PARENT SESSION
Poster Session #42: Restoration of Public Lands.
Wednesday, August 7. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Effects of shrub and herb competition on tree seedlings in an abandoned pasture in Puerto Rico.

Netherton, Jane^*,1, Gleeson, Scott¹, Myster, Randall², Zou, Xiaoming³, ¹ University of Kentucky, Lexington, KY² University of Central Oklahoma, Edmond, OK³ University of Puerto Rico, Institute for Tropical Ecosystem Studies, Rio Piedras, PR

ABSTRACT- Following abandonment, it is common for a matrix of grasses, herbs, vines, and shrubs to dominate early pasture succession. This existing vegetation is frequently an important factor limiting pasture recovery by outcompeting forest tree seedlings. In abandoned pastures in Puerto Rico, there tends to be a greater number of tree seedlings in shrub-dominated than herb-dominated vegetation patches. The goals of this research were: (1) to compare the performance of three tree species (Guarea guidonia, Inga laurina, and Tabebuia heterophylla) in the two vegetation patch types (mixed herb and Miconia shrub) found in an abandoned pasture adjacent to the Luquillo Experimental Forest near Sabana, Puerto Rico, and (2) to determine the limiting effects of competition with existing vegetation by manipulating above- and below-ground competition. Seedlings of each species were planted in patches of mixed pasture herbs and below Miconia shrubs. Seedlings were subjected to one of four treatments in both patch types: aboveground reduction of shading, root trenching, aboveground reduction and trenching, or control, and growth was measured monthly. There was no consistent difference in growth between patch types for all species. Growth of the early successional pasture colonizer, T. heterophylla, was improved by the aboveground competitor removal treatments, but not by the belowground only treatment. Effects on growth for the intermediate successional species G. guidonia and I. laurina were less consistent across treatments and patch types.

KEY WORDS: pasture, reforestation, competition, Puerto Rico