GUYAFOR, a network of forest research permanent plots, is dedicated to long term studies in forest dynamics and biodiversity. Forest plots have been established in French Guyana from the late 60's to recent years by Cirad, ONF and CNRS. From 2000, they are progressively integrated in the GUYAFOR network with standardized protocols for both tree inventories and environmental characterization. The network includes 45 plots distributed on 10 sites mainly in the coastal area.157 800 trees above 10 cm dbh are monitored within 235 ha at regular intervals (2 to 4 years). Undisturbed forests are monitored on all sites. Forests subjected to different logging treatments are also monitored on four sites (Paracou, Organabo, Risquetout and Montagne Tortue), providing a unique feature to this network. Recent works carried out on the Guyafor network include studies to understand patterns of tree biological diversity at specific, functional and evolutionary levels and studies on the effects of logging practices on the carbon cycle.