ICMGP 2022 – On-Demand / Poster Presentation

Abstract Information :

Litterfall is the natural process by which a fraction of the aerial tree biomass falls to the soil surface by processes related to its senescence or due to the action of meteorological factors. Litterfall has been recognized as one of the main vectors of atmospheric mercury (Hg) transference to the soil. In this study, Hg deposition by litterfall (needles, branches, bark and miscellaneous, etc.) was determined in a Pinus sylvestris mature stand located in northwestern Spain, from May 2019 to April 2021. The mean of total biomass flux (litterfall) was 484.7 g m?ý yr-1, with needles contributing on average to 60.4% of this biomass, whereas bark, small branches, miscellaneous and male flowers were 8.8, 13.8, 12.1 and 4.9% of litterfall, respectively. The average Hg concentration (THg) obtained for each biomass fraction in litterfall was: branches (59.1 ng g??), miscellaneous (50.4 ng g??), needles (49.8 ng g??), bark (43.4 ng g??) and male flowers (21.9 ng g??). Mercury concentration in needles and bark scarcely varied throughout the year, which is common in the case of coniferous species. However, THg for miscellaneous increases from September to December and THg in the branches peaked during February and August. The mean flux of Hg deposition through litterfall was 23.2 æg m?ý yr-1, being mostly due to the fall of needles which represented 65% of the total Hg deposited, followed by, miscellaneous and bark (12%), branches (9%) and male flowers (2%). The flux of Hg deposition through litterfall in the studied Pinus stand was comparable to those obtained for deciduous species in the same study area (21-26 æg m?ý yr-1). Monthly fluxes of Hg deposition associated to the needle fraction showed a greater dependence on its biomass flux (r=0.995; p=0.000; n=24) than its THg concentration (r=0.647; p=0.001; n=24).