ABSTRACT
Despite the large stocks of organic nitrogen (ON) in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen (IN), not ON. Although some vascular plants can assimilate ON directly, only recently has ON been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of ON to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition.
