The effects of root severance in savanna trees in Nylsvley Nature Reserve, Limpopo Province, South Africa

Abstract

Root severance has effect on Terminalia sericea and Burkea africana. Burkea africana is a deciduous tree belonging to the family Fabaceae (Caesalpinioideae) while Terminalia sericea is a deciduous tree of the family Combretaceae. Savanna trees respond to root severance in different ways including producing root suckers. Root suckering take place commonly following disturbance events such as fire, and root severance. The root suckers originate from primordia which are formed from meristematic cells in the cork cambium of the roots during secondary growth. The suckering of roots allows individuals spreading from the original establishment site, thereby promoting new sites colonization. Root suckering is affected by light, soil temperature, soil aeration, growth regulators, hormones, and root carbohydrates reserve. The study site was located subjectively in an area dominated by the species under study. Twenty juvenile and adult trees of the two species were selected where one lateral root was cut. The data collected in each selected species are basal stem diameter of trees, tree crown, and tree height; direction of root cut; number of root suckers produced; root sucker diameter and height of the trees. The result shows that root severance by producing root suckers as observed in Burkea africana and Terminalia sericea. More distal root suckers were produced than proximal root suckers. The health of the plant is not affected by either severing root or development of root suckers. The growth or vigour of root suckers depends on the parent root system, where they are initiated, micro environmental conditions such as soil temperature and herbivory. Juvenile plants produced more root suckers compared to adult plants of Burkea africana. Burkea africana responded quickly but Terminalia sericea needs more time to develop root suckers. Therefore, the knowledge of root sucker and root severance of the two species (i.e. Terminalia sericea and Burkea africana) in this study may contribute to the conservation and management recommendation of the population of the species.