ARQ - LMS - Número 20A
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Artigos publicados no Número 20A - 2003
CONTENTS:
Sjögren, E. - Azorean bryophyte communities - A revision of differential species.Cordeiro, N. & L. Silva. - Seed production and vegetative growth of Hedychium gardnerianum Ker-Gawler (Zingiberaceae) in São Miguel Island (Azores).
Moniz, J. & L. Silva. - Impact of Clethra arborea Aiton (Clethraceae) in a Special Protection Area of São Miguel Island, Azores.
Soares, A.O., R.B. Elias, R. Resendes & H. Figueiredo. - Contribution to the knowledge of the Coccinellidae (Insecta: Coleoptera) fauna from the Azores islands.
SHORT COMMUNICATIONS:
Schäfer, H. - New records of the fern hybrid Asplenium x rouyi Viane (A. onopteris L. x A. scolopendrium L.) in the Azores (Aspleniaceae, Pteridophyta).Bried, J. - Impact of vagrant predators on the native fauna: a Short-eared Owl (Asio flammeus) preying on Madeiran Storm Petrels (Oceanodroma castro) in the Azores.
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- Contribution to the knowledge of the Coccinellidae (Insecta: Coleoptera) fauna from the Azores islands.Publication . Soares, António O.; Elias, Rui B.; Resendes, Roberto; Figueiredo, HelenaAn updated list of the Coccinellidae species of the Azores archipelago is presented. New records for S. Miguel: Nephus (Sidis) hiekei; Sta. Maria: Rodolia cardinalis; S. Jorge: Stethorus punctilium, Clitosthetus arcuatus, Scymnus nubilus, N. (Sidis) hiekei; Pico: R. cardinalis; Graciosa: C. arcuatus, S. (Scymnus) interruptus, N. (Sidis) hiekei, Lindorus lophantae and R. cardinalis; Corvo: S. nubilus, N. (Sidis) hiekei and Coccinella undecimpunctata. Regressions of species richness against area of the islands and distance from the nearest mainland were performed. No statistical significant correlation between species richness against area was found but a statistical significant negative correlation between the number of species and the distance from the nearest mainland was obtained. The results are, in part, in accordance with the predictions of MACARTHUR & WILSON’S (1967) equilibrium theory of island biogeography, relating differences in the diversity within Azorean islands with isolation.
- Azorean bryophyte communities - A revision of differential species.Publication . Sjögren, ErikBryophyte alliances and associations of the nine Azorean islands have been described by the author in publications extending from 1978 to 1997. The present paper includes a revision of their differential species and their differential values. Alliances treated with suggestions of their associations (differential species of the alliances and associations in the relevé tables): Echinodion prolixi Sjn. 93 (epiphytic; mostly above 600 m in native cloud-zone forest types); Lepidozion azoricae Sjn 96 (epixylic; presence as the Echinodion prolixi); Aphanolejeuneo-Colurion Sjn. 78 (epiphyllous; presence as the Echinodion prolixi); Andoae-Nardion scalaris Sjn. 95 (epigeic; from ± 200-1000 m a.s.l.) Ptychomitrion azorici Sjn. 93 (epilithic; in strongly exposed habitats, in coast-near localities to altitudes above 1000 m.; Heterocladio-Jubulion Sjn. 95 (epilithic; in weakly exposed habitats, from about 300 to 800 m a.s.l.). It has benn stressed that differential species occur with different values, both at various altitudes on the individual islands and also with generally reduced values from E to W in the archipelago, due to climatic differences. Only few differential species are restricted to one bryophyte alliance. Also, few bryophyte species are restricted in their presence to one type of substrate. Some of the bryophytes treated are more or less severely threatened as to their survival. Several of these species are differential species of alliances or associations, which mainly occur in mature native forests at altitudes above 500 m. During the last century these forests have become progressively reduced and are now restricted to some of the Azorean islands. Their preservation is highly important and urgent, not only as endemic ancient forest types but also due to their constitution with a large number of endemic vascular plants and bryophytes. LIFE-projects in 1995-1997 have given considerable support to this statement.
