Short-term microbial responses to soluble inorganic P input in a tropical lowland rain forest in Amazonia

• Published in: Pedosphere Vol. 31; no. 6; pp. 964 - 972
• Main Authors: DE SOUSA, Yuri W.L., BUSCARDO, Erika, QUESADA, Carlos A.N., NASCIMENTO, Henrique E.M., NAGY, Laszlo
• Format: Journal Article
• Language: English
• Published: Beijing Elsevier Ltd 01-12-2021; Elsevier Science Ltd; National Research Institute for Amazonia,Manaus 69067-375(Brazil)%National Research Institute for Amazonia,Manaus 69067-375(Brazil); Department of Forestry,University of Brasilia,Brasilia 70910-900(Brazil); Centre for Functional Ecology,University of Coimbra,Coimbra 3000-456(Portugal)%National Research Institute for Amazonia,Manaus 69067-375(Brazil); Department of Animal Biology,University of Campinas,Campinas 13083-862(Brazil)
• Subjects: Amazon basin; arbuscular mycorrhizal fungi; Arbuscular mycorrhizas; Colonization; Cycles; Dosage; Drought; Forest ecosystems; Leaf litter; Litter fall; Microbiota; Microorganisms; nutrient addition; Nutrients; Phosphorus; phosphorus cycling; Rain; Rainforests; soil microbial biomass; Soil microorganisms; Soils; Symbionts; Terrestrial ecosystems; Tropical forests; phosphorus cycling; Amazon basin; arbuscular mycorrhizal fungi; nutrient addition; soil microbial biomass
• ISSN: 1002-0160; 2210-5107
• DOI: 10.1016/S1002-0160(20)60008-X

In non-flooded lowland rain forests with low soil phosphorus (P) in parts of Amazonia, P cycling largely occurs via leaf litter recycling by arbuscular mycorrhizal (AM) fungal symbionts. Occasional high input of P into these ecosystems occurs during drought years with increased litterfall. As the length and frequency of drought events are projected to increase in the region, a single-dose nutrient addition experiment was carried out to test how this would impact P cycling. An application rate of 4 kg P ha–1 was used, which corresponds to twice the amount of litter-derived P in an average year. It was hypothesized that i) the added mineral P would be immobilized by soil microorganisms, leading to measurable increase in soil microbial biomass carbon (C) and P and ii) AM colonization rate would be reduced by the pulse in mineral P available for plant uptake. The results did not support either of our hypotheses. The addition of P did not have an effect on AM root colonization, nor was P immobilized by soil microbiota during the experimental period. The lack of a difference between the control and treatment at our study site could be attributed to the relatively low one-off dose of P applied that did not change either the colonization rate of roots by AM fungi or the amount of soil available labile P. To obtain a mechanistic understanding of the availability, capture, and use of P by plant-symbiont associations in tropical rain forest ecosystems, further integrated studies of the soil-plant system combining long-term nutrient manipulations, modeling, and experimental approaches are required.