Carbon dynamics of high-elevation tropical cushion peatlands in the Andes

High-Andean tropical peatlands occur up to 5000 m a.s.l., where conditions vary from cool to freezing cold on a daily basis. In the tropical and subtropical Andes, these high-elevation peatlands are mainly composed of vascular cushion plants and occur in topographically wet locations in climates ranging from very humid paramos in the north to arid puna in the south. Like other peatlands, Andean cushion peatlands store large amounts of carbon, but with high amount of sediments and higher recent carbon accumulation rates. Often, these amounts have not been quantified, nor are the controls on carbon gains and losses sufficiently known to predict changes in carbon storage due to land-use and climate change. We reviewed the literature on carbon stocks and dynamics in (sub-)tropical Andean cushion peatlands, aiming to understand the topographic, hydrologic, climatic and biotic drivers and geographic patterns. We identified important roles for catchment size and sediment inputs, temperature in combination with water availability, and vegetation, but none of these roles can be quantified yet based on currently available data. However, it is clear that predicted regional differences in climatic changes (seasonality, permafrost behavior, temperature, precipitation regimes) imply that carbon-balance trends of cushion peatlands will differ regionally, with those in paramo most likely to continue as C sinks, while those in dry puna are more likely turning to C sources under increasing aridification.