Under the natural growth conditions, the rich and precious trees have thick branches and vigorous growth, often forming a broad oval crown, but most of them have low trunks and too many branches, forming "small old trees". Plastic surgery means straightening its trunk and pruning it in spring. In summer, pruning the side branches that compete with the trunk usually leaves no side branches below two meters. Large seedlings of rich trees used for landscaping are generally strong. First of all, we can choose 1 robust annual branch at the top as the trunk extension branch, then cut off one-third to one-half of its top, and then cut off the weak branches again (but not too heavy, otherwise the robust branches will not grow easily after cutting). If there are small weak branches near the incision, some branches should be cut off, and the upper branches should be cut short one by one, and the upper ends of side branches should not be higher than the main incision.

The time and quantity of pruning should be determined according to the purpose of afforestation. General afforestation should be pruned after the young forest is closed; In order to cultivate tall trunks and prevent excessive shading, the surrounding green spaces and shelterbelts should be trimmed properly in the first three years.

(1) Dewatering: If the trunk of a rich tree under 2 years old is low, vigorous and straight branches are generally selected as the main trunk, and the rest branches are drained according to different conditions. After the trunk is trimmed to a certain height, the strong competitive branches, overgrown branches, upright branches and some over-dense side branches, drooping branches and dead branches in the upper part of the crown are thinned out.

(2) Pruning: Pruning the upright and robust side branches in summer. According to the principle of keeping the pressure weak, straight and flat, the upper part of the crown should be cut again, and the lower part should be cut lightly for a long time. Branches should be cut off in several times, and small branches should not be cut off from the base to avoid wind folding or weak growth of the main tip. In winter or spring, for young trees with heading and stubble leveling, when the strong branches sprouted from the cutting mouth are about 30 cm long, keep the upright strong branches for whole branch culture, and cut off the remaining one third, which can be carried out for 2 ~ 3 times continuously. For the thick branches under the crown, it should be pruned year by year, and it is best to leave 1 to 2 thin branches.

Pruning should be carried out in summer, preferably from early June to early July. This has the advantage that the wound heals quickly and generally does not sprout a large number of branches, which is beneficial to the growth of young trees. Pruning should not be too heavy, and it should be close to the trunk without leaving piles to avoid forming knots. The tools used should be sharp and the wound should be smooth, so that the branches will not crack.

After pruning, the long branches on the trunk or main side branches should be removed or cut off; For sparse branches at the base of trunk and the top of trunk heading in winter, sprouted new buds and buds should be cut off as soon as possible.