What factors influence the occurrence of the genus Degelia (a threatened lichen) in central Spain?

The main factors determining the occurrence, abundance, growth and reproductive capacity of threatened lichens need to be known in order to implement conservation initiatives. The main objective of the present study was to evaluate which factors affect the conservation status of Degelia species-complex in central Spain. We undertook a nonparametric analysis to evaluate whether population sizes are larger in protected areas. We fitted generalized linear models (GLM) and mixed models (GLMMs) to analyze which variables are driving occurrence and abundance of Degelia, the thallus size and reproduction capacity. Results show that population sizes of Degelia are very variable, being larger in broad-leaved evergreen forests and inside protected areas. Tree characteristics play an important role in its local dynamics. a 2014 Elsevier Ltd and The British Mycological Society. All rights reserved. Introduction One of the major threats to biodiversity is forest fragBiodiversity conservation is a way to generate a holistic view of nature and so stop perceiving it as a set of individual components (Primack and Ros, 2002). Currently, numerous threats are affecting biodiversity worldwide, but most conservation programs have been directed at birds, mammals or plants, while other organisms are being overlooked (IUCN, 2012). Despite the importance and value of epiphytic lichens in many forest ecosystems (Carroll, 1979; Hayward and Rosentreter, 1994; Petterson et al., 1995), both in terms of species diversity and of ecological function (Longton, 1992; Dix and Webster, 1995), they are often overlooked in determining conservation biology priorities. fax: þ34916647490. I. Mart ınez). ier Ltd and The British M mentation and forest degradation. It affects the survival and conservation of species worldwide (Debinski and Holt, 2000; Fahrig, 2003), and therefore nowadays is a priority for Conservation Biology (Young and Clarke, 2000). Lichen-rich habitats, such as forests are being destroyed and the number of rare and extinct species has increased in recent decades (Mart ınez et al., 2012; Scheidegger and Werth, 2009). Degelia is a threatened genus of epiphytic lichen species in central Spain (Mart ınez et al., 2003; Ot alora et al., 2013). The current taxonomic treatment of Degelia species-complex in Europe recognizes four species (Blom and Lindblom, 2010): Degelia atlantica, D. cyanoloma, D. ligulata and D. plumbea. In Spain, D. atlantica and D. plumbea are the two species of this ycological Society. All rights reserved. Occurrence of the genus Degelia 51 genus which are better represented (Mart ınez et al., 2003; Ot alora et al., 2013), although D. cyanoloma has been recently recorded in some western localities (Blom and Lindblom, 2010). D. plumbea populations are distributed primarily in Mediterranean-Atlantic regions of Africa, Europe (Portugal to Norway and the Crimea), the Macaronesian islands and North Eastern America (COSEWIC, 2010). D. plumbea produces numerous sexual structures (apothecia) while D. atlantica seldom forms these structures but forms isidia. In central Spain, the genus Degelia is found in a very limited number of localities, specifically in humid valleys and ravines, and within well-preserved forests ranging from 750 to 1 280 m altitude (Carballal et al., 2010). The species are listed as vulnerable in the central Iberian Peninsula (Mart ınez et al., 2003). The main threats are forest fragmentation, logging and other forest management activities, drought, overgrazing, agricultural, recreational and environmental pollution (Mart ınez et al., 2003). This genus occurs typically in Lobarion pulmonariaeOschner (Barkman, 1958; Rose, 1988) communities, and it is highly susceptible to high incidence of light (Gauslaa and Solhaug, 1996) and the frequency and duration of dehydration events. In addition, Degelia distribution can also be limited by the availability of appropriate substrate, pollution and others factors related to dispersal (Gauslaa and Solhaug, 1998; Richardson and Cameron, 2004; COSEWIC, 2010). In a previous population genetics study in central Spain, Ot alora et al. (2013) found high levels of genetic similarity betweenD. plumbea and the inlandD. atlantica, suggesting that probably D. atlantica and D. plumbea do not correspond to two distinct species and an urgent study of species boundaries of this species-complex was needed (Ot alora et al. in prep.). Thus, the main objective of the present study was to assess the conservation status of populations of the Degelia speciescomplex (named “Degelia” elsewhere in the document) and to study the factors affecting its population size as the performance of individuals in central Spain. Our hypothesis was that the occurrence and abundance of Degeliawould be higher inside protected areas and in more humid places and that the reproductive capacity would be related to thallus size and microclimatic conditions. We examined: (1) which environmental variables determine occurrence and abundance of Degelia; (2) which microhabitat factors are affecting size and reproductive capacity of Degelia; and (3) differences among population sizes within and outside protected areas in the study area.