Bryophyte conservation on a North Atlantic hotspot: threatened bryophytes in Madeira and Selvagens Archipelagos (Portugal)

Abstract

On oceanic islands, the evolution of plants and animals with particular characteristics is favoured due to their isolation, populations normally comprising a large number of unique, endemic species. The Madeira and Selvagens archipelagos are considered biodiversity hotspots, containing an especially rich bryoflora. Due to its characteristically small size, this taxonomic group does not get much attention in conservation programmes. However, these plants are an important component of terrestrial ecosystems, representing a major part of biodiversity and playing a vital role in the ecosystem's functioning. As such, the development of the first Red List for Madeira and Selvagens Archipelagos has the potential to guide conservation efforts focused on taxa and habitats where threatened species and endemics are better represented. By applying the International Union for Conservation of Nature and Natural Resources (IUCN) criteria, recently revised to apply to small islands, it was possible to obtain the percentage of threatened taxa present in the archipelagos (23.6%), and for each habitat type. It was verified that high mountain habitats and the Laurel forest represent areas that host higher percentages of threatened taxa (29.5% and 22.2%). An important result of the present Red List is the identification of hotspots for bryophyte diversity, supporting the definition of reserves/microreserves. The information obtained can also be linked up with the Red Lists of other taxonomic groups to work towards the definition of a more holistic conservation strategy.

Trees as habitat islands: Temporal variation in alpha and beta diversity in epiphytic laurel forest bryophyte communities

“…In conclusion, our results suggest that there is a time‐lag of about 50–70 years before a substantial shift towards species‐rich epiphyte communities in Madeiran laurel forests. It is precisely among those indicator species for the oldest trees that we find the highest frequency of Macaronesian endemic species as well as red‐listed species considered as Vulnerable ( Cololejeunea schaeferi, Echinodium spinosum, Leptodon longisetus ) and Near‐Threatened ( Andoa berthelotiana, Exsertotheca intermedia, Frullania polysticta, Isothecium algarvicum, I. prolixum, Leucobryum albidum, Plagiothecium nemorale, Tetrastichium fontanum ) in Madeira (Sim‐Sim et al., ). Old trees, even if located in historically harvested forest remnants, exhibit rich epiphyte communities provided that they are located in climatically suitable areas (Edman, Eriksson, & Villard, ; Lindenmayer & Laurance, ).…”

Species Conservation Assessments in Oceanic Islands: the Consequences of Precautionary Versus Evidentiary Attitudes

“…Using evidentiary assessments under uncertainty may thus contribute to solve the problem of classifying nearly all species with small ranges in the top threat categories, which may overestimate extinction risks and make it difficult to identify those species most in need of urgent conservation action. In contrast to this approach, previous studies addressed small range sizes by changing the thresholds of Red List criteria (Martín 2009;Cardoso et al 2011;Seoane et al 2011;González-Mancebo et al 2012;Sim-Sim et al 2014), but this undermines the comparability of assessments across regions and taxonomic groups, as different assessors may use different ad hoc thresholds in different circumstances. Adjusting risk tolerance along the precautionary-evidentiary gradient may thus provide a practical approach to improve the utility of conservation assessments in oceanic islands, while maintaining the widely used IUCN Red List framework.…”

“…To solve these problems, previous studies suggested changing the thresholds of the Red List criteria, to accommodate the peculiarities of species with naturally small ranges (Martín 2009;Cardoso et al 2011;González-Mancebo et al 2012;Sim-Sim et al 2014). This is troublesome, because ad hoc changes in thresholds undermine the comparability of Red List assessments across taxonomic groups and regions.…”

Does altitude shape molecular diversity and richness of bryophytes in Madeira’s natural forest? A case study with four bryophyte species at two altitudinal levels

“…From a total of 538 bryophyte taxa present in Madeira and Selvagens Archipelagos we recorded 202, of which 21 were endemics, in the 92 plots sampled in this study (Sim-Sim et al 2014 Table 2 shows the results of the t-test comparison of the means (significant differences of the mean for p < 0.05) for each variable ('richness variables' and 'molecular variables'). We grouped the variables by species (cover and haplotype frequencies) to better identify the existence of coinci-dent patterns.…”