This dataset includes physicochemical and spectroscopic data from forest floor samples collected in forest ecosystems (different pure stands vs. mixed stands) across a latitudinal gradient in Europe. The following parameters were measured: Total Inorganic Carbon (TIC) Total Organic Carbon (TOC) Total Nitrogen (TN) TOC to TN ratio Total Phosphorus (TP) Ash content Additionally, the dataset contains parameters extracted from Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) spectroscopy, specifically derived from the characteristic peaks of the spectra corresponding to the same litter samples. These data allow for an in-depth assessment of the elemental composition and functional group characteristics of decomposing foliar material, relevant for studies on biogeochemical cycling, substrate quality, nutrient dynamics, and molecular characterization in forest ecosystems. Potential applications:This dataset may be of interest to researchers in soil ecology, biogeochemistry, applied spectroscopy, carbon science, and modeling of organic matter decomposition processes.