Short-term modifications of mycorrhizal fungi, glomalin and soil attributes in a tropical agroforestry

Abstract

Arbuscular mycorrhizal fungi (AMF) community and the Glomalin-related soil protein (GRSP) they produce plays important roles in maintaining soil ecosystem functions, promoting ecological restoration, and are important for monitoring changes in soil health from land use change. This research addressed the subtle modifications of AMF and GRSP in different land use types and their association with soil properties. Our objectives were: 1) to assess land use effects on AMF spore density, diversity, and composition besides glomalin fractions (EEG, easily extracted GRSP; TG, total GRSP), and 2) to quantify the relationships between glomalin, AMF community metrics, soil organic carbon (SOC), and key soil quality parameters. Soils were collected in the dry and rainy seasons of 2018 under five land uses, including: three types of agroforestry systems (AS1, AS2 and AS3), an unmanaged pasture and a secondary forest in the state of Rio de Janeiro, Brazil. Linear mixed-effects model and multivariate analyses showed that land uses had influenced the AMF community, meanly at the family level. On the other hand, seasonality has not proved to be an essential factor that modulates the changes of the AMF community and glomalin production. The management practices had influenced AMF sporulation and the number of total species in agroforestry systems. Glomalin is a potential contributor for SOC, mainly in agroforestry systems and pasture plots. Moreover, we found a correlation between the AMF community and key soil parameters. For example, most of the AMF families and spore density were positively correlated with the stability of soil aggregates and SOC. Our findings shed light on that land-use change can shift the AMF community, glomalin and their relationship to key soil quality parameters. Moreover, the adoption of agroforestry systems indicates maintenance of biodiversity and other soil quality parameters with future implications for their use to recover degraded areas.