Cycle annuel des éléments nutritifs dans un bassin-versant forestier: contribution de la litière fraîche

The contribution of fresh litter to the input of dissolved substances at the soil surface during the dormant period of vegetation (October–April) was studied in a Laurentian watershed dominated by sugar maple (Acersaccharum), American beech (Fagusgrandifolia), and yellow birch (Betulaalleghaniensis). Net cycling (total litter input minus throughfall or snowmelt total input) of Ca, Mg, and K in the litter solution was 256.3, 195.7, and 203.4 equiv. ha−1, respectively, for the whole period. These values are much larger than the annual basic cation input due to incident precipitation. Even though net SO4 cycling in the litter solution is high during dormancy (244.2 equiv. ha−1), the atmospheric contribution probably remains the dominant source of SO4 reaching the soil surface on an annual basis. H+ ions were neutralized in the litter during winter and spring while H+ production occurred in the fall. NO3 flux decreased as water flowed through the litter, possibly because of denitrification or consumption of N...