The threat-work: a network of potential threats to soil biodiversity.

Soils are estimated to contain more than half of the biodiversity on our planet, encompassing a rich spectrum of genes, organisms and functions that play a crucial role in many ecological processes, such as nutrient cycling, organic matter decomposition, and the creation of a well-structured soil matrix. However, soils encounter many threats that significantly challenge their functionality and biodiversity. The FAO Report on the State of Knowledge of Soil Biodiversity identified 12 primary threats to soil and soil biodiversity, highlighting regional and unique ecozonal perspectives. Most threats to soil come from anthropogenic land use activities and management practices associated with intensive agriculture, livestock, forestry, and other resource extraction activities, as well as industrial activities, infrastructure and urbanization, which vary in strength across various regions and ecozones. However, these threats are highly interconnected and often culminate in losses to soil organic matter (SOM) and soil organic carbon (SOC) also considered a threat itself –– that drives changes in physical, chemical and biological attributes of the soil environment that lead to soil biodiversity loss. We conceptualize these interlinked threats as a threat network or ‘threat- work’, where the loss of SOM plays a pivotal role. Addressing this threat-work requires a mechanistic understanding of how soil biodiversity loss occurs across diverse landscapes and ecozones. SOM is essential for creating a favorable environment for soil biodiversity by enhancing nutrient availability, water retention, and soil structure. Losses in SOM, closely tied to the mechanisms of soil biodiversity loss, alter physical, chemical, and biological soil attributes, leading to biodiversity decline. Such knowledge can identify priority areas for restoration and inform best practices to conserve soil biodiversity. Protecting and enhancing SOM is central to these efforts. By disentangling the drivers of soil biodiversity loss and their interactions within this threat network, we can develop holistic strategies to mitigate soil biodiversity loss, safeguard soil health, and ensure the sustainability of soil ecosystems globally.