Germination ecology of the clonal grassland herb Knautia arvensis: Regeneration strategy and geographic variation.
Peer reviewed, Journal article
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We investigated germination responses and seed recruitment in the clonal grassland herb Knautia arvensis (Dipsacaceae) throughout the species’ distributional range in Norway. Four predicted relationships between germination responses and field regeneration behaviour were tested using phytotron experiments and experimental and observational field studies. Seedlings appeared in all experimental microsites in the field, corroborating phytotron predictions that gap- or depth-sensing strategies should be absent in the species. Seasonal timing patterns were predicted from a cold-stratification response in the phytotron, but these were not supported in the field. The relationship between dormancy, germinability during storage, and seed carryover in the field largely conformed to expectation. Seeds from four different geographical regions in Norway responded differently to temperature and cold stratification, and partly also to storage. Dormancy and seed carryover was higher in seeds from a coastal population, where winters are relatively mild and the probability of repeated freeze-thaw events is high, than in populations from mountain and inland areas, where winters are colder. This is discussed against two alternative hypotheses about the relationship between climate and dormancy in seasonal climates.