## 4 Discussion  
In this study, multi-temporal images with similar acquisition time and climate situation in Linxia rangeland were selected to improve the comparability between study intervals. The results show that during the study period degraded rangeland area in the study region experienced an overall increase-to-decrease trend. Rangeland degradation is affected by various factors, including population increases and climate change [22; 23; 24], and human exploitation and policy [4; 25; 26]. In terms of climate change, for the special location of Linxia rangeland in the ecotone and transitional region, precipitation and temperature were the main natural factors influencing the rangeland degradation in the study region [6; 27]. During the study period, Linxia rangeland experienced an overall wetting and cooling trend with the average annual precipitation trending upward (10.80 mm/10a) and temperature going downward (\(-0.05\)\({}^{\circ}\)C/10a, Figure 7). Climate in the study region was changing in a direction conducive to the restoration of rangeland vegetation. However, Se-DR and M-DR areas increased 51.13% and 46.62% in the area during 1996-2001, which indicated that climate alone may not reverse the trend of rangeland degradation. Whereas on the other hand, since Gansu province implemented the \"Grain for Green\" program, the Three-North Shelterbelt Forest Program, and the region-wide grazing ban in 2000, the rangeland vegetation has continually been restored, and rangeland degradation has been effectively controlled. Together with climate change and other ecological measures, the implementation of policies was effective to support vegetation rehabilitation and degradation reversion in the Linxia rangeland. Furthermore, we noted that there was a significant decrease in area of reversed and notably reversed rangeland degradation in the third study interval (2006-2011) in comparison to that observed for 2001-2006; additionally, the area of Non-DR decreased by 54.51 km\({}^{2}\) from 2006 to 2011, which indicates that the degradation conversion pace in the study region slowed down during the 2006-2011 interval. In addition to the climate change impacts, a field analysis found that during the initial years since the rangeland degradation protection measures were implemented, due to the pressure of policy enforcement, a large area of fertile cultivated farmland was converted back to rangeland, \begin{table}
\begin{tabular}{c c c c c} \hline
**2011** & \multicolumn{4}{c}{**2006**} \\ \hline - & Sl-DR & M-DR & Se-DR & Non-DR \\ Sl-DR & 683.10 & 408.79 & 45.08 & 404.06 \\ M-DR & 225.39 & 613.92 & 99.18 & 12.86 \\ Se-DR & 9.42 & 87.65 & 144.58 & 8.03 \\ Non-DR & 343.24 & 22.31 & 3.21 & 331.38 \\ \hline \end{tabular}
\end{table} 
Table 7: Rangeland degradation changes (km\({}^{2}\)) from 2006 to 2011 in Linxia rangeland. Figure 7: Annual change in temperature and precipitation of the study region from 1996 to 2011. The black line is drawn according to the climate data from Linxia meteorological station, gray lines are the change trends of three study intervals (1996–2001, 2001–2006, 2006–2011), and the red dot lines represent the three-point running average. in order to achieve the set tasks. Meanwhile, the local herdsmen were prohibited to graze in their traditional rangelands during the grazing ban period; furthermore, they were suggested to move down to the settlements where they had to impound their livestock with a maximum of 22.7 yuan per Mu as subsidy (approximate $3.5 per 667 m\({}^{2}\)). Once the policy enforcement and supervision power weakened, the rangeland may be reconverted back to cultivation [28] or be rapidly overloaded by grazing, which may cause conflicts and violent events in the process of land use transition. These problems exist universally in the farming-grazing ecotone of China.