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Nijmegen, Netherlands

Gonzalez-Mancebo J.M.,University of La Laguna | Dirkse G.M.,Natuurmuseum Nijmegen | Patino J.,University of La Laguna | Patino J.,University of Liege | And 4 more authors.
Biodiversity and Conservation | Year: 2012

The International Union for Conservation of Nature (IUCN) Red List categories and criteria were applied to small-sized spore-producing plants with high dispersal capacities (bryophytes). The application of some of the IUCN criteria to bryophytes in small and highly environmental diverse islands implies several problems. The criteria applicability increases when the occupancy area is reduced. However, for common species restricted to a single type of vegetation belt, the use of the IUCN criteria is problematic because of inapplicable and/or misleading thresholds. We adapted the IUCN criteria by modifying the occupancy and occurrence area sizes and by specifying the location. This approach allowed us to establish the first Red List for the bryophyte species in the Canaries, which comprises 105 species (67 mosses and 38 liverworts); among them, 7 are critically endangered, 20 are endangered and 78 are vulnerable. Twenty-six species were classified as near-threatened, 245 were considered to be at low risk and 125 were data deficient (DD). Among the DD ones, 19 corresponded to newly reported species (DD-n) and 40 had no records during the last 30 years (DD-va). Our findings show that the freshwater habitats as well as the habitats in the most restricted cloud forests (with Erica platycodon) contain the majority of the threatened species, followed by other types of laurel forests and high mountain habitats. © 2012 Springer Science+Business Media Dordrecht.

Dirkse G.M.,Natuurmuseum Nijmegen | Losada-Lima A.,University of La Laguna | Stech M.,Naturalis Biodiversity Center | Stech M.,Leiden University
Journal of Bryology | Year: 2016

A morpho-molecular study was undertaken to solve the taxonomic identity of Riccia plants from the Canary Islands. These plants were assumed to belong to the South African endemic Riccia section Pilifer, but could not be assigned to a particular species in that section. In the interim they were named R. lamellosa (section Riccia), since R. lamellosa is the only European species with conspicuous white ventral scales. Molecular phylogenetic reconstructions based on trnL-F and ITS2 sequences confirmed that the respective Riccia plants belong to section Pilifer. The respective clade is clearly separated from the clades of R. lamellosa and R. elongata, the latter being morphologically most similar within section Pilifer. Based on the combined molecular and morphological evidence the Riccia plants from Canary Islands are described as a new species, R. boumanii, which represents the first species of section Pilifer outside South Africa. Based on revised herbarium specimens, R. boumanii occurs on five islands of the Canary Islands archipelago, namely El Hierro, Gran Canaria, La Gomera, La Palma, and Tenerife. © 2016, © British Bryological Society 2016.

Van Loon-Steensma J.M.,Wageningen University | Van Dobben H.F.,Wageningen University | Slim P.A.,Wageningen University | Huiskes H.P.J.,Wageningen University | Dirkse G.M.,Natuurmuseum Nijmegen
Applied Vegetation Science | Year: 2015

Question: Do low stone dams built to prevent erosion and to restore salt marshes through increased sedimentation affect plant species composition? Location: Dutch Wadden Sea area (ca. 53°N 5°E). Methods: Relevés (N = 170) were made of the vegetation of two restored salt marsh sites on the barrier islands Terschelling (Grië) and Ameland (Neerlands Reid). Existing relevés of salt-marsh vegetation (N = 6198) made along the entire Dutch Wadden Sea coast (both the mainland and the barrier islands) were used as a reference. The vegetation of the two restored sites (Grië NLR data) was compared with the reference by (1) simple species-by-species analysis based on frequencies in both data sets, and by (2) ordination, where relevés of the restored sites were projected into a multivariate space defined by the species' abundances in the reference relevés. Results: Out of the 37 species that are common (i.e. have a frequency >5%) in either the Grië NLR data or the reference data, 31 have frequencies that differ by less than a factor of five, and 23 differ by less than a factor of two. Furthermore, the Grië NLR data occupy a space that is well in the centre of the ordination space defined by the reference data. Conclusions: There are no conspicuous differences between salt-marsh vegetation behind low dams and the vegetation that has naturally developed on unprotected mudflats. We conclude that measures targeting salt marsh development in view of flood protection do not interfere with nature conservation. © 2015 International Association for Vegetation Science.

Dirkse G.M.,Natuurmuseum Nijmegen | Losada-Lima A.,University of La Laguna
Cryptogamie, Bryologie | Year: 2011

We provide first Canary Islands reports of Diphyscium foliosum (Hedw.) D. Mohr, Entosthodon longicolle (Trab.) Ros et M.J. Cano, Tortella alpicola Dixon and T. bambergeri (Schimp.) Broth., being the last three also new to Macaronesia. First individual island reports are given for Acaulon mediterraneum Limpr. (Gran Canaria, Tenerife), and Tortella limbata (Schiffn.) Geh. et Herzog (Tenerife). Brief taxonomic notes are added. Entosthodon fascicularis (Hedw.) Müll. Hal. is removed from the list of Fuerteventura and Tortella fragilis (Hook. Wilson) Limpr. from the list of the Canary Islands. © 2011 Adac. Tous droits réservés.

Dirkse G.M.,Natuurmuseum Nijmegen | Losada-Lima A.,University of La Laguna
Journal of Bryology | Year: 2011

We revised both the holotype and an isotype of Riccia teneriffae S.W.Arnell 1962 and additionally revised our own collections of Riccia cavernosa Hoffm. 1795 from the Canary Islands. Since the types of R. teneriffae represent R. cavernosa, and the latter name precedes the former, R. teneriffae should be treated as a synonym of R. cavernosa. In the Canary Islands, R. cavernosa appears to be rare. It has been found on La Gomera, Gran Canaria, Lanzarote, and Tenerife. We report it as new to Fuerteventura. R. cavernosa inhabits ephemeral, thin layers of mud. Very rarely it occurs on basaltic pyroclasts. SEM images of spores are presented. The local distribution is mapped. © British Bryological Society 2011.

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