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dc.date.accessioned2013-09-26T10:02:07Z
dc.date.available2013-09-26T10:02:07Z
dc.date.issued2013en_US
dc.date.submitted2013-09-11en_US
dc.identifier.citationHovden, Hanne. VARIATION IN EPIPHYTIC BRYOPHYTE COMPOSITION WITHIN AND BETWEEN ASH TREES AT TUNGESVIK, ETNE, W. NORWAY. Masteroppgave, University of Oslo, 2013en_US
dc.identifier.urihttp://hdl.handle.net/10852/37129
dc.description.abstractThe epiphytic bryophyte composition between and within 73 ash trees (minimum stem diameter at breast height 20 cm) at Tungesvik, Etne, West Norway was investigated. The main aim of the study was to investigate patterns of variation in epiphytic bryophyte species composition on ash (Fraxinus excelsior) by a multivariate (ordination) approach. The importance of pollarding for the epiphytic bryophyte composition was also investigated. Trees were selected randomly from all realized combinations of three strata: elevation above sea; tree diameter; and pollarding or non-pollarding. Each tree was divided into height zones and sectors, in combinations of which bryophytes and environmental variables were recorded separately to address variation within trees. Pollarded trees were divided into five height zones – basis, stem, top, pollarded crown and pollarded branches – while non-pollarded trees were divided into three height zones – basis, lower stem and upper stem. The ordination analysis revealed a main gradient in bryophyte species composition that reflected variation on two spatial scales, between as well as within trees. The most important factors making up the underlying complex gradient were bryophyte cover, tree circumference and height zones. On the scale of variation between trees, the main gradient described variation from trees with small diameter and high bryophyte cover to trees with larger diameter and lower moss cover. A tendency for decreasing bryophyte cover with increasing tree diameter may be explained by the age-aspect of the tree’s circumference, more specifically, that young trees with small circumference (which are not included in this study) are relatively rapidly colonised by a handful of species with good dispersal and establishment ability. In later phases of succession, the species richness increases and the species composition changes as the bark undergo structural (and chemical) changes. On the scale of variation within trees, the main gradient in bryophyte species composition was related to tree height zones, running from the basis of the tree with high moss cover and low (naked) bark and lichen cover to higher height zones with lower moss cover and higher cover of naked bark and lichen cover. This pattern may be explained by shifts in the slope between the zones, which affects the species' ability to hold on to a more vertical substrate, and by responses to a water availability gradient: with increasing height on the trunk, environments get drier due to greater wind speeds and turbulence and reduced influence by evaporation from the ground. The difference in species composition between pollarded and non-pollarded trees was shown to be small, although there was a small general trend for the pollarded zones to have lower bryophyte cover than non-pollarded trees was observed. This indicates that pollarding as such that is not important for bryophyte species composition, except for the tendency for pollarded trees to be larger.eng
dc.language.isoengen_US
dc.titleVARIATION IN EPIPHYTIC BRYOPHYTE COMPOSITION WITHIN AND BETWEEN ASH TREES AT TUNGESVIK, ETNE, W. NORWAYen_US
dc.typeMaster thesisen_US
dc.date.updated2013-09-20en_US
dc.creator.authorHovden, Hanneen_US
dc.subject.nsiVDP::488en_US
dc.identifier.bibliographiccitationinfo:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft.au=Hovden, Hanne&rft.title=VARIATION IN EPIPHYTIC BRYOPHYTE COMPOSITION WITHIN AND BETWEEN ASH TREES AT TUNGESVIK, ETNE, W. NORWAY&rft.inst=University of Oslo&rft.date=2013&rft.degree=Masteroppgaveen_US
dc.identifier.urnURN:NBN:no-38374
dc.type.documentMasteroppgaveen_US
dc.identifier.duo184802en_US
dc.contributor.supervisorRune Halvorsen og Hans Blomen_US
dc.identifier.fulltextFulltext https://www.duo.uio.no/bitstream/handle/10852/37129/1/Hovden-x-Master.pdf


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