Evolution of grassland ecological footprints based on variable structures of farming-pasturing interlocked areas

Siziwang Banner is a typical agri-pastoral ecotone of Inner Mongolia, where animal husbandry is the foundation supporting economic development. The grassland resources have a profound influence on the livestock industry. The time scale studied in this paper spans nearly 30 years, and during this period, the grassland resources of Siziwang Banner were degraded by human economic activities on a large scale. With the increasing awareness of environmental protection, the national and local governments have adopted a series of ecological measures, through projects such as returning farmland to grasslands, and the comprehensive management of grasslands to help improve their ecology. The transformation from grassland degradation to improving ecological, to a certain extent, reflects that regional economic construction is no longer purely at the expense of the environment but is gradually adopting a sustainable development approach. Coordination between economic construction and ecological protection should be emphasized. In order to study grassland ecology and economic development, a feasible ecological evaluation model is needed. The ecological footprint model has been widely used in China, but grassland ecological footprints are rarely found in agro-pastoral interlaced areas. The ecological footprint of the grassland and the time series of GDP per capita from 1987 to 2016 were used to analyze the grassland consumption and economic growth in Siziwang Banner, by using the Bai-Perron structural mutation co-integration test. The results of this co-integration test, which did not consider structural mutation, showed that it was not suitable for Siziwang Banner under a variety of grassland ecological protection policies. Besides, a co-integration test of structural mutation could reflect the economy of the agricultural and pastoral ecotone over a long period. The structural changes reflected the dynamic equilibrium between grassland consumption and economic growth and presented a one-way causality from grassland consumption to economic growth. The evolution of the grassland ecological footprint could be divided into three stages:a low-degree coordination stage (1987-2002), a policy-driven stage (2002-2009), and a rapid development stage (2009-2016). In the different stages, the absolute value of short-term fluctuations of the grasslands ecological footprint tended to be flat, but the long-term equilibrium coefficients gradually increased. The results showed that the ecological protection policy was helpful for improving the utilization efficiency of grassland resources. We found that the dependence of economic growth on grassland consumption gradually decreased, and the mode of economic growth at the expense of resources changed under the policies of ecological protection over the past 20 years. Sustainable methods for both economic development and ecological protection were advancing. Our results were not only beneficial to coordinate the development of regional economies and the utilization of grassland resources, but could also be used as reference for the future scientific planning of grassland ecological protection in the ecotones of agriculture and animal husbandry.