Infection by Plicosepalus curviflorus mistletoe affects the nutritional elements of Acacia species and soil nutrient recycling in an arid rangeland

Mistletoes are epiphytic hemiparasitic plants that are known to negatively affect the growth of their hosts, increase tree mortality, and as a consequence change the community dynamics. Mistletoe alters the mineral nutrition of the host and the nutrient cycle in the soil. In the present study, the elemental nutrient status is described for Acacia asak, A. ehrenbergiana, A. gerrardii, and A. tortilis that were infected with the mistletoe Plicosepalus curviflorus, at three levels of infection (no infection, low and high infection). The nutrients of the mistletoe and the soil under the studied acacias were also determined. The elemental contents of the infected Acacia species were significantly reduced compared to non-infected trees, particularly for potassium and sodium. The reduction in the elemental composition was also species-specific and dependent on infection density. Elemental contents of the mistletoe were significantly higher than their Acacia hosts, particularly for nitrogen, phosphorus, and potassium, and the concentrations of minerals in mistletoe tissues were host- and density-dependent. This study revealed a significant increase in nutrients in the soil beneath the canopy of infected Acacia compared to the non-infected trees. Overall, it appears that mistletoe infection has a dual effect. It threatens the health of the Acacia, potentially killing its host tree due to absorption of host nutrients particularly when the infection intense. It also has a positive effect in that it improves the availability of the micro-habitat of nutrients under the canopy, which in turn may contribute to the maintenance of biodiversity.