Fire-type heat increases the germination of Cistaceae seeds in contrast to summer heat

Abstract

Our analyses of data in Luna et al. (Fire Ecology 19:52, 2023) do not support the proposal that dormancy release of the hard seeds in 12 species of Cistaceae is a “two-step process” involving high summer temperatures followed by fire-type heat. The reverse is true: subjection to a month of daily alternating temperatures of 50/20 °C (summer heat) is more likely to induce dormancy among initially soft seeds or secondary dormancy among those softened by fire heat or reduce the ability of fire heat to soften the seeds. The need to inspect seeds for the presence of an open “water gap” following various heat treatments, and using more realistic summer temperatures in future studies, is clear.