Modeling the Change in Distribution of an Endangered Lichen Species Under Projected Climate Conditions

Abstract

Sulcaria spiralifera, or Dune Hair Lichen, is endemic to coastal dune forests along the Pacific coast in the continental United States. The species’ habitat is vulnerable to drought and temperature extremes. Modeling the possible impact of climate change can assist with conservation planning and bolster preservation of the entire ecosystem. This study investigates the impact of climate change on the distribution of a rare and endangered species by using the maximum entropy probability distribution principal to build a predictive species distribution model. The approach has demonstrated success in predicting the distribution of rare species that may include limited data and lack points of absence. The probable distribution of the species was modeled under current and historic climate conditions and used to train new models that would predict distribution under future climate conditions. Results of the project show a spatial change in habitat between 2021 and 2100 with suitable locations becoming more abundant. Positive changes in presence predict a shift inland while locations along the coast experience negative change. Despite an overall increase in suitable habitat, the predicted point of presence remains relatively stable with gradual increases around 2% every 20 years until a decrease of 4% between 2080 and 2100. Although the models show an increase in habitat suitability over time, it is unclear whether the Dune Hair Lichen could survive potential relocation as habitat shifts inland. The species distribution model under future climate conditions can help conservationists monitor and inventory the species to assess adaptation success.