Skip to main content

Ants accelerate litter decomposition in a Costa Rican lowland tropical rain forest

  • Terrence P. McGlynn (a1) and Evan K. Poirson (a2)

The decomposition of leaf litter is governed, in part, by litter invertebrates. In tropical rain forests, ants are dominant predators in the leaf litter and may alter litter decomposition through the action of a top-down control of food web structure. The role of ants in litter decomposition was investigated in a Costa Rican lowland rain forest with two experiments. In a mesocosm experiment, we manipulated ant presence in 50 ambient leaf-litter mesocosms. In a litterbag gradient experiment, Cecropia obtusifolia litter was used to measure decomposition rate constants across gradients in nutrients, ant density and richness, with 27 separate litterbag treatments for total arthropod exclusion or partial arthropod exclusion. After 2 mo, mass loss in mesocosms containing ants was 30.9%, significantly greater than the 23.5% mass loss in mesocosms without ants. In the litter bags with all arthropods excluded, decomposition was best accounted by the carbon: phosphorus content of soil (r2 = 0.41). In litter bags permitting smaller arthropods but excluding ants, decomposition was best explained by the local biomass of ants in the vicinity of the litter bags (r2 = 0.50). Once the microarthropod prey of ants are permitted to enter litterbags, the biomass of ants near the litterbags overtakes soil chemistry as the regulator of decomposition. In concert, these results support a working hypothesis that litter-dwelling ants are responsible for accelerating litter decomposition in lowland tropical rain forests.

