Synergistic global change impacts on belowground biodiversity and carbon stocks in mountain ecosystems.

Soil is one of the most complex and important resources on earth. It harbours vast biodiversity that underpins an array of ecosystem functions. Soil also stores more carbon (C) than the Earth's atmosphere and vegetation combined.

However, soils are facing multiple challenges globally that threaten to cause soil biodiversity loss, reduce ecosystem functioning, and diminish the capacity of soils to store C. Understanding how soil biodiversity and soil C stocks will respond to the combined effects of global environmental changes remains extremely challenging. Much of our past understanding is based on studies of single factors that fail to incorporate the complexity of the system and interactions of its component parts. Currently we know little about synergistic effects. Synergistic effects arise when the impact of two or more factors acting together cannot be predicted from their individual impacts. These unforeseen effects can lead to sudden and catastrophic losses in biodiversity and soil C.

Mountain ecosystems occur at all latitudes, are hotspots of biodiversity, and store significant amounts of soil C. However, they are very vulnerable to global environmental change. They are warming twice as fast as the global average, leading to upward shifts in vegetation, and increased extremes of drought and flooding. At the same time, agricultural and industrial pollution are overloading fragile mountain ecosystems with too much nitrogen (N), which can have negative effects one ecosystem processes. Synergistic effects are a particularly pressing knowledge gap in mountain ecosystems, where even fundamental data on soil microbial diversity, functioning, and soil C stocks are lacking.

During this fellowship, I will address the knowledge gap on belowground biodiversity in mountain soils and how this critically underpins C-cycling processes. I will determine how soil biodiversity and functioning respond to multiple drivers of global change, establish if there are synergistic effects, and what the consequences of these synergistic effects are for soil C stocks in mountain ecosystems worldwide