DUGi

Efecte de la radiació i la disponibilitat hídrica en la descomposició microbiana de fullaraca de Phillyrea angustifolia i Arbutus unedo

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@16245

Decomposition is a very important process for life, is the step from organic matter to inorganic components thanks to the help of microbiota and other factors. Climate change is varying the levels of ultraviolet radiation and the global climate so it is important to study its effects on the basic processes of nature. The aim of this study was to determine the effect of the radiation and water availability in the microbial decomposition of litter of Phillyrea angustifolia and Arbutus unedo and the effect on colonization just after the abscission by bacteria and the fungus in plants growing under different treatments. Also has focused on analysing the differences between the two species taking into account that they are Mediterranean species and have different leaf structures and climate adaptations. To analyse it, samples have been prepared under the UV0, UVA and UVAB radiation treatments and the “dry” and “water” water regimes. The carbon of fungus and bacteria of all the samples has been calculated over the course of 4 months and the percentage of organic matter remaining in the samples has been calculated. The results obtained indicate that the growth in different water treatments and availability of water entails changes in the microbial biomass just after abscission in the leaves of the two species: Phillyrea angustifolia and Arbutus unedo. In Phillyrea, bacteria prefer to colonize leaves under drought treatment while in Arbutus fungi prefer to colonize leaves under humid conditions. Also, exposure to UV-B radiation reduces fungal biomass and tends to reduce organic matter remaining in the decomposition process, especially in drought conditions, while UV-A seems to improve microbial colonization and the loss of weight They also indicate that low water availability reduces microbial colonization during the decomposition process. The results also indicate significant differences in microbial colonization between the two species. Phillyrea shows a greater weight loss and microbial colonization than Arbutus. This could be caused by the differences in its leaf structure. The results obtained in this work are part of the first phase of a study, which includes monitoring of decomposition during 12-18 months. In later studies it will be interesting to investigate the effect of the radiation and water availability in the levels of lignin and cellulose in these two species and the amount of bacterial and fungal enzymes in the leaves in order to see more clearly how microbiota interact with both types of leaf structure