Previous attempts to eradicate Senna spectabilis have been based on girdling or cutting trees and where possible removing fallen fruits and seeds. It would appear that these methods have been partially effective in so far as there appeared to be fewer seedlings arising from recently germinated Senna seeds of the previous rainy season.
During my visit to Mahale from 28 August to 30 August 1997, I observed that the girdling of Senna stems has not been systematic. Some of the trees were girdled 50-100 cm above the base of the tree, while a few others were girdled right down to the base of the tree below which adventitious roots of the tree arise. Invariably, these trees girdled above the root level produced side branches and continued to grow.
This being the case, I would recommend that:
(a) The girdling should be thorough, i.e. removing the bark all round the stem extending down to the base of the tree and where possible involving the exposed roots of the tree. This process should take place during the dry season.
(b) All saplings and young trees arising from stumps should be uprooted by digging them up to a depth of 10-15 cm and removing them by cutting the main root.
(c) Members of the Kasoge and Kansyana communities who live within the boundaries of the Park should make a habit of uprooting all small seedlings of Senna, especially after the start of the rainy season.
(d) It would be useful to undertake a feasibility study which would involve among other issues:
(i) the extent of the spread of Senna within the park.
(ii) the rate of spread
(iii) the means of dispersal
(iv) the cost involved in applying the recommended eradication methods.
We thank the Japan Environment Corporation for funding of this preliminary research.