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United States Department of Agriculture

Agricultural Research Service

Title: Shoot demographics for melaleuca and impacts of simulated herbivory on vegetative development

Authors
item Silvers, Cressida
item Pratt, Paul
item Rayamajhi, Min
item Center, Ted

Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 15, 2007
Publication Date: January 15, 2008
Citation: Silvers, C.S., Pratt, P.D., Rayamajhi, M.B., Center, T.D. Shoot demographics for melaleuca and impacts of simulated herbivory on vegetative development. Journal of Aquatic Plant Management. 46:121-125. 2008.

Interpretive Summary: We monitored branches of the invasive tree Melaleuca quinquenervia (Cav.) Blake (melaleuca) at two sites in southern Florida between January 2002 and May 2003 to elucidate patterns in vegetative shoot maturation. Six shoot stages characterize development from dormancy to fully expanded and lignified foliage. Foliar biomass was greater for shoots growing in apical compared to axillary positions on the stem, as was mortality. Shoot type did not, however, influence stem length or developmental rates. We applied an artificial herbivory treatment that simulated folivory by the introduced biological control agent Oxyops vitiosa to assess the influence of foliar damage on shoot developmental patterns. Interestingly, the two most susceptible shoot developmental stages were the least persistent. Simulated herbivory led to a break in apical dominance, with significant increases in production of axillary shoots. These data suggest that O. vitiosa feeding may increase carrying capacity, initiating a positive feedback loop by which folivory-induced flushes of vegetation could support O. vitiosa populations through much of the year. In addition, marked change in these growth characteristics affecting plant architecture may reduce the tree’s competitiveness and reproductive potential while simultaneously increasing costs associated with maintaining photosynthetic tissues.

Technical Abstract: We monitored branches of the invasive tree Melaleuca quinquenervia (Cav.) Blake (melaleuca) at two sites in southern Florida between January 2002 and May 2003 to elucidate patterns in vegetative shoot maturation. Six shoot stages characterize development from dormancy to fully expanded and lignified foliage. Foliar biomass was greater for shoots growing in apical compared to axillary positions on the stem, as was mortality. Shoot type did not, however, influence stem length or developmental rates. We applied an artificial herbivory treatment that simulated folivory by the introduced biological control agent Oxyops vitiosa to assess the influence of foliar damage on shoot developmental patterns. Interestingly, the two most susceptible shoot developmental stages were the least persistent. Simulated herbivory led to a break in apical dominance, with significant increases in production of axillary shoots. These data suggest that O. vitiosa feeding may increase carrying capacity, initiating a positive feedback loop by which folivory-induced flushes of vegetation could support O. vitiosa populations through much of the year. In addition, marked change in these growth characteristics affecting plant architecture may reduce the tree’s competitiveness and reproductive potential while simultaneously increasing costs associated with maintaining photosynthetic tissues.

Last Modified: 11/23/2014
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