Ultraviolet radiation accelerates photodegradation under controlled conditions but slows the decomposition of senescent leaves from forest stands in southern Finland

Marta Pieristè, Santa Neimane, Twinkle Solanki, Line Nybakken, Alan G. Jones, Estelle Forey, Matthieu Chauvat, Jevgenija Ņečajeva, T Matthew Robson

Research output: Contribution to journalArticleScientificpeer-review


Depending on the environment, sunlight can positively or negatively affect litter decomposition, through the ensemble of direct and indirect processes constituting photodegradation. Which of these processes predominate depends on the ecosystem studied and on the spectral composition of sunlight received. To examine the relevance of photodegradation for litter decomposition in forest understoreys, we filtered ultraviolet radiation (UV) and blue light from leaves of Fagus sylvatica and Bettda pendula at two different stages of senescence in both a controlled-environment experiment and outdoors in four different forest stands (Picea abies, Pagus sylvatica, Acer platanoides, Betula pendula). Controlling for leaf orientation and initial differences in leaf chlorophyll and flavonol concentrations; we measured mass loss at the end of each experiment and characterised the phenolic profile of the leaf litter following photodegradation. In most forest stands, less mass was lost from decomposing leaves that received solar UV radiation compared with those under UV-attenuating filters, while in the controlled environment UV-A radiation either slightly accelerated or had no significant effect on photodegradation, according to species identity. Only a few individual phenolic compounds were affected by our different filter treatments, but photodegradation did affect the phenolic profile. We can conclude that photodegradation has a small stand- and species-specific effect on the decomposition of surface leaf litter in forest understoreys during the winter following leaf fall in southern Finland. Photodegradation was wavelength-dependent and modulated by the canopy species filtering sunlight and likely creating different combinations of spectral composition, moisture, temperature and snowpack characteristics.

Original languageEnglish
JournalPlant Physiology and Biochemistry
Pages (from-to)42–54
Number of pages13
Publication statusPublished - Jan 2020
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 11832 Microbiology and virology
  • 1182 Biochemistry, cell and molecular biology
  • 4112 Forestry
  • Photodegradation
  • Phenolic compounds
  • UV radiation
  • Flavonoids
  • Understorey light environment

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