I believe specified forest dynamics plots are all larger than 1 ha (often 25 ha or larger) and monitored by the Smithsonian Tropical Research Institute Center for Tropical Forest Science and ForestGEO network. The full list of sites is available here: http://www.ctfs.si.edu/plots/
Sampling protocol and description: http://www.ctfs.si.edu/group/About/
To use the data from a specific site you can usually contact one of the PI's (also available on the CTFS website).