Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning.

The processes of matter and energy metabolism in forest ecosystems are largely dependent on the activity of the complex of invertebrates associated with litter and soil. To quantify the effect of forest harvesting on soil fauna, we used a meta-analysis to examine a database of 720 responses to harvesting collected from 52 publications from boreal and temperate forests. Overall, forest harvesting was found to decrease the abundance of soil fauna while not affecting its richness. However, the reaction of soil fauna to forest harvesting differed significantly among the taxonomic groups, with negative, neutral, and positive effects observed. We found that the negative effect of forest harvesting on soil fauna increased with decreasing body size. In addition, the type of forest and harvesting practice played important roles in driving the responses of soil biota to forest harvesting. The abundance of Nematoda, Oribatida, and Enchytraeidae recovered to control values occurring approximately 10 years after harvesting. Despite the limitations of the dataset, the results obtained from our meta-analysis expand our understanding of the reaction of soil fauna to forest harvesting.