WORLD PEAT OCCURRENCE AND THE SEASONALITY OF CLIMATE AND VEGETATION

The climatic controls on present-day peat formation are examined in or der to develop a uniformitarian tool for refining paleoclimate studies , and to create a retrodictive model for the coals of the geologic rec ord. A peat database has been compiled for the world and the resulting patterns are compared with aspects of precipitation and temperature d rawn from a gridded data set. Precipitation continuity through the ann ual cycle is important for biologic productivity in the terrestrial re alm. It is expressed in terms of the number of months with average pre cipitation above 40 mm. Temperature is limiting at higher latitudes wh ere the potential growing season may be defined by the number of month s with mean temperature exceeding 10-degrees-C. A map predicting the g rowing season has been constructed from these rainfall and temperature statistics which compares very well with actual vegetation persistenc e through the year as measured directly from satellite instruments. Ho wever, biologic production will not result in peat accumulation unless groundwater levels are maintained through the growing season. Our pea t prediction map therefore shows the percentage of time that precipita tion occurs during the potential growing season. Present-day peat accu mulations are well predicted by this map.