Print PageConsequences of woody encroachment into grasslands include changes in edaphic characteristics and community structure and function. Our study aimed at determining whether expansion of N-fixing Morella cerifera leads to increased N availability and suitable edge habitat for the non-N fixing Baccharis halimifolia on a N limited barrier island. Morella cerifera and B. halimifolia are both native shrubs to this system and increases in abundance of M. cerifera on the island are well documented, yet increases in B. halimifolia abundance have not been investigated. We hypothesized that close proximity of B. halimifolia to M. cerifera would lead to higher foliar %N concomitant with increases in total chlorophyll, photosynthesis, and light-adapted fluorescence. We compared B. halimifolia growing adjacent to M. cerifera (~1.4 m apart) to isolated B. halimifolia (~22 m from the nearest M. cerifera) on Hog Island, VA.
Results/Conclusions
Baccharis halimifolia growing near M. cerifera had significantly higher foliar %N compared to isolated B. halimifolia (2.98 vs. 1.46 %, respectively) thereby supporting our hypothesis. Close proximity to M. cerifera also resulted in higher total chl and light-adapted fluorescence and lower C:N for B. halimifolia (p ≤ 0.001 for each). The only parameter that did not differ for B. halimifolia with respect to distance to M. cerifera was Anet. We also quantified variations in foliar δ15N which were comparable for both M. cerifera and B. halimifolia adjacent to M. cerifera thickets suggesting a similar N source; however, isolated B. halimifolia had significantly higher δ15N values. Our foliar %N, C:N, and δ15N results indicate that close proximity to M. cerifera shrub thickets provides B. halimifolia with resources including but not necessarily limited to an additional N source on an N limited barrier island. Expansion of M. cerifera into grasslands leads to further woody encroachment by other species such as B. halimifolia.
