Abstract:
Autecological aspects of Burkea africana Hook., Eragrostis pallens Hack. and Terminalia sericea Burch. ex DC. which are typical representatives of the B. africana tree savanne on the Nylsvley Nature Reserve, were investigated. Aspects of the seed population of the three species in the soils of the Acacia spp.-veld as well as the B. africana tree savanne, were examined. Although seeds were recovered from the soil up to a depth of 200 mm, most seeds occurred in the upper 50 mm. Most seeds of B. africana and T. sericea were found in the soil underneath the trees of the specific species. In the case of E. pallens however, the concentration of seed of E. pallens were low under mature individuals. Seedlings of B. africana and T. sericea were examined under natural conditions in the field. Seedlings were grown simultaneously under controlled conditions to determine their potential to survive one season. Under natural conditions, more seedlings survived under trees than in the open except in cases where the undergrowth became too dense and competition thus too severe. The best germination results under controlled conditions were obtained during January 1980 when conditions in the field were favourable for seedling growth. This possibly indicates a rhythm in the seeds of all three species. Seed hardedness occurred in the seeds of B. africana while the seeds of T. sericea also germinated better when the pericarp of the fruit had been damaged. Light inhibited the germination of seeds of E. pallens, but it did not affect the germination of the seed of T. sericea in any particular way.
