Titre : | The ecological significance of sexual reproduction in peat mosses (Sphagnum) |
Type de document : | Livre |
Auteurs : | Sebastian Sundberg, Auteur |
Editeur : | Acta Universitatis Upsaliensis |
Année de publication : | 2000 |
Collection : | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology num. 581 |
Importance : | 37 p. |
ISBN/ISSN/EAN : | 91-554-4847-X |
Langues : | Anglais |
Mots-clés : | colonisation perturbation expérience longévité spore bryophyte |
Résumé : | "Peat mosses (Sphagnum) are widely distributed and are a major component of mire vegetationand peat throughout the boreal and temperate regions. Most boreal Sphagnum species regu-larly produce sporophytes, but the ecological role of the spore has been questioned. This studyshows that the spores can form a spore bank and have the ability to germinate and contributeto moss establishment whenever suitable conditions occur. The results suggest that spore pro-duction is important for explaining the wide distribution and omnipresence of Sphagnum innutrient-poor wetlands. The results further imply that initial recruitment from spores predomi-nates in Sphagnum after disturbance or formation of suitable habitats.A series of experiments showed that addition of phosphorus-containing substrates, suchas fresh plant litter or moose dung, resulted in spore establishment on bare, moist peat. A fieldexperiment indicated establishment rates of about 1% of sown, germinable spores on peatwith added substrates. Plant litter on moist soil, without a closed cover of bryophytes, is animportant safe site for the establishment of Sphagnum spores. The results fit the observed pat-tern of colonisation by Sphagnum beneath Eriophorum vaginatum tussocks in mires severelydisturbed by peat extraction. Successful long-distance dispersal was indicated by the occur-rence of several regionally new or rare Sphagnum species in disturbed mires.Spore number per sporophyte ranged among Sphagnum species from 18 500 to 240 000,with a trade-off between spore number and spore size. Annual spore production was estimatedat 15 million spores per square metre on two investigated mires. Sporophyte productionshowed a large interannual variation. Sporophyte production was positively related to theamount of precipitation the preceding summer. This was probably because a high water levelpromoted gametangium formation. Spore dispersal occurred in July and August. The earliertiming of spore dispersal in the more drought-sensitive, hollow-inhabiting sphagna should re-duce the risk of sporophytes drying out prematurely during summer droughts.Spores kept refrigerated up to 13 years retained high germinability. A field experimentshowed that Sphagnum can form a persistent spore bank, with a potential longevity of severaldecades." (source : auteur) |
Type de publication : | livre |
Référence biblio : | Sundberg S., [s. d.] - The ecological significance of sexual reproduction in peat mosses (Sphagnum). Acta Universitatis Upsaliensis, 37 p. (Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology ; 581). |
En ligne : | http://www.diva-portal.org/smash/get/diva2:166017/FULLTEXT01.pdf |
Format de la ressource électronique : | document |
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