Some Effects of Post-Fire Age on the Above-Ground Plant Biomass of Fynbos (Macchia) Vegetation in South Africa

(1) The South African vegetation type fynbos (macchia) is fire-adapted and firedependent. (2) Four sites which differed in the frequency with which they had been burned were sampled towards the end (4-37 yr) of a period between fires. (3) The above-ground shoot biomass was determined from clipped plots and regression analysis. Shoots smaller than 6 mm diameter were considered to be potential fuel. (4) The biomass was 670 g m-2 4 yr after burning; all of this was potential fuel. Fynbos 21 yr after burning had a biomass of 5100 g m-2 of which about half was potential fuel. Fynbos protected from fire for 37 yr had a biomass of 7600 g m-2, of which more than half was potential fuel. (5) Frequent burning keeps the biomass low. Protection from fire for longer than 30 yr results in a decline in live biomass and an accumulation of litter and potentially burnable vegetation. Fires in such senescent stands are usually very severe.

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