The carbon cycle in Mexico: past, present and future of C stocks and fluxes

[摘要] We modeled the carbon (C) cycle in Mexico with a process-based approach. Weused different available products (satellite data, field measurements,models and flux towers) to estimate C stocks and fluxes in the country atthree different time frames: present (defined as the period 2000–2005), thepast century (1901–2000) and the remainder of this century (2010–2100). Ourestimate of the gross primary productivity (GPP) for the country was 2137 ± 1023 TgC yr⁻¹ and a total C stock of 34 506 ± 7483 TgC,with 20 347 ± 4622 TgC in vegetation and 14 159 ± 3861 in thesoil.

Contrary to other current estimates for recent decades, our results showedthat Mexico was a C sink over the period 1990–2009 (+31 TgC yr⁻¹) andthat C accumulation over the last century amounted to 1210 ± 1040 TgC.We attributed this sink to the CO₂ fertilization effect on GPP, whichled to an increase of 3408 ± 1060 TgC, while both climate and land usereduced the country C stocks by −458 ± 1001 and −1740 ± 878 TgC,respectively. Under different future scenarios, the C sink will likelycontinue over the 21st century, with decreasing C uptake as the climateforcing becomes more extreme. Our work provides valuable insights onrelevant driving processes of the C cycle such as the role of drought indrylands (e.g., grasslands and shrublands) and the impact of climate changeon the mean residence time of soil C in tropical ecosystems.

[学科分类] 地球化学与岩石