Official
Magazine of the Nature Society (Singapore)
|
One way to find out is to look at the composition of the new trees being recruited. We asked whether some species had become "too common" and whether they were reproducing at a higher rate than other species. Our most common species was Santiria apiculata (Burseraceae) with 940 stems (7% of all the trees in the plot). Its rate of recruitment, however, was no higher than the average for the plot. Nor is its current dominance unusually high if compared to dipterocarp forests in Malaysia. Similarly, other species that were highly abundant did not show an excessive rate of recruitment. The diversity of new recruits was actually quite good. There were 885 new trees in the new 1 cm class and these represented 156 species. The plot itself had 321 species of trees.
may be reproducing at a lower rate than others Another question we tried to address was the vulnerability of tree species that need animals for dispersal. The fruit of trees in the nutmeg family, Myristicaceae, for example, are eaten and dispersed by hornbills. Except for the poor lost soul wandering in the Botanic Gardens area, the hornbill population in Singapore has vanished (for a correction on this statement). What of the trees that depend on them for dispersal. How critical were the hornbills for successful seed germination? This a question that cannot be easily answered and others will continue to work on it. However, our data was able to show that overall, the tree species in the plot that depend on biotic dispersal (as opposed to wind, etc.) were recruiting at a lower rate than abiotically dispersed seeds, and that Myristicaceae had a particularly low recruitment rate. The plot covers only 2 hectares of Bukit Timah so the results can only be extrapolated with caution. However, it is one of the only sources of detailed information such as this, so is invaluable. As we obtain longer term data through repeat inventories in the future, many more answers should become available.
<<Back to Issue contents |
||||||||||||||
© Nature Society Singapore |