Effects of fire on sandhill herbs: nutrients, mycorrhizae, and biomass allocation

Abstract

Differences in growth responses, tissue and soil inorganic nutrients, and mycorrhizal relationships of four herbaceous species were studied on burned and unburned sandhill sites in south-central Florida, USA. Three species, (Aristida stricta, Liatris tenuifolia var. laevigata, and Pityopsis graminifolia) responded positively to conditions following the burn by increased vegetative growth and flowering. The fourth species, Balduina angustifolia, is a fire-sensitive biennial and its first-year rosettes were, with an occasional exception, unable to survive or resprout following fire. Availability of all soil inorganic nutrients examined (Ca, K, Mg, and P) was low, as were total nitrogen, soil organic matter, and pH. There was a slight nutrient pulse of phosphorus into the soil following burning. For two species (Aristida and Liatris), shoot tissue concentrations of several inorganic nutrients (especially N and P) were higher on the burned site than the unburned site following burning. These differences generally dissipated over time since burning. The high concentration of tissue nutrients postburn followed by a decline on the burned site may result from rapid nutrient uptake after fire and dilution of this concentration following restoration of plant mass. Despite low levels of soil inorganic nutrients, including phosphorus, mycotrophy was absent or weakly developed among the herbaceous species examined, except for the tap-rooted Balduina angustifolia. Colonization of host plants by vesicular mycorrhizal fungi was unaffected by burning. Mycorrhizal inoculum potentials of sandhill soil were extremely low, varying seasonally from (mean +/- 1 SE) 0.3 +/- 0.2 to 3.8 +/- 0.7%.

Effects of Restoration Techniques on Soil Carbon and Nitrogen Dynamics in Florida Longleaf Pine (Pinus palustris) Sandhill Forests

“…This result was slightly unexpected given the structural changes in forest communities [19,20,42] but was consistent with earlier studies [30,31,36,69,70] that found little or no short-term effect of repeated fires on soil nutrients in nutrient-poor systems. This would also suggest that soil C and N are relatively resistant to degradation.…”

Influence of a native legume on soil N and plant response following prescribed fire in sagebrush steppe

“…It is possible that Lupinus tissue N is mostly derived from fixed N, making the amount of available soil N less influential than for other species. The 3-year post-fire treatment had the greatest amount of biomass production for Lupinus (and most other functional groups), but also the lowest amounts of available soil N. Although numerous studies have shown that tissue nutrient concentrations increase after fire (Anderson and Menges 1997;Bennett et al 2002;Rau et al 2008), studies examining response of legumes often find results similar to ours. Legume tissue N concentration was not affected by fire in pine forests, although other species did show an increase in tissue N concentrations (Lajeunesse et al 2006;Metzger et al 2006).…”

Short-term effects of fire on soil and plant nutrients in palmetto flatwoods

“…Soil δ 15 N and the difference between foliar and soil δ 15 N did not change over time for any species, however, suggesting that dependence on mycorrhizae for N uptake did not change after fire. In addition, Anderson and Menges (1997) and Eom et al (1999) found that fire had no effect on colonization of roots by arbuscular mycorrhizae. Schmidt and Stewart (1997) found that plant δ 15 N signatures were more similar among species with the same mycorrhizal status than among species with the same post-fire response (e.g.…”