Microbial influences on forest responses to climate change
We have been studying tree interactions with rhizosphere microbial communities for several years. Our central questions are 1) Are tree populations adapted or maladapted to their local microbial communities, and what consequence does this adaptation have for gene flow among populations in response to climate change, 2) Can microbial communities impede or accelerate the establishment of tree populations in novel sites, as is necessary for successful tracking of shifting climates, and 3) Can alterations to soil microbial communities provide unexpected climate tolerance to vulnerable tree populations, but substituting traits of the rhizosphere community in place of traits in the tree hosts? To date we have found that disrupting historical relationships between plants, microbial communities, and abiotic soil conditions can all have consequences for seedling growth. We are currently expanding our efforts with funding from the NSF CAREER program, and will be studying tree adaptation and microbial interactions in field settings throughout Wisconsin and Illinois.
We are particularly interested in the role of mycorrhizal fungi in determining forest resposnes to changing climates. Temperate forest tree species tend to form one of two types of mycorrhizal fungal symbioses, arbuscular or ecto-mycorrhizae. We are interested in the ecosystem consequences of these two alternative strategies, and the potential for positive and negative demographic feedbacks at the guild level to structure forests and determine their resistance to climate induced changes. With our colleage Nina Wurzburger at the University of Georgia, we have found that forest stands with a higher dominance of ectomycorrhizal tree species tend to have higher ratios of carbon to nitrogen in their soil. Additionally, we have found that during past and contemporary climate warming, ectomycorrhizal tree species have tended to show greater tolerance to novel climates at their southern range boundary. With Cassandra Allsup (see People), we are currently testing experimentally if dominance by EM or AM tree species creates conditions more conducive to EM or AM tree seedlings, which could create positive feedbacks that entrench the dominant mycorrhizal type, while allowing turnover of tree species within these guilds.
Microbial communities and soil health in agroecosystems
Soil microbial communities are essential to providing the key functions in a healthy soil: cycling nutrients and making them available to plants, modifying soil structure to make water more persistent and accessible, and suppressing soilborne plant pathogens. We are investigating how the structure and diversity of soil microbial communities in potato fields in Wisconsin relates to their ability to provide these functions to crops. In particular, we are interested in whether we see trade-offs or synergies in the provisioning of multiple functions (ecosystem multifunctionality), and what community structures lead to these outcomes. Our work to date suggests that ability of microbial communities to suppress disease and promote high yields may trade-off, but, as in many ecological systems, maintaining high diversity may be key to combining multiple functions. We work closely with numerous Wisconsin potato growers, as well as the Wisconsin Potato and Vegetable Grower’s Association and the vegetable crops extension team at UW to ensure that our research aligns with grower needs and interests, and benefits from grower participation throughout the process.
In addition to our main projects on potato soil health, we are also investigating how potato – microbial community interactions have evolved during the domestication of the crop, and how rhizosphere microbial structure responds to oat genotypes (in collaboration with Lucia Gutierrez). With these projects, we hope to set the stage to understand how past crop breeding has changed a crop’s ability to benefit from is associated microbial communities, and potentially develop breeding strategies to enhance these benefits for low-input conditions.
For an up to date list of our publications, click here: