| Summary: | Thesis (MSc)--Stellenbosch University, 2016. ENGLISH ABSTRACT: There is currently a worldwide interest in grouping species on the basis of their functional characteristics into plant functional types (PFTs). This reduces the complexity of models that predict the effects of global change on vegetation and ecosystem processes. Marion Island has vegetation dominated by bryophytes and is experiencing intense climate change. However, there is no accepted scheme and no consensus on the most useful traits for a bryophyte PFT classification. This study aimed at grouping 38 of the island bryophyte species into functional groups. A suite of 14 photosynthetic traits related to light or desiccation response were obtained from chlorophyll fluorescence quenching analysis and water relations. The characteristics were subjected to analysis of variance, box plot rankings, principal component and clustering analyses to group the species into functional types. Seven light response groups and nine desiccation response groups were recognized. Six groups were recognized in the combined analysis of light and desiccation traits. The species with the highest photosynthetic capacity and lowest photoinhibition had low or moderate saturated moisture content, dried out slowly, low or moderate photoprotection capability in high light and when desiccated and moderate recovery of photochemistry upon rehydration. The species with the lowest photosynthetic capacity and highest photoinhibition had the highest saturated moisture content, dried out very fast, had low photoprotective capability in high light and when desiccated and showed very low to moderate recovery. The group of species with low photosynthetic capacity was distinguished from the group with the lowest photosynthetic capacity by having a higher quantum yield of electron transport at the optimal photosynthetically active radiation (PAR). The two groups consisting of moderate or high photosynthetic capacity species were distinguished by the fraction of open reaction centres in high ...
|
|---|