(Baolong Huang)

Afforestation method with vegetative organs such as stems, branches and roots of trees and underground stems of bamboo as planting materials. Also known as meristem afforestation. Planting afforestation can save the time and cost of seedling raising, and the construction technology is relatively simple, but only poplar, willow and other tree species whose vegetative organs can take root and sprout can be planted afforestation.

Isolated afforestation plays an important role in afforestation in China. Chinese fir, poplar, willow and bamboo (partly or mostly) are isolated for afforestation, which has high survival rate and good growth. China has a long history of afforestation by this method. As early as 65,438+0,400 years ago, willow cuttings were recorded in the Book of Qi Yaomin written by Jia Sixie in the Northern Wei Dynasty. However, planting afforestation is often limited by site conditions and material sources, and the soil in the afforestation site should be moist and loose, otherwise the cuttings are not easy to take root and survive, and this afforestation method cannot be adopted on a large scale in places with limited number of mother trees. According to the position and propagation mode of vegetative organs used, clonal afforestation can be divided into cutting, cutting, rooting, tillering and underground stem.

Cutting afforestation

It is the most widely used method of clonal afforestation to use a branch as a cutting and insert it directly into the afforestation site. Cutting age varies with tree species. Generally, 1 ~ 2-year-old branches or seedlings are used, but 2 ~ 3-year-old branches can be used for trees with developed roots such as willow. Cuttings mostly come from excellent mother trees in the middle and prime years, especially the branches sprouting from the roots. For example, Chinese fir should adopt roots or root sprouting strips with a diameter of about 1 cm and a length of 40 ~ 50cm；; Excellent cuttings are those with thick and straight branches, dark green or brown leaves, hard, sharp and shiny tips, complete terminal buds, long internodes and white pulp in incisions. The cutting specifications of poplar and willow broadleaf trees generally require DBH of 65438 0.5 cm and length of 30 ~ 70 cm. The suitable time for picking strips is after defoliation in autumn and before germination in spring. Cutting is usually done while picking. Soaking willow cuttings before afforestation can increase water content, enhance drought resistance and improve afforestation survival rate. In northern China, poplar and willow afforestation sites should choose floodplain, wet sandy land, river bank beside canal and so on with high groundwater level and deep soil layer. In the south, Chinese fir cuttings are mostly planted below the mountainside, preferably on shady slopes, foothills or valleys. Before afforestation, comprehensive soil preparation should be carried out to loosen the soil, facilitate cutting and improve the survival rate. Cutting afforestation season, generally in spring and autumn. The cutting depth of evergreen tree species can reach1/2 ~1/3 of the cutting length; Deciduous trees can leave the ground 5 ~ 10 cm in areas with good soil moisture, but they should be completely inserted into the soil in arid areas. In addition, in saline-alkali soil, cuttings should be exposed properly to prevent the incision from being soaked in saline-alkali water. When cutting in autumn, bury the cut on the cutting with soil in time to prevent water evaporation.

Dry planting

Also known as stem cutting afforestation. Use thick branches of trees, trunks and seedlings of young trees to plant directly on afforestation land. Suitable tree species are mainly poplar, willow, banyan and other tree species that are easy to take root. Cuttings are mostly 2-4 year-old branches, with a diameter of 3-5 cm and a length of 2-3 m, and inserted into the soil for 40-80 cm. Dry planting is mainly used in riparian wetlands and surrounding open spaces. The afforestation season is usually before the sap begins to flow in early spring, so it is advisable to plant trees as soon as possible. To plant trees on all sides, it is necessary to dig big pits and loosen the soil. In order to prevent excessive water loss, asphalt can be applied to the top incision after planting. Afforestation in wind erosion and desertification land should be buried deep. This method can form a forest in a short time, with quick effect and labor-saving in raising young trees.

Root-divided afforestation

Some tree species with strong germination and rooting ability, such as Paulownia, Robinia pseudoacacia, Catalpa bungeana, Ailanthus altissima, etc., are widely used, while Rhus verniciflua is mostly propagated by dividing roots. This method is suitable for tree species with difficult propagation of seeds or cuttings. Root-cutting ears can be dug from healthy mother trees after defoliation in autumn to the following spring, or cut off when seedlings are raised in nursery. Generally, root segments with a diameter of 1 ~ 3cm and a length of 15 ~ 20cm are cut. When cutting, the thick end is upward and cannot be inverted. Afforestation is mostly in spring, with local soil preparation, inclined roots buried, slightly exposed upper ground and lightly covered with soil. After the new branches grow, leave a strong branch to strengthen the tending and protection work of that year. The advantages of root-splitting afforestation are strong root germination, high survival rate of afforestation and vigorous growth of young trees; However, collecting cuttings is more difficult than cutting afforestation, and it is not suitable for large-scale afforestation.

Tillering afforestation

Generally, tree species with strong tillering ability, such as Populus tomentosa, Populus davidiana, Robinia pseudoacacia, jujube, etc., are dug out from the root system of the mother tree and used for afforestation. Split horseshoe afforestation of Chinese fir in southern China is also tillering afforestation, but it cannot be widely used because of the limitation of material source.

Tuber planting

Main afforestation methods of bamboo. The underground stems of scattered bamboo, also called "bamboo whip", are scattered in the soil, and bamboo shoots are extracted from the bamboo whip every year. Tufted bamboos germinate from the base of culms and draw bamboo shoots into bamboo. (See Bamboo Afforestation)