Abstract - Patterns in Grass Silicification: Response to Grazing History and Defoliation
Cid, M.S., Detling, J.K., Brizuela, M.A. and Whicker, A.D. 1988. Patterns in Grass Silicification: Response to Grazing History and Defoliation. Oecologia 80. pp. 268-271.
Morphologiaclly distinct populations of a North American perennial grass, Agropyron smithii, collected from a heavily grazed prairie dog (Cynomys ludovicianus) colony (PDC) and a grazing exclosure (EX), were grown in an environmental chamber to determine whether: (1) leaf silicon (Si) concentrations are greater in plant populations which differentiated under heavy grazing pressure, and (2) leaf silification is inducible by defoliation. Mean shoot Si concentration of nondefoliated plants was greater in the PDC population (2.2%) than the EX population (1.9%) over the 18 wk experiment, largely as a result of differences in Si concentrations in leaf blades. However, leaf Si concentration was lower in defoliated plants of each population than in nondefoliated plants, indicating that leaf silicification was not an inducible herbivore defense mechanism in A. smithii. The higher leaf Si concentrations from the heavily grazed population may be associated with grazing-related environmental stresses such as a warmer, drier microclimate or with morphological characteristic related to grazing tolerance or avoidance.