REWM 3500Rangeland Plant EcophysiologyMonday, 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)

responsesp-A sp-B

Neutral 0 0Mutualism + +Commensalism + 0Amensalism - 0Parasitism + -Herbivory + -Predation + -Competition - -

Biotic interactions

Facilitation of Agave by Hilaria

Facilitation of neighboring plants

Hydraulic lift in Artemisia improves growth of neighbor plants

Facilitation of neighboring plants

Tilman (1988) model of resource competition

Direct evidence of resource competition

Can plants sense presence of other plants?

Mahall and Callaway 1991

Root-root communication and interference

Ambrosia roots growing into Larrea roots

Larrea roots growing into Ambrosia roots

Mahall and Callaway 1991

Root-root communication and interference

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

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

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

Terms and concepts to know:

facilitationparasitismneutral interactions competition nurse plantresource competitioninterference competition (Allelopathy)relative growth rateGrime and Tilman models of competitionR/FR light ratios