一、前言美杨(Populus pyramidalias Rozier)原产阿富汗、伊朗、中亚细亚等地。我国引种将近百年的历史。现于黄河流域、江淮平原及东北各省均广泛栽培,为城市绿化、河川道路与防护林带的主要树种之一。但目前各地栽培的美杨,尤其是较大面积的林木,发现生长衰退现象,为探讨其原因,提高林木生产力,我们曾在美杨栽培较多的河 First, the foreword Young (Populus pyramidalias Rozier) native to Afghanistan, Iran, Central Asia and other places. China’s introduction of nearly a hundred years of history. Now in the Yellow River Basin, the JAC Plain and the northeastern provinces are widely cultivated, for urban greening, road and shelterbelt one of the major tree species. However, the current cultivation of the United States Yang, especially large areas of trees, found that the phenomenon of recession, in order to explore the reasons for improving forest productivity, we have been cultivated in the United States more River