conditions. Abstract : The consequences of a loss of plant diversity on the combined and potentially nonadditive net effects of herbivores and pathogens on plant performance remain unexplored. We analysed how herbivory, fungal pathogen damage, and their potential interactive effects influence tree growth, and how tree diversity and functional characteristics of the tree species modify this influence. Our findings indicate that biodiversity loss and tree species identity can change the associations between, and the ecosystem response to, different types of plant consumers.