Due to the lengthy historic land use by humans and the climate change characterized by warming and drying, the Loess Plateau has been plagued by ecosystem degradation for a long time. A series of ecological conservation projects launched since the 1970s altered the land use pattern greatly, and exerted a profound influence on the ecosystem services. Based on the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) and Carnegie-Ames-Stanford Approach (CASA) models, we assessed the historical fluctuation of sediment control, water yield, and net primary production (NPP) in the Loess Plateau. The results showed that sediment retention was greatly consolidated indicated by the sharp decrease of sediment export. Water yield decreased at first and increased later. Both sediment export and water yield showed an increasing ‘spatial homogenization’ tendency during the period. NPP was steady between 1990 and 2000, and then increased greatly after 2000. Ecosystem services are interlinked closely and complexly. Correlation analyses indicated a positive relationship between the difference in sediment export and water yield (r2=0.776**) from 1975 to 2008, with negative correlations between the difference of NPP and water yield (r2=-0.422**)/sediment export (r2=-0.240*) from 1990 to 2008. This, to some extent, implies that there are tradeoffs between the services of water yield and sediment control/NPP, and there is synergy between sediment control and NPP. Climatic and land use changes are the major drivers on ecosystem services fluctuation. Correlation analyses showed that the decrease of precipitation significantly hindered water yield (r2=0.980**) and sediment export (r2=0.791**). The increase of temperature exerted a slight negative influence on water yield (r2=-0.350**). A spatial concordance existing between the ‘cropland to grass/woodland’ area and the high sediment control (r2=0.313**)/NPP (r2=0.488**) area indicated that the land use change from cropland to woodland/grassland significantly consolidated sediment control and NPP production. The observed spatio-temporal variation of ecosystem services and their correlations provide an operable criterion for land use management policies.
1978 saw the start of the Three-North Shelter Forest Program (TNSFP), the then largest ecological reforestation program in the world accounting for 42.4% of Chinese territory. In 1995, various comprehensive ecological re- habilitation projects were carried out on small watersheds in the Loess Plateau. In 1999, the Chinese government launched the GfG project with the Loess Plateau as the pilot area. specifically here testing land that has been converted from cropland to grasslands and woodlands
|Climate change impacts||Effect of Nbs on CCI||Effect measures|
|Reduced water availability||Unclear results||water yield (ton/ha) calculated using InVEST The input data includes average annual precipitation, annual poten- tial evapotranspiration (ET0), soil depth, plant available water content (PAWC), Land Use and Land Cover (LULC), root depth, elevation, etc.|
|Soil erosion||Positive||Sediment control determined using InVEST --> sediment export (ton/ha)|
|Biomass cover loss||Positive||NPP (ton/ha) forest and grassland area increase (detected through remote sensing) over time|
Entire Loess Plateau - The Loess Plateau (33°43′7′′N–41°16′7′′, 100°54′ 7′′–114°33′ 7′′E) is located in the upper and middle reaches of the Yellow River in northern China