National Natural Science Foundation of China-Guizhou Provincial People''s Government Karst Science Research Center Project (U1812401); National Natural Science Foundation of China Project (41867001); Guizhou Province Science and Technology Uplifting Talent Support Program for General Higher Education Institutions (Qian Education and Cooperation KY  042); Guizhou Province Science and Technology Program Project (Qian Science and Cooperation Support  4Y016); Guizhou Province Water Resources Science and Technology Project (KT202108)
Studying the change trend and sustainability of vegetation net primary productivity (NPP) of terrestrial ecosystems in different global climatic zones is important for estimating the structure, function and carbon sources (sinks) of global terrestrial ecosystems. In this article, the change trend and sustainability of NPP of terrestrial ecosystems in different global climatic zones were analyzed using Mann-Kendall mutation test, Theil-Sen slope estimation, and Hurst index. The results showed that: (1) The global terrestrial NPP had obviously regional differentiation. The NPP value was higher in the lower latitude regions than the higher latitude regions, and higher in coastal regions than hinterland. The area of NPP improved accounted for 48.79% of the global terrestrial ecosystem. Among these improved areas, the significantly improved area accounted for 8.45% of the global terrestrial ecosystem, which is mainly distributed in the north and central of North America, the west of the Amazon Basin, the Congo Basin, southern Europe, the northwest of the Indian Peninsula and the Loess Plateau of China; The slightly improved area accounted for 40.34% of the global terrestrial ecosystem, mainly distributed in central and southern South America, Eastern Asia and eastern Australia. (2) The change trend and mutation point of NPP in each climate zone were as follows: NPP in tropical, subtropical, and polar zones showed a non-significant decreasing trend (R2=0.111,P=0.176;R2=0.144,P=0.120;R2=0.002,P=0.854), with no significant mutation point in the tropics, the mutation point of the subtropics in 2015, and the mutation point of the polar zone in 2005; the NPP in arid showed a non-significant increasing trend (R2=0.036,P=0.450) with the mutation point in 2009; the NPP in temperate and cold temperate zone showed a significant increasing trend (R2=0.533,P=0.001) with the mutation point in 2014. (3) For the relationship between NPP with precipitation and temperature in each climate zone, NPP in arid climate zones and polar zones were moisture-limited, NPP in tropical and temperate cold climate zones were heat-limited, and NPP in subtropical zones was not significantly affected by temperature and precipitation. (4) In the coming period, the global terrestrial NPP shows a decreasing area (51.31%) more than increasing area (48.69%). The area of NPP is decreasing significantly more than the increasing in the arid climate zones, subtropical zones, and temperate cold temperate zones, which are the key focus areas for preventing NPP degradation in the future. These findings can provide references for domestic and international colleagues to compare and analyze the carbon source (sink) function of terrestrial ecosystems in different global climatic zones.