The Past and Future of the Mammoth Steppe Ecosystem

Abstract

During the Last Glacial Maximum (LGM) the mammoth steppe was the planet’s biggest biome. Ice rich loess-like soils of this biome covered vast northern territories. These soils are currently one of the biggest carbon reservoirs. It is likely that in this century the bigger part of these soils will thaw. This would lead to massive erosion, destruction of modern ecosystems and a large emission of carbon dioxide and methane into the atmosphere, which are produced from the decomposition of Pleistocene organics. Minimizing these effects is possible only through the restoration of ecosystems similar to the Pleistocene mammoth steppe. Skeleton densities in the permafrost show that the mammoth steppe was a highly productive ecosystem similar to African savannas. Biomass of animals in the north of Siberia was ~10t/km2. Herbivores enhanced biocyclicity, trampled moss and shrubs and maintained pastures. Therefore this ecosystem was only partially dependent on climate. Analyses of climate dynamics, vegetation and animals shows that today the climate in the north of Siberia, Alaska and Yukon are close to the optimum of the mammoth steppe, and that climate warming did not destroy this ecosystem. Rather, humans are the more likely cause. After the LGM, climate warming allowed humans to penetrate the north, where they decreased animal densities to the point where they became insufficient to maintain pastures. In this chapter we discuss questions of preservation of bones and artifacts in the permafrost, physiology and evolution of pasture ecosystems and the role of humans in this ecosystem.