Net Ecosystem CO2 Exchange in Mountain Grasslands Is Seriously Endangered by the Temperature Increase in the Eastern Pyrenees

Mediterranean mountain grasslands, including the Pyrenees, are highly vulnerable to climate change, due increasing temperatures and heat weaves frequency, among other factors. However, effects of increased on CO2 fluxes in those ecosystems have been barley explored. To address this gap knowledge, we established FLUXPYR-ECOFUN micrometeorological flux network, which included three eddy covariance stations grasslands along a management climatic gradient (montane subalpine) at Pyrenees; aimed assessing interactions environmental phenological drivers fluxes, with special attention role temperature as driver under different conditions across studied gradient. Our results showed that drove dynamics ways. At subalpine grassland net uptake was linearly enhanced by had not reached shifting point yet (according segmented linear models) would become emissions. This suggests short term, incoming temperatures, sub-alpine Pyrenees might increase their uptake, although mid long-term may be compromised. On contrary, montane already presented emissions highest most likely driven decrease greenness photosynthesis, expected reduce sink capacity temperatures. Overall, mid- experience reduction current change scenario.