Dose–responses for solar radiation exposure reveal high sensitivity of microbial decomposition to changes in plant litter quality that occur during photodegradation

Summary Plant litter decomposition is a key process for carbon (C) turnover in terrestrial ecosystems. Sunlight has been shown to cause and accelerate C release in semiarid ecosystems, yet the dose–response relationships for these effects have not been evaluated. We conducted a two‐phase experiment...

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Bibliographic Details
Published in:The New phytologist 2022-09, Vol.235 (5), p.2022-2033
Main Authors: Méndez, M. Soledad, Ballaré, Carlos L., Austin, Amy T.
Format: Article
Language:English
Subjects:
Abiotic factors
Biodegradation
Biological activity
carbon cycle
Decay
Decomposers
Decomposition
Degradation
Ecosystems
Lignin
Litter
Microbial activity
Microorganisms
Photodegradation
photofacilitation
plant litter decomposition
Plants
Radiation
Radiation dosage
Radiation effects
Saccharification
Solar radiation
Sunlight
Terrestrial ecosystems
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Summary:Summary Plant litter decomposition is a key process for carbon (C) turnover in terrestrial ecosystems. Sunlight has been shown to cause and accelerate C release in semiarid ecosystems, yet the dose–response relationships for these effects have not been evaluated. We conducted a two‐phase experiment where plant litter of three species was subjected to a broad range of cumulative solar radiation (CSR) exposures under field conditions. We then evaluated the relationships between CSR exposure and abiotic mass loss, litter quality and the subsequent biotic decomposition and microbial activity in litter. Dose–response relationships demonstrated that CSR exposure was modestly correlated with abiotic mass loss but highly significantly correlated with lignin degradation, saccharification, microbial activity and biotic decay of plant litter across all species. Moreover, a comparison of these dose–response relationships suggested that small reductions in litter lignin due to exposure to sunlight may have large consequences for biotic decay. These results provide strong support for a model that postulates a critical role for lignin photodegradation in the mechanism of photofacilitation and demonstrate that, under natural field conditions, biotic degradation of plant litter is linearly related with the dose of solar radiation received by the material before coming into contact with decomposer microorganisms.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.18253