Abstract
From data on colonisation and extinction rates it is possible to predict current and future occurrence patterns and extinctions risks of species. However, to obtain such data is time-consuming and for many organisms even impossible. Methods to interpret colonisation-extinction dynamics from snapshot studies have been developed but have rarely been evaluated. In this project I will make such evaluations for invertebrate species dependent on dead wood. I will compare species associated with dead wood items of different durability, as habitat patch durability obviously affects the colonisation-extinction dynamics; species in recently dead trees colonise new dead wood items in every generation, while other may occur in the same tree for > 100 yrs. Occurrence data will be used to parameterise a colonisation-extinction model - the incidence function model - and modifications of that model, which all require snapshot data on presence/absence data per patch. The modifications take into consideration the age of individual habitat patches and assume different dispersal functions. The predictions from the models will be compared with direct observations of local colonisations and extinctions, which will be made by experiments and repeated surveys. This study will imply that metapopulation models are for the first time parameterised for species associated with dead wood of conservation concern.
Sweden