Abstract

In northern New Zealand, Beilschmiedia tawa has shown recruitment failure in some sites. The Beilschmiedia genus has been shown to contain allelopathic compounds in its leaves and bark. In addition, the distribution of the main seed disperser for tawa, the kerer (u) over cap (Hemiphaga novaeseelandiae), has declined in recent years. In this study I assessed whether B.tawa leaf leachate can affect recruitment of B.tawa, particularly in disturbed sites. I also tested whether simulated endozoochory (removal of mesocarp) had an effect on germination. Results show that under laboratory conditions, leachate can have either a negative or a positive effect, depending on the concentration. At high concentrations (1:1), higher than normally experienced in the field, radicles were shorter than in the less concentrated treatment. At lower concentrations (1:50) there was a 50% higher germination index compared with the control and high concentration (1:1) treatments. Using soils from sites with different levels of anthropogenic disturbance did not have an effect on germination or hypocotyl length. Removal of the mesocarp positively affected germination (1.5-fold). Based on the results of this study, inhibition of germination and growth of B.tawa is unlikely to be caused by phytotoxicity of their own leachate under field conditions.