- Impact of vagrant predators on the native fauna: a Short-eared Owl (Asio flammeus) preying on Madeiran Storm Petrels (Oceanodroma castro) in the Azores.Publication . Bried, JoëlThe impact of introduced predators on the native fauna of oceanic islands has proven to be catastrophic in many cases. In some instances, however, predation is caused by very few individuals arrived without any human assistance. Here, I report on the impact of a vagrant Short-eared Owl on the small population (200 breeding pairs) of cool-season Madeiran Storm Petrels from Praia Islet (0.12 km2), off Graciosa Island, Azores archipelago. The owl fed almost exclusively on storm petrels and killed between one and two individuals every night. The number of prey remains found suggests that it must have been present on the islet ca two weeks before its presence was noticed. Although the Short-eared Owl is a rare vagrant in the Azores, these observations show that a single individual may have a strong impact on a vulnerable population of Madeiran Storm Petrels.
- New records of the fern hybrid Asplenium ×rouyi Viane (A. onopteris L. × A. scolopendrium L.) in the Azores (Aspleniaceae, Pteridophyta).Publication . Schäfer, HannoSeveral individuals of the fern hybrid Asplenium × rouyi are recorded from Santa Maria Island, Azores. After the destruction of the single plant known on Faial Island, these are the only currently known living individuals of this extremely rare hybrid and should be protected by the local authorities.
- Seed production and vegetative growth of Hedychium gardnerianum Ker-Gawler (Zingiberaceae) in São Miguel Island (Azores).Publication . Cordeiro, Nuno; Silva, LuísHedychium gardnerianum is an important plant invader in the Azores Archipelago. In this research we analysed fecundity, fertility, seed bank and vegetative growth of this herbaceous perennial at three sites at different altitudes in São Miguel Island. The mean number of spikes per hectare varied from 2.7 to 4.0x107. The mean numbers of fruits and seeds per hectare were 8.8x106 and 1.6x107, respectively. However, the number of seeds remaining in the soil was very low when compared to the same number at time of seed shed. Vegetative growth occurs by annual addition of one to four new corms to the rhizome. Each new corm usually originates new leaves, and eventually a spike. In general, older corms do not show leaves, working as storage organs. In H. gardnerianum a high seed production might be a key factor in dispersion, while vegetative growth allows a rapid establishment at new sites.
- Impact of Clethra arborea Aiton (Clethraceae) in a Special Protection Area of São Miguel Island, Azores.Publication . Moniz, João; Silva, LuísClethra arborea Aiton (Clethraceae) is a tree endemic to Madeira Island, and a recent introduction to São Miguel Island at Tronqueira/Pico da Vara, a Special Protection Area (SPA) included in Natura 2000, habitat of the endemic bird Pyrrhula murina Godman (Aves: Fringillidae). In this work the impact of C. arborea on the native vegetation was evaluated. Microhabitats associated with C. arborea and with native trees, and areas with different degrees of infestation by C. arborea were compared for soil pH, soil conductivity, soil macronutrient availability, leaf litter production, number of seedlings and vegetation structure. There were no clear differences in soil pH, conductivity and macronutrient availability, either between micro-habitats associated with C. arborea and with native trees, or between areas with different degrees of infestation by C. arborea. Leaf litter production was significantly higher in micro-habitats associated with C. arborea and higher still in areas with high levels of infestation. The number of seedlings and the percentage of endemic seedlings differed significantly between microhabitats associated with C. arborea and those associated with endemic trees. Invasion by C. arborea modified vegetation structure, especially biovolume, which was much higher in invaded areas. By considerably decreasing the proportion of biovolume allocated to native trees, C. arborea infestations may have a negative impact on the conservation efforts at the SPA.