Peat accumulation rate in Rwanda and Burundi. An indicator of long term climatic change
1998
Pajunen, H. (Geological Survey of Finland, Kuopio (Finland))
The time of mire initiation and the accumulation rate of peat and carbon were studied in the Akanyaru swamp complex and in two smaller peat deposits situated in the western rift valley. The time of mire initiation varies from 20,200-1,600 year B.P. (before the present). The oldest peat deposits are in the southern part of the Akanyaru swamp complex and the youngest are in the rift valley region. During the last glacial stage the climate was mainly dry and peat accumulation rates remained low. Increasing humidity in the early Holocene made conditions favourable for accumulation of peat and increasing dryness after mid-Holocene made them again unfavourable. The increased dryness of the climate is more clearly distinguishable in the accumulation rates than the increasing humidity. In most of the mires there were periods with high accumulation rates during the last two millennia, caused by the increased humidity of the climate and by non-climatic factors. The effect of human activities on the peat accumulation rate becomes more significant the closer we get to the present, and it may totally obscure the effect of small climatic changes.
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