CO2 and CH4 soil exchanges in managed woody species of Sierra Nevada mountains (Spain) 

<p>To avoid tree mortality, biodiversity losses and maintain the ecosystem services under climate change context, the management of forests is essential. A common practice in Mediterranean mountains is clearing and thinning, leaving the main branches lopped off and the wood left <em>in situ. </em>These activities generate bare soil and vegetation pruning patches in the ecosystem creating different microhabitat conditions and, therefore, affecting carbon dioxide (CO₂) and methane (CH₄) soil exchanges. This study is focused on oak and holm oak groves and pine reforestation, dominant woody species in Sierra Nevada mountains (Spain) that have problems of adaptation to climate change fostered by a long history of human management.&#160;</p> <p>On this subject, we are monitoring both with biophysical field measurements and satellite products on the experimental managed forests. Concretely, we are measuring for one year CO₂ and CH₄ soil fluxes of the different patches. For this purpose, a portable gas analyzer system (Smart chamber + Li7810, Li-Cor) is used biweekly over 24 collars (2 treatments [vegetation pruning vs immediate bare soil] x 3 replicas x 4 collars [sub-replicas]) on each one of the 4 experimental forests (<em>Quercus pyrenaica, Quercus ilex, Pinus halepensis and Pinus sylvestris</em>). At the same time, soil water content, soil temperature and litter are measured in each campaign. &#160;On the other hand, Landsat products (NDVI, LST and LSWI) were evaluated before and after the establishment of the treatments for temporal follow-up. Additionally, since January 2023 we are starting to characterize microclimatic conditions (velocity and direction wind, air temperature, soil water content and precipitation) and continuous CO₂ concentration in soils (GMP252, Vaisala).</p> <p>The preliminary results show that oaks with vegetation respires more (soil CO₂ emissions) than oak grove bare soil. Although both patches are methane sinks, the CH₄ flux is enhanced with vegetation presence. A relationship with soil temperature and moisture was found. We hypothesize that these variations could be due to autotrophic respiration, and more prolonged activity of microorganisms in the soil enhanced by litter input. Regards pines sites, no significant differences in fluxes of the different microclimate&#8217;s patches were found (no relationship with soil variables was detected) which seems to indicate that the management leaving vegetation pruning does not affect soil fluxes.</p> <p>This work was supported by the projects B-RNM-60-UGR20 (OLEAGEIs) and LifeWatch-2019-10-UGR-01, co-funded by the MICINN through the FEDER funds.</p>