Water redistribution via mycelia networks of saprotrophic fungi
P 1.2 in From Cradle to Reality: Research Ideas at the Beginning
Summer droughts are common in temperate forests and especially upper soil horizons experience soil drought. Drought events can be accompanied by negative effects for forest ecosystems but many plants have the ability to reduce the impact of drought by hydraulic redistribution (HR). HR is a passive relocation of water driven by a gradient in soil water potential via the root system. Similar processes were recently described for ectomycorrhizal networks but no information is available for mycelia networks of saprotrophic fungi. They strongly contribute to belowground nutrient cycling, C and N mineralization.
We hypothesize that water relocation via saprotrophic fungi is a common phenomenon in soil and that relocated water is of relevance for mineralization under drought conditions.
To test the hypothesis that mycelia networks of saprotrophic fungi contribute to water relocation in soil we conduct experiments using specific mesocosms consisting of two chambers, separated by a 2 mm air gap to prevent bulk flow of water. One chamber will be inoculated with plugs of fungal cultures and experiments will be started when an appreciable mycelia growth is detectable in both chambers. After desiccation of the chambers, one chamber will be irrigated with deuterium and florescent labelled water. At the end of the experiment, soil samples as well as hyphae will be analysed for stable isotope content and fluorescent labelling, respectively. A negative control will be provided by a second set of mesocosms in which hyphal connections between the compartments will be severed before starting the drought experiment.