Epiphytic Plants in a Changing World-Global: Change Effects on Vascular and Non-Vascular Epiphytes

Epiphytes have been called particularly vulnerable to climate change because of their existence at the interface of vegetation and atmosphere. We review the available evidence for this notion and put our analysis into the larger context of human-induced changes in general. Besides climate change, land use changes adversely affect epiphytes, while other factors, e.g. biotic exchange, are of lesser importance in this life form. Both land use change and climate change primarily affect hygrophilic taxa, while drought-resistant species may sometimes even benefit. Vascular and non-vascular epiphytes in tropical cloud forests will seriously suffer from decreased moisture input. In contrast, varying precipitation in more seasonal lowland forests seems to affect vascular species rather little, but a possible negative impact of rising temperatures on plant performance is unexplored. For co-occurring lichens and bryophytes, however, rising temperatures could have disastrous effects, as suggested by model calculations. In the temperate zones, global warming should allow range extensions towards the poles for vascular epiphytes and lead to new assemblages among non-vascular epiphytes. In spite of this mixed picture, epiphytes as a group may indeed be “particularly” threatened by global change, because the habitats characterised by exceptional species richness, e.g. tropical cloud forests, are those most seriously affected.