Efecte de la radiació ultraviolada (UV) i la sequera sobre les taxes de descomposició de les fulles d’Arbutus unedo

Abstract

A consequence of climate change will be a reduction in cloud cover and, therefore, an increase in ultraviolet radiation (UV) and a decrease in precipitation in the coming years. The main objective of this study was to investigate how UV radiation and precipitation affect the decomposition of the leaves of a Mediterranean plant, specifically Arbutus unedo. In addition, we also wanted to determine what are the main invertebrates that can be involved in this decomposition and if the composition of their community can be affected by changes in these climatic factors. The study was carried out for 8 months, from November to June, using 18 plots of 9 m2 exposed to 3 levels of UV radiation (UV-A radiation, UV-A radiation plus UV-B radiation and no radiation) and 2 of precipitation (natural precipitation and reduced precipitation). Different parameters were studied, such as the percentage of organic matter remaining, weight loss, enzyme activity and the content of C and N of the leaf litter. The research also included the study of the community of invertebrates present in leaf litter where we studied different ecological indexes and the abundance of the different orders. Neither the exposure to UV radiation, nor the reduction of precipitation affected negatively the enzyme activity of β-glucosidase. Regarding the percentage of organic matter remaining, at the end of the experiment (June), we saw that the decrease is higher when the litter is under reduced precipitation. In drought plots, the litter showed a greater weight loss when exposed to UV radiation. We have also observed that the content of C and N increases in respect to the initial values, especially in the case of the C within the plots with UV radiation and natural precipitation. On the other hand, the ratio of C:N decreases in respect to the initial values. Regarding the composition of the community on invertebrates, we have seen that the most abundant groups are mites, larvae and diptera. Although the treatments have not affected the ecological indexes studied, they have affected the relative abundance of some of the invertebrate groups