Maintaining Ecosystem Function Under Climate Change: Understanding and Managing Plant-Soil Microbe Community Dynamics

EPA Grant Number: F13B20426
Title: Maintaining Ecosystem Function Under Climate Change: Understanding and Managing Plant-Soil Microbe Community Dynamics
Investigators: Gravuer, Kelly Lynn
Institution: University of California - Davis
EPA Project Officer: Packard, Benjamin H
Project Period: September 29, 2014 through September 29, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Ecology

Objective:

Current and predicted changes in climate are likely to affect many of the ecosystem services that support people’s quality of life, including water purification, soil fertility and forage production. By improving the ability to predict effects at the local and landscape levels, mitigation and adaptation actions can be targeted to more effectively maintain these services. Focusing on ecologically important California grasslands, this research asks several questions: (1) How will predicted precipitation change affect the ecosystem functions that support critical ecosystem services? (2) Does soil type or nutrient status need to be considered in landscapescale predictions of these effects? (3) Do the functional traits of the co-occurring soil microbial and plant communities that provide these ecosystem functions respond similarly to climate change? To what degree might they be decoupled by predicted changes?

Approach:

Precipitation manipulations have been implemented across a northern California grassland, and this research measures ecosystem functions, including decomposition potential (soil enzyme activity), nitrogen mineralization, nitrification and soil carbon storage. Experimental treatments have been replicated across three distinct soil types and crossed with a nutrient addition treatment to investigate the sensitivity of ecosystem functional responses to these factors. The project will explore potential mechanisms of these impacts using a plant-microbial functional trait framework. Specifically, it assesses soil microbial community composition with DNA-based approaches and estimates a functional trait of bacteria (resource response as indicated by rRNA gene copy number) using phylogenetic methods. These data will be compared to corresponding plant community measures to determine response similarity and decoupling.

Expected Results:

All of the measured ecosystem functions are expected to be greater in wetter plots, although different pathways of organic matter decomposition (activities of different soil enzymes) may not all be affected equally. The magnitude of these responses is likely to depend significantly on soil type and nutrient status, such that characterizing these dependencies should improve the ability to predict landscape-level changes in ecosystem functions. Soil microbial functional trait responses will likely be similar in direction to those of plant communities, but more temporally variable, with greater responses at times of greater soil moisture effects. This result may highlight the importance of changes in the timing and magnitude of precipitation for soil communities, to a degree that would not be apparent from aboveground observations.

Potential to Further Environmental/Human Health Protection

This work should improve the ability to predict the impact of climate change on key ecosystem functions and services, such as nutrient cycling and plant productivity, in California’s grasslands. In addition, employing a functional trait framework to understand plant and microbial responses will facilitate the use of these results to understand potential responses of other ecosystems. Ultimately, this research will highlight where efforts to mitigate and/or adapt to these effects can best be focused to maintain the ecosystem services on which people depend.

Supplemental Keywords:

climate change, grasslands, ecosystem function

Progress and Final Reports:

  • 2015
  • Final