Soil fauna includes a myriad of organisms, ranging from tiny microfauna invertebrates (with body sizes <100 μm) to meso (>100 μm to 2 mm) and macrofauna (>2 mm). Among soil mesofauna, some of the typical invertebrates that represent this group include mites, springtails, and small insects such as psocopterans and Diptera larvae. These invertebrates play a crucial role in decomposition and nutrient cycling by breaking down litter and affecting the activity of soil microbial communities. The communities of soil mesofauna are regulated by different environmental and biotic factors which operate at different scales. For example, the availability of soil organic matter and nutrients determine how much energy is available for fueling these communities. Furthermore, the composition of plant communities determines the amount and quality of organic matter entering the soil, thereby the cover of different life forms can be highly relevant for determining the composition and structure of soil mesofauna communities.
Along an environmental gradient determined by soil properties and plant communities, the authors explored community patterns of soil mesofauna comprising composition, abundance and richness of taxa and feeding guilds, in vegas of the Argentine Puna. Vegas are wetlands distributed from 3200 to 5000 m a.s.l. in the arid Argentine Puna region. As these ecosystems develop in an extremely arid placed, vegas are essential for local communities in these mountain areas, providing fiber and freshwater for raising livestock. Also, these wetlands play a significant role in global climate regulation as their soils have stored large amounts of carbon during decades, even centuries. However, vegas are facing intense pressures from global changes, including raising temperatures due to climate change and land use activities, such as lithium mining. Despite their ecological importance, some gaps in our comprehension of the mechanisms and patterns regulating belowground diversity, especially soil mesofauna, still persists.
The study measured soil properties related to resource quantity (the content of organic matter and nutrients) and quality (the ratio of carbon to nitrogen), and also considered abiotic factors related to soil habitat (soil humidity and acidity/basicity determined by soil pH). In addition, the relative cover of different plant life forms (grasses, graminoids, cushions, etc) was also measured to determine whether the responses of soil mesofauna communities are related to the abundance of these different plant life forms. These variables were measured in 10 vegas along an elevation range of 1425 m (from 3323 to 4748 m a.s.l.).
The study found that mites were the most abundant taxa followed by springtails. In terms of feeding guilds, most vegas were dominated by detritivores. Variation in soil abundance and richness was primarily explained by factors related to food quantity and quality. In addition, soil humidity and the cover of cushion plants also have a positive association with soil mesofauna. However, none of these variables were related to differences in the identity of taxa of soil mesofauna communities between vegas. This work represents a first approach to disentangle the community patterns in the composition and structure of soil mesofauna in Andean wetlands, emphasizing the key role of local environmental variation in shaping these belowground organisms. Also, the results show the importance of cushion plants, important ecosystem engineers, for the maintenance of soil mesofauna abundance and richness in these high elevation wetlands.
Given the ecological significance of vegas, protecting these wetlands is fundamental to sustaining the belowground biodiversity and ecosystem processes driven by soil mesofauna.
DOI
10.1007/s42832-025-0312-4