Escape and Naturalization of Tagetes patula in Western Ethiopia

Abstract

This study was carried out on an introduced ornamental - Tagetes patula L., which has escaped cultivation and has been naturalized in Benishangul-Gumuz National Regional State (bgnrs), western Ethiopia. Another introduced ornamental - Zinnia elegans Jacq. and the native species - Bidens prestinaria (Sch. Bip.) Cufod. were included in some of the experiments for comparison. Pre-prepared semi-structured interviews were administered, on the arrival, spread and impact of T. patula. The result showed that the escaped T. patula has no negative impact on the daily life of people, except weeding in farmlands. T. patula was found associated with species that prefer shade and moisture in semi-natural vegetation. It produces a large number of relatively small propagules and has a seed bank. These characters might enhance its invasive ability and make it a potential threat to grazing fields and natural landscapes in western Ethiopia. The result of fire simulation experiment, however, revealed that fire had an effect on seed germination, as there was no seed germination at higher temperature treatment (120°C/5 minutes). The annual fire occurring existing in the woodlands of bgnrs might not allow invasion by the species that are not adapted to fire, like T. patula and Z. elegans. In the absence of annual woodland fire, invasion of the woodland vegetation in bgnrs by T. patula and Z. elegans is most likely to occur.