ENGGOH GLAK @ MD. IRWAN ABDULLAH

Plants of the Rafflesia genus are complete parasites, which have no stem or leaves of their own, being totally dependent on the host for nutrients. The only vine that is able to host this parasitic plant is in the genus Tetrastigma. Overall, Rafflesia is rare, but one species (Rafflesia tuan-mudae) grows in many places in Gunung Gading National Park.

More research could be done on the Rafflesia of the Park, in particular long term studies to document the development of the buds and the vines.

Flowers of the genus Rafflesia are the world's largest flowers (Simons, 1992). The plants are complete parasites, and the buds and flowers are found growing on the roots of vines which belong to the genus Tetrastigma.

One particular species, Rafflesia tuan-mudae, grows in many places in Gunung Gading National Park (Moktar, 1988), at altitudes between 75 and 750 metres along moist, rocky streams.

A number of plots, each 40m x 40m (0.16ha), were laid out at six sites inside the park. All the sites are in pristine forest, ie with no evidence or history of past clearing. Four of these sites (40 plots) are easily accessible and regularly used by visitors, while two sites (18 plots) are not visited. The number of vines in each plot was recorded, as well as the girth of each vine, the number of buds on each vine and the diameter of the buds. The results are summarised in Table 1.

There was no clear evidence of visitor impacts on the distribution of Rafflesia in the study sites. The density of vines in both situations is almost the same and the number of buds per vine are similar. The biggest vine (presumably the oldest or healthiest) was found in a plot with visitors, but there was a wide range of girths in all plots. The size of the bud indicates its stage of development, and each vine and bud was tagged so that future development can be monitored.

Field observations were made along a 12.6km section of the boundary around the south and west sides of the Park. For each 20 metre section along the boundary line, the number of vines and the number of buds on them were noted. The age of the forest was also estimated, classified as pristine (no evidence of clearing), old secondary (cleared for rice farming 15-20 years ago), or mixed, including patches of old secondary, young secondary (cleared approximately 10 years ago) and pristine forest near the rivers. The results are shown in Table 2.

* No Rafflesia vines were found in areas which had been clear-felled for cultivation less than fifteen years ago.

Vines and buds were found in old secondary as well as pristine forest, which indicates that parts of the park which have been disturbed are still valuable provided the forest can recover.

As stated in the literature, Rafflesia has become so evolutionarily specialised that the entire plant is just a single flower without leaf, stem or roots and is completely a parasite. The only plant that hosts this parasite is a vine of the genus Tetrastigma.

The study shows about the same density of vines in the visitor area than in the undisturbed area, and the average number of buds per vine is slightly higher. There is no evidence that use by visitors damages the vines.

The vines and Rafflesia can recolonise secondary forest, as found along the boundary of the Park, so disturbed areas are still important for conservation.

Rafflesia tuan-mudae is the only species identified at Gunung Gading National Park so far. Other species may occur in the park, so local experts should study the vines and Rafflesia, not only for research, but to produce a database which can provide important information for the scientific community as well as for visitors to the park

Simons, P. (1992) Rafflesia, the world's largest flower. Biological Sciences Review 5(1) : 7-9.

Mohtar, Abg.Mohd.Abg.Pawozan. (1998). Bunga Pakma Rafflesia tuan-mudae Becc. Unpublished report by Forest Department.