Assessment Of Mistletoe - Host Interactions In A Highland Savanna In Windhoek, Namibia

ABSTRACT

Mistletoes have detrimental effects in ecosystems where they occur. Mistletoes negatively reduce the growth of the host plants and increase the chance of tree mortality. Apart from tree mortality, infected trees suffer from reduced growth and loss of vigor hence contributing to overall low productivity of hosts and resulting in changes in the structure and function of savanna communities. This study’s aim was to determine and to compare mistletoe - host interactions between the Botanic Garden and the Aloe Trail in Windhoek. For the assessment of prevalence and infectivity of mistletoes on woody trees, plot based sampling techniques were used to select and demarcate fifty 20mx20m plots from both the Botanic Garden and the Aloe Trail. All woody plants in the plots were measured for height and stem diameter. Each woody plant was then examined for presence of mistletoes and the total number of mistletoes on each individual plant was determined. The host species sampled were Senegalia mellifera (Vahl) Seigler & Ebinger and Boscia albitrunca (Burch.) Gilg & Gilg-Ben. The mistletoes species studied were Tapinanthus oleifolius (J.C.Wendl.) Danser and Viscum rotundifolium L.f. The Aloe Trail had a significantly higher prevalence than the Botanic Garden (Mann-Whitney test U, Z = -0.4562, p < 0.001) because of the better management efforts such as removing the mistletoes. Infectivity of Senegalia erubescens and Dichrostachys cinerea was significantly high in the Aloe Trail than the Botanic Garden (Mann Whitney U test, Z = -0.4.568, p = 0.00