| The effect of fire frequency, fire season, and fire temperature on tallgrass prairie plants were studied in three separate but related studies. First, I examined the effect of fire on the life history traits of five species of tallgrass prairie forts (Baptisia bracteata, Oenothera speciosa, Vernonia baldwinii, Salvia azurea, and Solidago missouriensis). The forts studied here did not exhibit a positive response to any one particular burn frequency, while four of the five did respond positively to summer burning. There were only two underlying similarities among these five species of forts, a lack of a relationship between percent cover data and sexual reproductive effort and all five forts behave like satellite species, becoming temporarily locally absent at least once during the last 18 years. Neither fire frequency or fire season produced an overriding influence on plant growth and reproduction.; In the second study, I examined what role fire frequency and fire temperature play in altering rhizome development and depth distribution. Rhizome depth was found to be greatest on infrequently burned watersheds. The best predictor of maximum soil temperature generated by fire was initial soil temperature. Fire frequency did influence rhizome depth, but the differences in rhizome depth were not directly due to lethal fire temperatures. Rhizome and tiller density was highest on frequently burned watersheds, though the probability of tillering was greatest on infrequently burned watersheds.; Finally, I study examined the effects of fire on the tallgrass prairie fort Solidago canadensis. S. canadensis showed increases in percent cover, genet size, aboveground biomass, reproductive biomass, flower number and sexual reproductive effort (SRE) in response to infrequent burning. Mean rhizome number, length, depth, and mass were all significantly greater in sites with low fire frequency. Data indicate that this species is negatively affected by frequent fire, however, sexual reproductive effort was significantly higher in infrequently burned sites, providing no support for the hypothesis that clonally herbs in unfavorable sites "escape" poor conditions though increased SRE. |
