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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT & EVALUATION OF BIOLOGICAL CONTROL AGENTS FOR INVASIVE SPECIES THREATENING THE EVERGLADES & OTHER NATURAL AND MANANGED SYSTEMS

Location: Invasive Plant Research Laboratory

Title: Litter cover of the invasive tree Melaleuca quinquenervia influences seedling emergence and survival

Authors
item Rayamajhi, Min
item Pratt, Paul
item Tipping, Philip
item Center, Ted

Submitted to: Open Journal of Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 23, 2012
Publication Date: August 10, 2012
Repository URL: http://www.scrip.org/journal/OJE/
Citation: Rayamajhi, M.B., Pratt, P.D., Tipping, P.W., Center, T.D. 2012. Litter cover of the invasive tree Melaleuca quinquenervia influences seedling emergence and survival. Open Journal of Ecology. 2(3):131-140.2012.

Interpretive Summary: Plant litter biomass on forest floors is likely to influence seedling emergence and survival. We examined these assumptions in mature stands of the invasive tree melaleuca using series of field-based experiments. Leaf removed and litter-not-removed plots were seeded with melaleuca and two native species, namely sawgrass and wax myrtle. Some plots were not seeded and used as control plots for comparison with the seeded plots. Natural enemies (insects and plant pathogens) were excluded from some plots by periodically spraying with insecticide and fungicide. Results from the experiment showed that the melaleuca litter inhibited seedling emergence of all species but did not affect survival. However, litter removal during wet periods created favorable environment for both seedling emergence and survival. Litter removal experiments revealed that 1) emergence of melaleuca seedlings was initially higher in arenaceous (compared to organic) soils but not later; 2) increasing densities of monocotyledonous plants followed melaleuca declines in both soil types with dicots ultimately dominating ; and 3) sawgrass and wax myrtle densities remained stable. Protection from natural enemies allowed weedy woody plants to dominate the experimental plots. Overall, disturbance of litter increased seedling emergence and survival. Surviving dominant plants were suppressed when they were exposed to natural enemies resulting in an increase in plant species diversity.

Technical Abstract: Accumulated plant litter biomass on forest floors likely influences seedling emergence and survival. Natural enemies of dominant plants may also influence these processes. We examined these assumptions in mature stands of the invasive tree Melaleuca quinquenervia (melaleuca) using four sequential 12-wk experiments. Leaf litter was removed from half of the plots in one experiment while the others served as controls. All litter was removed in a second 96-wk experiment. Plots were then seeded with M. quinquenervia, one of two native species (Morella cerifera or Cladium jamaicense), or not seeded. Natural enemies were excluded for additional 104-wk period in a third experiment using insecticide and fungicide. Melaleuca litter inhibited seedling emergence of all species but did not affect survival. However, litter removal during wet periods created favorable environment for both seedling emergence and survival. Litter removal experiments revealed that 1) emergence of melaleuca seedlings was initially higher in arenaceous (compared to organic) soils but not later; 2) increasing densities of monocotyledonous plants followed melaleuca declines in both soil types with dicots ultimately dominating ; and 3) sawgrass and wax myrtle densities remained stable. Protection from natural enemies allowed weedy woody plants to dominate the experimental plots. Overall, disturbance of litter increased seedling emergence and survival. Surviving dominant plants were suppressed when they were exposed to natural enemies resulting in enhanced plant species diversity.

Last Modified: 7/25/2014
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