Non-climatic causes for low productivity of Siberian tundra ecosystems

Tundras are low-productivity communities. If it is only a consequence of unfavourable climate, then how could herb communities that fed numerous large herbivores (mammoth fauna) exist during more severe periods of the late Pleistocene in the same latitude? There is an imbalance between climatic potential and real productivity of tundras. It is associated with an extremely low content of plant nutrients in soils. The imbalance occurred after late Pleistocene pastoral ecosystems had alternated with modern tundras. The disappearance of large herbivores, a keystone species of Pleistocene ecosystems of Siberia, was one of the reasons for this. In Pleistocene landscapes, there were two mechanisms for recycling nutrients. The first one was a biological rotation related to plants’ taking nutrients that had been released in the process of mortmass mineralisation. It still exists in tundra though now it is less effective. The second mechanism was animals’ returning nutrients from low relief parts to higher surfaces...