Changes in litter production following back and head fires, some soil characteristics and root and litter turnover were quantified over two growing seasons for a semi-arid grassland. Sampling of litter production took place at approximately bi-monthly intervals to account for major seasonal changes over the 2000/01 and 2001/02 seasons. Soil compaction was determined by a simple rod penetrometer, soil temperature by mercury thermometers and soil-water content by a neutron hydroprobe. Litterfall of 5.88% and 1.13% (as a proportion of annual aboveground phytomass production) for unburnt and burnt grassland, respectively, was obtained. Two seasons following the fire, litter was still 47% lower due to fire. The litter production was not significantly different between the head and back fires. The fire, while causing a lower plant cover over the two years following burning, also significantly increased soil compaction and soil temperature. The biggest difference in soil temperature between burnt and unburnt grassland to a depth of 50mm was 7degreesC. After only two months the soil-water content over the first 900mm depth decreased by 23% due to burning. Fire lengthened the period for replacement of the total root system by about a year and decomposition of litter by three months. Small changes caused by fire to the fragile ecosystems of semi-arid climates may have longlasting consequences. The overall effects of fire on belowground systems and the resulting processes that feed back to aboveground systems are complex.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.