Modelling the spread of Agriculture across East Asia: Insights on the Spread of Agriculture to the Tibetan Plateau

Abstract:

Moving agriculture into the highlands of the Tibetan Plateau, was a challenging process. Short growing seasons, cold winters and spring frost mean that the Tibetan plateau presented considerable challenges to the movement of domesticates into this region. In this paper, I describe the creation and employment of crop niche models aimed at outlining the constraints associated with practicing a range of different crops on the Tibetan plateau and in the foothills of the Himalayas.

Thermal crop niche models based on a crop’s accumulated heat requirements (growing degree days) predict that contrary to previous arguments (Jones et al. 2011) wheat and barley are more adapted to growth in high latitude and high altitude Eurasia than millets. Millets were able to flourish only in select niches on the southeastern Tibetan Plateau (SETP), and only during the warmer Holocene climatic optimum (although even here, models indicate that their potential success was low). In contrast, the frost tolerance and lower GDD requirements of wheat and barley enabled these crops to be rapidly adopted as staples on the Tibetan Plateau and its margins. Local ecology and climate coupled with crop phenology thus had a marked impact on crop adoption in high altitude environments, one that differed substantially from the lowlands. The end of the climatic optimum had a marked effect on what crops could be grown in this area.

I argue that these models allow for more complex interprtetations of agricultural behavior in the past and understanding the impact that climate had on past agricultural systems.