Abstract
In this Ph.D. project, different strategies to preserve ancient trees are compared regarding their effect on the persistence of threatened species. Methods for parameterising metapopulation models based on only snapshot presence-absence data will be tested. Such methods will make data collection for population viability analyses more cost-effective. Seven lichen species confined to old oaks are used as model species. Snapshot field data will be used to parameterise a metapopulation model considering the age of each local habitat patch. By repeated surveys at a per tree level, assumed equilibrium between colonisations and extinctions will be tested. Moreover, a metapopulation model will be parameterised based on information about habitat history and current occurrence patterns. That is possible because oaks have been surveyed in Sweden in 1749 and later. A Bayesian approach will be used to fit the metapopulation models. A metapopulation model will be combined with a habitat model at a landscape level. The models will be used to predict the extinction risks of lichens given different conservation scenarios. In particular, the effect of the spatial distribution of conservation efforts will be analysed. The project will contribute to a deeper general understanding of how to protect species associated with a naturally patchy habitat where each patch has a limited life-time.
Sweden