Isotopic evidence of the effects of herbivory and landscape position on plant nitrogen sources in a riparian ecosystem

• Published in: Isotopes in environmental and health studies Vol. 45; no. 1; pp. 41 - 52
• Main Author: Menezes, Rômulo S.C.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 01.03.2009
• Subjects: Animals; Carex Plant - metabolism; Colorado; Deer - physiology; Ecosystem; elk; Feeding Behavior; Fresh Water - chemistry; natural abundance; Nitrogen - analysis; Nitrogen - chemistry; Nitrogen - metabolism; Nitrogen Isotopes - analysis; nitrogen-15; reed-grass; Rocky Mountain National Park; Salix - metabolism; Seasons; Water Supply; willow; Colorado; USA, Colorado, Rocky Mountain Natl. Park
• ISSN: 1025-6016; 1477-2639; 1477-2639
• DOI: 10.1080/10256010802522150

This study used 15 N natural abundance techniques to investigate whether elk herbivory affects the capability of willow (Salix spp.) and reed-grass (Carex spp.) to access N from groundwater in upper and lower landscape positions within riparian areas of the Rocky Mountain National Park. For this, δ 15 N values of plant, soil, rainfall and groundwater samples were measured within a replicated field experiment. Despite the relatively high variability in the 15 N data, it provided evidence of the effects of grazing and lanscape position on plant N sources. Carex seemed to acquire less groundwater N in upper landscape positions compared to Salix, maybe due to the deeper willow rooting system. However, grazed willows in upper landscape positions seemed to acquire less groundwater N as compared to willows protected from herbivory. These findings were in accordance with other isotopic and non-isotopic studies conducted in the same experimental site.