Foliar nutrient concentrations and ratios of scrubby flatwoods species change with time after fire

Plant nutrient stoichiometry, which regulates carbon fixation and plant growth, is often strongly affected by soil nutrient availability. Disturbances such as fire can affect the absolute and relative availability of soil nitrogen (N) and phosphorus (P), as well as biotic constraints on plant nutrient uptake and allocation. In these ways, disturbances can have strong legacy effects on plant growth by altering nutrient stoichiometry. Florida scrubby flatwoods are pyrogenic ecosystems where fires are frequent and intense, and the dominant species resprout after fire. We measured foliar N and P concentrations, nutrient ratios, and δ¹⁵N of ten species in scrubby flatwoods 1 yr, 3 yr, and 12 yr after fire to determine how fire affects nutrient stoichiometry. Across all species, foliar %N and %P decreased then increased with time after fire, and were positively correlated with each other. In contrast, foliar N:P ratios increased then decreased with time after fire. The effects of time after fire on nutrient concentrations and ratios, however, were not consistent among species. For example, %P of palmettos was highest 1 yr after fire, while %P of ericaceous shrubs was highest 12 yr after fire. Our study suggests that scrubby flatwoods may be colimited by N and P, species may be differentially limited by N and P, and species may experience greater N or P limitation depending on time after fire.