1. Introduction of main fine varieties
Metasequoia (Metasequoia? Water pine? Hu? et？ Cheng) is a big deciduous tree of Metasequoia. The maximum height is 40 meters, DBH is 2.5 meters, and the base of the trunk is often enlarged; The young crown is narrow cone-shaped and becomes wide oval with age; The bark of young trees is reddish brown, and the bark of old trees is dark gray or grayish brown, with shallow longitudinal cracks and strip peeling; The big branches extend obliquely upwards. The winter buds are oval or oval. The leaves are opposite, linear, flat and soft, 8-17mm long and1-2mm wide, light green, with concave midvein and convex midvein, with 4-8 stomatal lines on each side. Leaves grow on deciduous branchlets and fall with deciduous leaves in winter. Monoecious, male cones are solitary leaf axils, arranged in a general or conical shape, with a total length of 21-24 (31) cm; The female cones are scattered on the branches singly or in pairs, and the pearl scales are opposite, with 5-8 (2-9) ovules in the middle. The cone stalk is long, pendulous, nearly round or rectangular, slightly quadrangular, with a length of 1.6 cm and a width of 1.5 cm. Seed scales are woody, lintel-shaped, with wide grooves at the top and wedge-shaped at the base. The seeds are obovate, flat, surrounded by narrow wings, with concave top, about 6 mm long and 5 mm wide. Unearthed cotyledons, 2, rare 3.
Metasequoia glyptostroboides is an ancient rare tree species, which used to be considered "extinct" in the world, but this kind of relict plant has been preserved in China. It was not until the forties that it was discovered and identified by China scientists in lichuan county, Hubei Province. Since liberation, this ancient tree species has been widely cultivated all over the country.
The oldest Metasequoia fossils were found in the early Cretaceous strata of Mesozoic, and distributed in the Arctic Circle at 80-82 degrees north latitude in the late Cretaceous. In Tertiary, Metasequoia plants were distributed in vast areas north of 35 degrees north latitude, such as Europe, Siberia, northeast China, Korea, Japan and North America. During this period, Metasequoia plants grew luxuriantly and had a wide variety, with as many known fossil species as 10. The discovery of Metasequoia glyptostroboides is known as a "living fossil" in the scientific community.
The primary Metasequoia glyptostroboides is preserved in the adjacent areas of lichuan county, Hubei Province, Shizhu County, Sichuan Province and Longshan County, Hunan Province, but it is concentrated around the small river in western lichuan county. There are as many as 5000 Metasequoia glyptostroboides with DBH above 20 cm in this area.
Metasequoia glyptostroboides has been introduced in various parts of China since the early 1950s, and its cultivation area has been continuously expanded. At present, Metasequoia glyptostroboides is cultivated in Beijing, Yan 'an and southern Liaoning in the north, Guangdong, Guangxi and Yunnan-Guizhou Plateau in the south, East China Sea, Yellow Sea and Taiwan Province Province in the east, and Sichuan Basin in the west. Especially in Jiangsu, Zhejiang, Shanghai, Hubei, Anhui, Jiangxi and other places in the Yangtze River basin, the scale of seedling raising and afforestation has been expanding year by year. Metasequoia glyptostroboides was introduced into Dongting Lake area of our province in the early 1960s, and then it was used as the backbone tree species of farmland shelterbelts to build large-scale farmland shelterbelts. However, at present, the farmland shelterbelt in Dongting Lake area has been basically replaced by Populus euramericana, and only a few areas can still see the Metasequoia forest belt.
Metasequoia glyptostroboides has been introduced to more than 50 countries and regions in Asia, Africa, Europe, America and other continents, and all grow well, so it can overwinter outdoors in high latitudes such as Leningrad, Copenhagen and Alaska. It is rare for a tree species to be introduced in such a wide area with such strong adaptability.
Choose land
3. Soil preparation
Generally, according to the row spacing of planting plants, large holes are used for soil preparation, with a hole diameter of 50-60 cm and a depth of 50 cm. Properly apply decomposed organic fertilizer as base fertilizer when returning to the field. When intercropping forest and grain, comprehensive soil preparation can be adopted, the depth is 20-25 cm, and then a big pit can be dug according to the row spacing of trees.
plant
Afforestation density: Metasequoia glyptostroboides grows rapidly, likes light, has strong top advantage, straight trunk, and the lateral branches are not excessively elongated, so the afforestation density should not be too large. In the past, the stand with planting distance less than 2 meters became too dense in 3-5 years, the plants squeezed each other, the growth was inhibited, a large number of side branches of the standing tree died, and the growth was in a stagnant state. Patch afforestation can adopt 2× 3m row spacing, with 65,438+065,438+00 plants per mu, thinning once in 65,438+00 years and 65,438+05 years, and adjusting the row spacing to 3× 4m and 4× 6m respectively. When planting in single row or strip, the planting spacing of 2 meters can be used because of the good side lighting conditions. The survival rate is very high. Because the roots of Metasequoia glyptostroboides germinate earlier, the planting time is 30-40 days before the overground part germinates. The planting time of large seedlings can be earlier than that of small seedlings, but it is not suitable for planting in the cold season when the soil is frozen.
