Microbial properties in tropical montane forest soils developed from contrasting parent material—An incubation experiment

Abstract

AbstractBackgroundSoil microbes are key drivers of carbon (C) and nutrient cycling in terrestrial ecosystems, and their properties are influenced by the relationship between resource demand and availability.AimsOur objective was to investigate patterns of microbial properties and their controls to understand whether they differ between soils derived from geochemically contrasting parent material in tropical montane forests.MethodsWe measured microbial biomass C (MBCSoil), potential extracellular enzyme activity (pEEA), and assessed microbial investments in C and nutrient acquisition at the beginning and end of a 120‐day laboratory incubation experiment using soils developed from three geochemically contrasting parent material (i.e., mafic, mixed sediment, and felsic) and three soil depths (0–70 cm).ResultsWe found that MBCSoil and pEEA were highest in soils developed from the mafic parent material. Microbial investment in C acquisition was highest in soils developed from mixed sedimentary rocks and lowest in soils developed from the felsic parent material. We propose that our findings are related to the strength of contrasting mineral‐related C stabilization mechanisms and varying C quality. No predominant microbial investment in nitrogen (N) acquisition was observed, whereas investment in phosphorus (P) acquisition was highest in subsoils. We found lower microbial investment in C acquisition in subsoils indicating relatively high C availability, and that microbes in subsoils can substantially participate in C cycling and limit C storage if moisture and oxygen conditions are suitable. Geochemical soil properties and substrate quality were important controls on MBCSoil per unit soil organic C (MBCSOC), particularly after the exhaustion of labile and fast cycling C, that is, at the end of the incubation.ConclusionAlthough a laboratory incubation experiment cannot reflect real‐world conditions, it allowed us to understand how soil properties affect microbial properties. We conclude that parent material is an important driver of microbial properties in tropical montane forests despite the advanced weathering degree of soils.