Post-fire uptake of nutrients by diverse ephemeral herbs in chamise chaparral

Abstract

Diverse populations of ephemeral herbs form the dominant element of community biomass in the first year of growth following a fall burn in chamise chaparral. Ephemeral herbs constituted 337 kg ha^-1 of above-ground biomass after the first season of post-fire growth. This was 64% of the total, with the majority of the remaining biomass being in resprouts of Adenostoma fasciculatum. Ephemeral herb biomass following fire in other stands was as high as 1117 kg ha^-1. Nutrient contents of ephemeral herbs were 6.68 kg N ha^-1, 0.71 kg P ha^-1, 10.05 kg K ha^-1, 4.75 kg Ca ha^-1 and 0.91 kg Mg ha^-1. These were 55, 54, 81, 71 and 70% respectively of the above-ground totals. In the second year following fire, the total herb biomass was 40% higher, but the nutrient pool in above-ground biomass of these herbs was only 30-60% of what it had been the first year. Resprouts of A. fasciculatum and short-lived wood shrubs constituted more than 90% of above-ground biomass at this stage of postfire succession.