Into the soil labyrinth: soil physical structure as a driver of trophic interactions and soil biodiversity

The high diversity of densely packed organisms occurring in small volumes of soils has long been intriguing and we still poorly understand what drives such diversity. Exploring the role of small scale physical structure of the soil, constituting the habitat of these organisms offers unprecedented clues for explaining how organisms interact, notably through trophic interactions and how, in turn, these interactions drive this extraordinary diversity. We review here how restrictions on soil organisms’ ability to sense (e.g. volatiles) and access food resources/prey imposed by the soil physical structure and aqueous habitats within are important drivers for trophic interactions, and consequently, of soil biodiversity. Examples from micro- to macrofauna are presented, focusing on organisms unable to create their own pore space, such as bacteria, fungi, protists, nematodes and microarthropods. Finally, we discuss interdisciplinary challenges to develop research merging soil physics and soil food web ecology.