When planting, pay attention to the stretching of the root system, fill it in layers and then pat it tightly. It is best to use suitable soil for transplanting big seedlings, and keep the lateral roots as much as possible.
Step 5: plastic trimming
Generally speaking, the viability of dormant buds of Metasequoia glyptostroboides can only be maintained for 2-3 years, and plants over 3-4 years old are often difficult to germinate again after pruning, which affects the formation of crown and adversely affects growth. Therefore, pruning is generally not needed before forest formation, and it should be moderate after forest formation, so as not to affect diameter growth and delay maturity. When the average tree height is 6- 10 m, the pruning height is one quarter to one third of the tree height; When the tree height is10-15m, the pruning height is one third to one half of the tree height.
fertilize the soil or land
Two years later, it is very necessary to apply fertilizer once before spring germination and twice before vigorous growth, which is also quite effective in promoting growth. The soil fertility of Metasequoia glyptostroboides afforestation land is generally low, especially the newly opened riverbanks are all raw soil. Planting two crops of green manure and leguminous crops every year is an important way to improve soil. As a farmland forest belt in our province, Dongting Lake area usually does not need fertilization because of its deep soil layer and high soil fertility, and its forest belt grows well.
7. Tending management
After afforestation, Metasequoia glyptostroboides should be strengthened in time to ensure survival and rapid recovery of growth, so as to strive for higher growth in previous years and lay a good foundation for rapid growth and high yield in the future. In addition to adequate watering during afforestation, watering again in April-May is the key to ensure survival. Special attention should be paid to drought resistance in high temperature season when planting large seedlings. Weed and loosen the soil two or three times a year, so that the newly-built young forest is often in a state of loosening the soil without grass, and the effect is most obvious in the early tending of Metasequoia glyptostroboides in May-June and August-September. In the afforestation of Metasequoia glyptostroboides in Taicang seawall, Jiangsu Province, the intercropping between forest and farmers has achieved fine tending, and at the same time, it has played a good short-term growth and auxiliary promotion role for the forest.
8. Pest control
The main disease is stem rot, which usually has a high incidence in seedling stage and young tree stage. Generally, broad-spectrum antibacterial agents can be sprayed. Pests are mainly marsupials. Usually, when the dry season (July-August) comes, the leaves can be eaten up in a few days, which seriously affects the growth of trees. The control method can be to manually remove larvae (bags), collect them and burn them; Or spraying 800- 1000 times of broad-spectrum pesticides on the current market.
9. Harvest, processing or logging
Rapid growth is one of the most prominent advantages of Metasequoia glyptostroboides. In the country of origin, the average annual growth of tree height is 30-80 cm, which was generally maintained at about 60-80 cm 50 years ago; The average annual growth of DBH is 1- 1.75cm, which increases rapidly after 20 years, and generally remains at around 1.3- 1.6cm, and tends to slow down after 80- 100 years. According to the data of stem analysis, the annual growth peak of tree height (1.43m) appeared in10/5 years in the country of origin, and the annual growth peak of DBH (2. 1cm) appeared in 20-25 years in the introduction place, while the maximum values of tree height and diameter appeared earlier. Guanghua Temple Farm in Qianjiang County, Hubei Province, when the tree age is 16, the average tree height is1/0.5m, the average DBH 14.5cm and the maximum DBH 18cm. Metasequoia glyptostroboides grows faster in a single row or single plant, such as Chuxian County, Anhui Province. At the age of 25, the tree was 23 meters high and DBH 53 cm. The above growth shows that Metasequoia glyptostroboides can reach maturity in about 15-20 years under general cultivation conditions. In recent years, Metasequoia glyptostroboides has shown the characteristics of rapid growth through intensive cultivation, such as the Democratic Brigade of Honghu County, Hubei Province. At 7 years old, the average tree height is 9.5 meters, and the average DBH 10.5 cm. Therefore, the maturity of Metasequoia glyptostroboides is expected to be shortened to 10- 15 years under the conditions of suitable site conditions and fine cultivation measures.
Metasequoia glyptostroboides wood grain is straight, light and soft, and its air-dried bulk density is 0.29-0.38g/cm3. Small difference in drying shrinkage, easy processing, good paint and adhesive properties, suitable for building, furniture, shipbuilding and so on. With high cellulose content, it is a good raw material for papermaking. Beautiful tree shape, it is a good greening tree species.