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

Abstract

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 matter. 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 precipitation. 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.

Seasonal patterns in decomposition and nutrient release from East African savanna grasses grown under contrasting nutrient conditions

“…in the dry season), 40-50% of N and 50-70% of P had been released. The rapid N and P release that did not match the C loss and suggest that in the long term, both N and P are likely to limit the microbial decomposition process unless there is an external source of nutrients to drive the decomposition process or photodegradation would prevail and short-circuit the decomposition process leading to direct C loss to the atmosphere (Austin and Vivanco, 2006). On the other hand, Couteaux et al (1995) suggested that decrease in litter quality could lead to increased production of ligninolytic enzymes, leading to increased degradation of recalcitrant compounds.…”

Corrigendum to: New handbook for standardised measurement of plant functional traits worldwide

“…A new method is available to include coarse woody debris together with fine litter in such comparative common-garden studies, taking into account differences in size and time scale of decomposition. Cornelissen (1996); Cadisch and Giller (1997); Cornelissen et al ( , 2007; Garnier et al (2004); Austin and Vivanco (2006); Parton et al (2007); Adair et al (2008);Cornwell et al (2008);Fortunel et al (2009);Freschet et al (2012).…”

Contribution of Topography and Incident Solar Radiation to Variation of Soil and Plant Litter at an Area with Heterogeneous Terrain

“…This determines the ionic composition of the soil solution by affecting litter and soil nutrient release rates (García et al, 2006). The sunlight regime also causes variation in the metabolism of microorganisms that control nutrient cycling by imposing different litter decomposition and mineralization rates (Austin and Vivanco, 2006). Incident solar radiation in a given area is largely determined by terrain topography.…”