Biodegradation processes of lichen and mosses in cryptogamic polar covers

• Main Authors: Rodríguez González, Esther, Rey, Ana, Ríos, Asunción de los
• Format: Conference Object
• Language: unknown
• Published: CSIC - Museo Nacional de Ciencias Naturales (MNCN) 2020
• Subjects: Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10261/233983

Las IV Jornadas Científicas del Museo Nacional de Ciencias Naturales tuvieron lugar en el Salón de Actos del MNCM (Madrid) del 24 al 25 de febrero de 2020 Cryptogamic covers are the main living form of terrestrial ecosystems in polar regions. Despite the recognised importance, no study to date has investigated their decomposition in situ. Thus, we do not know to what extent they contribute to soil organic matter accumulation and whether the decomposition drivers are similar to those for plant litter. Here we report the first results from a litter decomposition experiment carried out with two biocrust-forming species (lichen versus mosses) in well-developed and bare soils in Antarctica. We evaluated how litter decomposition was affected by light exposure to test whether abiotic processes play a role in litter decomposition there. We carried out an experiment for a year and measure litter decomposition of lichen and mosses during the growing season and over an entire year. We also manipulated the incidence of UV radiation using mesh material that blocked 10% or 90% of incoming radiation. Our results indicate that after one year in the field, lichens and mosses decompose 7% and 8% of the initial mass. Light exposure inhibit decomposition in both, 40% and 22% in lichens and mosses litter, respectively. Most degradation occurred during the summer months. Contrary to our initial hypothesis, colonised soils exhibit lower decomposition rates than litter placed on bare soil, particularly in the case of moss litter. Our results show that decomposition of cryptogamic cover is slow in Antarctica compared to other regions and that is strongly limited by low temperatures, that contrary to what occurs in plant litter in semiarid regions, light exposure inhibited decomposition and is not favored by the presence of biological cover. Thus, our findings highlight the need to further investigate litter decomposition in polar regions in order to incorporate cryptogamic litter decomposition into carbon cycling models to better ...