| Abstract |
Natural regeneration is an important component of forest dynamics, therefore the knowledge of the forest and requirements of different species are vital for proper planning of sustainable forest management. It is also important to understand how abiotic and biotic factors affect forest regeneration. This study looked at the effect of browsing, plant competition and fire on the regeneration of woody species in Onkumbula community forest in northern Namibia.
The study was divided into two experiments. Experiment 1 looked at the effect of browsing and plant competition on seedling density, seedling species richness, seedling growth and survival. Experiment 2 assessed the effects of fire on woody species regeneration density, species richness, mortality and shoot production. The study sites for Experiment 1 were set in three villages selected based on the last inventory for the community forests where high numbers of timber species were recorded. Three sites were selected; eight plots per study site were established. At each site, four subplots were fenced off to observe the effect of browsing protection on seedlings. A treatment of competition removal to observe the effect on seedlings was also applied. The effects of the treatments to seedlings were monitored between March 2018 and April 2019. In Experiment 2, ten plots were set in the burnt areas of the 2017/18 fire season and ten plots in the adjacent, not burned area and the effect of fire on woody species regeneration was observed five months after the fire.
According to the results, browsing protection did not affect seedling density (p=0.116) and species richness (p=0.445). However, browsing protection significantly improved the growth of seedlings both in height and diameter (p<0.001) but did not significantly improve seedlings survival (p=0.591). Plant competition removal did not significantly influence seedlings’ species richness (p=0.132) or growth (p=0.441 for height growth and p=0.307 for collar diameter growth). The treatment did also not influence seedling survival (p=0.838). Burned plots recorded a significantly higher number of seedlings by 31% compared to unburned plots and recorded 8 species more compared to 5 species in the no-fire treatment. Shoot production in trees and saplings increased with fire, recording average shoots of 3.9 in saplings and 4.5 in trees. Fire significantly affected sapling survival with 36% of saplings recorded dead in the fire plots compared to 2% in the unburned plots. The results of this study will help in the proper management of tree regeneration in Namibia forests by providing more insight into the extent that natural regeneration is affected by external disturbances such as herbivory, fire and plant competition.
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