Improving the representation of tropical peatland processes in the JULES land surface model using data from the central Congo Basin.

Abstract

Tropical peatlands are not currently represented in large-scale terrestrial ecosystem models. Recent work in the central Congo Basin (CCB) measuring peatland processes and reconstructing peatland evolution and past climate provides a unique opportunity to further develop such models. Here, we modify the peatland scheme in the Joint UK Land Environment Simulator (JULES), the land surface component of the UK Earth System Model, in particular changing the vegetation litter composition and the dependence of peat decay on soil moisture. The modifications are informed by field measurements and by comparing the simulated peat accumulation and loss over 20 000 years with peat core records, including the 'Ghost Interval' period when reduced precipitation starting approximately 5000 years before the present (BP) resulted in significant peat loss. We drive JULES with a reconstruction of precipitation from peat core proxy data and other meteorological data from a global palaeoclimate model. The original JULES peatland scheme was unable to accumulate the observed quantities of peat or simulate the losses of peat suggested by palaeo records. Our updated version of JULES simulates peat increases until 3000 BP, when reduced precipitation results in substantial loss until 1000 BP. Correct representation of vegetation cover over time is also crucial for realistic peatland evolution. A French translation of this abstract is available in the supplementary material. This article is part of the discussion meeting issue 'African tropical peatlands: function, value and vulnerability'.