Spatial heterogeneity of carrying capacity on the Tibetan Plateau: An ecosystem service approach

In ecology, carrying capacity is typically defined as the maximum number of organisms of a particular species that can be supported indefinitely in a given environment. However, this way of defining carrying capacity has been hard to apply in regional sustainability and management. Here, we propose that carrying capacity is the ability of ecosystems to sustainably provide maximum ecosystem services without damaging the ecosystem in a given region. That is, carrying capacity is multidimensional. We apply this approach to evaluate carrying capacity based on the ecosystem service provision, including ecosystem processes and functions such as soil conservation, carbon sequestration and water purification, and constituents of human well-being such as grassland productivity and water retention on the Tibetan Plateau. The results showed that carrying capacity of water retention, water purification, soil conservation, grassland forage production and carbon sequestration were estimated at 267.80 billion m³, 12.93 million tons, 34.24 billion tons, 97.70 million SU and 0.16 billion tons. Overall, grassland forage production is severely overloaded, with a loading ratio of 1.50. The loading ratios of water retention and water purification are 0.05 and 0.02, loading ratio of soil conservation is 0.80, loading ratio of carbon sequestration is 0.83, and all of them are not overloaded. However, soil conservation and carbon sequestration were severely overloaded in 10 and 47 counties, respectively. The overloading varies with carrying capacity and loading ratios in different counties. 108 and 54 counties are severely overloaded and overloaded respectively, and 34 counties are not overloaded.