Glomalin production in Atlantic Forest: Effects of soil properties and plant families

Abstract Glomalin, a glycoprotein produced by arbuscular mycorrhizal fungi (AMF), contributes to soil aggregation, carbon sequestration, and nutrient cycling. We present the first comprehensive assessment of environmental factors associated with glomalin availability, measured as easily extractable (easily extractable glomalin‐related soil protein [EE‐GRSP]) and total glomalin (total glomalin‐related soil protein [T‐GRSP]), in Atlantic Forest reference ecosystems within the Rio Doce watershed, Minas Gerais, Brazil. Across 225 plots in riparian forests spanning five regions (Mariana, Rio Casca, Ipatinga, Conselheiro Pena, and Aimorés), EE‐GRSP was more responsive to local variation, peaking in Mariana, whereas T‐GRSP varied numerically but did not differ significantly among regions. Nine soil attributes influenced glomalin fractions. Carbon and manganese were positively associated with both fractions, whereas coarse sand showed negative associations. Potassium and calcium were positively related only to T‐GRSP, while aluminum was negatively associated with this fraction. Iron and fine sand were positively associated with EE‐GRSP, whereas clay showed a negative association with EE‐GRSP. Plant diversity was positively correlated with EE‐GRSP, underscoring ecological links with mycorrhizal‐related processes. Myrtaceae and Fabaceae emerged as families strongly associated with glomalin deposition, suggesting that mycotrophic species tend to occur in sites with higher glomalin‐related soil protein contents. In contrast, forest cover at broader landscape scales was not significantly related to glomalin availability, suggesting that vegetation composition may be more important than extent. These findings identify glomalin as a sensitive indicator of soil–plant associations in tropical ecosystems and emphasize its potential to inform restoration strategies that consider AMF host species and favorable soil conditions.