Global gaps in soil biodiversity data

 Soil biodiversity represents a major terrestrial biodiversity pool, supports key ecosystem services and is under pressure from human activities1. Yet soil biodiversity has been neglected from many global biodiversity assessments and policies. This omission is undoubtedly related to the paucity of comprehensive information on soil biodiversity, particularly on larger spatial scales. Information on belowground species distributions, population trends, endemism and threats to belowground diversity is important for conservation prioritization, but is practically non-existent. As a consequence, much of our understanding of global macroecological patterns in biodiversity, as well as mapping of global biodiversity hotspots, has been based on aboveground taxa (such as plants2) and has not considered the functionally vital, but less visible, biodiversity found in soil.

 

We mapped the study sites from existing global datasets on soil biodiversity (soil macrofauna3, fungi4 and bacteria5) to examine key data gaps (Fig. 1). Our map indicates significant gaps in soil biodiversity data across northern latitudes, including most of Russia and Canada. Data are also lacking from much of central Asia and central Africa (for example, the Sahara Desert), as well as many tropical regions. The higher density of soil biodiversity sampling sites in Europe and the United States is similar to patterns observed for data on terrestrial bird, mammal and amphibian species6, as well as plants7. Yet, in such aboveground datasets, the gaps in understudied regions are much less pronounced than in the soil biodiversity datasets shown here. The comparative lack of soil biodiversity data across these regions limits our ability to examine global macroecological patterns and to quantify potential mismatches between aboveground and soil biodiversity. The potential for such mismatches (areas with high aboveground diversity, but low soil biodiversity, or vice versa) may be substantial, as evidence suggests that plant species richness declines more rapidly towards the North Pole than fungal species richness, which reaches a plateau.