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Plant litter decomposition in a semi-arid ecosystem controlled by photodegradation


The carbon balance in terrestrial ecosystems is determined by the difference between inputs from primary production and the return of carbon to the atmosphere through decomposition of organic matter1. Our understanding of the factors that control carbon turnover in water-limited ecosystems is limited, however, as studies of litter decomposition have shown contradictory results and only a modest correlation with precipitation2,3,4,5. Here we evaluate the influence of solar radiation, soil biotic activity and soil resource availability on litter decomposition in the semi-arid Patagonian steppe using the results of manipulative experiments carried out under ambient conditions of rainfall and temperature. We show that intercepted solar radiation was the only factor that had a significant effect on the decomposition of organic matter, with attenuation of ultraviolet-B and total radiation causing a 33 and 60 per cent reduction in decomposition, respectively. We conclude that photodegradation is a dominant control on above-ground litter decomposition in this semi-arid ecosystem. Losses through photochemical mineralization may represent a short-circuit in the carbon cycle, with a substantial fraction of carbon fixed in plant biomass being lost directly to the atmosphere without cycling through soil organic matter pools. Furthermore, future changes in radiation interception due to decreased cloudiness, increased stratospheric ozone depletion, or reduced vegetative cover may have a more significant effect on the carbon balance in these water-limited ecosystems than changes in temperature or precipitation.

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Figure 1: Effect of solar radiation and biocide on litter decomposition in the Patagonian steppe.
Figure 2: Effect of soil substrate additions of labile carbon and nitrogen on litter decomposition in the Patagonian steppe.

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  1. Olson, J. S. Energy storage and the balance of producers and decomposers in ecological systems. Ecology 44, 322–331 (1963)

    Article  Google Scholar 

  2. Montaña, C., Ezcurra, E., Carrillo, A. & Delhoume, J. P. The decomposition of litter in grasslands of northern Mexico: a comparison between arid and non-arid environments. J. Arid Environ. 14, 55–60 (1988)

    Article  ADS  Google Scholar 

  3. Moorhead, D. L. & Reynolds, J. F. Mechanisms of surface litter mass loss in the northern Chihuahuan desert: a reinterpretation. J. Arid Environ. 16, 157–163 (1989)

    Article  ADS  Google Scholar 

  4. Steinberger, Y., Shmida, A. & Whitford, W. G. Decomposition along a rainfall gradient in the Judean desert, Israel. Oecologia 82, 322–324 (1990)

    Article  ADS  CAS  Google Scholar 

  5. Whitford, W. G. et al. Rainfall and decomposition in the Chihuahuan desert. Oecologia 68, 512–515 (1986)

    Article  ADS  CAS  Google Scholar 

  6. Meentemeyer, V. Macroclimate and lignin control of litter decomposition rates. Ecology 59, 465–472 (1978)

    Article  CAS  Google Scholar 

  7. Swift, M. J., Heal, O. W. & Anderson, J. M. Decomposition in Terrestrial Ecosystems (Univ. California Press, Berkeley, 1979)

    Google Scholar 

  8. Aber, J. D. & Melillo, J. M. Nitrogen immobilization in decaying hardwood leaf litter as a function of initial nitrogen and lignin content. Can. J. Bot. 60, 2263–2269 (1982)

    Article  CAS  Google Scholar 

  9. Austin, A. T. Differential effects of precipitation on production and decomposition along a rainfall gradient in Hawai'i. Ecology 83, 328–338 (2002)

    Google Scholar 

  10. Gholz, H. L., Wedin, D. A., Smitherman, S. M., Harmon, M. E. & Parton, W. J. Long-term dynamics of pine and hardwood litter in contrasting environments: toward a global model of decomposition. Glob. Change Biol. 6, 751–765 (2000)

    Article  ADS  Google Scholar 

  11. Vossbrinck, C. R., Coleman, D. C. & Wooley, T. A. Abiotic and biotic factors in litter decomposition in a semiarid grassland. Ecology 60, 265–271 (1979)

    Article  CAS  Google Scholar 

  12. Schlesinger, W. H. & Lichter, J. Limited carbon storage in soil and litter of experimental forest plots under increased atmospheric CO2 . Nature 411, 466–469 (2001)

    Article  ADS  CAS  Google Scholar 

  13. Nemani, R. R. et al. Climate-driven increases in global terrestrial net primary production from 1982 to 1999. Science 300, 1560–1563 (2003)

    Article  ADS  CAS  Google Scholar 

  14. Kieber, D. J., McDaniel, J. & Mopper, K. Photochemical source of biological substrates in sea water: implications for carbon cycling. Nature 341, 637–639 (1989)

    Article  ADS  CAS  Google Scholar 

  15. Miller, W. L. & Zepp, R. G. Photochemical production of dissolved inorganic carbon from terrestrial organic matter: significance to the oceanic organic carbon cycle. Geophys. Res. Lett. 22, 417–420 (1995)

