On the relationship between landscape plants and environmental factors, and how to use these relationships to regulate plant growth in the process of landscape greening.

Relationship between garden plants and environmental conditions. Garden plants, like other things, are inseparable from the environment. On the one hand, factors such as temperature, moisture, light, soil and air in the environment have important ecological effects on the growth and development of garden plants; On the other hand, garden plants have different reactions and adaptability to the changing environment. In landscaping or plant landscaping, we should fully consider the basic laws of the interaction of various ecological factors in the environment. 1. The effects of various ecological factors in the environment on garden plants are comprehensive, that is to say, plants live in comprehensive environmental factors, and without any factor, plants cannot grow normally. 2. The ecological factors in the environment are interrelated and mutually restricted. The change of any single factor in the environment will inevitably lead to the change of other factors in different degrees, such as the change of light intensity, which often directly leads to the change of air temperature and air relative humidity, thus causing the change of soil temperature and humidity. Dominant factors In the whole ecological environment, although all ecological factors are necessary for plant growth and development, there are often 1-2 factors that play a decisive role in the influence of a plant or even a certain growth and development stage of a plant. This decisive factor is called "leading factor". For example, tropical orchids are mostly tropical rain forest plants, and the dominant factor is high temperature and high humidity, while cactus is a tropical grassland plant, and its dominant factor is high temperature and dryness. Without high temperature, both plants would die. Another example is rhododendron alpine. Air humidity is the dominant factor for survival when low altitude flat land is introduced. 1. Different plant species 1 grow in different habitats. Most species of Palmae are required to grow in tropical and subtropical high temperature areas in the south, such as coconut, oil palm, queen sunflower, betel nut, Japanese eggplant, pocket coconut and betel nut. 2. Larch, spruce, fir and birch are required to grow in cold northern or high altitude areas; 3. Peach, plum, kapok, bougainvillea, Ficus alba, Ficus microcarpa and Ficus macrophylla are required to grow in sunny places; 4. Shady environments such as hemlock, golden millet, Ardisia japonica, willow in the snow and wild fan flowers; 5. Rhododendron, camellia, gardenia, vetiver, smiling, etc. Like acidic soil; 6. Tamarix chinensis, Sabina vulgaris and Caragana can grow on saline-alkali land; 7. Elaeagnus angustifolia, Dracaena draconis and Elaeagnus glabra can grow tenaciously in the arid desert; 8. Lotus, water lily, peach blossom and Acorus gramineus grow in lakes and ponds. Second, the change of ecological factors in the environment, the change that affects the growth and development of plants, the ecological factors in the environment are not fixed, but are in periodic changes. Therefore, different environments can affect the changes of external morphology and internal structure of plants. For example, long sunshine can change gladiolus from vegetative growth to reproductive growth. On the other hand, the environment also affects the changes of organic matter in plants. Since many medicinal plants were introduced and cultivated in the wild, they have undergone great changes. For example, in a cold climate, the roots of aconite become non-toxic. Eucommia ulmoides leaves The sunny side contains about 60% Eucommia ulmoides Oliv. The leaves on the shady side only contain 3%-4% Eucommia ulmoides Oliv. Generally speaking, starch and carbohydrate are the main substances in various parts of wild plants and cultivated plants in temperate and humid areas, but in areas with high temperature, dry soil and abundant sunshine, it is beneficial to the formation of protein. Ecological function and landscape effect of main ecological factors on garden plants. Temperature is one of the important factors affecting garden plants, which not only affects the geographical distribution of plants, but also restricts the speed of plant growth and development. 1, the influence of temperature on the growth of garden plants. The change of temperature directly affects the physiological functions of plants such as photosynthesis, respiration and transpiration. The growth of each plant has a minimum, optimum and maximum temperature, which is called three basic points of temperature. Generally speaking, the temperature range of plant growth is 4-36℃. However, the temperature requirements of different plants and different growth stages are quite different. Tropical plants such as betel nut and coconut need an average daily temperature above 18℃ to start growing. Subtropical plants such as camphor tree, banyan tree, white banyan tree and bamboo began to grow at about 65438 05℃. Warm temperate plants such as peach blossom, purple leaf plum and plum blossom began to grow at 10℃ or even below 10℃, while temperate tree species such as yew, spruce and birch began to grow at 5℃. Generally, in the temperature range of 0-35℃, the growth rate of plants increases with the increase of temperature and slows down with the decrease of temperature. However, when the temperature exceeds the minimum and maximum temperature limits that plants can tolerate, some organs of plants will suffer, or even the whole plant will die. In real life, the influence of low temperature on plant growth is more prominent, which makes plants suffer from cold damage and freezing damage. Cold damage refers to the damage suffered by plants at temperatures above 0℃, which mostly occurs in tropical and subtropical regions; Freezing injury refers to the plant injury caused when the temperature is lower than 0℃. Of course, the damage degree of freezing injury depends on the extreme low temperature value, low temperature duration and cooling speed, and it is also related to the resistance of plants. Under the same low temperature condition, the faster the cooling speed, the more serious the damage to plants, and the longer the duration of low temperature, the greater the damage. The low temperature of soil is also harmful to garden plants. 