The Three-Rivers Headwater Region (TRHR) is the headwater of the Yangtze River Basin (YARB), Yellow River Basin (YRB), and Lancang River Basin (LRB); it is known as China’s ‘Water Tower’ owing to its important supply of freshwater. In order to assess ecosystem changes in the TRHR during 2000–2012, we systematically and comprehensively evaluated a combination of model simulation results and actual observational data. The results showed the following: (1) Ecosystem pattern was relatively stable during 2000–2010, with a slight decrease in farmland and desert areas, and a slight increase in grassland and wetland/water-body areas. (2) A warmer and wetter climate, and ecological engineering, caused the vegetation cover and productivity to significantly improve. (3) Precipitation was the main controlling factor for streamflow. A significant increase in precipitation during 2000–2012 resulted in an obvious increase in annual and seasonal streamflow. Glacier melting also contributed to the streamflow increase. (4) The total amount of soil conservation increased slightly from 2000 to 2012. The increase in precipitation caused rainfall erosivity to increase, which enhanced the intensity of soil erosion. The decrease in wind speed decreased wind erosion and the frequency of sandstorms. (5) The overall habitat quality in the TRHR was stable between 2000 and 2010, and the spatial pattern exhibited obvious heterogeneity. In some counties that included nature reserves, habitat quality was slightly higher in 2010 than in 2000, which reflected the effectiveness of the ecological restoration. Overall, the aforementioned ecosystem changes are the combined results of ecological restoration and climate change, and they are likely a local and temporary improvement, rather than a comprehensive and fundamental change. Therefore, more investments and efforts are needed to preserve natural ecosystems.
in 2005, the state council promulgated and implemented the ‘Overall Planning of Eco-environment Protection and Construction in the TRHR’ project, commonly referred to as the ‘TRHR Project’….included 18 nature reserves, with a total area of 15.2 × 104 km2...The total project investment amounted to 1.2 billion USD, including expenses for returning pasture and farmland to forest, afforestation, and comprehensive treatment of soil degradation in black soil beach areas...The project named ‘Returning Pas- ture and Farmland to Forest’ accounted for the largest proportion of the expenditures from supplementary material, also show nature reserves protecting coniferous forests, grasslands, wetlands, and mountains
|Climate change impacts||Effect of Nbs on CCI||Effect measures|
|Biomass cover loss||Positive||Fractional Vegetation Cover (FVC) - obtained from remote sensing images, is a comprehensive quantitative indicator that describes the vegetation canopy density.|
|Freshwater flooding||Unclear results||water conservation: seasonal streamflow (spring and summer) reflected the ecosystem’s capacity to regulate streamflow in flood seasons.|
|Reduced water availability||Unclear results||Water conservation: annual streamflow reflected the water re- source level and water supply capacity of the ecosystem|
|Soil erosion||Mixed results||The amount of soil conservation was estimated by determining wind erosion and water erosion. We used the RUSLE and the RWEQ for estimations calculated soil conservation by using soil retention and sand fixation estimates, both in units of (t ha−1 year−1)|
The Three-Rivers Headwater Region (TRHR) is a nature reserve located in the hinterland of the Qinghai- Tibet Plateau … The TRHR includes 22 counties and cities, and it has a total area of 39.5 × 104 km2.