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Harvard Forest Symposium Abstract 2006
- Title: Nitrogen cycling dynamics in the northern pitcher plant, Sarracenia purpurea
- Primary Author: Jessica Butler (Harvard Forest)
- Additional Authors: Aaron Ellison (Harvard University)
- Abstract:
Sarracenia purpurea, is a carnivorous plant found in nutrient poor, ombrotrophic (rain-fed) bogs throughout Canada and the Eastern United States. S. purpurea produces pitcher-shaped leaves that fill with rain water and support a four-trophic-level food web consisting of bacteria, rotifers, protozoa, mites, and fly larvae. The base of this detritus-based food web is captured prey. In addition to obtaining any readily available nutrients released by the food web, S. purpurea pitchers also obtain nitrogen (N as NH4 and NO3) from atmospheric N deposition. At present, the dynamics of N cycling within S. purpurea are poorly understood. We conducted two greenhouse experiments to better understand the dynamics of N cycling within (assimilation and translocation) and across (storage and remobilization) growing seasons. We examined the contribution of stored N versus current uptake of N to growth in the present season. We also examined the significance of N obtained by the first pitcher produced in the growing season to plant growth and/or maintenance later in the growing season. We used 5 atom% 15NH415NO3 to follow the assimilation, translocation, and remobilization of N fed to roots and/or pitchers. S. purpurea relied on stored nitrogen for early season growth; less than 20% and 5% of the supplied N was assimilated by pitchers and roots, respectively in the early growing season. Pitcher uptake increased to ~60% later in the growing season while root uptake remained low. Pitchers represented the most significant sink for acquired N regardless of whether N was taken up via pitchers or roots. Nitrogen taken up by the first pitchers produced in the growing season contributed to the production and maintenance of subsequent pitchers, roots, and rhizomes. However, on a mass basis, the N translocated from the first pitcher to new pitchers, roots, and rhizomes represented a relatively small portion of their total N pool (less than 10%). This suggests that plant growth later in the season relies on prey, stored N, and probably N translocated from other pitchers produced earlier in the growing season.
- Research Category: Physiological Ecology, Population Dynamics, and Species Interactions
