PARENT SESSION
Poster Session: Ecological Impacts of Invasive Plants
Tuesday, November 4, 2003, 5:00 PM to 7:00 PM
Global Ballroom
The invasion of a Brazilian tropical forest fragment by the Australian palm tree Archontophoenix cunninghamiana.
Pivello, Vania*,1, Russo, Felipe2, Ferrini, Renato2, Dislich, Ricardo1, 1 Universidade de São Paulo, Sao Paulo, SP, Brazil2 Universidade Mackenzie, Sao Paulo, SP, Brazil
ABSTRACT- Small, isolated habitat fragments are commonly severely threatened by biological invasions. As an example of such a problem we report the invasion of a 10 ha tropical forest fragment (CUASO Reserve; Sao Paulo, Brazil, 23°34′S - 46°43′W) by a palm tree native to Australia, Archontophoenix cunninghamiana H. Wendl. & Drude, describing some of its population dynamic attributes. Three surveys in 1997, 2000 and 2002 (medium interval of 2.5 years) were carried out on a 1.45 ha plot, considering all trees with DBH ≥9.5 cm. In the first survey, there were 154 individuals of A. cunninghamiana in the plot; in 2000 and 2002, the numbers increased to 240 and 263 individuals, respectively. This species showed the highest density in the community, comprising 22.5% of the total number of individuals in the 2000-year census and 25.2% in 2002. Its population size structure according to the frequency distribution of DBH classes follows a negative exponential model, indicating a growing population. For the period 1997-2000 mortality rate was 0.78 %.year-1, recruitment rate was 20.01 %.year-1 and population net growth was 19.42 %.year-1. For the period 2000-2002 mortality rate was 2.47 %.year-1, recruitment rate was 6.15 %.year-1 and population net growth was 3.88 %.year-1. These data reveal that local biodiversity in the CUASO Forest Reserve is already severely threatened by the invader A. cunninghamiana, whose density is very high and tends to increase even more. Urgent management actions are required to reverse the invasion process already established.
Key words: invader palm tree, tropical forest, population dinamics