Soil micro- and mesofauna as drivers of microbial necromass dynamics

Projektinformationen

Soil Fauna MIND

ID Finanzhilfevereinbarung: 101105509

DOI

10.3030/101105509

Projekt abgeschlossen

EK-Unterschriftsdatum 21 April 2023

Startdatum 1 September 2023

Enddatum 28 Februar 2026

Finanziert unter

• Marie Skłodowska-Curie Actions (MSCA)

Gesamtkosten

Keine Daten

EU-Beitrag

€ 211 186,42

Koordiniert durch

KONINKLIJKE NEDERLANDSE AKADEMIE VAN WETENSCHAPPEN - KNAW
Netherlands

Periodic Reporting for period 1 - Soil Fauna MIND (Soil micro- and mesofauna as drivers of microbial necromass dynamics)

Berichtszeitraum: 2023-09-01 bis 2026-02-28

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

Soils hosts the majority of biodiversity and are the largest terrestrial carbon reservoir. Soil carbon cycling is driven by the decomposition and utilisation of organic matter by soil organisms. Current conceptual frameworks and models focus on the role of soil microorganisms (fungi and bacteria) while the role of bigger organisms, the fauna, is currently overlooked.
My MSCA project aims at advancing our understanding of the mechanistic role of soil micro- and mesofauna in soil carbon cycling and soil organic matter dynamics. By manipulating the composition of microarthropod communities, my goal is to determine how the loss of specific organism groups resulting from global changes can influence soil carbon cycling.
The objectives of this project are:
- to develop a method to separate different soil microarthropod groups (slow decomposers, fast decomposers, predators) for subsequent experiments
- to determine how the structure of soil microarthropod communities (and the loss of these specific groups) influences soil carbon cycling.
Impact will be primarily made through scientific publications and conference presentations.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

Through a stable isotope probing experiment, I traced the carbon entering the soil from two major pathways: litter and root exudates. These two pathways are typically studied separately, but I integrateed them together to determine their relative importance in soil carbon stabilization mechanisms in forest soils. This will substantially advance the field of biogeochemistry by filling a major fundamental knowledge gap: are belowground carbon inputs more important than aboveground ones? In addition to characterizing the soil faunal communities, I investigated how their community structure can influence microbial dynamics related to carbon cycling (microbial growth and necromass formation) and the resulting stabilization of carbon in different pools.
I succesfully developed a method to effectively separate different functional groups of soil microarthropods, based on their trophic role and on their sensitivity to global changes. I expect this method to open many doors for future research to manipulate soil fauna communities and gain a mechanistic understanding of their role. This is extremely important in the context of global changes, as most of the literature is based on correlations or very low diversity experiments.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The method to separate microarthropod groups could reduce predators by 30%, significantly increasing the ratio of decomposers-to-predators. However, by the end of the 4 month-experiment, these differences were reduced. This method is promising for short-term mescososm experiments, but further research is needed to establish how long differences in microarthropod community composition last.
The stable isotope probing experiment showed that although microarthropod community composition did not affect heterotropic respiration, they did impact microbial biomass and necromass accumulation, an important pool of stable soil carbon. However, the type of carbon (litter or root exudates or a combination thereof) added to the mescosms modulated the response and influenced both heterotrophic respiration and microbial biomass.
Combining litter and root exudates led to higher heterotrophic respiration, although lower than what would be expected from cumulative effects. It appears that the presence of root exudates slowed down litter decomposition.
Fungal biomass was lower in the absence of root exudates and was not affected by microarthropod community composition. In contrast, bacterial biomass decreased over time when slow decomposers (Oribatida) were removed, only with litter.
Overall, microarthropods increased microbial turnover, but only in the absence of root exudates.
These results show a significant impact of microarthropod community composition on soil carbon cycling and a stronger effect for litter-derived than for root exudate-derived carbon.