Responses of tree seedlings to the removal of Chromolaena odorata Linn. in a degraded forest in Ghana

Abstract

Chromolaena odorata is a dominant plant species in degraded forest areas in Ghana. This species forms a very dense canopy. Although tree seedlings have been observed growing under the canopy of this species, they have scarcely been seen growing through the canopy of Chromolaena odorata. To study the response of tree seedlings to the removal of Chromolaena odorata, 108 plots were established 20 m apart in a degraded dry semi-deciduous forest in Ghana. Chromolaena odorata was removed from 50% of the plots to release tree seedlings and left the other half intact. Seedling height, the number of leaves per seedling, and seedling mortality were assessed in both released and unreleased plots immediately after the release treatment (June 1998) and again three months later (September 1998). It was found that the seedling height increment and the increase in number of leaves per seedling were three times greater in released plots than the unreleased plots three months after the release treatment. Twenty eight tree species were found in the plots and 89% of the species had higher height growth after the release treatment. Similarly, 93% of the tree species had more new leaves in released plots than in the unreleased plots. Sixty four percent of the species suffered various levels of mortality in the unreleased plots, but all the seedlings of all the species survived in the released plots. The results suggest that there is a great potential to restore the degraded area back to forest using natural seedlings by removing Chromolaena odorata, the competing vegetation.