A study on distribution law of microclimate factors in poplar-crop intercropping system

The study on poplar-crop intercropping systems shows that the farm microclimate factors have a great variance because of poplar planted in farmland,of which the solar radiation density,wind speed and air relative humidity are the most and the formers two decrease and the latter increases evidently as well.Thesolar radiation at different points among rows(the points under tree crown,out of tree crown and in the middle of rows)varies with intercropping year and tree spacing.The sunshade of young trees with smaller spacing is 31.5%～45.6%,with an average of 31.5%;but that of mature stands with bigger spacing is 7.4%～54.3%,with an average of 18.1%. The other factors,however,have smaller variance among rows and have little relation with intercropping spacing(10～56m)and years(4～14year).