In the area of coastal sand soil

It has a obvious benefits of using forest to prevent and control the soil and water loss on embankment surface of river

gully

and irrigation canal.The average annual thickness of soil loss may be reduced by 13.5～16.6mm.In the respect of ecoenvironment

the wind velocity may be weakened by 74.2%～83.5%

the evaporation decreased by 30.3%～33.1%

the organic substance of slope soil increased by 0.4～2.8g/kg

and the salt content decreased by 30.4%～40.8%.The ratio between benefit and cost

namely

the economical benefit(E)is 5.5

that is to say that E1