Above ground litter decomposition is the result of three interlinked processes: leaching, fragmentation and catabolism. Litter decomposition estimates are most commonly based on measurements of mass loss from litter residues, confined in mesh bags. This method provides a rough estimate of leaching and catabolism, while preventing fragmentation from occurring. Alternatively, litter decomposition is studied in the laboratory as microbial respiration of litter residue. In this case, generally only catabolism is measured. While those limits are often discussed, their careful assessment has never been attempted. We present here results from a study where the decomposition rate of Arbutus unedo leaf litter, at a throughfall manipulation experiment, was investigated using: 1) litterbags; 2) turnover based on litter input/standing litter pool; 3) 14 C-bomb spike; 4) laboratory incubation; 5) DayCent modeling. Aims of this study were: 1) to quantitatively assess the hypothesis that the litterbags and the laboratory incubation methods, by preventing fragmentation, overestimate above ground litter mean residence time; 2) to evaluate the ability of the above methods to capture the effects of changes in precipitation on litter decay rates. Results confirmed our hypothesis and demonstrated that the litterbag and the laboratory incubation methods do capture the effects of the water manipulation treatment on litter decay rates.