Observations on savanna vegetation-types in the Guianas

The vegetation was studied of a number of savannas in northern and southern Surinam, and in French Guiana. The results are compared in particular with the vegetation classification proposed earlier for northern Surinam, and with some records from the northern Rupununi Savanna, Guyana (Van Donselaar 1965). The savannas studied near Brownsweg (northern Surinam) have vegetation types that correspond completely with those of some other savannas of the same geological-pedological type more to the North, as described before. New is the finding of a type of scrub bordering the savanna, being the scrub equivalent of a type of bushes described earlier as the Marlierea type. On the top and the slopes of the Blauwe Berg near Berg en Dal (northern Surinam) an anthropogenic savanna has developed. Two new vegetation types are recorded here that belong to the alliance Rhynchosporo-Trachypogonion. At the foot of the hill a flat savanna supports a vegetation that gives the impression of being of recent origin and unbalanced. It appears possible to apply the existing classification to the communities found on savannas near Cayenne (French Guiana). In this area the conspicuous Byrsonima verbascifolia (var. villosa fo. spathulata) occurs in several undescribed vegetation types that belong to various entities. A xerophilous and a hygrophilous community of Byrsonima verbascifolia are distinguished, belonging to the Rhynchosporo-Trachypogonion and the Bulbostylidion lanatae, respectively. On the Sipaliwini Savanna in southern Surinam most vegetation types do not fit into one of the existing alliances. However, if new alliances would be described, it should be possible to include them into the existing orders. There probably is an alliance, called here “communities of Trachypogon plumosus and Bulbostylis spadicea”, that might be regarded as the southern counterpart of the Rhynchosporo-Trachypogonion in the order Trachypogonetalia plumosi, and a supposed alliance with much Rhynchospora graminea and R. globosa might have the same position with regard to the Imperato-Mesosetion in the order Paspaletalia pulchelli. Among the communities that might be included in the alliance Axonopodion chrysitidis there is one occurring on sandy soil without a hog-wallow structure at the surface. Floristically it has connections with the Paspaletalia pulchelli but it also has many characteristic species of its own. Whether this community has to be placed in a distinct alliance will have to depend on the results of further investigations in this area. Anyhow, more data are needed for the drafting of a complete picture of the rich and interesting Sipaliwini Savanna. On a savanna south-west of the airstrip “Sipaliwini” (southern Surinam) the vegetation consists mainly of communities belonging to the Bulbostylidion lanatae. Summarizing the above-mentioned results, one may say that a number of communities not studied before are added to the picture of the savanna vegetation of the Guianas. It proved possible to integrate these communities without much difficulty in the classification presented earlier that so far has functioned as a practical framework.