Climate change fosters the decline of epiphytic Lobaria species in Italy

Abstract

Similarly to other Mediterranean regions, Italy is expected to experience dramatic climatic changes in the coming decades. Do to their poikilohydric nature, lichens are among the most sensitive organisms to climate change and species requiring temperate-humid conditions may rapidly decline in Italy, such in the case of the epiphytic Lobaria species that are confined to humid forests. Our study, based on ecological niche modelling of occurrence data of three Lobaria species, revealed that in the next decades climate change will impact their distribution range across Italy, predicting a steep gradient of increasing range loss across time slices. Lobaria species are therefore facing a high extinction risk associated with reduction of their range. The current patterns indicate that only L. pulmonaria still has a continuous distribution across Italy, with potential contact between Apennine and Alpine populations. This situation is consistent with the wider climatic niche of this species, still offering a major opportunity for its successful long-term conservation. Results (a) support the inclusion of the three Lobaria species in European conservation policies, such as the Habitat Directive, and (b) warn against an over-estimation of the indicator power of single flagship species to establish conservation priorities for lichens, indicating that even lichens with peculiar and similar climatic envelopes may fail to co-occur within a given forest stand. A multiple indicator approach could provide more useful tools for a community-based conservation strategy for epiphytes.

Impact of forest management on threatened epiphytic macrolichens: evidence from a Mediterranean mixed oak forest (Italy)

“…Forest management strongly influences biodiversity (Kraus & Krumm 2013, Sitzia et al 2017 and affects forest structure and dynamics, as well as environmental parameters relevant to dispersal, establishment and maintenance of epiphytic cryptogams (Aragón et al 2010, Nascimbene et al 2013a. This fully applies to the epiphytic forest lichen Lobaria pulmonaria Hoffm., which has suffered a general decline throughout Europe as a consequence of global change and forestry (Otálora et al 2011, Nascimbene et al 2016, whose effects are expected to be further exacerbated by climate change (Nascimbene et al 2016). Its occurrence and abundance are used as indicators of forest ecological con-tinuity (Rose 1976, Nadyeina et al 2014 and for mapping forest sites worthy of conservation (Campbell & Fredeen 2004, Bergamini et al 2005, Nascimbene et al 2010, Brunialti et al 2015.…”

Altered fire regimes cause long‐term lichen diversity losses

“…If forests reestablish in high‐severity burn patches, it seems reasonable that suitable conditions for lichens could again occur in several‐to‐many decades, when tree canopies again provide buffered microclimates. However, lichen climate niches are undergoing rapid geographic shifts due to climate change, and empirical observations suggest that lichen populations readily decline under drier, warmer conditions (Allen & Lendemer, ; Ellis, ; Nascimbene et al, ). In fact, there is evidence that dry, lower‐elevation forests, such as those we sampled in the Sierra Nevada, contain some of the lichen communities that are most threatened by climate change in the USA (Smith, ).…”

“…Line thickness is scaled to the strength of relationships (standardized path coefficients). Conditional R 2 values (R 2 C ) represent the combined explanatory power of fixed and random effects geographic shifts due to climate change, and empirical observations suggest that lichen populations readily decline under drier, warmer conditions (Allen & Lendemer, 2016;Ellis, 2013;Nascimbene et al, 2016). In fact, there is evidence that dry, lower-elevation forests, such as those we sampled in the Sierra Nevada, contain some of the lichen communities that are most threatened by climate change in the USA (Smith, 2017).…”

“…The consequences of altered fire regimes for lichens may be particularly significant in light of expected effects of climate change on lichen communities. Climate envelopes for lichens are rapidly shifting, suggesting that large areas of contemporary lichen ranges may become inhospitable, potentially leading to range shifts or contractions (Allen & Lendemer, 2016;Nascimbene et al, 2016;Rubio-Salcedo, Psomas, Prieto, Zimmermann, & Martínez, 2016). Organisms often experience the strongest and most limiting environmental filters in the establishment life phase, and establishment has been shown to limit lichen distributions (Werth et al, 2006).…”

Retaining unlogged patches in Mediterranean oak forests may preserve threatened forest macrolichens

“…is such an example: an endangered forest macrolichen (Rose 1988); con-sidered as a "flag" indicator species (Scheidegger & Werth 2009) of forest ecosystems with long ecological continuity worthy of conservation (Nascimbene et al 2010); red-listed and legally protected in several European countries, but not in the Mediterranean area. The species is overall declining throughout Europe as a consequence of air pollution and intensive forest management (including habitat fragmentation), whose effects are expected to be further exacerbated by climate change (Nascimbene et al 2016). Oak-dominated forests are one of the main habitats for L. pulmonaria populations in the Mediterranean area (Rubio-Salcedo et al 2015).…”