The construction of expressway results in the changes of the ecosystem service value via changing the land use types.Based on the classification and evaluation method of global land ecosystem service value first used by Costanza et al.(1997) as well as ecosystem service values of unit area of each land use type estimated by Chinese scholars

the changes in ecosystem service value of different land use types were evaluated after the construction of the Huxian-Mianxian section of Xi'an-Hanzhong expressway.During the construction

1116.4 hm2 farmland

6.8 hm2 orchard

125.2 hm2 woodland and 125.8 hm2 grassland were used.However

after the construction

areas of the woodland and grassland were increased by 155.3 hm2 and 21.4hm2

respectively

due to vegetation restoration and landscaping.The ecological service values of climate adjustment

habitats

and recreation increased due to increases in woodland and grassland areas.The construction nullified the ecosystem service value of farmland and orchard

which reduced ecological service functions of biological control

food supply

and pollination by 90%

73%

and 62%

respectively.In general

the overall ecosystem service value tended to decrease

about 1400 yuan per year per kilomemter after the construction of the expressway.However

the loss of ecosystem service value is expected to be far less than the economic and social benefits that the expressway can bring to the area.