## 3 Result
### Spatiotemporal Changes in FPAR
#### 3.2.2 Temporal Trends  
The FPAR showed a significant increasing trend with a slope of 0.10% (\(R^{2}=0.7\), \(p<0.01\)) over Chinese terrestrial ecosystems from 1980 to 2018 (Figure 2). The FPAR was 0.37 during the period from 1980 to 2018, but a turning point emerged around 2010. The regional mean FPAR increased from 0.36 in the first period (1980 to 2010) to 0.39 in the second period (2010 to 2018) and showed an increase of 7 times in the second period with a rate of 0.42% a\({}^{-1}\) (\(R^{2}=0.95\), \(p<0.01\)) compared to the rate of 0.06% a\({}^{-1}\) (\(R^{2}=0.47\), \(p<0.01\)) in the first period (Figure 2, Table S5). A high increase mainly occurred in southeast and central China while the slowest increase was in the Tibetan Plateau (Figure 3). FPAR increased rapidly in South China (0.21% a\({}^{-1}\)), Central China (0.20% a\({}^{-1}\)), North China (0.19% a\({}^{-1}\)), and Southeast China (0.16% a\({}^{-1}\)). The growing rates of FPAR were lower in the Tibetan Plateau (0.02% a\({}^{-1}\)), Inner Mongolia (0.03% a\({}^{-1}\)), and Northeast China (0.03% a\({}^{-1}\)). In Northwest China and Southwest China, the growth rates are 0.07% a\({}^{-1}\) and 0.13% a\({}^{-1}\) (Table S5). The increasing trend of FPAR was significant in the area for 66.9% of the study area with a confidence level above 95% (\(p<0.05\)), and 57% of the area had a confidence level above 99% (\(p<0.01\)). An increasing rate of change was observed mainly in croplands (0.15% a\({}^{-1}\)) and EBF (0.14% a\({}^{-1}\)). The trends for FPAR varied across the four decades over the terrestrial ecosystems in China from 1980 to 2018 (Figure 3). The FPAR showed a rapid and significant increasing trend (\(p<0.01\)) with a rate of 0.20% a\({}^{-1}\) over the extended area of 84.5% of the terrestrial ecosystem in China for the decade beginning in 1980. In the 1990s, however, FPAR showed an insignificant decline trend (\(p=0.81\)), with a slope of \(-0.014\)% a\({}^{-1}\) over all of China, and the total area with an increasing trend accounted for only 49.5% of all vegetated lands. However, a significant upward trend was found again with a slope of 0.12% a\({}^{-1}\) (\(p<0.05\)) over 62.1% of the area in the 2000s and further sped up to the rate of 0.42% a\({}^{-1}\) with wider spatial scope (83.7%) through the 2010s (Figure S5). Figure 2: The inter-annual variability and the linear trend of the ANN-based FPAR (FPAR\({}_{\rm ANN}\)) developed in this study over the terrestrial ecosystems in China and its nine regions for the whole period from 1980 to 2018 and for each decade. (**a**) South China (SC), (**b**) Southeast China (SE), (**c**) Central China (CC), (**d**) Southwest China (SW), (**e**) Northeast China (NE), (**f**) North China (NC), (**g**) Inner Mongolia (IM), (**h**) Tibetan Plateau (TP), (**i**) Northwest China (NW), and (**j**) the whole China. As shown in Figure 4, the stability of FPAR in SC and SW showed a similar trend, i.e., higher in the first two decades and lower in the second two decades. In CC, NW and the whole of China, the stability in the 1990s and 2000s were higher while in the 1980s and 2010s was lower. In SE and NC, there was little difference in stability in each period. The stability of FPAR in NE in the 1990s was higher than in other decades, and it was lower in the last two decades than in the first two decades. In IM, the stability was higher in the first three decades than in the last. In TP, the stability of FPAR gradually improved, and stability in the 2010s was significantly higher than that in the other three periods (Figure 4). We further counted the proportion of areas with high stability in each period, which were 75.89%, 78.05%, 77.72% and 83.33%, respectively, showing that the area with higher variation degree increased after 1990. Figure 4: The temporal stability of the FPAR of the terrestrial ecosystems in China and its nine regions in each decade from 1980 to 2018.