Elevation and temperature are strong predictors of long-term carbon accumulation across tropical Andean mountain peatlands

Mountain peatlands are understudied globally, especially in tropical regions such as the Andes. Their high abundance across the landscape and thick carbon (C)-rich soils establish them as regionally important C reservoirs. However, they are at high risk of degradation due to unsustainable land use and climate change. Mitigation of these threats requires detailed inventories of C stocks present and improved understanding of the major drivers of long-term C accumulation in these ecosystems. We cored 24 peatlands located between 3000 and 4800 m elevation across Colombia, Ecuador, Peru, and Bolivia, calculated C storage and long-term and recent apparent rate of C accumulation (LARCA and RARCA, respectively), and tested their relationships to environmental variables (elevation, temperature, precipitation, and solar radiation). The peatlands had a mean thickness of 4.7 m (range, 0.7‒11.25 m). The mean age of peatland was 7918 yrs B.P., with a range from 490 to 20,000 yrs B.P. The mean C stock was 1743 Mg ha^-1 and did not significantly vary by climatic region or basal age but did increase with elevation. LARCA was best predicted by age and elevation, while RARCA was negatively related to mean annual temperature. These findings indicate that peatlands in the tropical Andes store thick deposits of soil C that are likely influenced by temperature, making them vulnerable to changes in climate. To inform climate policy, there is a need for science that will determine the potential for adaptation and mitigation treatments to increase the resilience of these C-rich ecosystems to climate change.