Management of oil producing Jatropha curcas silvopastoral systems: Risk of herbivory by indigenous goats and competition with planted pastures

摘要

There is potential for Jatropha curcas production in South Africa especially in silvopastoral systems where the co-occurrence of oil production and grazing results in the optimal use of increasingly limited land. However, in South Africa there is a moratorium on J, curcas cultivation due to insufficient information on this species. The aim of this study was to assess the potential growth and suitability of J- curcas in silvopastoral systems. For such systems to succeed there needs to be limited competition between J. curcas and the forage component and the former must not be at risk to defoliation by livestock. The effect on the growth of 15-month old J, curcas trees by neighbouring forage species was addressed by removing planted pastures at 0,60,120 and 300 cm from the base of J. curcas individuals. Final height, basal diameter and percentage leaf abscission of trees with pasture removed up to 60 and 120 cm away did not differ significantly from treatments with the greatest and least amount of competition. Therefore, removing up to 60 cm will allow for growth similar to that of trees with 300 cm of pastures removal while still providing sufficient pasture for grazing. The palatability of J. curcas was determined through two two-choice and three-choice trials. Since goats spent ＜3.77% of their time browsing J. curcas it is a suitable candidate for silvopastoral systems provided that surrounding vegetation is removed at a recommended distance of 60 cm from the base of the tree.