Mistletoe Infection in an Oak Forest Is Influenced by Competition and Host Size

Abstract

Host size and distance from an infected plant have been previously found to affect mistletoe occurrence in woody vegetation but the effect of host plant competition on mistletoe infection has not been empirically tested. For an individual tree, increasing competition from neighbouring trees decreases its resource availability, and resource availability is also known to affect the establishment of mistletoes on host trees. Therefore, competition is likely to affect mistletoe infection but evidence for such a mechanism is lacking. Based on this, we hypothesised that the probability of occurrence as well as the abundance of mistletoes on a tree would increase not only with increasing host size and decreasing distance from an infected tree but also with decreasing competition by neighbouring trees. Our hypothesis was tested using generalized linear models (GLMs) with data on Loranthus europaeus Jacq., one of the two most common mistletoes in Europe, on 1015 potential host stems collected in a large fully mapped plot in the Czech Republic. Because many trees were multi-stemmed, we ran the analyses for both individual stems and whole trees. We found that the probability of mistletoe occurrence on individual stems was affected mostly by stem size, whereas competition had the most important effects on the probability of mistletoe occurrence on whole trees as well as on mistletoe abundance. Therefore, we confirmed our hypothesis that competition among trees has a negative effect on mistletoe occurrence.

Impact of Common Mistletoe (Viscum album L.) on Scots Pine Forests—A Call for Action

“…infection include reduced tree vitality, shoot die-off, and reduction of the quality and volume of wood produced (Figure 1). The influence of common mistletoe (Viscum album L.) on deciduous trees, especially along roadsides, in parks, and in plantations, has been well studied for years [1][2][3]. According to Barney et al [4], mistletoe colonizes over 450 species and varieties of trees.…”

Host spatial structure and disperser activity determine mistletoe infection patterns

“…The number of mistletoe seeds are usually limited, so the decrease in the probability of mistletoe infection with an increase in competition from neighboring hosts may arise not from changes in resource availability but simply from a decreasing probability of receiving mistletoe seeds due to increased number of neighboring host. Matula et al (2015) found the same mechanism, that competition among host has a negative effect on occurrence of the mistletoe, Loranthus europaeus , in an oak forest in the Czech Republic.…”

Modelación de la distribución espacial del muérdago (Santalales: Loranthaceae) en las áreas verdes de la delegación Tlalpan, México

“…Kuijt, Santales: Loranthaceae) es una planta arbustiva que parasita los brotes aéreos de los hospederos; son organismos que pueden fotosintetizar, es decir, solo obtienen nutrientes minerales y agua del huésped (Mathiasen et al 2008). Tienen un papel importante en el mantenimiento de la diversidad forestal al proporcionar recursos alimentarios claves para muchas especies animales debido a la disponibilidad de su fruto en épocas en que otros alimentos son escasos (Matula et al 2015). Los efectos estudiados en el muérdago varían en función no solo de su capacidad de tomar agua y nutrientes del árbol hospedante, sino, también, dependen de las condiciones ambientales en las que se desarrolla el anfitrión, su tamaño, edad y densidad.…”