These R scripts and datasets (CSV-files) were used to write the article 'Does drought advance the onset of autumn leaf senescence in temperate deciduous forests' published in the journal Biogeosciences (see https://doi.org/10.5194/bg-2020-337). Please cite the corresponding article from Mariën, B., Dox, I., De Boeck, H., Willems, P., Leys, S., Papadimitriou, D. and Campioli, M. 'Does heat stress and increased atmospheric aridity advance the onset of autumn leaf senescence in temperate deciduous forests' appropriately when using the R scripts or datasets (see https://doi.org/10.5194/bg-2020-337). The R scripts GAM_Nsite, GAM_Betula, GAM_Fagus and GAM_Quercus were used to run the generalized additive models (models 1 – 4) corresponding to the chlorophyll content index and canopy greenness, and to plot their respective smoothers and line plots (Fig. 4 – 7). The corresponding CSV-files are named CCI_Nsite_saplings, Coloration_Nsite_saplings, CCI_Leaf_Fall_mature_trees and Coloration_Leaf_Fall_mature_trees, ...