The Effects of Enhanced UV-B on Plant Competition

: An Application of Metabolic Fingerprinting

Crynodeb

Concerns about increased stratospheric ozone depletion increasing ambient levels of ultraviolet-B radiation (UV-B), and the fact that some ecosystems are naturally exposed to high levels, has resulted in an increased interest in the effects of UV-B on plant communities. Despite this, there has been a paucity of studies into its effects on plant competition. Artificial plant communities consisting of Lolium perenne and Lotus corniculatus and a sub-montane community consisting of Agrostis tenuis, Festuca ovina and Galium saxatile (also including different nitrogen levels) were created using the response surface approach. The long-term effects of UV-B were also studied on a natural sub-Arctic community in Abisko, Sweden. In addition, all plant samples were analysed by Fourier-Transform Infrared Spectroscopy (FT-IR) to obtain a ‘metabolic fingerprint’ which was used to detect chemical differences to the whole biochemical complement of the sample. The results showed that enhanced UV-B altered the competitive interaction of Lolium perenne and Lotus corniculatus in favour of Lolium perenne although ambient levels of UV-B did not elicit an effect in the sub-montane community. Only one dwarf shrub species in the sub-Arctic experiment, Vaccinium myrtillus, was negatively affected by UV-B. In most cases, elevated UV-B elicited a change in the metabolic fingerprint in the samples and in some cases an alteration in competitive stress altered the metabolome. This suggests that FT-IR can be used as a screening tool to detect for both abiotic stress and competitive biochemical alterations. In addition, this thesis proposes that the facilitative effect between the grass-legume mixture of Lolium perenne and Lotus corniculatus is not related to nitrogen fixation in the early stages of competition which has traditionally been believed.

Dyddiad Dyfarnu	21 Ebr 2008
Iaith wreiddiol	Saesneg
Sefydliad Dyfarnu	Prifysgol Aberystwyth
Goruchwyliwr	Dylan Gwynn-Jones (Goruchwylydd) & Luis Mur (Goruchwylydd)