Biological Invasions

, Volume 11, Issue 4, pp 1045–1052 | Cite as

Tree leaf litter composition and nonnative earthworms influence plant invasion in experimental forest floor mesocosms

Original Paper


Dominant tree species influence community and ecosystem components through the quantity and quality of their litter. Effects of litter may be modified by activity of ecosystem engineers such as earthworms. We examined the interacting effects of forest litter type and earthworm presence on invasibility of plants into forest floor environments using a greenhouse mesocosm experiment. We crossed five litter treatments mimicking historic and predicted changes in dominant tree composition with a treatment of either the absence or presence of nonnative earthworms. We measured mass loss of each litter type and growth of a model nonnative plant species (Festuca arundinacea, fescue) sown into each mesocosm. Mass loss was greater for litter of tree species characterized by lower C:N ratios. Earthworms enhanced litter mass loss, but only for species with lower C:N, leading to a significant litter × earthworm interaction. Fescue biomass was significantly greater in treatments with litter of low C:N and greater mass loss, suggesting that rapid decomposition of forest litter may be more favorable to understory plant invasions. Earthworms were expected to enhance invasion by increasing mass loss and removing the physical barrier of litter. However, earthworms typically reduced invasion success but not under invasive tree litter where the presence of earthworms facilitated invasion success compared to other litter treatments where earthworms were present. We conclude that past and predicted future shifts in dominant tree species may influence forest understory invasibility. The presence of nonnative earthworms may either suppress of facilitate invasibility depending on the species of dominant overstory tree species and the litter layers they produce.


Ailanthus altissima Castanea dentata Decomposition Earthworms Invasional meltdown Leaf litter Lumbricus terrestris Plant invasions 



We thank Debbie Wiley and Aaron Teets for assistance in the greenhouse and lab. Bobbie Niederlehner helped with the carbon and nitrogen analysis. Erik Nilsen provided greenhouse space and helpful comments on earlier drafts. Jessica Homyack, Aimeé Classen, and Martin Nuñez provided helpful comments during manuscript preparation. Cindy Hale, Carola Haas, Tom Fox, Nate Sanders, and Dan Simberloff provided helpful comments and ideas during project conception. The work was supported by NSF-DBI grant # 0400684, USDA-NRI grant # 2005-35101-15363 and a Virginia Tech WPI Environmental Fellowship.


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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Department of Biological SciencesVirginia TechBlacksburgUSA

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