title: Performance and allocation patterns of the perennial herb, Plantago lanceolata, in response to simulated herbivory and elevated CO2environments.
abstract: We tested the prediction that plants grown in elevated CO2environments are better able to compensate for biomass lost to herbivory than plants grown in ambient CO2environments. The herbaceous perennial Plantago lanceolata (Plantaginaceae) was grown in either near ambient (380 ppm) or enriched (700 ppm) CO2atmospheres, and then after 4 weeks, plants experienced either 1) no defoliation; 2) every fourth leaf removed by cutting; or 3) every other leaf removed by cutting. Plants were harvested at week 13 (9 weeks after simulated herbivory treatments). Vegetative and reproductive weights were compared, and seeds were counted, weighed, and germinated to assess viability.Plants grown in enriched CO2environments had significantly greater shoot weights, leaf areas, and root weights, yet had significantly lower reproductive weights (i.e. stalks + spikes + seeds) and produced fewer seeds, than plants grown in ambient CO2environments. Relative biomass allocation patterns further illustrated differences in plants grown in ambient CO2environments. Relative biomass allocation patterns further illustrated differences in plant responses to enriched CO2atmospheres: enriched CO2-grown plants only allocated 10% of their carbon resources to reproduction whereas ambient CO2-grown plants allocated over 20%. Effects of simulated herbivory on plant performance were much less dramatic than those induced by enriched CO2atmospheres. Leaf area removal did not reduce shoot weights or reproductive weights of plants in either CO2treatment relative to control plants. However, plants from both CO2treatments experienced reductions in root weights with leaf area removal, indicating that plants compensated for lost above-ground tissues, and maintained comparable levels of reproductive output and seed viability, at the expense of root growth.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., 02138, Cambridge, MA, USA.
authors.forename: E D
authors.initials: ED
authors.lastname: Fajer
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., 02138, Cambridge, MA, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Bowers
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., 02138, Cambridge, MA, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Bazzaz
keywords: Allocation; Compensatory growth; Defoliation; Reproductive effort; Seed quality