The plight of Amazonia's oldest peatland

Peatlands are globally important ecosystems in terms of biodiversity, hydrology, and for the role they play in the carbon cycle. They store approximately one-third of the carbon contained in the terrestrial biosphere, whilst covering only approximately 3% of the land and freshwater surface. Tropical peatlands represent an important component of this carbon store and can be found in Asia, Africa, South and Central America. However, tropical peatlands are also under severe threat of destruction from human activities including deforestation, agricultural expansion and resource exploitation. In South America, the Pastaza–Marañon foreland basin (PMFB) in NW Peru represents the most carbon dense landscape in Amazonia due to an abundance of peatlands, including nutrient-poor ombrotrophic peat domes and river-influenced minerotrophic swamps. The Aucayacu peatland in the PMFB is a nutrient-poor peat dome and represents the oldest peatland yet reported in Amazonia. It is a relatively large peatland—it is estimated that Aucayacu has maximum dimensions of 33 km (NW-SE) by 15 km (NE-SW) (Fig.). The flora of the site is characterized by stunted vegetation due to low nutrient status, known as ‘pole’ and ‘dwarf’ forest, which at Aucayacu grows above a patchy understory of grasses and ferns (Fig.). Recent research has shown that Aucayacu has laid down peat up to 7.5 m deep in ∼ 8900 years.