| dc.description.abstract | The purposes of this study were to examine the effects of various fire burning intervals on the
dynamics of woodland structure and the resultant herb layer in the savanna vegetation of eastern
Botswana. Plots of 1.2 ha were burnt at the interval of 0, 1, 2, 3, 4, and 5 years, using head fires
from 1958 to 2003 in an Acacia nigrescens/Combretum apiculatum tree vegetation. In 1982 and
2003 the first and second evaluations, were assessed for bush density, grass basal cover, grass
yield, composition and for soil properties when all burning treatments coincided for the first and
second time, respectively. The data were analyzed using ANOVA procedure in Statistical
Analysis System and means were separated using the Fisher’s test. Annual burning revealed an
increase in the vigour and abundance of Eragrostis regidior and Bracharia nigropedata while
Digitaria eriantha and litter accumulation increased with less burning frequency. Total grass
basal cover was increased although not significantly (p>0.05) from 2.43±2.25% in 1982 to
3.08±0.52% in 2003. Fire was successful in opening up woodland structure by shifting large
trees to smaller size classes. Total woody plant density declined although not significantly in
2003 (1498±154 plants per ha) compared to 1982 (1623±285 pants per ha). The changes in soil
properties resulting from low frequency of burning were small to account for any differences in
vegetation composition. In the semi-arid savanna, once fire is used to control bush, it should not
be a one time activity, but should be continued in order to control the re-growth of recruited
seedlings and preventing their recruitment to adulthood. | en_US |
