Does light exposure make plant litter more degradable?
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Many field experiments have indicated that litter decomposition in semi-arid areas may be partly or fully controlled by photodegradation. We devised a study to test our hypothesis that light exposure makes plant litter more degradable. Dry, senescent, aboveground plant litter from Miscanthus x giganteus was exposed to light including ultraviolet (UV) radiation for various lengths of time from 0 to 289 days. Weight loss was measured after exposure and appeared to be modest and did not increase with time of exposure. The litter of the longest and shortest exposure time as well as controls were then incubated with soil and moisture for 35 days and CO2 and N2O production were measured. The longest exposed litter degraded much faster than any other treatment during incubation with moisture, about twice as fast as the unexposed control. The shortest exposed however, degraded only slightly faster than the unexposed control. This suggests that increasing litter degradability is a more important mechanism for photodegradation than direct light-induced mass loss. N2O production from decomposition of the exposed litter was high in the beginning, suggesting that nitrogen may be released quickly. The mechanism is probably that light exposure leaves the nitrogen in plant litter easily available to microbial utilisation upon wetting. Such a mechanism might play an important role for nutrient cycling in semi-arid areas.
KeywordsPhotodegradation Decomposition Nitrous oxide 13C
The authors wish to thank Dr. John Clifton-Brown at IGER, UK for supplying the Miscanthus plant material, and Dr. David Burslem at Aberdeen University for supplying soils from a tropical environment. Professor David Robinson at Aberdeen University is acknowledged for helping with light spectrum measurements. This study was funded by the University of Aberdeen. Professor Pete Smith at Aberdeen University is acknowledged for helping to obtain funding.
- Allen S (1989) Chemical analysis of ecological materials. Wiley, Blackwell, LondonGoogle Scholar
- Bernoux M, Cerri CC, Neill C, de Moraes JFL (1998) The use of stable carbon isotopes for estimating soil organic matter turnover rates. Gendarme 82:43–58Google Scholar
- Cadish G, Giller KE (1997) Driven by nature: plant litter quality and decomposition. CAB International, WallingfordGoogle Scholar
- Carre M, Bentaleb I, Blamart D, Ogle N, Cardenas F, Zevallos S, Kalin RM, Ortlieb L, Fontugne M (2005) Stable isotopes and sclerochronology of the bivalve Mesodesma donacium: potential application to Peruvian paleoceanographic reconstructions. Palaeogeography, Plaeoclimatology, Palaeoecology 228:4–25CrossRefGoogle Scholar
- Friedlingstein P, Cox P, Betts R, Bopp L, von Bloh W, Brovkin V, Cadule P, Doney S, Eby M, Fung I, Bala G, John J, Jones C, Joos F, Kato T, Kawamiya M, Knorr W, Lindsay K, Matthews HD, Raddatz T, Rayner P, Reick C, Roeckner E, Schnitzler KG, Schnur R, Strassmann K, Weaver AJ, Yoshikawa C, Zeng N (2006) Climate-carbon cycle feedback analysis: results from the C4MIP model intercomparison. J Climate 19:3337–3353CrossRefGoogle Scholar
- Mayer ML, Schick LL, Hardy KR, Estapa ML (2009) Photodissolution and other photochemical changes upon irradiation of algal detritus. Limnol Oceanogr 54:1688–1698Google Scholar
- Pancotto VA, Sala OE, Robson TM, Caldwell MM, Scopel AL (2005) Direct and indirect effects of solar ultraviolet-B radiation on long-term decomposition. Global Change Biol 11:1982–1989Google Scholar
- R Development Core Team (2008) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Reynolds JF (2001) Desertification. In: Levin S (ed) Encyclopedia of biodiversity. Academic, San Diego, pp 61–78Google Scholar