BROWN, G. G.

MASCHIO, W.

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P a g e  | 10  The 10th International Symposium on Earthworm Ecology 22nd to 27th June 2014, Athens, Georgia, USA  Earthworm populations in Eucalyptus plantations and effects of two worm species on seedling growth  Wagner Maschio1 and George G. Brown1,2  1 Departmento de Ciência do Solo, Universidade Federal do Paraná, Brazil 2 Embrapa Forestry, Brazil  Worldwide, earthworm populations have been assessed in approximately 30 sites with plantations of various Eucalyptus spp., of which more than half are in Brazil. At most sites, earthworms were identified to species level and the plantations consisted mainly of exotic species, and were notably dominated by the widespread pantropical Pontoscolex corethrurus and exotic megascolecid species (especially Amynthas spp.). The abundance of these exotic earthworms ranged from a few individuals up to >300 individuals m-2, both in Brazilian sites and elsewhere in the world. Only at a few sites, such as in the interior regions of Santa Catarina (Brazil) and Orissa (India), native worms predominated. It is well known that A. gracilis and P. corethrurus have important effects on soil fertility and that these species can also affect plant growth. Assuming that the high abundance of exotic worms in these plantations might affect important ecosystem services such as plant growth, we performed three experiments to test the effects of P. corethrurus and A. gracilis on Eucalyptus spp. seedling growth, under greenhouse conditions.  Seedlings of E. grandis, E. benthamii and E. dunnii were grown in a highly acid (pH 4.2), organic matter rich (3.2% C) cambisol for 50 d in presence of four P. corethrurus or two A. gracilis. There was complete mortality of P. corethrurus due to a severe frost, but only 10% of A. gracilis had died by the end of the trial. Eucalyptus dunnii was not affected by either earthworm species, but E. benthamii growth was increased 17% by P. corethrurus and E. grandis growth increased 13% with A. gracilis. This is the first study of which we are aware of the effects of earthworms on Eucalyptus spp. plants, and considering the variable results with the species tested, further trials are needed to clarify the mechanisms of the effects of these plant x worm interactions.    

Earthworm populations in Eucalyptus plantations and effects of two worm species on seedling growth.

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