A tropical Sphagnum peatland ecosystem in lowland Belize

Tropical peatlands are globally significant ecosystems for carbon cycling and storage, hydrological regulation and unique biodiversity. There is a diversity of tropical peatland types globally, but tropical peat-forming ecosystems are typically forested without the Sphagnum groundcover that is often characteristic of high latitude peatlands. Here we report on a unique tropical peatland situated in Belize that challenges our understanding of both tropical and extra-tropical peatlands owing to the presence of Sphagnum in the undergrowth. We employed a suite of methods to investigate its composition, distribution and history. The 2175 ha peatland is comprised of a complex mosaic of open scrub and forested communities which are compositionally similar to northern temperate peatlands at higher taxonomic levels. Palaeoecological data show that the peatland originated as a mangrove swamp beginning > 7,700 yrs BP and Sphagnum spores and macrofossil remains suggest this moss was locally established by c. 4,000 yrs BP. Drier conditions from 4,500 yrs BP impacted carbon accumulation rates and may have enabled burning, but the peatland remained intact despite these pressures. Floristics and structural affinities with coastal Panamanian peatlands suggests the existence of a rare Central American peatland type that is underreported and may be already fragmented and threatened. This previously undocumented peatland highlights the knowledge gaps in tropical biodiversity that conceal important ecological and biogeographical insights. These florist, palaeoecological and remote sensing datasets provide insights vital to understanding the functional diversity and climate resilience of globally important tropical peatland ecosystems.