Biogeochemistry directs ecological recovery of secondary forests, and thereby impacts the rate of carbon accumulation along succession. Recent observations suggest that cations (calcium, magnesium, potassium) limit forest productivity in the tropics, although research to date has largely focused on nitrogen and phosphorus. Moreover, the intensification of land-use change impacts cation availability at the onset of succession, likely further constraining regrowth rates of secondary forests. FORECAT (legacy effects on tropical FOrest REcovery through CATion limitation) strives to understand the fundamental role of cations in limiting productivity of secondary forests in the tropics, and to quantify how land-use change and its intensification affect cation limitation on forest recovery rates. FORECAT will integrate observational, experimental and modelling approaches. This work will be conducted along tropical forest successional gradients and land-use intensity gradients, to disentangle how the legacy land-use history affects recovery trajectories through cation cycling. Additionally, a large scale nutrient addition experiment in different-aged forest will further uncover the role of changed nutrient availability along succession. The field-based data will constitute the most detailed nutrient mapping – including cations – of secondary tropical forests to date. These data will then be integrated in a state-of-the-art biogeochemical model to provide projections of long-term effects of different land-use change scenarios on forest recovery in the tropics. Due to the sheer magnitude of projected land-use intensification in the tropics, cation limitation on the carbon uptake rate of secondary forest regrowth will impact global carbon cycle. Furthermore, FORECAT will drastically improve our land-scape scale understanding of forest regrowth in the tropics, and will set the stage to inform managers and decision makers on optimal and sustainable land-use change planning.