Achieving landscape-scale conservation for Scotland's rainforest epiphytes

Within the UK, the continuing biodiversity crisis has led to a policy driven shift in the conservation sector; moving away from localized site scale conservation to a landscape-scale. This approach encourages fragmented habitat patches to be integrated into a much larger habitat network. Epiphytic lichens provide an ideal model system for studying the effectiveness of conservation initiatives within fragmented habitats, due to their metapopulation structures whereby individual trees within woodlands (and woodland stands within wooded landscapes), represent isolated habitat patches. Old-growth woodland in particular provides suitable habitat to a suite of lichens known as the Lobarion community, which are declining throughout Europe. Regeneration within these old growth areas, though essential for future habitat persistence, causes shading and ultimately leads to local extinctions of shade intolerant lichen epiphytes. A landscape scale conservation strategy that relies on habitat permeability to balance colonisation of post-regeneration woodland patches with extinctions in ageing woodland patches elsewhere in the landscape has been proposed as a management strategy to meet the needs of both lichen epiphytes and their woodland habitat. The unique conditions found in western Scotland, combining a relative abundance of high quality old growth habitat (in a European context) coupled with robust populations of some members of the Lobarion community, could provide an ideal opportunity to test such a management strategy. In this thesis, the plausibility of landscape-scale conservation as a management strategy for epiphytic lichens is explored, using a suite of nine target epiphytes of contrasting ecological traits set within Glen Creran, a temperate rainforest on the west coast of Scotland: 1. The habitat requirements of nine target epiphytes were identified and predictions of species distribution made over an entire glen using a species distribution modelling (SDM) approach. The SDM’s were found to apply more generally within the wider biogeographic area for five of the nine species, providing an evidence base for future conservation plans in Scotland’s rainforest zone. 2. A novel method to determine dispersal distance in lichen epiphytes was developed, combining a mechanized propagule trap with molecular techniques. This methodological advance allowed the first direct comparative study of lichen epiphytes in a natural context. 3. An agent based model was developed combining the results of 1. and 2. above to investigate the effect of habitat connectivity on colonisation in six contrasting lichen epiphytes, enabling inferences of species response to landscape-scale conservation scenarios within the study system to be made