Seedling emergence and seed longevity of the tree weeds Celtis sinensis and Cinnamomum camphora

Factors influencing germination and seed survival of Celtis sinensis Pers. and Cinnamomum camphora (L.) Presl. were investigated in a series of experiments conducted under natural rainfall regimes in the field and under irrigation in a growth tunnel. Germination from surface‐sown seeds of C. camphora was virtually nil under natural rainfall, in contrast to almost 100% germination under irrigation. This suggests that surface‐lying seeds of this species will germinate only in highly protected microsites in the field. For C. sinensis , however, in one of the two field experiments germination from surface‐sown seeds was similar (≈40%) to that achieved under irrigation. Germination from intact fruits of both species was generally considerably less than from seeds. Seeds of both species were relatively short‐lived under field conditions. A maximum of 1% of seeds of C. camphora remained viable at 12 months post‐sowing under field conditions, whereas a maximum of 8% viable seeds of C. sinensis was detected at 24 months post‐sowing in one of the field experiments.