Climate Change, Bioclimatic Models and the Risk to Lichen Diversity

Abstract

This paper provides an overview of bioclimatic models applied to lichen species, supporting their potential use in this context as indicators of climate change risk. First, it provides a brief summary of climate change risk, pointing to the relevance of lichens as a topic area. Second, it reviews the past use of lichen bioclimatic models, applied for a range of purposes with respect to baseline climate, and the application of data sources, statistical methods, model extents and resolution and choice of predictor variables. Third, it explores additional challenges to the use of lichen bioclimatic models, including: 1. The assumption of climatically controlled lichen distributions, 2. The projection to climate change scenarios, and 3. The issue of nonanalogue climates and model transferability. Fourth, the paper provides a reminder that bioclimatic models estimate change in the extent or range of a species suitable climate space, and that an outcome will be determined by vulnerability responses, including potential for migration, adaptation, and acclimation, within the context of landscape habitat quality. The degree of exposure to climate change, estimated using bioclimatic models, can help to inform an understanding of whether vulnerability responses are sufficient for species resilience. Fifth, the paper draws conclusions based on its overview, highlighting the relevance of bioclimatic models to conservation, support received from observational data, and pointing the way towards mechanistic approaches that align with field-scale climate change experiments.

Range shifts of native and invasive trees exacerbate the impact of climate change on epiphyte distribution: The case of lung lichen and black locust in Italy

“…This information would help to refine predictive models, also accounting for potential adaptation dynamics and microrefugia (Ellis, 2020) that allow the persistence of the species under unsuitable climatic conditions. In contrast to vascular plant modelling, adaptation dynamics are still poorly accounted for lichens (Ellis, 2019), thus requiring further research.…”

Climate change refugia: landscape, stand and tree-scale microclimates in epiphyte community composition

“…Forest and woodland managers are challenged to find locally relevant actions that mitigate the negative effects of global climate change (Ogden & Innes 2007; Keenan 2015; Sousa-Silva et al 2018). Focusing on the conservation of forest/woodland biodiversity, bioclimatic studies have demonstrated the threat to lichen epiphytes of climate change (Ellis 2019 a , references therein); this threat is relevant from the standpoint of both species protection (Nitare 2000; Nilsson et al 2001) and in maintaining the resilience of ecosystem functions and services (Jönsson et al 2017). There is therefore a pressing need to identify relevant local actions that can reduce the vulnerability of lichen epiphytes to global climate change.…”

“…The broad scale projected response of lichen distributions to climate change, for a given region, for a given climate change pathway (Nakićenović & Swart 2000; Moss et al 2010; van Vuuren & Carter 2014), and over a given timescale, can be characterized as the species ‘exposure’ (Ellis 2013), that is the degree to which the climate will become more or less suitable. Exposure is widely estimated using the bioclimatic technique of matching a species distribution to the macroclimate in which it occurs, and quantifying the loss or spatial shift in suitable climate space (Pearson & Dawson 2003; Thomas et al 2004), an approach that can be used to assess climate change risk for lichens (Ellis 2019 a ). While quantifying the species exposure to climate change may be a useful first step in assessing risk, the future outcome for a species depends, critically, on its ‘vulnerability’ (Ellis 2013).…”

Networks of epiphytic lichens and host trees along elevation gradients: Climate change implications in mountain ranges

“…However, due to their poikilohydric nature, epiphytic lichens are among the most sensitive organisms to climate change (Ellis, 2019;). This supposes a major threat for alpine ecosystems, which are predicted to be strongly affected by climate change (Gobiet et al, 2014).…”