2. Effect of temperature on flowering of garden plants The effect of temperature on flowering of garden plants is first manifested in flower bud differentiation. In addition, temperature also has a certain influence on color, because the formation and accumulation of anthocyanins and pigments are controlled by temperature. When the temperature is right, the color is bright, otherwise it is dim. 3. Temperature and Plant Landscape In the configuration and landscaping of garden plants, we should advocate the application of native tree species as much as possible, and control the southern tree to move northward and the northern tree to move southward, or use it after the cultivation experiment is feasible. Coconut, for example, grows vigorously in the south of Hainan Island and bears countless fruits. In the north, the fruit becomes smaller and the yield is obviously reduced. In Guangzhou, it was not only fruitless, but even frozen. Another example is the phoenix tree, which originated in tropical Africa and grew very vigorously there. The flowering period is earlier than that of leaves, and it was introduced to the south of Hainan Island. The flowering period is obviously shortened, and the phenomenon that flowers and leaves bloom together appears. After it was introduced into Guangzhou, most of the flowers came first, and the number of flowers decreased obviously, even only the leaves did not bloom, which greatly affected the landscape effect. In garden practice, due to the adaptation of different garden plants to temperature, attention should be paid to the collocation of deciduous trees and evergreen trees, and the collocation of flowering plants in four seasons, so that there are landscapes in four seasons and flowers in four seasons to reflect the relationship between temperature change and plant landscape. Second, the influence of light on garden plants is mainly manifested in three aspects: light intensity, day length and light quality. 1. Plant ecological types with different light intensity requirements According to the light intensity requirements of plants, plants are traditionally divided into positive plants, negative plants and shade-tolerant plants in between. Positive plants: require strong light, are not tolerant of shading, and grow well in full light, otherwise the branches are slender, the leaves are yellow and thin, the flowers are small and light, and the flowers are poor. In natural plant communities, most of them are upper-layer trees. Such as kapok, rubber tree, ginkgo, Lagerstroemia indica, Casuarina equisetifolia, coconut, willow, palm and most annual and biennial herbs. Negative plants: Most of them are native to the shady slopes of tropical rain forests or alpine forests. Generally, luminosity needs to account for 5-20% of the total sunshine, and they can't stand too much light. In natural plant communities, they are often in the middle and lower layers, or grow in damp and cool places, such as Taxus chinensis, Cinnamomum cassia, Eupatorium odoratum, Ivy, Panax notoginseng, Ginseng, Coptis chinensis, Reineckea carnea, Ophiopogon japonicus, ferns, Eupatorium odoratum, orchids, asparagus and so on. Shade tolerant plants; Generally, it grows best in the case of sufficient light, but it also has different degrees of shade tolerance, and the luminosity is between positive and negative plants. Most plants belong to this category, such as Podocarpus, Bamboo cypress, Luanshu, Junqianzi, Platycodon grandiflorum, Bletilla striata, Tang Di, Pearl Plum, Rhododendron, Camellia, Hydrangea macrophylla, Aesculus chinensis, and Acer mono. 2. The application of shade tolerance of garden plants in plant configuration and landscaping. In plant configuration and landscaping, temperature, moisture and soil factors can be met and controlled by measures such as adapting the ground and trees, strengthening management and changing soil. Only by understanding the shade tolerance of various tree species and herbs can we scientifically plant and form a beautiful and stable artificial community on the basis of conforming to nature. Judging the shade tolerance of plants according to experience is the main basis in plant landscaping at present, but it is extremely inaccurate. According to research: 1. Rhododendron should be planted at the edge of the forest, the edge of the orthographic projection of the crown of an isolated tree or the place where the branches are high above and below, the branches are sparse and the density is low; 2. When camellia is planted under the magnolia tree, the branches and leaves are luxuriant, and red and white flowers bloom in early spring. 3. Camellia should not be planted under Magnolia grandiflora; 4. Begonia is planted in osmanthus flowers, under camphor trees and in the north of the building. In addition, in garden practice, the flowering period is controlled by adjusting the light to meet the needs of landscaping. For example, Poinsettia is a short-day plant, and its normal flowering period is in the middle and late February of 12. In order to make it bloom in November, shading treatment is generally started in early August, and 8- 10 hours a day can be used to decorate flower beds, beautify streets and various occasions on National Day. 3. Water is an important part of plants. Both the absorption and transportation of nutrients by plants and a series of physiological and biochemical reactions in plants must be carried out with the participation of water. Water is also an important ecological factor affecting plant morphological structure, growth and development. 1, air humidity and air humidity of plant landscape have great effects on plant growth. In nature, there are all kinds of ornamental plants on the misty mountain. They grow on rock walls, cracks or epiphytes of other plants. These plants have no solid soil foundation, and their survival is closely related to high air humidity. For example, in the tropical rain forest with high temperature and high humidity, there are usually large ferns attached to tall trees, such as bird's nest fern, rock ginger fern, book belt fern and so on. They hang down and look like hanging gardens from a distance; 2. Different plant species, different water and plant landscapes have formed different ecological habits and adaptability to water demand due to long-term living in different water environments. According to the water demand of garden plants, they can be divided into four ecological types: aquatic, hygrophytic, mesophytic and xerophytic. (1) Aquatic plants landscape Aquatic plants live in water, some sink, some float and some protrude from the water surface, so the water landscape is very different. Garden aquatic plants are as follows, as shown in table 2-2- 1. The family of plant names is unique and suitable for water depth (meters). 3.0-5.0 annual floating aquatic herbs of Trapaceae. 0.5- 1.5 of perennial aquatic herbs of Nymphaeaceae. 0.25-0.35 for perennial aquatic herbs of Nymphaeaceae. Shallow floating perennial aquatic herbs of Nymphaeaceae. Eichhornia crassipes 0.3- 1.0, Araceae 0.10.15, Typha Typha 0.3- 1.0 or less. 0.3- 1.0, a perennial swamp herb of Oenantheraceae, or 0.3- 1.0 2, a shallow water shepherd's purse, a water lily family) Wetland plant landscape In nature, the roots of such plants are often not in shallow water or moist soil, which requires high air humidity. It usually does not grow well in a dry environment. Plants that can be used for plant landscaping include Pinus tabulaeformis, Taxodium ascendens, Pinus tabulaeformis, weeping willows, Salix matsudana, