Collaborative Research: Microbiome mediation of multi-trophic interactions in a tree diversity experiment

Sometimes referred to as the great unseen, plant-associated bacteria and fungi are hidden yet potentially pivotal components of ecosystems. Although the global leaf surface area is more than double the surface area of the earth, the drivers and functions of leaf microbes are still mostly unknown, particularly for trees. Because forests provide ecosystem services to humans, including climate mitigation, timber production, nutrient retention, water filtration, and habitat for diverse plants and animals, understanding the role of plant-associated microbes in forests is critical. Forests that house a diverse mixture of many tree species may be more productive than stands with only a single tree species, in part because of their interactions with microbes. However, natural forests are losing diversity worldwide, and nearly all forest plantations and restorations are planted as single species stands. This research project explores the value of forest biodiversity, including trees and their associated microbes, by linking the effects of tree diversity to leaf chemistry and the associated communities of leaf microbes, root microbes, and insects. By determining whether and how tree and microbial diversity affects important ecological functions like tree productivity, this project will help determine best practices for sustainable forests and silvicultural plantations. Additional project impacts include engagement with invested stakeholders through workshops, the development of a field-based “Bugs and Microbiomes” educational module, and training opportunities for undergraduate interns, graduate students, and post-doctoral researchers. The overarching goal of this project is to predict the effects of microbes on tree productivity during the critical canopy closure stage of forest establishment. Researchers will utilize a large scale (32 acres) tree biodiversity experiment established in 2013 in Edgewater, Maryland, USA. Specifically, the project will track how tree species diversity affects above and belowground microbial diversity, while simultaneously characterizing leaf chemistry, insect communities and damage, and tree productivity. Targeted laboratory experiments will further determine the strength and directionality of the relationships observed under field conditions. Finally, a quantitative modeling approach will be used to link project components to determine their individual and combined effects on tree productivity. The results will provide a model for understanding how changes in multiple components of plant diversity ultimately influence plant productivity over time. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.