Seedling recruitment in a northern temperate forest: the relative importance of supply and establishment limitation

We quantified supply and establishment limitation as components of seedling recruitment for five species common to the temperate forests of central Ontario. Establishment limitation was the primary cause of recruitment failure for the three most common species: Acer saccharum Marsh., Betula alleghaniensis Britt., and Tsuga canadensis (L.) Carrière. The main barrier to establishment (including germination and seedling emergence) was a lack of suitable substrates, rather than a lack of light. Supply limitation, on the other hand, was the primary cause of recruitment failure for two less common species, Abies balsamea (L.) Mill. and Fagus grandifolia Ehrh. The cause of supply limitation was a lack of parent trees, in the case of A. balsamea, and low fecundity, in the case of F. grandifolia. Our results suggest that niche differences (i.e., germination requirements) are more important than dispersal in structuring temperate forest communities. Our results also suggest that availability of suitable substrates is the primary factor limiting seedling recruitment following logging.