Miller
E. E.
Miller
E. E.
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ArticlePlant nitrogen dynamics in fertilized and natural New England salt marshes : a paired 15N tracer study(Inter-Research, 2008-02-07) Drake, Deanne C. ; Peterson, Bruce J. ; Deegan, Linda A. ; Harris, Lora A. ; Miller, E. E. ; Warren, R. ScottWe examined the effects of increased nutrient availability on nitrogen (N) dynamics in dominant New England salt marsh plants (tall and stunted Spartina alterniflora and S. patens) using paired large-scale nutrient and 15NO3– tracer additions. This study is one component of a long-term, large-scale, salt marsh nutrient and trophic manipulation study (the Trophic Cascades and Interacting Control Processes in a Detritus-based Aquatic Ecosystem [TIDE] Project). We compared physiological variables of plants in fertilized (~17× ambient N and P in incoming tidal water) and reference marsh systems to quantify NO3– uptake and uptake efficiency, allocation of N to tissues, end-of-season N resorption, leaf litter quality and other potential responses to increased nutrient availability. Reference system plants sequestered ~24.5 g NO3-N ha–1 d–1 in aboveground pools during mid-summer, while fertilized plants sequestered ~140 g NO3-N ha–1 d–1. However, NO3– uptake efficiency (% of total incoming NO3-N sequestered aboveground) was higher in the reference system (16.8%) than in the fertilized system (2.6%), suggesting that our fertilization rate (~70 µM NO3– in incoming water) approaches or exceeds the uptake saturation point for this vegetation community. Leaf litter quality was clearly affected by N availability; N resorption efficiency was lower in all plants of the fertilized system; senesced leaves from the fertilized creek contained ~43% (tall S. alterniflora), 23% (stunted S. alterniflora) and 15% (S. patens) more N per unit biomass than reference creek leaves.