Mistletoes via input of nutrient-rich litter increases nutrient supply and enhance plant species composition and growth in a semi-arid savanna, southwest Zimbabwe

Abstract

Parasitic plants via input of nutrient-rich litter increase nutrient supply and enhance growth of other plants. Despite this recognition, the effects of parasitic plant litter on community structure remain poorly understood. We investigated the effects of mistletoe on leaf litter, soil fertility and the understorey grass species composition and biomass yield in semi-arid savanna, southwest Zimbabwe. Leaf litter was significantly greater by up to 39 % beneath infected trees than beneath uninfected trees due to the additional mistletoe litter and the effect of mistletoe on infected tree leaf litter. As a result, soil nutrient concentrations under infected trees were higher by 34 % for N, 36 % for Mg, 46 % for P up to 72 % for K than those below uninfected trees. Associated with these changes in leaf litter and soil nutrient concentrations was an increase in the species richness, density and biomass yield of the understorey grass community. Changes in leaf litter and soil fertility also led to altered root biomass allocation in Andropogon gayanus. Therefore, by increasing leaf litter and soil fertility under canopies of infected trees, mistletoe positively influences the composition, productivity and biomass allocation of understorey grasses. These findings reflect similar findings with other parasitic plants suggesting that increase in litterfall, soil fertility and plant species composition and productivity may be a general consequence of parasitic plants.