| Title: | Woody plant secondary chemicals increase in response to abundant deer and arrival of invasive plants in suburban forests |
| Author(s): | Morrison JA; Roche B; Veatch-Blohm M; |
| Address: | Department of Biology The College of New Jersey Ewing New Jersey USA. RINGGOLD: 3280 Department of Biology Loyola University Maryland Baltimore Maryland USA. RINGGOLD: 28521 |
| ISSN/ISBN: | 2045-7758 (Print) 2045-7758 (Electronic) 2045-7758 (Linking) |
| Abstract: | "Plants in suburban forests of eastern North America face the dual stressors of high white-tailed deer density and invasion by nonindigenous plants. Chronic deer herbivory combined with strong competition from invasive plants could alter a plant's stress- and defense-related secondary chemistry, especially for long-lived juvenile trees in the understory, but this has not been studied. We measured foliar total antioxidants, phenolics, and flavonoids in juveniles of two native trees, Fraxinus pennsylvanica (green ash) and Fagus grandifolia (American beech), growing in six forests in the suburban landscape of central New Jersey, USA. The trees grew in experimental plots subjected for 2.5 years to factorial treatments of deer access/exclosure x addition/no addition of the nonindigenous invasive grass Microstegium vimineum (Japanese stiltgrass). As other hypothesized drivers of plant secondary chemistry, we also measured nonstiltgrass herb layer cover, light levels, and water availability. Univariate mixed model analysis of the deer and stiltgrass effects and multivariate structural equation modeling (SEM) of all variables showed that both greater stiltgrass cover and greater deer pressure induced antioxidants, phenolics, and flavonoids, with some variation between species. Deer were generally the stronger factor, and stiltgrass effects were most apparent at high stiltgrass density. SEM also revealed that soil dryness directly increased the chemicals; deer had additional positive, but indirect, effects via influence on the soil; in beech photosynthetically active radiation (PAR) positively affected flavonoids; and herb layer cover had no effect. Juvenile trees' chemical defense/stress responses to deer and invasive plants can be protective, but also could have a physiological cost, with negative consequences for recruitment to the canopy. Ecological implications for species and their communities will depend on costs and benefits of stress/defense chemistry in the specific environmental context, particularly with respect to invasive plant competitiveness, extent of invasion, local deer density, and deer browse preferences" |
| Keywords: | Microstegium vimineum multiple stressors plant defense structural equation modeling suburban forest white-tailed deer; |
| Notes: | "PubMed-not-MEDLINEMorrison, Janet A Roche, Bernadette Veatch-Blohm, Maren eng England 2022/04/19 Ecol Evol. 2022 Apr 13; 12(4):e8814. doi: 10.1002/ece3.8814. eCollection 2022 Apr" |