Corresponding author
1Corresponding author. Email:
Hide All
BESTELMEYER B. T., AGOSTI D., ALONSO L. E., BRANDÃO C. R. F., BROWN W. L., DELABIE J. H. C. & SILVESTRE R. 2000. Field techniques for the study of ground-dwelling ants: an overview, description and evaluation. Pp. 122144 in Agosti D., Majer J., Alonso L. E. & Schultz T. D. (eds.). Ants: Standard methods for measuring and monitoring biodiversity. Smithsonian Institution Press, Washington, DC.
BRADFORD M. A., TORDOFF G. M., EGGERS T., JONES T. H. & NEWINGTON J. E. 2002. Microbiota, fauna, and mesh size interactions in litter decomposition. Oikos 99:317323.
BYRNE M. M. 1994. Ecology of twig-dwelling ants in a wet lowland tropical forest. Biotropica 26:6172.
CLEVELAND C. C., TOWNSEND A. R. & SCHMIDT S. K. 2002. Phosphorus limitation of microbial processes in moist tropical forests: evidence from short-term laboratory incubations and field studies. Ecosystems 5:680691.
CLEVELAND C. C., REED S. C. & TOWNSEND A. R. 2006. Nutrient regulation of organic matter decomposition in a tropical rain forest. Ecology 87:492503.
COQ S., SOUQUET J.-M., MEUDEC E., CHEYNIER V. & HÄTTENSCHWILER S. 2010. Interspecific variation in leaf litter tannins drives decomposition in a tropical rain forest of French Guiana. Ecology 91:20802091.
CUSACK D. F., CHOU W. W., YANG W. H., HARMON M. E. & SILVER W. L. 2009. Controls on long-term root and leaf litter decomposition in neotropical forests. Global Change Biology 15:13391355.
ESPELETA J. & CLARK D. 2007. Multi-scale variation in fine-root biomass in a tropical rain forest: a seven-year study. Ecological Monographs 77:377404.
GONZÁLEZ G. & SEASTEDT T. R. 2001. Soil fauna and plant litter decomposition in tropical and subalpine forests. Ecology 82:955964.
HÄTTENSCHWILER S. & GASSER P. 2005. Soil animals alter plant litter diversity effects on decomposition. Proceedings of the National Academy of Sciences USA 102:15191524.
HÄTTENSCHWILER S., TIUNOV A. V. & SCHEU S. 2005. Biodiversity and litter decomposition in terrestrial ecosystems. Annual Review of Ecology, Evolution and Systematics 36:191218.
HENEGHAN L., COLEMAN D. C., ZOU X., CROSSLEY D. A. & HAINES B. L. 1998. Soil microarthropod community structure and litter decomposition dynamics: a study of tropical and temperate sites. Applied Soil Ecology 9:3338.
HUNTER M. D., ADL S., PRINGLE C. M. & COLEMAN D. C. 2003. Relative effects of macroinvertebrates and habitat on the chemistry of litter during decomposition. Pedobiologia 47:101115.
JACQUEMIN J., MARAUN M., ROISIN Y. & LEPONCE M. 2012. Differential response of ants to nutrient addition in a tropical brown food web. Soil Biology and Biochemistry 46:1017.
JOHNSON J. & OMLAND K. 2004. Model selection in ecology and evolution. Trends in Ecology and Evolution 19:101108.
KASPARI M. 1996a. Worker size and seed size selection by harvester ants in a Neotropical forest. Oecologia 105:397404.
KASPARI M. 1996b. Litter ant patchiness at the 1-m2 scale: disturbance dynamics in three Neotropical forests. Oecologia 107:265273.
KASPARI M. & YANOVIAK S. 2008. Biogeography of litter depth in tropical forests: evaluating the phosphorus growth rate hypothesis. Functional Ecology 22:919923.
KASPARI M. & YANOVIAK S. P. 2009. Biogeochemistry and the structure of tropical brown food webs. Ecology 90:33423351.
KASPARI M., GARCIA M., HARMS K., SANTANA M., WRIGHT S. & YAVITT J. 2008. Multiple nutrients limit litterfall and decomposition in a tropical forest. Ecology Letters 11:3543.
LACH L., PARR C. & ABBOTT K. 2010. Ant ecology. Oxford University Press, Oxford. 432 pp.
MCDADE L., BAWA K. S., HESPENHEIDE H. A. & HARTSHORN G. S. 1994. La Selva: ecology and natural history of a Neotropical rain forest. University of Chicago Press, Chicago. 493 pp.
MCGLYNN T. P. 2006. Ants on the move: resource limitation of a litter-nesting ant community in Costa Rica. Biotropica 38:419427.
MCGLYNN T. 2010. Polygyny in thief ants responds to competition and nest limitation but not food resources. Insectes Sociaux 57:2328.
MCGLYNN T. P. & OWEN J. P. 2002. Food supplementation alters caste allocation in a natural population of Pheidole flavens, a dimorphic leaf-litter dwelling ant. Insectes Sociaux 49:814.
MCGLYNN T. P., FAWCETT R. M. & CLARK D. A. 2009a. Litter biomass and nutrient determinants of ant density, nest size and growth in a Costa Rican tropical wet forest. Biotropica 41:234240.
MCGLYNN T., CHOI H., MATTINGLY S., UPSHAW A., POIRSON E. & BETZELBERGER J. 2009b. Spurious and functional correlates of the isotopic composition of a generalist across a tropical rainforest landscape. BMC Ecology 9:23.
MEZGER D. & PFEIFFER M. 2010. Is nest temperature an important factor for niche partitioning by leaf-litter ants (Hymenoptera: Formicidae) in Bornean rain forests? Journal of Tropical Ecology 26:445455.
MOORE J., BERLOW E., COLEMAN D., RUITER P., DONG Q., HASTINGS A., JOHNSON N., MCCANN K., MELVILLE K. & MORIN P. 2004. Detritus, trophic dynamics and biodiversity. Ecology Letters 7:584600.
POWERS J. S., MONTGOMERY R. A., ADAIR E. C., BREARLEY F. Q., DEWALT S. J., CASTANHO C. T., CHAVE J., DEINERT E., GANZHORN J. U., GILBERT M. E., GONZ·LEZ-ITURBE J. A., BUNYAVEJCHEWIN S., GRAU H. R., HARMS K. E., HIREMATH A., IRIARTE-VIVAR S., MANZANE E., OLIVEIRA A. A. D., POORTER L., RAMANAMANJATO J.-B., SALK C., VARELA A., WEIBLEN G. D. & LERDAU M. T. 2009. Decomposition in tropical forests: a pan-tropical study of the effects of litter type, litter placement and mesofaunal exclusion across a precipitation gradient. Journal of Ecology 97:801811.
SCHMITZ O. J., HAMBACK P. A. & BECKERMAN A. P. 2000. Trophic cascades in terrestrial systems: a review of the effects of carnivore removals on plants. American Naturalist 155:141153.
SEASTEDT T. 1984. The role of microarthropods in decomposition and mineralization processes. Annual Review of Entomology 29:2546.
SHURIN J. B., BORER E. T., SEABLOOM E. W., ANDERSON K., BLANCHETTE C. A., BROITMAN B., COOPER S. D. & HALPERN B. S. 2002. A cross-ecosystem comparison of the strength of trophic cascades. Ecology Letters 5:785791.
SRIVASTAVA D. S., CARDINALE B. J., DOWNING A. L., DUFFY J. E., JOUSEAU C., SANKARAN M. & WRIGHT J. P. 2009. Diversity has stronger top-down than bottom-up effects on decomposition. Ecology 90:10731083.
TOWNSEND A., ASNER G. & CLEVELAND C. 2008. The biogeochemical heterogeneity of tropical forests. Trends in Ecology and Evolution 23:424431.
WIEDER W. R., CLEVELAND C. C. & TOWNSEND A. R. 2009. Controls over leaf litter decomposition in wet tropical forests. Ecology 90:33333341.
WILSON E. O. 2005. Oribatid mite predation by small ants of the genus Pheidole. Insectes Sociaux 52:263265.
WOOD T., LAWRENCE D. & CLARK D. 2006. Determinants of leaf litter nutrient cycling in a tropical rain forest: soil fertility versus topography. Ecosystems 9:700710.
WYMAN R. L. 1998. Experimental assessment of salamanders as predators of detrital food webs: effects on invertebrates, decomposition and the carbon cycle. Biodiversity and Conservation 7:641650.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Tropical Ecology
  • ISSN: 0266-4674
  • EISSN: 1469-7831
  • URL: /core/journals/journal-of-tropical-ecology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 2
Total number of PDF views: 26 *
Loading metrics...

Abstract views

Total abstract views: 201 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 17th December 2017. This data will be updated every 24 hours.