Arbuscular Mycorrhizal Fungal Communities Pushed Over the Edge – Lessons from Extreme Ecosystems

Abstract

The diversity and structure of soil microbial communities are crucial elements in understanding the ecological impacts of rapidly changing environments. One important group of soil microbes is the ubiquitous plant symbiotic arbuscular mycorrhizal (AM) fungi. Their diverse communities are shaped by complex interactions of their abiotic and biotic environments. Locally extreme ecosystems have proven to be useful for natural long-term experiments in the ecology and evolution of AM fungi, giving an insight into much-needed processes of adaptation and acclimation of natural communities to abiotic stress. For example, data from natural CO2 springs (mofettes) show that when exposed to extreme long-term stress (soil hypoxia and elevated soil CO2 concentrations) specific and temporary stable AM fungal communities form with a high abundance of specialised, stress-tolerant taxa. Moreover, in both natural– and human-impacted ecosystems there are several such cases. This chapter covers a wide range of extremes (abiotic stresses) in the pedosphere, from high to low temperatures, drought and floods, hypoxia, salinity, and soil pollution. An overview of several specific stressed environments where AM fungal community ecology has been studied is presented. In some of these cases, locally extreme environments have already been used and could further serve as a powerful tool to study slow ecological and evolutionary processes that normally require long-term observations and experiments to study them.