Ecological interactions mediated by the European mistletoe, Viscum album subsp. austriacum, in Mediterranean forests-an integrated perspective

Abstract

In this thesis, we seek a deeper and broader understanding of the ecological interactions mediated by the mistletoe Viscum album subsp. austriacum in Mediterranean forests. Mistletoes constitute an interesting group of hemiparasitic epiphytes widely distributed around the world that have been thoroughly investigated with respect to their physiology, morphology, pharmacology and their role as forest pest. However, many aspects of their ecology remains a mystery. Better known as harmful parasites that decrease the vigor of their host trees, today we have little knowledge about the ecological interactions mediated by these parasites, as well as their direct and indirect effects on natural communities and ecosystems. In this thesis, we show that, although being a minor component of the forest community (in terms of abundance and biomass), mistletoe can play a relevant role in the forest. Besides its detrimental effect on the host, mistletoe parasitism promotes a series of direct and indirect effects able to affect the structure and dynamic of the forest community, as well as key ecosystem processes, such as nutrient cycling. Spread over five chapters we study the close relationship of mistletoe with its host trees and seed dispersers, as well as the effect of the parasite on different organisms of the natural community and ecosystem properties.