2002 Volume 19 Issue 1 Pages 33-41
The initial growth of Persea thunbergii seedlings was studied at a rookery site of streaked shearwaters (burrow nesters) in evergreen broad-leaved forests on Kanmurijima Island and at a non-rookery site on Jajima Island in Kyoto, Japan. Seeds of P. thunbergii collected on Kanmurijima Island in August were experimentally sown in order to survey the initial growth of the seedling. The height of the first-year seedlings of P. thunbergii in a rookery site was found to be lower than that of first-year seedlings in a non-rookery site. The height for the first-year seedlings of P. thunbergii in protected plots significantly differed from the height in unprotected plots on Kanmurijima Island. The leaf area for the older seedlings (more than one year old) of P. thunbergii in a rookery site was conspicuously small in the P. thunbergii seedlings from different regions. The total area of leaves per seedling indicated a converse J-shaped frequency distribution for the P. thunbergii seedlings on Kanmurijima Island, but indicated a normal distribution for seedlings on Jajima Island and for those sown for the experiment. This result suggests that physical disturbance of burrow nesters causes a decrease in leaf area and height in the initial stage of P. thunbergii seedling growth.
