Catalpa trees —— — upstart of urban greening
In China's urban greening, there is a general problem of monotony and lack of aesthetic shape, and many cities will introduce holly, weeping willow, locust and other tree species. If only a few trees are used in the whole city, the visual effect is poor and cannot bring the residents the enjoyment of beauty. Therefore, the introduction of new plant varieties and the design of more flexible and beautiful shapes are the key to overcoming the monotonous problem of urban green landscape, and it is also the only way for the future development of China's urban greening undertakings.
1 Problems in urban greening in China
1.1 Lack of attention to publicity
Many cities have beautiful natural scenery, but the green landscapes established according to them have been ignored because the local government and relevant departments have not publicized enough, or have not done positive publicity at all. For example, in a city landscape garden in the northern region, Zhong Lingyuxiu and Cuizhu are everywhere, looking as if they are in a green ocean, if there is a wind blowing, the bamboo leaves rustle, like a magnificent symphony. However, with such a beautiful natural scenery, not many people know, until recent years, the city to create a large-scale green landscape based on landscape sightseeing and agricultural experience, the use of the Internet to show the local beautiful scenery, has gradually expanded its popularity, become a famous tourist attraction.
1.2 Copying and copying, lack of character
Many local governments do not consider the local environment and local characteristics when planning green landscapes, but directly imitate the construction of greenery in some areas, introduce plants that are not suitable for growing in the local area and prune styles that cannot be integrated with the local natural landscape, making the entire landscape appear very abrupt and cannot bring people a pleasant spiritual enjoyment.
1.3 Planning is divorced from reality
Many cities fail to consider the actual local situation when planning the green landscape, neither consider the water, soil, light and other conditions required for the normal growth of plants, nor consider the living environment that some plants with strong ornamental properties need, blindly introduce alien species, blindly follow the design drawings for construction, do not make any changes, increase the difficulty and cost of plant maintenance in the later stage, and even the large-scale death of precious plants, or the invasion of alien organisms. In addition, a large number of off-season seedlings are planted, which not only increases the construction cost, but also increases the cost of replanting.
2 Introduction to catalpa trees
2.1 Patterns
Catalpa trees belong to the Rosaceae family, up to 7 to 8 m tall, the petals are white, nearly round or broadly ovate, the fruit is red, similar to the spherical shape, flowering period in June, fruit period from September to October.
2.2 Distribution
Natural catalpa trees are widely distributed in the northern region of China, and are planted in the northeast region and Hebei, Shanxi, Shandong and other provinces. In recent years, catalpa trees have been introduced in many southern regions, and today they are found in all provinces of the country. Natural catalpa trees often grow on the slopes or valleys at an altitude of 900 to 2500 m, and the environment of the growth area is quite different. But whether it grows in high mountains or valleys, catalpa trees thrive thanks to their strong resistance and adaptability.
2.3 Growth habits
Catalpa trees are highly resistant, drought-tolerant, wet-tolerant, cold-tolerant, barren-tolerant, have strong adaptability, high transplanting survival rate, can adapt to the climate environment of almost all provinces in China, and can be planted in most cities. Catalpa trees do not have strict soil fertility requirements, preferring acidic soil, moist environment and sunlight.
3 Key values
3.1 Ornamental value
The catalpa tree has a beautiful appearance, the leaves are green, the petiole is red, and the red and green of spring are very beautiful. The flowering period is green and lush, white flowers, pleasing to the eye, autumn leaves change color, fruitful, and even some fruits will not fall off in winter, can add color to the silver-clad winter, its trunk is white, very smooth, with high ornamental value.
3.2 Economic Value
The wood is strong and can be used to make furniture, the fruit is edible, and it can also be used for by-products such as winemaking and fruit vinegar, which contains a variety of vitamins and is of high edible value after processing.
3.3 Medicinal Value
The stems, skins, leaves and fruits of the catalpa tree have medicinal value, can suppress cough and phlegm, strengthen the spleen and water, and are often used in traditional Chinese medicine to treat cough and tuberculosis caused by respiratory diseases. The skin of the catalpa can also be used to make sugar-coated tablets of Western medicine, which has a cough suppressant effect.
3.4 Garden Value
Catalpa trees have strong anti-pollution ability, and are highly resistant to harmful gases commonly found in cities, such as sulfides and carbon dioxide. Moreover, its photosynthesis is strong, can absorb a large amount of carbon dioxide, provide fresh oxygen for the city, and is very suitable for urban greening. Its vitality is tenacious, it can be pruned into various shapes, and in addition, it can be paired with different tree species to obtain a good ornamental effect.
