Different role of host and habitat features in determining spatial distribution of mistletoe infection

Abstract

Tree mortality and forest decline have been attributed to the several factors including mistletoe infection in Oak Zagros forest, western Iran. As a result of climate change and fragmentation Loranthus europaeus has the potential to be more abundant and distributed in these forests. However, little attention has been given to the need for an ecosystem approach to their management. To manage it, scientific understanding of its ecology including recognition of mistletoe spatial pattern and its shaping mechanisms are essential. Using spatial analysis, we examined the spatial distribution pattern of mistletoes in terms of life stages and vertical and horizontal host crown classification in relation to its controlling mechanisms, including host and habitat features. The results showed that twenty-three percent of the trees were infected, infected trees having an average of 4.08mistletoes. Mistletoes were higher in the middle, lower and inner portion of the infected trees crown, corroborating that mistletoes were aggregated in these parts of the crown. The small scale pattern (451m) of adult mistletoe distribution was observed, whereas juvenile and medium-aged mistletoes were spread at larger distances of 5110 and 4537m. Mistletoe prevalence spatially autocorrelated up to about 2km while plot intensity distributed at small range of 316m. The results suggest that mistletoes first establish in the middle crown part then develop downward into lower crown. The spatial patterns of plot intensity, adult and lower crown mistletoes with smaller ranges were spatially correlated to host size (crown diameter and area). Whereas habitat features were the predictors of the large ranges of prevalence and juvenile mistletoe. To manage mistletoes, considering their roles as keystone species, a focus on reducing the intensity of infection would be of management value at large distances considering spatial relationship between mistletoe and host and habitat features.