Direct and indirect effects of photodegradation on carbon turnover in temperate plant species of South America

AUSTIN, A.T.; BALLARE, C.L.

Valencia

Congreso; FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology; 2010

FESPB

Recent experimental evidence has shown that, in semiarid ecosystems, photodegradation can be important in controlling litter decomposition; however, plant species effects on decomposition through litter quality and its interaction with photodegradation is not known. Our objective in this study was to evaluate the susceptibility to photochemical mineralization in a range of temperate species in order to quantify the importance of abiotic photodegradation on mass loss and subsequent biotic decomposition. We harvested litter from 25 native and introduced species growing in temperate ecosystems in Argentina. While direct photodegradative losses were relatively small overall, the magnitude of the effect with attenuation of UV and visible light was 12% and 65% respectively. When these litter samples were then  placed on the soil surface for biotic incubation, we observed a strong and consistent (P<0.0001) photofacilitation effect, with litter previously exposed to full solar radiation decomposing up to 120% more quickly. These results suggest that a wide variety of plant litter types could be susceptible to photodegradation, and that both direct and indirect effects of photodegradation could play an important role on carbon loss and nutrient release in a range of terrestrial ecosystems.