An assessment on the benefits of yield Increase and water conservancy resulting from development of farmland forest shelter belts

Based on arnalysis of the published information about the results of field protective forest，it is concluded that yield of grain crops was increased by 14．9% and cotton by 4．6%，evapotranspiration WaS decreased by 16．0% by the forest shelter belts n Hebe Province.According to statistic data and calculations，it is estimated that the effectively protected cultivated land in Hebei Province by the forest shelter belts takes up about 34．7％ of the total farmland．Further calculation shows that，in Hebei Provincet annua1 water saved by forest shelter belts in farmland is worthy 0．286 to 0．327 billion Yuan in terms of agricuhural investment for irrigation；the economic benefits from yield increase is about 1．109 billion Yuan annually；then the total ecoeconomic benefita are about 1．395 to 1．436 billion Yuan.