4 Planting
4.1 Seed Collection
The fruit of the catalpa tree ripens in September to October, so seeds can be collected in mid-to-late October, and after the collection is completed, they are softened, mashed, and impurities such as fruit and pulp are removed.
4.2 Treatment of seeds
Catalpa seed treatment emphasizes low temperatures, stopping germination when temperatures exceed 5°C. Therefore, the seeds must be kept in the refrigerator at a controlled temperature of 0 to 5°C. In addition, it is necessary to soak in warm water for 24 hours before sowing, then soak and disinfect with potassium permanganate dilute solution, wash and germinate in a nursery or seedbed, and then sow.
4.3 Sowing points
4.3.1 Number of seeds sown. Sowing too many seeds will lead to too small plant spacing, competition for nutrients and sunlight, and intra-population competition, resulting in unnecessary losses. Sowing too little will cause a lot of land to be wasted, so it is especially important to master the number of seeds.
4.3.2 Sowing depth. If the seed is buried too deep when sowing, the oxygen supply is insufficient, and the seed is difficult to germinate; if it is buried too shallowly, the seedlings are too shallow to take root, and it is easy to have a large-scale lodging phenomenon when it encounters wind blowing. Due to the low rainfall and deep groundwater level in some areas, the burrow should be deeper when sowing in these areas, about 4 to 5 cm; in some areas, the soil moisture content is higher, and the hole can be slightly shallower, 3 to 4 cm. After sowing, the soil should be covered in time to compact the soil gaps so that the seeds can be in full contact with the soil.
4.3.3 Water and fertilizer management. Sowing seeds under sufficient bottom moisture increases seed germination rates and allows seedlings to thrive more vigorously. Before sowing, the bottom of the sown land should be examined and watered appropriately according to the actual situation [4]. In May, the saplings enter the rapid growth period, which can be flooded with small water and nitrogen fertilizer is applied before monthly watering.
4.4 Planting points
4.4.1 Fertilization should be appropriate and weeding should be timely. Catalpa trees do not have high requirements for soil fertility, the amount of fertilizer should be controlled when fertilizing, and the concentration of a certain fertilizer component in the soil is too high, which will affect the plant root system to absorb water, thereby adversely affecting growth, and it is also easy to pollute nearby water sources. After the emergence of seedlings should be weeded in time to prevent weeds and saplings from competing for nutrition and light, if the weeding is not timely, it is easy to cause the root system of the weeds and the root system of the catalpa tree to be entangled, and the root system of the tree will be injured by mistake when weeding.
4.4.2 Watering should not be excessive. Catalpa trees have strong drought resistance, if the soil is too wet, it is easy to cause the root system of the catalpa tree to be unstable, lodging phenomenon occurs, more attention should be paid to observing the growth status of the catalpa tree, and decide whether to water.
4.4.3 Pest control. At present, the control of catalpa tree diseases and insect pests mainly relies on pesticides, but pesticides are more polluting to the natural environment, and the amount of pesticides should be reduced. In recent years, with the improvement of people's awareness of environmental protection, many new harmless control technologies have gradually been born, for example, biological control can be taken for insect pests, dragonflies, praying mantises and other beneficial insects are introduced in the flower tree forest, and the natural enemies of pests are used to control scarab beetle insect pests and avoid damage to the natural environment. It is also possible to use light trapping to kill the pest by using its phototropism, but this method may also kill beneficial insects, so use with caution. In addition, bioinforms can be used to kill specific species of pests in a targeted manner without affecting other species.
5 Application in urban greening
When the catalpa tree is introduced into the city, it is necessary to introduce and domesticate and select seeds according to local conditions, the catalpa tree is native to the higher altitude areas, the summer temperature will not be too high, and it is easy to cause sunlight due to the long direct sunlight and high temperature in the summer when introducing the low altitude area, and it is impossible to survive smoothly. Therefore, varieties with higher adaptability in low-altitude cities can be introduced and shading measures can be taken to alleviate the impact of long-term high temperatures in summer. In addition, catalpa trees are native to mountainous areas, have strong cold resistance, and generally do not die after wintering after being introduced to the city, and can not be protected in winter.
6 Conclusion
Catalpa trees have many values, and strong adaptability, can be planted in most cities in China, can promote the good development of greening, worthy of promotion and application.