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Factors Affecting Germination of Chaparral Seeds





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Factors affecting germination of chaparral seeds by Jon E. Keeley. Bull. Southern California Acad. Sci., 83(3): 1 13-120, 1984. Seedling establishment is uncommon under mature chaparral but abundant after fire. Germination from soils collected beneath chaparral and in an adjacent burned site were compared after various treatments. Application of an aqueous leachate from the dominant overstory shrub (Adenostoma fasciculatum) failed to produce any inhibition of seedling emergence from the mature chaparral soil but rather increased germination. Soil heating and powdered charred wood (charate) stimulated germination of dicots but not grasses. Tests of specific species showed Phacelia cicutaria and Salvia columbariae markedly stimulated by charate whereas Cryptantha muricata and Lotus salsuginosus were not. Grasses were abundant in the bum soil and germinated readily without treatment; their residence time in the soil, however, may be limited as they were uncommon in the mature chaparral soil. Light was a significant factor in germination of both monocots and dicots. Continuous darkness significantly reduced germination over a 12 hour photoperiod at ~230 μE m-2 s-1 or ~20 μE m-2 s-1 or periodic (several hours/ week) light of variable intensity.