A Study Of Net Primary Productivity Appropriation By Trade Activities In China Based On The Input-output Approach

With the continuous development of the economy and society,the rapid increase in human demand for land and the expansion of human activities are threatening the sustainable development of ecosystems.To meet local development needs,trade-in biomass-related products have grown rapidly,and more and more areas are obtaining material and energy from outside the region,leading to an increasing spatial disconnect between the areas where biomass production-related environmental impacts occur and the areas where biomass consumption occurs.China is the world’s largest developing country,and interregional trade activities are becoming increasingly frequent,occupying a large number of land resources to meet consumer demand and intensifying resource consumption,thereby causing certain impacts on land use intensity.Land use intensity can be measured by the degree to which human activities change ecosystem functioning.Net primary productivity（NPP）is a key factor in ecosystems,and the degree of human intervention in this factor is referred to as human appropriation of NPP（HANPP）.In order to explore the influence and change characteristics of inter-regional trade on land use intensity transfer in China,HANPP,a comprehensive social ecological index,was selected in this study and a multi-regional input-output model was adopted.Combined with the Lund-Potsdam-Jena Model Dynamic Global Vegetation Model（LPJ-DGVM）,remote sensing data and socio-economic statistics,the HANPP footprints generated by inter-provincial trade in China over many years were analyzed.That is,HANPP that meets the needs of consumer trade of products The study also used urban-scale input-output tables to analyze the HANPP footprints of cities within the three major urban agglomerations of Beijing-Tianjin-Hebei,Yangtze River Delta,and Pearl River Delta in China.This study provides a reference for identifying specific regions responsible for ecological pressure,thereby providing direction for achieving coordinated development of economic growth and ecological protection.The conclusions of this study are as follows:（1）The distribution characteristics of potential natural vegetation productivity（₀）and current primary net productivity(₍(6(6(6(6（6（6））generated under current vegetation coverage in China both show a decreasing trend from the northwest inland regions to the southeast coastal regions.Regions with higher harvested productivity（_h）are mainly located in provinces with developed agriculture,forestry,and animal husbandry.HANPP shows a distribution pattern of more in the north and less in the south.From 2007 to 2015,China’s HANPP decreased from 1.17Pg C(=1.17×10³Tg C=1.17×10¹⁵g C)in 2007 to 1.12 Pg C in 2015,but the proportion of_h,which is an important component of HANPP,increased year by year,from 68.21%in 2007 to 85.15%in 2015.The above research shows that human occupation of ecosystem productivity in northern China is greater than in southern China,and the impact of human harvesting on land use intensity and productivity occupation is gradually increasing.（2）The proportion of inter-provincial HANPP footprint caused by inter-provincial trade in China from 2007 to 2015 increased from 41.70%in 2007 to 45.90%year by year,indicating that the impact of trade on ecology and land in various regions of China is constantly increasing.In addition,the HANPP footprint of nine provinces in northern China,including Hebei,Liaoning,and Shaanxi,as well as Henan,has always been dominated by production from 2007 to 2015,while the HANPP footprint of 13 eastern coastal provinces such as Shanghai,Beijing,Tianjin,Jiangsu and Guangdong have always been dominated by consumption.This indicates that eastern coastal provinces in China have shifted some of their environmental pressure to northern provinces to meet final demand.（3）In the three major urban agglomerations of Beijing-Tianjin-Hebei,the Yangtze River Delta,and the Pearl River Delta,the cities with a large production-side human appropriation of net primary productivity（HANPP）footprints are mainly caused by the final demand of provincial capital cities and other economically developed cities.Specifically,in the Beijing-Tianjin-Hebei urban agglomeration,Baoding and Zhangjiakou have larger production-side HANPP footprints,which are 8.21 Tg C and8.03 Tg C,respectively,mainly due to the final demand of cities such as Shijiazhuang and Tangshan.In the Yangtze River Delta urban agglomeration,Yancheng,Yangzhou,and Chuzhou have larger production-side HANPP footprints,which are 4.68 Tg C,2.70Tg C,and 3.69 Tg C,respectively,mainly due to the final demand of cities such as Nanjing,Wuxi,Suzhou,and Hefei.In the Pearl River Delta urban agglomeration,Huizhou,Jiangmen,and Zhaoqing have larger production-side HANPP footprints,which are 2.16 Tg C,1.22 Tg C,and 1.18 Tg C,respectively,mainly due to the consumption demand of cities such as Guangzhou,Shenzhen,and Dongguan.In addition,as municipalities directly under the central government,Beijing,Tianjin,and Shanghai have ecological impacts caused by final demand,which not only affects cities within their regions but also transfers to other provinces in China.In summary,trade has an increasing impact on the intensity of land use in China.To balance the relationship between economic development and ecological conservation in different regions,targeted environmental policies should be formulated.The consumption-oriented regions with high HANPP should be compensated to shift towards production-oriented regions,in order to improve the efficiency of resource utilization.Additionally,some production activities could be relocated to areas with less ecological impact.