2Anderson D. 1990. Carbon fixing from an economic perspective[R]. Forestry Commission's First Economic Reaserch Conference, York University.
3Costanza R, Arge R, Groot R, et al. 1997. The value of the world's ecosystem services and natural capital[J]. Nature, 386:253- 260.
4Pearce DW. 1990. Assessing the returns of economy and to society from investments in forestry[A]. Whiteman A(ed). Forestry Expansion [ C]. Edinburgh: Forestry Commission.