    Article  ADS  CAS  Google Scholar 

  16. Mopper, K. et al. Photochemical degradation of dissolved organic carbon and its impact on the oceanic carbon cycle. Nature 353, 60–62 (1991)

    Article  ADS  CAS  Google Scholar 

  17. Tarr, M. A., Miller, W. L. & Zepp, R. G. Direct carbon monoxide production from plant matter. J. Geophys. Res. 100, 11403–11413 (1995)

    Article  ADS  CAS  Google Scholar 

  18. Anesio, A. M., Tranvik, L. J. & Granéli, W. Production of inorganic carbon from aquatic macrophytes by solar radiation. Ecology 80, 1852–1859 (1999)

    Article  Google Scholar 

  19. Schade, G. W., Hormann, R. M. & Crutzen, P. J. CO emissions from degrading plant matter. Tellus B 51, 899–908 (1999)

    ADS  Google Scholar 

  20. Johnson, D., Campbell, C. D., Lee, J. A. & Callaghan, T. V. Arctic microorganisms respond more to elevated UV-B radiation than CO2 . Nature 416, 82–83 (2002)

    Article  ADS  CAS  Google Scholar 

  21. Pancotto, V. A., Sala, O. E., Robson, T. M., Caldwell, M. M. & Scopel, A. L. Direct and indirect effects of solar ultraviolet-B radiation on long-term decomposition. Glob. Change Biol. 11, 1982–1989 (2005)

    Google Scholar 

  22. Gehrke, C., Johanson, U., Callaghan, T. V., Chadwick, D. & Robinson, C. H. The impact of enhanced UV-B radiation on litter quality and decomposition processes in Vaccinum leaves from the subarctic. Oikos 72, 213–222 (1995)

    Article  Google Scholar 

  23. Moody, S. A. et al. The direct effects of UV-B radiation on Betula pubescens litter decomposing at four European field sites. Plant Ecol. 154, 29–36 (2001)

    Article  Google Scholar 

  24. Moorhead, D. L. & Callaghan, T. V. Effects of increasing UV-B radiation on decomposition and soil organic matter dynamics. A synthesis and modeling study. Biol. Fertil. Soils 18, 19–26 (1994)

    Article  CAS  Google Scholar 

  25. Pancotto, V. A. et al. Solar UV-B decreases decomposition in herbaceous plant litter in Tierra del Fuego, Argentina: potential role of an altered decomposer community. Glob. Change Biol. 9, 1465–1474 (2003)

    Article  ADS  Google Scholar 

  26. Sala, O. E., Golluscio, R. A., Lauenroth, W. K. & Soriano, A. Resource partitioning between shrubs and grasses in the Patagonian steppe. Oecologia 81, 501–505 (1989)

    Article  ADS  CAS  Google Scholar 

  27. Yahdjian, L., Sala, O. E. & Austin, A. T. Differential controls of water input on litter decomposition and nitrogen dynamics in the Patagonian steppe. Ecosystems 9, 128–141 (2006)

    Article  CAS  Google Scholar 

  28. Smith, S. D. et al. Elevated CO2 increases productivity and invasive species success in an arid ecosystem. Nature 408, 79–82 (2000)

    Article  ADS  CAS  Google Scholar 

  29. Jackson, R. B., Banner, J. L., Jobbágy, E. G., Pockman, W. T. & Wall, D. H. Ecosystem carbon loss with woody plant invasion of grasslands. Nature 418, 623–626 (2002)

    Article  ADS  CAS  Google Scholar 

  30. Thomas, D. S. G., Knight, M. & Wiggs, G. F. S. Remobilization of southern African desert dune systems by twenty-first century global warming. Nature 435, 1218–1220 (2005)

    Article  ADS  CAS  Google Scholar 

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We acknowledge the late A. Soriano for establishment of a research program at the INTA study site more than 50 years ago; C. Mazza, L. Raiger, P. Flombaum, N. Sala, J. Vrsalovic, P. Araujo, L. Gherardi, M. Gonzalez-Polo, V. Marchesini, A. Fernández-Souto, P. Rojas, M. Taglizacchi and L. Yahdjian for field and laboratory assistance; and O. Sala, P. Vitousek, K. O'Shea, G. Piñeiro and C. Ballaré for comments on the manuscript. We acknowledge financial support from the Fundación Antorchas and the Fundación YPF of Argentina, the Inter-American Institute for Global Change Research, the US National Science Foundation, the Agencia Nacional de Promoción de Ciencia y Tecnología (ANPCyT) and the Universidad de Buenos Aires (UBACyT) of Argentina.

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Correspondence to Amy T. Austin.

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Austin, A., Vivanco, L. Plant litter decomposition in a semi-arid ecosystem controlled by photodegradation. Nature 442, 555–558 (2006).

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