Leaf litter production and decomposition are important pathways of carbon and nutrient cycles in terrestrial ecosystems. To elucidate the effects of human-induced changes on litter production and decomposition, we investigated them between primary and young-secondary forests of four types, i.e., Dry Dipterocarp (DDF), Dry Evergreen (DEF), Mixed Deciduous (MDF) and Moist Evergreen (MEF) forests along a drought gradient in Thailand. The changes in the annual leaf litter production and in the amount of accumulated leaf litter on the forest floor between the successional stages were different among the four forest types. This suggested that the responses in leaf litter decomposition rate to disturbances may differ depending on forest types. Further, we investigated which factors, including microenvironments and functional traits, affect leaf litter decomposition by litter-bag experiment with leaf litter of the selected 15 tree species for each forest type. We found that the factors explaining leaf litter decomposition were different among the forest types. In the presentation, we will discuss how the leaf litter decomposition was changed due to human-induced disturbance in different types of forests.