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Rood sterrenmos (Mnium marginatum Hedw.) nieuw voor Oost-Twente
E.J. Weeda
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1-16
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Mnium marginatum Hedw. new to eastern Twente (prov. of Overijssel)
For the moss flora of the lowland parts of the Netherlands Mnium marginatum s.lat. (incl. M. ambiguum) is a relatively late acquisition. Outside the hills in the southern part of Limburg it was only observed from 1928 onwards, and is confined to habitats flooded by rivers or brooks. Probably the absence of 19th century finds of Mnium marginatum is not due to overlooking. Like Conocephalum conicum it might well be a comparatively recent acquisition, taking profit from changes in the character of brooks. At present lowland brooks, as far as they have not been canalized, have steeper banks and are more shaded than in previous centuries. Open spots on such banks are suitable sites for Mnium marginatum, provided that they are held together by tree roots, Conocephalum blankets, algae mats &c. Two such sites, hitherto unknown, were recorded in 1997 and 2003 in eastern Twente (surroundings of Enschede and Oldenzaal). Both sites, as well as one further to the south near Winterswijk, were visited by the German bryologist Carsten Schmidt and the present author in 2005. At one site only very few, poorly developed, sterile specimens were observed. Similar plants were recorded at the other sites, but in both cases a thorough investigation yielded some tufts which had produced archegonia. Because of their apparent dioicy combined with a dentated nerve Schmidt identified them as Mnium ambiguum. Sofar this taxon was not recognized at species level in the Netherlands. Renewed investigations of the Mnium marginatum complex are recommended.
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Weelderige groeiplaats van Kaal leermos (Peltigera hymenina (Ach.) Delise ex Duby) bij Garderen-Ouwendorp gespaard
J.L. Spier & K.W. van Dort
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17-20
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Site of the very rare Peltigera hymenina (Ach.) Delise ex Duby near Garderen is going to be preserved. On the fringe of a young Prunus serotina wood near Garderen a lush population of Peltigera hymenina (Ach.) Delise ex Duby was found. Inland it is very rare and usually found along the coast and on the Wadden Sea islands. The site was threatened by removing Prunus serotina. The Forestry Commission could be convinced of the value of this site. A regional management plan has been suggested.
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Leucodon sciuroides (Hedw.) Schwägr. (Eekhoorntjesmos) in Nederland
J. Koopman, H. Waltje & E.J. Weeda
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21-44
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Leucodon sciuroides (Hedw.) Schwägr. in the Netherlands. Leucodon sciuroides has been a rather rare species in the Netherlands at least for the last 150 years. Traditionally it has shown a strong preference for trees with a eutrophic, neutral bark, especially Ulmus and Salix. Its decline in the western part of the country and on some trees (notably on Ulmus, due to elm disease) is partially counter-balanced by its increase elsewhere. However, in contrast with many other epiphytic mosses (e.g. Cryphaea heteromalla and several Orthotrichaceae) no large-scale expansion has been observed in the last two decades. This might be due to its dioicy on one hand, and to its preference for older trees on the other hand. A rather recent phenomenon is its increasingly frequent occurrence on stony substrata, preferable near water. Much clearer tendencies are shown by its fertility and vitality. Already in the 19th century fertile Leucodon was a rarity in the Netherlands, but after 1913 no fruiting specimens have been observed anymore. Its vitality was also decreasing for a long time. The greater part of the 19th century collections have branches longer than 2 cm, whilst in the 20th century such specimens were exceptional. Towards the end of the century long-branched material was observed again in four localities, however. Strikingly enough, three of these finds refer to stony substrata and only one to a tree.
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Blad-, lever- en korstmossen op dood hout in het Speulderbos
K.W. van Dort & J.L. Spier
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45-53
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Bryophytes and lichens on dead wood in the Speulderbos (prov. Gelderland, The Netherlands). An inventory has been made of mosses, liverworts and lichens on dead wood of beech and oak in the Speulderbos, a forest reserve in the Netherlands. Dead wood shows a positive effect on the biodiversity. Several vulnerable species of the severely impoverished ground flora, suffocating under high amounts of hardly decomposing litter, are able to survive on logs. The extremely rare Cladonia parasitica has been found on a log of oak.
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Erratum: Ketner-Oostra et al. (2005), Buxbaumiella 72: 50 (figuur 1)
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54-54
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Een mosflora voor Nederland en België (boekbespreking)
R.J. Bijlsma
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55-59
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Jaarverslag BLWG 2005
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60-63
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Wijzigingen ledenlijst BLWG t/m 25 maart 2006
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63-64
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