The hidden half of ecosystem responses to climate change: what happens belowground?

Christine V. Hawkes, University of Texas at Austin

Abstract

Our goal is to understand how soils and soil microorganisms will respond to climate change and how these responses will feedback to ecosystem carbon cycling. Saprophytic fungi responsible for decomposition and mycorrhizal fungi that transfer carbon from above- to belowground are likely to be the dominant biotic drivers behind the amount of soil carbon released to the atmosphere, with recent work suggesting that both types of fungi can respond independently of plants. A broad evaluation of climate change effects on soil fungi is integral to predicting future soil carbon storage and loss and may facilitate mitigation strategies.

We will ask three key questions:

1. How do roots and fungi respond to predicted changes in precipitation and temperature?
2. How do belowground responses to climate change affect soil carbon balance?
3. Are mycorrhizal fungi adapted to local climatic conditions such that fungal communities could be manipulated to facilitate carbon storage under projected climate scenarios?

To do this, we will use three approaches:

1. Determine functional responses of plant roots and soil fungi to altered precipitation with field manipulation of precipitation at the community level;
2. Determine response mechanisms and identify target fungi with greenhouse manipulation of precipitation and temperature at the species level;
3. Examine broader regional patterns of response by sampling plant roots and soil fungi in other ongoing field experiments manipulating temperature and precipitation.

The manipulative field experiment will be set up at the UT Ladybird Johnson Wildflower Center in Austin, TX in an area designed for public education (other experiments already include semiarid green roof physiology and turfgrass species leaching). The greenhouse experiments will be set up in the UT greenhouse facility using both walk-in incubators and glasshouse benches. Sites to be sampled for broader regional patterns are grassland ecosystems that are part of the PrecipNet network.

This research will provide the information needed to quantitatively assess how belowground responses, particularly soil fungal responses, will alter soil carbon cycling under projected future climate scenarios. Ultimately, we hope this work will lead to the development of simple strategies for manipulating fungi to increase carbon sequestration in soil, such as ‘high sequestration’ fungal amendments.