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Title: Life history constraints in grassland plant species: A growth-defense trade-off is the norm

Author
item LIND, ERIC - University Of Minnesota
item BORER, ELIZABETH - University Of Minnesota
item SEABLOOM, ERIC - University Of Minnesota
item ADLER, PETER - Utah State University
item BAKKER, JONATHAN - University Of Washington
item Blumenthal, Dana
item CRAWLEY, MICK - Imperial College
item DAVIES, KENDI - University Of Colorado
item FIRN, JENNIFER - Queensland University - Australia
item GRUNER, DAN - University Of Maryland

Submitted to: Ecology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2013
Publication Date: 1/24/2013
Citation: Lind, E., Borer, E., Seabloom, E., Adler, P., Bakker, J., Blumenthal, D.M., Crawley, M., Davies, K., Firn, J., Gruner, D. 2013. Life history constraints in grassland plant species: A growth-defense trade-off is the norm. Ecology Letters. 16:513-521.

Interpretive Summary: Plants face distinct challenges in acquisition of limited resources (light, water, and nutrients), addition of tissue, and protection of tissue from consumers. We tested for competition-defense and growth-defense tradeoffs following fertilization and fencing treatments at 39 grassland sites worldwide. Species increasing with the alleviation of nutrient limitation also increased following removal of consumers, providing evidence for a growth-defense tradeoff. This result held across the global extent of the dataset, within each plant functional type, and within the majority of individual sites. Thus a growth-defense tradeoff is the norm, and mechanisms maintaining grassland biodiversity must operate within this constraint.

Technical Abstract: Plants face distinct challenges in acquisition of limited resources, addition of tissue, and protection of tissue from consumers, leading to contrasting tradeoff possibilities. The competition-defense hypothesis posits a tradeoff between competitive ability and defense against herbivory. The growth-defense hypothesis suggests strong competitors for scarce nutrients are also defended against herbivores, at a cost to growth rate. We tested these hypotheses using observations of unique species in plant communities before and one year following fertilization and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided evidence for a growth-defense tradeoff: species increasing with the alleviation of nutrient limitation increased following removal of consumers. This result held across the global extent of the dataset, within each plant functional type, and within the majority of individual sites. Thus a growth-defense tradeoff is the norm, and mechanisms maintaining grassland biodiversity must operate within this constraint.