If you are looking for a quick screening tree the Populus genus may be right for you. It is a soft wooded tree and it will grow up to 3 - 5 feet a year depending upon placement and growing zone. Sound like the perfect answer for you? It just might be but you will need to be aware of the a couple of deficiencies.
The poplar tree is weak limbed which can result in many small twigs and branches on the ground. The trees life span is around 15 years, that is if the tree has been well watered throughout it's life span. The poplar will tolerate partial shade but does best in full sun.
So, with these deficiencies, why plant a poplar tree? We find that the poplar is used for a couple of great applications. A row of poplars can be planted for that almost instant screen. A row of conifers that are much slower growing are planted as the permanent screen. If you maintain your poplar trees, in 12 - 15 years your conifer screen is ready to replace the poplar screen. A saw and wood chipper cleans out a screen of poplars in a quick fashion. The poplar tree is also planted in a backyard to be a workhorse shade tree until your plantings of hardwood trees can take over and the poplar can be cut down.
Also a good windbreak tree if you have a garden in a wide open area.