Regime shifts of Mediterranean forest carbon uptake and reduced resilience driven by multidecadal ocean surface temperatures

Jofre Carnicer, Cristina Domingo-Marimon, Miquel Ninyerola, Jesus Julio Camarero, Ana Bastos, Jorge López-Parages, Laura Blanquer, Belén Rodríguez-Fonseca, Timothy M. Lenton, Vasilis Dakos, Montserrat Ribas, Emilia Gutiérrez, Josep Peñuelas, Xavier Pons

Research output: Contribution to journalArticleResearch

8 Citations (Scopus)

Abstract

© 2019 John Wiley & Sons Ltd The mechanisms translating global circulation changes into rapid abrupt shifts in forest carbon capture in semi-arid biomes remain poorly understood. Here, we report unprecedented multidecadal shifts in forest carbon uptake in semi-arid Mediterranean pine forests in Spain over 1950–2012. The averaged carbon sink reduction varies between 31% and 37%, and reaches values in the range of 50% in the most affected forest stands. Regime shifts in forest carbon uptake are associated with climatic early warning signals, decreased forest regional synchrony and reduced long-term carbon sink resilience. We identify the mechanisms linked to ocean multidecadal variability that shape regime shifts in carbon capture. First, we show that low-frequency variations of the surface temperature of the Atlantic Ocean induce shifts in the non-stationary effects of El Niño Southern Oscillation (ENSO) on regional forest carbon capture. Modelling evidence supports that the non-stationary effects of ENSO can be propagated from tropical areas to semi-arid Mediterranean biomes through atmospheric wave trains. Second, decadal changes in the Atlantic Multidecadal Oscillation (AMO) significantly alter sea–air heat exchanges, modifying in turn ocean vapour transport over land and land surface temperatures, and promoting sustained drought conditions in spring and summer that reduce forest carbon uptake. Third, we show that lagged effects of AMO on the winter North Atlantic Oscillation also contribute to the maintenance of long-term droughts. Finally, we show that the reported strong, negative effects of ocean surface temperature (AMO) on forest carbon uptake in the last decades are unprecedented over the last 150 years. Our results provide new, unreported explanations for carbon uptake shifts in these drought-prone forests and review the expected impacts of global warming on the profiled mechanisms.
Original languageEnglish
Pages (from-to)2825-2840
JournalGlobal Change Biology
Volume25
DOIs
Publication statusPublished - 1 Aug 2019

Keywords

  • carbon sink
  • climate
  • forest
  • multidecadal drought
  • regime shift
  • resilience

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