Castellano, Steven M. , Gorchov, David L. .
Using 15N stable isotope to label Lonicera maackii (Amur honeysuckle) seeds: Linking seed to source.
Seed dispersal of invasive plants profoundly influences spatial patterns of new populations and is of critical interest for understanding invasion dynamics. However, the inability to match seeds and recruits to their source makes it difficult to study dispersal. Here we demonstrate that seeds of the invasive shrub Lonicera maackii (Amur Honeysuckle) are labeled with a stable nitrogen isotope (15N) when reproductive adult shrubs receive foliar application of 15N-urea. During fruit development, we used a hand sprayer to treat each of 53 reproductive shrubs with c. 750 ml of 15N-urea and wetting agent, in a 3 x 3 design: 3 temporal treatments (5 sprayings throughout summer, 1 Aug., and 1 Sept. spraying) crossed with 3 concentrations (0.025, 0.20, 0 g/l). Ripe fruit was collected from each shrub and seeds were hand removed and dried. In November we randomly selected two seeds from each of 42 shrubs for 15N analysis. 15N levels of seeds differed significantly among concentration treatments, with a significant interaction of concentration X temporal treatment (p < 0.0001), with no direct effect of temporal treatment, using a linear mixed effects model with variance weighted by concentration. For both the 0.02 and the 0.025 g/l concentrations, individual pair wise comparisons revealed the 5 spray treatment resulted in the strongest 15N signals; while August did not differ from September; 15N signals from the 0.20 g/l concentration were strongest across all spray treatments. These results are qualitatively similar to analysis of eight seeds from each of the other 11 shrubs from which fruit was collected at an earlier date. This study demonstrates that foliar application of 15N during fruit development can be used to label offspring of this woody invasive shrub, thus linking seed to source. This labeling method may prove to be a useful tool in dispersal and recruitment studies of invasive plants, providing valuable information for our understanding of invasion dynamics and assisting the development of appropriate invasive species management.
Log in to add this item to your schedule
1 - Miami University, Botany, 316 Pearson Hall, 700 East High Street, Oxford, OH, 45056, USA
2 - Miami University, Department of Botany, Oxford, Ohio, 45056, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM