Tropical forests are central to the global carbon cycle, but it is unclear, if they can maintain their C sink function under increasing atmospheric CO₂ concentrations. Processes in the rhizosphere - a key interaction zone of plants, soil minerals and microbes - could be crucial for regulating transfer and long term storage of carbon from plants to soils. 

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RHIZ:SOM investigates how elevated atmospheric CO₂ influences soil organic matter (SOM) dynamics in tropical forest rhizospheres, with a focus on plant–microbe interactions, carbon stabilisation, and nutrient cycling.

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The project aims to:

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(i) quantify root exudation and its response to eCO₂;

(ii) determine effects on rhizosphere microbial activity and nutrient cycling; and

(iii) identify how rhizosphere processes regulate SOM transformation under elevated CO₂.

 

RHIZ:SOM will use the unique AmazonFACE free-air CO₂ enrichment experiment in a mature tropical forest in Central Amazonia. The project will use state-of the art methods to quantify plant-derived C inputs, microbial activity and C and nutrient cycling, including stable-isotope probing and root-trait analyses, as well as to partition plant, fungal and microbial contributions to SOM formation and persistence. This will provide mechanistic evidence on tropical soil C–climate feedbacks, improve predictions of soil C responses to future CO₂ scenarios, and generate benchmark data for ecosystem models.

 

The RHIZ:SOM project is funded by the Austrian Science Fund, and will be conducted in collaboration with researchers from the National Institute of Amazon Research and University of Campinas in Brazil. 

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