Sex Distribution, Reproductive Biology And Regeneration In The Dioecious Species Osyris Lanceolata (African Sandalwood) In Tanzania

Abstract

Sex distribution, reproductive biology and regeneration of African Sandalwood (Osyris lanceolata) were assessed in six natural populations of Tanzania between January 1999 and February 2001. The aim was to acquire basic information required for efficient management, conservation and sustainable utilization of the species. The study had four objectives: to assess the spatial distribution of male and female trees in O. lanceolata supporting stands and whether this has any significance in influencing the reproductive success; to document the phenological events occurring between flower initiation and fruit ripening; to examine the reproductive success of various stages through pollination experiment; and to assess the regeneration mode and potential of the species. The study revealed that, the distribution of male and female trees in most populations was random with no evidence of sex clustering. It takes 104 days from flowering until when 25% of fruit initiated become ripe. About 75% of the initiated fruits become ripe in 163 days. This study has also demonstrated absence of agamospermy behaviour in O. lanceolata. A limited reproductive success was noted however, due to either low level of pollen production or limited pollinators\' movement. Assisted pollination significantly increased the reproductive success of the species. The tree regenerates through seeds, rootstocks and coppice. Of the total regenerating plants assessed at sapling stage, 61% had originated from rootstock or coppice while 39% came from seed source. It is concluded that, recruitment of the species relies mainly on rootstock or coppice source although the importance of seeds cannot be ignored. Thus uprooting of the species as a mode of harvesting has to be discouraged since the practice is likely to severely limit the recruitment rate.

TJFNC Vol. 76 2007: pp. 118-133