# The Impacts of Climate and Human Activities on Grassland Productivity Variation in China
## 3 Results
### The Effects of Human Activities on Grassland GPP  
Human activities can also contribute to grassland variation. In the past 20 years, the social and economic factors have experienced considerable changes, and the variations in six socioeconomic factors are shown in Figure 6. The large livestock in all provinces (autonomous regions) showed an increasing trend before 2005 or 2006 and a decreasing trend after 2005 or 2006, except in IMG, QH, and NX. For sheep, the same trend as that of large livestock was shown in HB, SX, TB, SAX, and QH provinces (autonomous region), and an obvious increasing trend was shown in IMG, SC, GX, and NX provinces (autonomous regions). In addition, increases in both large livestock and sheep were observed in IMG and NX provinces (autonomous regions). The population and primary industry showed a relatively consistent growth trend. In addition, the area of forbidden grazing showed a rapid increase followed by a downward fluctuating trend in recent years. Furthermore, the area of rodent and pest control fluctuated greatly.  
Figure 6: Temporal variation of the coefficient between GPP and six human activities during 2000–2018 in ten provinces (autonomous region).  
To reveal the effects of human activities on grassland vegetation, the GTRW method was used to detect the qualitative and quantitative effects of human activities on grassland GPP. The model fitted using GTWR had good performance, with R\({}^{2}\) = 0.97. The temporal variation during 2000-2018 and spatial distribution of the multi-year mean of the coefficients are shown in Figures 6 and 7, respectively. In general, the positive and negative effects of each socioeconomic factor on grassland were obviously different. Large livestock had a negative relationship with grassland GPP in most provinces (autonomous regions). Therefore, the coefficient showed an obvious weakening trend, with the number of large livestock decreasing in HB, SX, SC, and GS provinces and increasing in IMG, QH, and NX provinces (autonomous regions). The relationship of sheep with grassland GPP was mainly positive, consistent with the relationship of large livestock, and the coefficient of sheep showed a consistent weakening trend in many provinces (autonomous regions). The relationship between population and grassland GPP exhibited a positive correlation in all provinces. However, it weakened in HB, SX, and NMG and strengthened in SC, SAX, GS, QH, and NX provinces (autonomous regions). Moreover, there was an obvious fluctuation in TB and XJ, but the magnitude change at the beginning and end of the study was not significant. Furthermore, in provinces (autonomous regions) such as HB, SX, and IMG, the relationship between primary industry and grassland GPP shifted from positive to negative. In contrast, in SAX, GS, QH, NX, and XJ provinces (autonomous regions), this relationship transitioned from negative to positive. In most provinces, there was a negative correlation between forbidden grazing and grassland GPP. The negative correlation showed a weakening trend from approximately 2005 to 2015, but in recent years, this trend has rebounded. The relationship between pest and rodent control and grassland GPP was intricate, with alternating positive and negative impacts. Nevertheless, in SC and SAX provinces, this relationship notably transitioned from positive to negative.  
Figure 7: Multi-annual spatial distribution of the coefficient between GPP and six human activities (large livestock (**a**), sheep (**b**), population (**c**), primary industry (**d**), forbidden grazing (**e**) and rodent and pest control (**f**)) during 2000–2018 in ten provinces (autonomous region).