Spatial and temporal variations in ecosystems in the three northern regions of China, 2000-2010

This study analyzed the ecosystem macrostructure,quality,and key services and their driving forces in the three northern regions( northeastern,northwestern,and northern) of China,in the first 10 years of the 21 stCentury. The results showed that( 1) during 2000-2010,forestland area increased by 10,300 km2; grassland decreased by 900 km2; wetland area decreased by 33. 9 km2; farmland increased by 1900 km2; artificial coverage increased by 12400 km2; and other ecosystems decreased by 23700 km2 in the three northern regions.( 2) The normalized difference vegetation index( NDVI),leaf area index( LAI),and aboveground vegetation productivity in these regions increased slightly over the past10 years,especially in the Loess Hilly Region. However,the vegetation coverage decreased slightly.( 3) The soil erosion modulus per unit area decreased by 27. 25% in the three northern regions,with an annual reducing rate of 1. 13 t / hm2.The amount of sand-fixing services was low because the force of wind erosion decreased annually,suggesting that a reduced force in wind erosion decreases the amount of soil erosion. In soil water erosion zones of the three northern regions,the soil water erosion modulus showed a slight increasing trend in the past 10 years,whereas the modulus in the Loess Plateau and sand areas showed decreasing trends. The amount of ecosystem soil conservation service per unit area showed an increasingtrend,with an annual increasing rate of 0. 28 t / hm2,indicating improved soil conservation capacity.( 4) The temperature increased by 0. 02[degrees]C / a,and precipitation increased by 3. 00 mm / a in the past 10 years in the three northern regions,and the moderate warming and increased precipitation were useful for vegetation recovery. The human disturbance index showed decreasing trends in Loess Plateau and in the agricultural areas of Northeast and North Plain,indicating that the effect of human disturbances on natural ecosystems has been suppressed in these two regions.