| Title: | Seasonal variation in effects of herbivory on foliar nitrogen of a threatened conifer |
| Author(s): | Schaeffer RN; Soltis NE; Martin JL; Brown AL; Gomez S; Preisser EL; Orians CM; |
| Address: | "Department of Biology, Tufts University, Medford, MA 02155, USA. Present address: Department of Entomology, Washington State University, Pullman, WA 99164, USA. Present address: Department of Plant Sciences, University of California Davis, Davis, CA 95616, USA. Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA" |
| ISSN/ISBN: | 2041-2851 (Print) 2041-2851 (Electronic) |
| Abstract: | "Invasive herbivores can dramatically impact the nitrogen (N) economy of native hosts. In deciduous species, most N is stored in stem tissues, while in evergreen conifer species N is stored in needles, making them potentially more vulnerable to herbivory. In eastern forests of the USA, the long-lived, foundational conifer eastern hemlock (Tsuga canadensis) is under the threat of extirpation by the invasive hemlock woolly adelgid (HWA: Adelges tsugae). We assessed the impact of HWA infestation on the patterns of seasonal foliar N availability in hemlock planted in a deciduous forest understory. Over the course of a year, we sampled needles and twigs and measured N, carbon (C), C:N ratio, and total protein concentrations. Tissue sampling events were timed to coincide with key life-history transitions for HWA to determine the association between HWA development and feeding with these foliar nutrients. In uninfested trees, needle and twig N concentrations fluctuated across seasons, indicating the potential importance of N storage and remobilization for the N economy of eastern hemlock. Although N levels in HWA-infested trees also cycled annually, the degree to which N concentrations fluctuated seasonally in tissues was significantly affected by HWA feeding. These fluctuations exceeded N levels observed in control trees and coincided with HWA feeding. HWA feeding generally increased N concentrations but did not affect protein levels, suggesting that changes in N do not occur via adelgid-induced protein breakdown. Herbivore-induced mobilization of N to feeding sites and its rapid depletion may be a significant contributor to eastern hemlock mortality in US forests" |
| Keywords: | Adelges tsugae Tsuga canadensis nitrogen remobilization nitrogen storage protein; |
| Notes: | "PubMed-not-MEDLINESchaeffer, Robert N Soltis, Nicole E Martin, Jennifer L Brown, Aden L Gomez, Sara Preisser, Evan L Orians, Colin M eng England 2017/04/26 AoB Plants. 2017 Feb 28; 9(2):plx007. doi: 10.1093/aobpla/plx007. eCollection 2017 Mar" |
