Bryophyte and lichen communities in boreal forests are maintained through the dispersal and establishment of asexual propagules
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Date
2019-08
Authors
Pasiche-Lisboa, Carlos J.
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Abstract
Bryophyte and lichen communities in boreal forests are partly shaped by the dispersal and establishment of propagules (meiotic spores and asexual propagules), yet it is not well known how asexual propagules shape these communities. This thesis examined some of the roles of asexual propagules in shaping the extant cryptogam community through propagule trapping and association of asexual propagules (number, size, and type) within different tree-dominated forest stands and environmental conditions (Chapter 2, 3), the characterization of wind dispersal-deposition patterns of select epiphytic and ground-dwelling mosses and lichens (Chapter 4), the assessment of abundance and richness of local bryophyte and lichen communities and that of the soil bank environmental DNA (eDNA) (Chapter 5), and the exposure of bryophytes to different temperature treatments to understand establishment outcomes (Chapter 6). Asexual propagules of small size were dispersed throughout the year, but lichen thallus fragments were dispersed in higher numbers than other propagules—particularly, during winter. Asexual propagules were deposited in higher numbers in coniferous forest stands and on trees, which are linked to their bryophyte and lichen communities having higher abundance and/or richness when compared to the communities on hardwood stands or the forest floor substrata. Bryophyte and lichen communities on trees having a higher dispersal capability than those on the forest floor may allow for their communities to be maintained and to be formed at farther distances. The dispersal capacity of bryophytes and lichens on the forest floor may be limited to maintaining the local community and its soil bank. Though the soil bank is partly maintained by the local dispersal of propagules, the eDNA in the soil bank may represent a past community structure and/or long-dispersal events. Once the soil bank is disturbed, the establishing propagules may change the extant community composition. Of the moss propagules that become established, the higher propagule regeneration via protonemata and branch production at low-medium temperatures may facilitate ground-dwelling species to occupy their heterogenous substrata while spores may be required for epiphytic species to become established. Overall, bryophyte and lichen asexual propagules are fragmented and dispersed from the local community, with propagule establishment helping to maintain or change the local bryophyte and lichen communities in boreal forests.
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Keywords
Lichens, Bryophytes, Community Ecology, Molecular Ecology, eDNA, Asexual propagules