Alpine flower meadows are iconic landscapes of mountain regions. Their beauty and diversity depend not only on what is visible aboveground, but also on the health of the soil beneath them. Healthy soils provide essential ecosystem services, including nutrient cycling, plant productivity, carbon storage, and water regulation. A key component in maintaining healthy soils is a hidden community of small soil-dwelling organisms such as springtails and mites. Although only a few millimetres in size, these arthropods play an important role in breaking down organic matter, regulating microbial communities and distributing nutrients. Understanding how these organisms respond to environmental change is therefore crucial for predicting the future functioning of alpine ecosystems.
Climate warming and biodiversity loss are two major challenges affecting mountain regions. While the direct effects of warming on plants and animals have been widely studied, much less is known about how warming interacts with changes in aboveground biodiversity to affect life belowground. Because plants, insects, microorganisms, and soil animals are connected through complex ecological relationships, changes aboveground can influence how soil communities respond to warming in unexpected ways.
To investigate these effects, we conducted a field experiment in alpine grasslands around Davos. We simulated future warming conditions using open-top chambers made of acrylic glass and we experimentally reduced selected groups of aboveground organisms through targeted exclusion treatments. Thousands of soil arthropods were subsequently collected from the experimental plots. To accelerate the time-consuming sorting and trait measurements, we used image-based machine-learning alongside manual identification. This enabled us to quantify changes in abundance, community composition, body size, and pigmentation of soil arthropods.
We found that warming alone had only limited effects on soil arthropods such as springtails. However, when warming was combined with the reduction of aboveground insects, springtail numbers more than doubled. This suggests that the effects of climate change on soil life depend not only on temperature itself but also on the structure of the surrounding food web. The experimental treatments also altered the composition of soil communities and shifted springtail characteristics towards smaller and less pigmented individuals. These characteristics are typically associated with species living deeper within the soil, indicating that environmental change may influence how soil communities are structured and how they interact with their environment. Together, this suggest that climate change and biodiversity loss can influence not only the number of organisms living in the soil, but also their ecological roles and the services they provide.
Our results show that responses to climate change cannot be understood by looking at individual environmental factors in isolation. Instead, changes above- and belowground are closely connected, and biodiversity loss can modify the effects of warming. As global change progresses in mountain regions, understanding these hidden changes belowground will be increasingly important for conserving the biodiversity, ecosystem functions, and flower-rich alpine grasslands that characterize landscapes in Davos and across Graubünden.