1. REWM 3500 Rangeland Plant Ecophysiology Monday, November 9, 2009 Plant-plant interactions Facilitation and Competition Models of resource competition Can plants sense presence of neighbors? What traits confer competitive success in arid and semiarid rangeland? Interference competition (Allelopathy)

2. response sp-Asp-B Neutral00 Mutualism++ Commensalism+0 Amensalism-0 Parasitism+- Herbivory+- Predation+- Competition-- Biotic interactions

3. Facilitation of Agave by Hilaria Facilitation of neighboring plants

4. Hydraulic lift in Artemisia improves growth of neighbor plants Facilitation of neighboring plants

5. Tilman (1988) model of resource competition

6. Direct evidence of resource competition

7. Can plants sense presence of other plants?

8. Mahall and Callaway 1991 Root-root communication and interference

9. Ambrosia roots growing into Larrea roots Larrea roots growing into Ambrosia roots Mahall and Callaway 1991 Root-root communication and interference

10. Allelopathic compound released to soil may account for root-root interference

11. Allelopathic compound leached from leaves of black walnut (Juglans niger)

12. Bais et al. (2003) - Allelopathy in spotted knapweed (Centaurea maculosa)

13. Terms and concepts to know: facilitation parasitism neutral interactions competition nurse plant resource competition interference competition (Allelopathy) relative growth rate Grime and Tilman models of competition R/FR light ratios