After the first year, pruning the side branches competing with the main branches and a few lower side branches; Pruning rough competitive branches in the second and third years, and pruning a few lower side branches; Prune once every four years until a smooth young poplar forest with 6 meters of dry wood is formed. Before enclosure, if the lighting conditions in the forest are still good, less pruning or no pruning;

Try to keep the big crown to increase the photosynthetic area, but you need to remove the competitive branches, and only choose to keep one when there are competitive branches (double-headed phenomenon); If the main branch is dead and broken, one side branch should be erected instead of the main branch to extend and grow and cultivate a new central main branch.

Trim the side branches at the lower part of the trunk in time and gradually improve the branch points. 1-3 years, with a small amount of pruning. 4-5 years, pruning to the height of 1/3. After 6 years, the tree was pruned to the height of 1/2- 1/3 until it was 6 meters.

Extended data:

Poplar is the most widely distributed and adaptable tree species in the world. Mainly distributed in temperate and cold temperate forest trees in the northern hemisphere, latitude 22-70, altitude as low as 4800 meters. In China, the distribution range spans 25 ~ 53 N and 76 ~ 134 E, covering northeast, northwest, north and southwest.

Poplar natural forest covers an area of more than 20 million hectares (poplar is the dominant tree species in the world), and there are about 100 natural tree species. The countries with the widest distribution of natural poplar varieties are Russian, China, Canadian, American, Italian, French and other countries.

Poplar seeds are small, and the capsules will crack when they mature, so the seeds are collected from cutting ears or ground. Seeds are easy to lose germination ability, so they should be sown with the harvest. Sowing seedlings on sandy loam soil containing humus.