In forest ecosystems, litterfall collected in trapping devices is exposed to periods of wetting and drying, which may initiate the first stages of decomposition. This could lead to an underestimation of organic matter and nutrient input due to leaching or an overestimation due to immobilization.
The objectives of this study were to quantify changes in mass and nutrient stocks of sugar maple (Acer saccharum Marsh.), basswood (Tilia americana L.), and beech (Fagus grandifolia Ehrh.) leaves under in situ conditions and to quantify changes in leaf mass and nutrient
stocks and leachate concentration when exposed to different quantities of moisture (high = 100 mm, medium = 60 mm, and low = 30 mm) under ex situ conditions. Results from this study showed that sugar maple and basswood had a significantly greater (P < 0.05) mass loss than beech in
the in situ and ex situ study. Nutrient stocks either decreased significantly (P < 0.05) or remained the same, depending on species in the in situ study. Similar results were observed in the ex situ study, in which carbon, nitrogen, phosphorus, and potassium stocks decreased significantly
(P < 0.05) with increasing exposure to moisture, but calcium and magnesium stocks showed less pronounced changes. Mean concentrations of dissolved organic carbon, dissolved organic nitrogen, and ammonium were significantly different (P < 0.05) between species and moisture
treatments, whereas nitrite showed no such differences. Results from this study suggested that the collection of leaf litter should take place frequently during the peak leaf abscission period and during periods of high precipitation. This would provide a more accurate quantification of the
quantity of nutrients entering the forest ecosystem in the within-system pathway between live vegetation and the forest floor detritus pool. In addition, more frequent litterfall collection may also minimize litter decomposition and nitrification.