The forest ecosystem has a variety of natural and social service functions. It plays an important role in ecological security, biological species protection, conservation of the living environment, and realizing the sustainable development of economy and society. Based on the "Forest Ecosystem Services Assessment Standards (LY/T1721-2008)" issued by the State Forestry Administration, this paper evaluates five key functions of forest ecosystems-water conservation, soil conservation, carbon fixation and oxygen release, nutrient accumulation, and atmospheric environment purification. Focusing on the Changbai Mountain forest region in Northeast China, this study provides some quantitative evidence that the implemenationt of the Natural Forest Protection Program (NFPP) initiated in 1998 has had positive effects on the values and material quantities of ecosystem service functions. The results show that both material and value quantities of these functions tended to increase in the 12 years following the initiation of the program, the first phase of which was completed in 2010. With respect to water resource conservation, the amount of increment regulating water flow has been 657.28×10⁴ m³, reflecting a cumulative increase in value of 11.345 billion RMB. Regarding soil conservation, the amount of increment of soil fixation was 4.6×10⁴ t, while the amount of reduction in nitrogen loss, phosphorus loss and potassium loss has been 0.02×10⁴ t, 0.01×10⁴ t, and 0.01×10⁴ t, respectively. The cumulative increase in value of soil conservation is 0.29 billion RMB. With respect to the carbon fixation and oxygen release function, the increments of carbon fixation and oxygen release have been 0.64×10⁴ t and 0.36×10⁴ t, respectively, with a the cumulative increase in value of 11 million RMB. Regarding nutrient accumulation, the nitrogen content, solid phosphorus content, and solid potassium content each increased by 0.01×10⁴ t, with a cumulative increase in value of 30 million RMB. Finally, in regard to the atmospheric environment purification function, the absorption of sulfur dioxide, nitrogen oxides, fluorides and dust have increased by 24.71×10⁴ kg, 0.64×10⁴ kg, 1.08×10⁴ kg and 1962.76×10⁴ kg, respectively, with a cumulative increase in value of 0.51 billion RMB. On an overall basis, from 1998-2010, the gross value of all of the aforementioned forest ecosystem service functions increased by 12.19 billion RMB, which is equivalent to an average annual rise of approximately 1 billion RMB. This exceeded the total annual investments. The aggregate values of the ecosystem services over this period were ranked in the following order: 1) water conservation; 2) carbon fixation and oxygen release function; 3) soil conservation function; 4) atmospheric environment purification; 5) nutrient accumulation. While not all of the values created via implementation of the NFPP were captured by the local forest region, other value increments were experienced by the entire country and even on a global scale as well. From a national perspective, it will be important to draft and launch a series of policies and measures for ecological compensation in a timely manner, which will not only insure social justice but also enhance the potential that the ongoing implementation of the NFPP will further strengthen both resource protection and the sustainable development of China's natural forests.