Grantee Research Project Results
Effects of Lantana camara on Rainforest Regeneration in Northeastern AustraliaEPA Grant Number: U915430
Title: Effects of Lantana camara on Rainforest Regeneration in Northeastern Australia
Investigators: Silber, Kristi R.
Institution: Rutgers SUNJ
EPA Project Officer: Broadway, Virginia
Project Period: July 1, 1998 through June 1, 2001
Project Amount: $48,628
RFA: STAR Graduate Fellowships (1998)
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems
The objective of this research project is to gain insight into the mechanisms controlling rainforest succession in lLantana camara thickets. Because since the exotic shrub seems to impede forest regrowth to varying degrees at different sites, I sought factors such as interaction with native fauna to explain lLantana's camara's impact.Approach:
In order to examine the effects of Lantana camara on soil, I conducted a "bioassay" by growing rainforest trees from seed in soil removed from under Lantana camara and in an adjacent pasture. This revealed significantly greater growth in Lantana camara soil for 1one of the 3three species tested. Additional further sampling showed soil physical factors (bulk density, water infiltration rate, and pH) to be more conducive to growth in Lantana camara. I used root and canopy exclusion of Lantana camara to test its competitive effects on four species of rainforest tree seedlings. Periodic canopy removal generally had a positive effect on growth, but no effect on mortality. This experiment accidentally revealed the great setbacks due to disease and mammalian herbivory experienced by some species. Seed predation pressure was addressed by small mammal trapping, and seed removal trials in Lantana. camara, and by a neighboring rainforest. There is apparently heavier seed predation pressure in Lantana camara, and the small mammal community it supports is as diverse as that found in the forest. In an attempt to test the hypothesis that more seeds of native woody species were deposited in Lantana camara than in an adjacent pasture, soil samples were removed to a shade house, and all germinating seedlings were identified and counted. The samples from only one of three sites contained more than a few tree seeds; at that site, they were concentrated in Lantana camara.Supplemental Keywords:
fellowship, soil, ecological effects, rainforest regeneration, ecosystem, restoration, seed predation, invasive, Australia, rainforest, Lantana camara.