ABSTRACT
The field area is divided into four orographical zones: The mean annual temperature in the lowlands is higher than 20 C but rainfall never exceeds 1000 mm a year. In northern Burundi, at the limit of the montane belt, peatlands of the lower zones extend in the Buyongwe and the Akanyaru valleys. The Kashiru peatland at Ijenda is situated to the east of Bujumbera on the Zaire-Nile ridge in the Mugamba Region. It is actually the contact zone between the montane rain forest and the Afromontane undifferentiated forest. The Kivu Basin became a closed system until the beginning of the Holocene, when the Rusizi River joined it with Lake Tanganyika. A integrated chronology of the vegetational changes revealed in the Kashiru sequence can be proposed by correlation with the strandlines produced by lacustrine fluctuations. After a new cooler period conducive to development of savannas, the present climatic conditions set in stimulating a temporary forest increase, rapidly annihilated by human activity.
