PARENT SESSION
Poster Session 7: Grasslands
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Soil nutrient patchiness does not affect belowground competition.

Rajaniemi, Tara^{*,1, 2}, Reynolds, Heather¹, ¹ Indiana University, Bloomington, IN² University of Massachusetts Dartmouth, North Dartmouth, MA

ABSTRACT- Nutrient heterogeneity is ubiquitous in natural soils, but its role in structuring plant communities is largely unknown. We tested the effect of small-scale nutrient heterogeneity, occurring within the rooting area of individual plants, on the outcome of belowground competition. Plants were grown in a target-neighbor design in the greenhouse, and aboveground competition was prevented by using nets to hold neighbor shoots away from targets. Fertilizer was either mixed throughout the pot or concentrated in two discrete patches. Three neighbor species (Bromus inermis, Leucanthemum vulgare, and Festuca rubra) competed with Achillea millefolium targets. These four species have been shown to differ in root weight ratio, root growth rate, and root response to nutrient patches. Neighbor densities varied from 0 to 4 neighbors per pot, and regression was used to quantify per-gram effects of neighbors. Belowground competitive effects did not differ with patchiness of soil nutrients. Furthermore, despite their differences in root traits, the neighbor species did not differ in per-gram competitive effects.

Key words: plant competition, community ecology