THE REMARKABLE SIMPLICITY OF TROPICAL PEAT SWAMP FORESTS

Tropical peat swamp forests are modern analogues for coal deposition but now many emit large fluxes of CO2 as they are deforested and drained. I will describe one of the last remaining pristine tropical peat forests found on the island of Borneo. Through a combination of hydrologic, carbon-flux, and LIDAR data we have developed a new framework for understanding the coupled hydrologic and ecological processes that shape tropical peat lands. Carbon dates from cores are consistent with the modeled evolution of the peat landscape and both the simulations and data agree that the peat land has reached a steady-state over five millennia such that: (1) Vadose-zone dynamics are uniform across the peat even as the watertable responds to rainstorms and; (2) The topographic curvature of the land surface is described by a spatially uniform Laplacian value that is predicted by rainfall statistics. These spatially uniform characteristics indicate that carbon accumulation and loss are likely balanced across the landscape. We estimate how this steady-state topography, and hence the peat volume, will shift if rainfall characteristics such as seasonality and intensity change. We also predict how drainage, deforestation, and sea level rise may affect the carbon store of tropical peat lands.