Submitted to: Ecological Society of America Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 6, 2003
Publication Date: November 15, 2003
Citation: Polley, H.W., Wilsey, B.J., Derner, J.D. 2003. Plant species diversity in native and restored tallgrass prairies: patterns and controls [abstract]. Ecological Society of America Abstracts. p. 269.
One goal of ecological restoration is to restore diversity of native vegetation, but mechanisms responsible for diversity in targeted communities often are poorly understood. We measured diversity (Simpson's index, 1/D) of plant species and functional groups of species in replicated 0.5-m2 plots within paired restored and relict tallgrass prairies at three locations in central Texas. To identify mechanisms responsible for diversity differences between prairie types, we decomposed diversity into richness (S) and evenness (E; relative biomass) and into spatial (alpha, beta, gamma) components and assessed relationships between species and functional group richness in small plots. Species S was greater in native than in restored prairies at the within-plot (alpha), among-plot (beta), and prairie (gamma) scales. Proportional contribution of alpha and beta S to gamma S did not differ between prairie types, indicating that prairies did not differ in proportional scaling of S across space. Species diversity was greater in native than in restored prairies at alpha and gamma scales. The beta component of diversity, however, contributed proportionally more to gamma diversity in native than in restored prairies, implying that the contribution of E to diversity changed with spatial scale. Indeed, although small-scale or plot E did not differ between prairie types, E at the prairie scale was greater in native than in restored grasslands. Plot-scale richness and evenness of functional groups (defined based on growth form and phenology) both were greater in native than in restored prairies. Because ecological function should differ more consistently between functional groups than between species, the greater functional group richness and evenness observed in small plots in native grasslands implies that niche differentiation contributes to the high diversity of native tallgrass prairie.