Forest management modulates the relationship between soil aggregation, carbon, and glomalin in Caatinga dry forest

Abstract

The Caatinga is the world’s largest continuous tropical dry forest, but has historically been subjected to intense anthropogenic pressures. Consequently, sustainable forest management has become a key strategy for reconciling conservation with the use of forest resources, yet its effects on the mechanisms responsible for soil organic carbon (SOC) stabilization in this ecosystem remain poorly understood. We hypothesize that increasing forest management intensity progressively impairs the mechanisms underlying SOC stabilization, particularly soil aggregation and glomalin accumulation, leading to lower SOC stocks. Thus, we evaluated three forest management practices (clear-cutting - CC, selective cutting by diameter - SCD, and selective cutting by species - SCS) to test this hypothesis, with unmanaged Caatinga (UC) as a control. Soil samples were analyzed for aggregate size classes (>6, 6–4, 4–2, and <2 mm), morphological classes (biogenic, physiogenic, and intermediate), SOC, glomalin, and arbuscular mycorrhizal fungi (AMF) community attributes. Forest management practices established a canopy openness gradient, with increasing values in the SCS (~9%), and through the SCD (19.63%) to the CC (57.33%) management systems. AMF spore abundance and average species richness were consistently higher in managed treatments, increasing by more than 65% relative to UC. SOC stocks were maintained in the SCS, with similar values to the control (30.23 Mg ha⁻¹), while CC and SCD reduced these stocks by approximately 19% (25.12 Mg ha⁻¹). Biogenic aggregates predominated in all treatments (78.49%), with an increase in managed systems, while total glomalin content was reduced by management (18.14 mg g⁻¹) compared to the UC (25.85 mg g⁻¹). Overall, CC had the strongest negative effects on canopy cover, litter dynamics, and SOC stocks, whereas SCS maintained soil conditions closer to those of UC. Despite SCD’s intermediate level of vegetation removal, it showed more similar soil carbon responses to CC. Forest management influenced SOC through indirect pathways linking canopy openness and soil moisture to AMF spore abundance, glomalin, soil aggregation, and aggregate-associated C, showing that SOC responses resulted from interconnected above- and belowground processes.

The authors' abstract, as published at the source. Forest Ecology and Management, 2026 · DOI ↗