西藏河谷地区几种主要引种杨树苗木生长研究

杨树是西藏河谷地区的主要造林树种．其中北京杨为传统的主栽品种．１９９４年引进毛白杨、中林诸杨和优胜杨进行扦插育苗试验，结果表明，其成活率可达到７０％左右，毛白杨的成活率可达到８７％，与北京杨差异不大．在栽培措施相同的条件下，毛白杨的地径生长量、高生长量、光合速率、总叶面积和最大光合速率，分别比北京杨高１４．２％，２２．３％，２４．６％，４６．１％和６２％．说明在该区引种毛白杨具有发展潜力．

Study of the Growth of Several Main Introduced Poplar Cuttings in the River Valley Region of Tibet

Some species of Populus are the main afforested species in the River Valley Region of Tibet and one of them, Populus nigra var. italiea, is a traditional cultivated species. In 1994,an introduction experiment was made with the cuttings of Populus tomentosa,the poplar cultivated by CAF and the Yousheng Poplar. The results are as follows.The survival rate of the introduced poplar reaches about 70%,that of P. tomentosa reaches 87%. The survival difference between P. tomentosa and P. nigra var. italica is not obvious. But with the same cultivating measures,P. tomentosa is superior to P. nigra var. italiac in increment of diameter at foot, height accretion, photosynthesis rate, total leafarea,and maximum photosynthesis rate. their increment percentages are respectively: 14. 2%, 22.3%, 24. 6%, 46. 1 %and 62. 0%. It is proved that introducing P. tomentosa into this regionhas a developable potential.