COMPETITIVE INTERACTIONS BETWEEN THE INVASIVE Symphyotrichum lanceolatum (Willd.) G. L. Nesom AND NATIVE Achillea millefolium L.

摘要

This study set out to explore the influence of reduced N concentration and competition on vegeta- tive growth and resource allocation of Symphy- otrichum lanceolatum (Willd.) G. L. Nesom and Achillea millefolium L. Comparison of two different genera from the family Compositae will allow the assessment of the impact of morphological or physi- ological constraints on resource allocation in species occupying the same habitat. Plants were grown in hydroculture. Culture types included two monocul- ture (invasive S. lanceolatum and native A. mille- folium) and mixed culture (combination of those two species). Basic morphological and growth parame- ters from different treatments (reduced N concentra- tion and control) were determined. Dry above- ground and below-ground biomass were measured. as well as the N concentration in leaves and P and K concentration in the above-ground and below- ground biomass. The results showed that S. lanceo- latum and A. millefolium produce approximately equal above-ground biomass, while S. lanceolatum produces significantly higher below-ground biomass. Further, the study suggests that S. lanceolatum toler- ates a lower nitrogen concentration and that it out- competes A. millefolium. This S. lanceolatum growth strategy could contribute to its spread since it allo- cates biomass to below-ground biomass at the begin- ning of its ontogenetic development, and thus creates the potential for greater resource acquisition.