## 5 Discussion and Conclusions  
### Discussion  
The forces driving LULC change can generally be summed up as the natural factors and human activities [36]. [PERSON] _et al._[37] found that, on a ten-year time scale, climate change is the determining factor for vegetation growth, and that human activities can accelerate the process of change. Therefore, we analyzed the driving forces primarily in terms of climate change, the ecological projects, and livestock rearing. Climate change was analyzed based on the monitoring data from 1975 to 2012 obtained from the Tuotuo River meteorological station in the headwaters of the Yangtze River, and from the Maduo, Dari and Zhongxin meteorological stations in the headwaters of the Yellow River. As shown in Figures 6 and 7 the climate in the headwaters of the Yellow River was warmer and wetter than in the headwaters of the Yangtze River. In the headwaters of the Yangtze River, temperature and precipitation showed an upward trend from the late 1970s to 2012, with the change rates being \(0.52\,^{\circ}\)C/10a and \(26.88\) mm/10a, respectively. From the late 1970s to the early 1990s, temperature and precipitation showed a non-significant decrease; from the early 1990s to 2012, temperature and precipitation showed a significant upward trend, with the change rates being \(0.89\,^{\circ}\)C/10a and \(76.05\) mm/10a, respectively; compared to before and after the early 1990s, the average temperature and precipitation increased by \(0.99\,^{\circ}\)C and \(43.22\) mm, respectively. In the headwaters of the Yellow River, temperature showed a significant upward trend from the late 1970s to 2012, with the change rate being \(0.69\,^{\circ}\)C/10a, while the precipitation levels remained relatively stable; from the late 1970s to 2004, while temperature  
Figure 5: The LULC change index in the headwaters of the Yangtze River and Yellow River. showed a significant upward trend, with the change rate being 0.59 \({}^{\circ}\)C /10a, precipitation showed a non-significant downward trend; from 2004 to 2012, both temperature and precipitation showed a non-significant upward trend; compared to before and after the early 1990s, the average temperature and precipitation increased by 1.456 \({}^{\circ}\)C and 443.17 mm, respectively. Warm and wet climatic conditions were considered to have promoted vegetation growth and an increased forage yield in the headwaters of both the Yangtze River and the Yellow River (2012). Since the implementation of the Livestock-Reduction project in 2003, the number of livestock in the headwaters of the Yellow River (The number of livestock for each county in the region was obtained from statistical data provided by the Qinghai government, and the number of livestock in the headwaters of the Yellow River was represented by statistics data of Banma, Chengduo, Dari, Gande, Maduo, Maqin and Qumalai counties.) has significantly reduced, with a reduction of 30.57% compared  
Figure 6: The annual average temperatures in the headwaters of the Yangtze River and Yellow River from 1975 to 2012. Figure 7: The annual precipitation in the headwaters of the Yangtze River and Yellow River from 1975 to 2012.  
to the period before the project (1988-2002) (Figure 8), and the grazing pressure [20] decreased from 3.59 to 1.09. In the county of Tanggulashan, where the headwaters of the Yangtze River are mainly located, the livestock was reduced in total by \(4.81\times 10^{4}\) sheep units [39]. The decrease in the grazing pressure would be helpful in the recovery of the grassland. The implementation of various ecological projects has been playing a key role in LULC change.