PROJECT PROFILE: Fungal Diversity in Response to Nitrogen Deposition and Soil Warming

By Samuel Perez

Hello everyone, my name is Samuel Perez and I am working on microbial communities at Harvard Forest with Professor Anne Pringle from Harvard University. I am a rising senior majoring in Organismic and Evolutionary Biology.

This summer, I am working with decomposer fungi in the Chronic Nitrogen Plots and the Soil Warming Plots in Barre Woods. My project at the Harvard Forest is to study the effects of nitrogen deposition and soil warming on the species diversity of decomposer fungi.

The process of decomposition is important because it allows nutrients sequestered in living organisms to return to the soil to be used by other organisms in building their physical structures and powering up chemical processes. If everything living continued building matter without breaking things down, the Earth would run out of basic nutrients required for building new things. Part of the microbial community provides the essential ecological benefit of breaking down dead organic matter to feed themselves, and in doing this, they release nutrients back into the soil to be used in other terrestrial processes. Microbial communities that are involved in the process of decomposition include bacteria, protists and fungi, and my particular interests lie with the last of these.

Harvard Forest provides many great opportunities for studying global change, and in the umbrella of global change, factors like global warming, nitrogen deposition, soil warming and other large-scale changes will be important in predicting the future of Earth's ecosystems. These large scale changes have been implicated in potential decreases in species diversity across many different types of organisms, and the Pringle lab want to see if species diversity in the decomposer community could decrease as a result of global change.

Decomposer fungi provide a good system for studying global change because unlike most microbial communities, they produce readily-visible fruitbodies, which is a clear advantage in biodiversity studies. This summer, I have been collecting all the fungal fruiting bodies I can find and culturing them at the Torrey Lab's microbial facilities. Later in the summer we will do a species identification for them. We will record the species diversity of plots with nitrogen deposition (control, low nitrogen deposition, high nitrogen deposition) and with soil warming (control, +5 C above ambient temperature).

We predict that we will see fewer species of decomposer fungi in plots with excess nitrogen in the soil and with warmer soils, but the negative effects will be disproportionate, with some groups able to adapt to their environments while others will be unable to grow in the manipulated conditions or be at a disadvantage.

The project will form part of my senior thesis and will be used by the Pringle Lab and the Frey Lab at the University of New Hampshire in their long-term studies of microbial communities in the soil.