Environmental change has direct impacts on plants since plant growth depends on factors like nitrogen, temperature, and drought. However, environmental change can also have ?indirect effects?, by altering the abundance of co-occurring species that either positively or negatively affect the plant being studied. While indirect effects through plant competitors and animal herbivores have been well studied, indirect effects via microbes (including fungi and bacteria) have received little attention. A vast array of microbes inhabits all plants, and they have a variety of effects: some microbes cause disease while others are beneficial and promote plant health. Environmental change may alter the amount of disease-causing or beneficial microbes, which will have consequences for plant growth via indirect effects. This project will assess linkages among environmental change, microbes, and plants in the alpine tundra in the Rocky Mountains. A deeper understanding of how microbes will be affected by changing environmental conditions, and implications for plant growth in the future, is important for managing our natural resources. This is especially true in the Rocky Mountains, a much-loved tourist destination that supports a lot of wildlife. This work may also lead to identification of plant diseases that may increase in the future, or beneficial microbes that may be useful for restoration. This project includes training opportunities for graduate and undergraduate students as well as outreach to middle school students and teachers.
To test how environmental change may influence microbial communities and plant growth, the researchers will measure plant performance (growth, flower production) and microbes abundance and diversity (in soil and plant roots) in: 1) a field survey across different environments in the alpine tundra encompassing cool/wet to warm/dry conditions and 2) a field-based experiment that manipulates growing season length and temperature. Path analysis will be used to evaluate direct vs. indirect effects of environmental change on plant performance. The survey and experiment are replicated across a range of environmental conditions in the alpine in order to assess whether the strength and direction of indirect effects vary across a heterogeneous landscape. To understand mechanisms that alter microbial community composition and diversity, the researchers will measure abiotic (e.g., soil moisture, snow depth) and biotic (e.g., plant stress) factors in the survey and experiment and relate them to microbial community structure. Functions of important microbial players in this system will be explored by classifying microbes as pathogen, mutualist, or decomposer using existing databases, and by measuring the function of some microbial taxa using culture-based lab inoculation experiments.
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.
