The biomass and dynamics of disturbed and degraded tropical forests have mostly been ignored in the recent scientific literature, partly because of a spotlight on old-growth forests but also due to a lack of long-term data from degraded forests. There is a pressing need to understand the rates and patterns of growth, mortality and recruitment in degraded forests, not only because they are increasing in area relative to old-growth forests, but also due to their potential capacity to sequester large amounts of carbon dioxide from the atmosphere. This paper introduces a permanent forest plot network and database, FORMNET-B (GIVD ID# NA-BZ-001), designed to study the long-term dynamics of disturbed and degraded tropical forests in Belize, Central America.