Regeneration of a dominant Mediterranean dwarf-shrub after fire

The regeneration after fire of the dominant east Mediterranean dwarf-shrub Sarcopoterium spinosum was studied under various habitat and geographic conditions in northern Israel, northern Crete and the Aegean coast of Turkey. Age structures of regenerating stands were determined 3 - 9 yr after fire on 13 1m x 1m sample stands by analysis of growth rings in the taproot crown of 874 plants. S. spinosum regenerated either by massive seedling recruitment in some habitats or by resprouting from surviving meristems in others. This versatility facilitates adaptation of the species to widely different environmental conditions and is a factor in the maintenance of its dominance after fire at occupied sites. In the years after fire, the growth of younger plants within the stand at all sites was severely suppressed by the older shrubs. Consequently, the age structure of the stands was dominated by one or two older cohorts that became established soon after fire. In addition, on most habitats, older shrubs (usually older than 6 yr) were often composed of clusters of plants that suggested clonal proliferation of ramets. The strongly peaked age structure, together with the appearance of clonal regeneration on the older plants, suggests that subsequent maintenance of the stand was not dependent on recurrent seedling recruitment. This can explain the persistence of S. spinosum in stands of herbaceous vegetation despite the extreme sensitivity of the seedlings to competition under such conditions.