Elevated atmospheric nitrogen (N) deposition can alter forest biogeochemistry leading to adverse impacts on terrestrial ecosystems. Experimental studies often apply N to the forest understorey at greatly elevated loads, bypassing important canopy interactions. Using a narrow N deposition gradient (0, 5, 10, 15, 20, and 25 kg N·ha−1·year−1), we measured changes in jack pine ( Pinus banksiana Lamb.) forest biogeochemistry in the bituminous sands region of northern Alberta, Canada after 5 years of above-canopy N additions. The canopy intercepted approximately 46% of applied N across all treatments, but during the final year, N interception was reduced to 7% in the highest treatment. Nitrogen concentrations in nonvascular organisms increased with treatment and N was also immobilized in decomposing litter in the highest treatment. Otherwise, vascular plant biomass, foliar chemistry, and soil processes exhibited no relationship with treatment over 5 years. This work suggests that jack pine forests in the region have a high capacity to immobilize N inputs over the short-term (5 years), which restricts other biogeochemical responses traditionally associated with elevated N deposition.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.