Foliar Litter Contribution to the Retention of Atmospheric Nitrogen in Appalachian Hardwood Forests.

Immobilization of nitrogen in foliar litter during litter decomposition represents a potential mechanism for nitrogen retention of atmospherically-deposited N in forest ecosystems. Recent work in Appalachian hardwood forests shows that up to 160% of original litter N may be immobilized in litter 6 months after leaf fall. When leaf litter begins to mineralize N around April, plant N uptake can assume the primary role in N retention. The strength of these retention mechanisms is likely to decrease and then possibly subside when plant uptake diminishes and new litter layer (Oi) is yet to form at the end of the summer/ early fall. We calculate nitrogen retention in leaf litter and in aboveground forest biomass, and compare it to nitrate exports on a monthly basis to better understand the contribution of foliar litter to atmospheric nitrogen retention.  Our assessment indicates that nitrogen retention by these mechanisms diminishes in early fall, and at that time, may contribute to nitrate production and potential nitrate export from forests.