## 4 Results
### Spatial Autocorrelation Analysis of Vegetation Dynamics in the ARB  
The global Moran's I was investigated for the four period-averaged LAI, FVC, and GPP during 1982-2013 over the ARB. The global Moran's I values of LAI for the four periods were 0.898, 0.897, 0.913 and 0.917 with \(p\)-values all being less than 0.01, respectively, which indicated a significant positive spatial autocorrelation and persistent high-high or low-low aggregations of the LAI. Similarly, the global Moran's I values of FVC and GPP for the four stages were also all above 0.8, with \(p\)-values all less than 0.01, indicating positive spatial autocorrelation and persistent high-high or low-low aggregations. However, the global Moran's I values do not indicate the possible spatial changes of spatial autocorrelation of the studied indexes across the basin. Figure 3: Temporal changes in area-averaged annual LAI (**a**), FVC (**b**) and GPP (**c**), and sequential Mann–Kendall tests for the annual LAI (**d**), FVC (**e**) and GPP (**f**) with the forward-trend _UIFk_ and backward-trend _UIBk_ in the ARB during 1982–2013. \(p<0.05\) indicates significance at the 95% confident level. Figure 5 presents the clustering maps of the local Moran's I of LAI, FVC and GPP in the ARB for the four studied periods (Figure 5a-d show Periods 1-4, respectively). The local Moran's I for LAI in the four periods ranged from \(-1.83\) to \(-10.41\), \(-1.82\) to \(9.47\), \(-1.57\) to \(5.55\) and \(-0.90\) to \(5.93\), respectively. With respect to the local Moran's I of the LAI dataset for Periods 1-4, the areas of low-low agglomeration were always concentrated in the Mongolian region and the Songnen Plain and the Inner Mongolian Autonomous Region of China over four different phases. The clustering maps of the local Moran's I values further revealed that the local spatial autocorrelation of the Sanjiang Plain demonstrated the most significant change and the low-low agglomeration in the Sanjiang Plain decreased persistently. Among these changes, the most significant changes were found between Period 2 and Period 3: i.e., the autocorrelation changed the most around 2000 over the Sanjiang Plain, while the low-low agglomeration in the Sanjiang Plain disappeared after 2000. Figure 4: Spatial patterns of Sen’s slope, the Mann–Kendall \(Z\) score and the significance of changes for the annual LAI (**a–c**), FVC (**d–f**) and GPP (**g–i**) from 1982 to 2013 in the ARB. Figure 5e-h presented the clustering maps of local Moran's I of FVC in the ARB for four studied periods. The local Moran's I of FVC for the four periods ranged from \(-\)0.67 to 6.45, \(-\)0.69 to 6.67, 0.57 to 6.21 and \(-\)0.65 to 6.63, respectively. Like the LAI spatial autocorrelation, the local spatial autocorrelations of FVC for the four periods were relatively stable, especially for the high-high agglomeration in the northern part of the basin. The clustering maps for the four periods all displayed strong high-high and low-low agglomerations, whereas the spatial outliers (high-low clustering or low-high clustering) were not conspicuous. A similar decreasing trend in low-low agglomeration areas in the Sanjiang Plain was also found during the study period. Figure 5i-l presents the clustering maps of local Moran's I of GPP in the ARB for four studied periods. The local Moran's I of GPP for the four periods ranged from \(-\)1.77 to 8.24, \(-\)1.94 to 8.59, \(-\)1.70 to 6.27 and \(-\)1.90 to 6.93, respectively. For the four periods, the areas characterized with low-low agglomeration were always found in the Mongolia and the Songnen Plain and the Inner Mongolian Autonomous Region of China. Unlike that of the other two indexes, the spatial autocorrelation of GPP on the Sanjiang Plain changed very slightly, with no obvious low-low clustering in this area.