Effects of increased litterfall in tropical forests

Emma J. Sayer, Jennifer S. Powers, Edmund V.J. Tanner

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Aboveground litter production in forests is likely to increase as a consequence of elevated atmospheric carbon dioxide (CO2) concentrations, rising temperatures, and shifting rainfall patterns. As litterfall represents a major flux of carbon from vegetation to soil, changes in litter inputs are likely to have wide-reaching consequences for soil carbon dynamics. Such disturbances to the carbon balance may be particularly important in the tropics because tropical forests store almost 30% of the global soil carbon, making them a critical component of the global carbon cycle; nevertheless, the effects of increasing aboveground litter production on belowground carbon dynamics are poorly understood. We used long-term, large-scale monthly litter removal and addition treatments in a lowland tropical forest to assess the consequences of increased litterfall on belowground CO2 production. Over the second to the 5th year of treatments, litter addition increased soil respiration more than litter removal decreased it; soil respiration was on average 20% lower in the litter removal and 43% higher in the litter addition treatment compared to the controls but litter addition did not change microbial biomass. We predicted a 9% increase in soil respiration in the litter addition plots, based on the 20% decrease in the litter removal plots and an 11% reduction due to lower fine root biomass in the litter addition plots. The 43% measured increase in soil respiration was therefore 34% higher than predicted and it is possible that this “extra” CO2 was a result of priming effects, that is stimulation of the decomposition of older soil organic matter by the addition of fresh organic matter. Our results show that increases in aboveground litter production as a result of global change have the potential to cause considerable losses of soil carbon to the atmosphere in tropical forests.

Original languageEnglish (US)
Title of host publicationEnvironmental Chemistry
Subtitle of host publicationNew Techniques and Data
PublisherApple Academic Press
Pages36-45
Number of pages10
ISBN (Electronic)9781466558496
ISBN (Print)9781926692777
StatePublished - Jan 1 2011

Keywords

  • Control plots
  • Infra-red gas analyzer
  • Microbial biomass
  • Soil carbon
  • Soil respiration rates
  • Soil temperature

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