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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #246108
Title: Exotic tree leaf litter accumulation and mass loss dynamics compared with two sympatric native species in South Florida, USA

Author
item Rayamajhi, Min
item Pratt, Paul
item Center, Ted
item VAN, THAI - Retired ARS Employee

Submitted to: European Journal of Forest Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2010
Publication Date: 10/20/2010
Citation: Rayamajhi, M.B., Pratt, P.D., Center, T.D., Van, T.K. Exotic tree leaf litter accumulation and mass loss dynamics compared with two sympatric native species in south Florida, USA. European Journal of Forest Research. 129:1155-1168. 2010.

Interpretive Summary: Melaleuca trees form dense forests in ecologically sensitive areas including portions of the Florida Everglades. Within these stands, forest understories have fewer plant and forest floors remain covered with dense layer of accumulated melaleuca litter. However, the quantity, quality and decomposition rate of melaleuca litter is poorly understood. Herein, we quantified litter accumulation and decomposition rates between melaleuca leaves, and two co-occurring plant species, sawgrass slash pine at four locations on two soil types. Total litter accumulation in melaleuca dominated stands prior to June 1997 ranged from 12.27-25.63 Mg/ha. Melaleuca leaves decomposed at a faster rate in organically rich versus arenaceous soils. Within organic soils, leaf decomposition was slower for both melaleuca and sawgrass leaves in melaleuca invaded and uninvaded sawgrass marshes. In arenaceous soils, foliage decomposition rates were similar for melaleuca and pine in both melaleuca invaded and uninvaded pine flatwoods. Complete mineralization of sawgrass leaves occurred in 258 wks, whereas, melaleuca and pine foliage samples had 2-14% and 13-19% original biomass left after the 322-wk study period. Total carbon (C) in decomposing leaves varied slightly over time but total nitrogen (N) steadily increased for all three species; the greatest (ca 4-fold) increase was in sawgrass. Such increases in N concentration caused decreased C:N ratio for leaves of all species but the ratio was optimal (20-30) for sawgrass leaves to result an accelerated decomposition compared to melaleuca leaves and pine needles.

Technical Abstract: The invasive tree Melaleuca quinquenervia (melaleuca) forms dense forests in ecologically sensitive habitats, including portions of the Florida Everglades. Within these stands, forest understories are characterized by low species diversity and a dense layer of accumulated melaleuca litter. However, the quality and decomposition dynamics of melaleuca litter is poorly understood. Herein, we quantified litter accumulation and decomposition rates between the leaves of melaleuca and one sympatric native species of plant, either Cladium jamaicense (sawgrass) or Pinus elliottii (pine) have been compared at four locations that varied in soil type. Total litter accumulation in melaleuca dominated forests prior to June 1997 ranged from 12.27-25.63 Mg/ha. Melaleuca leaves decomposed at a faster rate in organically rich versus arenaceous soils. Within organic soils, leaf decomposition was slower for both melaleuca and sawgrass leaves in melaleuca invaded and uninvaded sawgrass marshes. In arenaceous soils, foliage decomposition rates were similar for melaleuca and pine in both melaleuca invaded and uninvaded pine flatwoods. Complete mineralization of sawgrass leaves occurred in 258 wks, whereas, melaleuca and pine foliage samples had 2-14% and 13-19% original biomass left after the 322-wk study period. Total carbon (C) in decomposing leaves varied slightly over time but total nitrogen (N) steadily increased for all three species; the greatest (ca 4-fold) increase was in sawgrass. Such increases in N concentration caused decreased C:N ratio for leaves of all species but the ratio was optimal (20-30) for sawgrass leaves to result an accelerated decomposition compared to melaleuca leaves and pine needles.