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In another study, Trapnell (1959) examined the ecological results of woodland burning experiments at Ndola in Zimbabwe, a station located at 13 degrees S latitude and 1200 m in elevation. Twenty three years of study using several controlled burning regimes clearly showed that Brachystegia - Julbernardia woodland, which also contains many elements common with the drier woodlands on Madagascar, can be totally destroyed by regular late-season burning, precisely the type of burning regime practiced in Madagascar.
David Burney and his collaborators have also underlined another important factor that must be taken into consideration. It is clear that the climate and vegetation of Madagascar have changed dramatically over the time scale of tens of thousands of years, and that the extent of various vegetation types has expanded and contracted many times (Burney, 1987a, 1987b).
This can be inferred from the current distribution of certain plant groups. For example, Hildegardia erythrosiphon is an important tree in the deciduous forests of the west.
The genus is also represented in the heart of the wet forests of
the east by Hildegardia perrieri, which stands out remarkably by
being one of the extremely few deciduous species in otherwise
completely evergreen forest.
Similarly, Phyllarthron, a genus of Bignoniaceae endemic to Madagascar, has about a dozen species, all of which have phyllodes -- the modified petiole/rachis of a compound leaf that has lost its leaflets -- that function like leaf blades. These phyllodes are clearly adaptations to dry environments. Phyllarthron berniereanum occurs in the extremely dry south, where one would expect to see it. But a number of other species (e.g., P. articulatum, P. cauliflorum, and P. antongiliensis), all of which have these distinctive phyllodes, are found in some of the country's wettest forests.
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