Mapping peat thickness and carbon stocks of the central Congo Basin using field data

The world's largest tropical peatland complex is found in the central Congo Basin. However, there is a lack of in situ measurements to understand the peatland's distribution and the amount of carbon stored in it. So far, peat in this region has been sampled only in largely rain-fed interfluvial basins in the north of the Republic of the Congo. Here we present the first extensive field surveys of peat in the Democratic Republic of the Congo, which covers two-thirds of the estimated peatland area, including from previously undocumented river-influenced settings. We use field data from both countries to compute the first spatial models of peat thickness (mean 1.7 +/- 0.9 m; maximum 5.6 m) and peat carbon density (mean 1,712 +/- 634 MgC ha(-1); maximum 3,970 MgC ha(-1)) for the central Congo Basin. We show that the peatland complex covers 167,600 km(2), 36% of the world's tropical peatland area, and that 29.0 PgC is stored below ground in peat across the region (95% confidence interval, 26.3-32.2 PgC). Our measurement-based constraints give high confidence of globally significant peat carbon stocks in the central Congo Basin, totalling approximately 28% of the world's tropical peat carbon. Only 8% of this peat carbon lies within nationally protected areas, suggesting its vulnerability to future land-use change. Field surveys suggest peatlands in the central Congo Basin are globally significant carbon stocks, storing approximately 28% of the world's tropical peat carbon.

Automated summary

The world's largest tropical peatland complex is located in the central Congo Basin, covering 167,600 km(2) and storing approximately 29.0 PgC of carbon below ground. The peat in this region has been largely sampled in the north of the Republic of the Congo, but this study presents the first extensive field surveys in the Democratic Republic of the Congo, which covers two-thirds of the estimated peatland area. The findings reveal that the central Congo Basin plays a globally significant role in storing tropical peat carbon.