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

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.