Soils are increasingly recognized as complex systems, emphasizing the need to study properties such as long-tailed scaling laws and the role of indirect interactions among arboreal soil invertebrates. However, few studies consider the above-below-ground connections mediated by invertebrate activity. Given previous work showing that arboreal ants can affect ground foragers as well as alter foraging behavior on different host trees, it is plausible that ground ant exclusion mediated by persistent above-ground ant nesting could affect soil properties including structure and chemistry. This study analyzes soil aggregation, water infiltration, and macro-chemical data associated with longer-term arboreal ant nesting in tropical agroforest. Results show that, 1) ant nesting maintained scaling law exponents or fractal dimensions of soil aggregate size distributions, and was significantly associated with larger micro-aggregate diameters and log-normal variance in macro-aggregate size distributions, suggesting more consistent aggregation processes similar to host tree effects; 2) areas around trees with dominant ant nests had three-times faster water infiltration than areas around trees without dominant ant nests; and 3) changes in soil carbon and nitrogen stocks by one-quarter depending on host tree. These patterns are consistent with expected effects of ground ant suppression by a keystone arboreal ant, and are supported by previous studies reporting positive ground ant nest effects on soil chemistry and documenting ground ant foraging as a source of soil aggregate fragmentation. This study presents new ecological processes affecting ecosystem-scale functions, and underscores the need for research on indirect interaction cascades to advance fundamental understanding of whole-ecosystem processes.
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