Abstract

EMETERIO, Layla M. San et al. Effects of climate change in soil organic matter molecular structure in a Mediterranean savanna. Rev. de Ciências Agrárias [online]. 2022, vol.45, n.4, pp.1041-1050.  Epub Dec 01, 2022. ISSN 0871-018X.  https://doi.org/10.19084/rca.28747.

Mediterranean savannahs (dehesas) are typical agro-sylvo-pastoral systems, characterized by the scattered presence of oak trees (Quercus spp) and shruby species, along with the integration of other practices. These ecosystems are subjected to a marked seasonality characteristic of the Mediterranean climate, and expected to be reflected in soil microbial dynamics. The interplay of driving factors on the microbial dynamics (climate, vegetation and soil) is key to understanding biogeochemical cycles in Mediterranean forests that, in turn are expected to be reflected in soil organic matter (SOM) structure. In this communication analytical pyrolysis (Py-GC/MS) was used for the molecular characterization of SOM in a field manipulative experiment aimed to evaluate the impact of forecasted warming and drying in a five-year experiment (2017-2021). Among all the biogenic compounds that were found (a total of 117), fatty acids and aliphatic compounds (n-alkanes) were found most responsive to climatic treatments. Also, a preferential degradation of holocellulose derived compounds and accumulation and preservation of lignin derived compounds, pointing to non-favourable lignin decomposition conditions. The results suggest that SOM molecular composition, hence the application of Py-GC/MS encompasses information on soil environmental shifts having biomarker value for monitoring climate change in Mediterranean soils.

Keywords : analytical pyrolysis; soil organic matter; climate change; Mediterranean ecosystem.

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