SUP:RHIZE | Supply mechanisms of phosphorus in the rhizosphere in tropical soils – interactions of plants and microorganisms

The Amazon rainforest stores large amounts of carbon in plant biomass and in soils, and is an important sink for atmospheric CO2 setting off increased emissions from anthropogenic fossil fuel combustion and land use change. However, in large parts of the Amazon Basin plant productivity appears to be controlled by soil phosphorus availability, which could constrain the forest’s capacity to sequester more CO2 from the atmosphere.

Plants have developed multiple strategies to optimize nutrient acquisition from the soil to avoid phosphorus limitation – involving strong competition or tight cooperation with soil microorganisms. Yet, the scarcity of observations and the small scale, where plant-microbe interactions and microbe mediated nutrient cycling are occurring, currently constrains a quantitative upscaling of the prevailing strategies.

Within the SUP:RHIZE project I want to investigate plant and microbial interactions in rhizospheres of a tropical rainforest in Central Amazonia growing on highly weathered and phosphorus depleted soils. Using state-of-the art analytical methods and a combination of field, laboratory and modeling experiments, I aim to disentangle mechanisms that are facilitating phosphorus supply for plants and microbes by:

  • inquiring the influence of fine roots on the fate of phosphorus during leaf and root litter decomposition
  • identifying major phosphorus fluxes in the soil and characterizing microbial groups being responsible for soil phosphorus mineralization
  • tracing the fate of labile plant carbon inputs in the soil and their effect on phosphorus dynamics at the rhizosphere scale in tropical forest soils.
  • to estimate C use and C costs that are  involved in competition and cooperation between plants and microbes in the rhizosphere.
  • Laynara F. Lugli and C. Alberto Quesada (INPA, Manaus, Brazil) and the AmazonFACE program
  • Anja Rammig and Katrin Fleischer at the chair of LSAI (TUM, Freising, Germany).
Investigated by:



Fine roots in a decomposing tree branch at the AmazonFACE field site © Lucia Fuchslueger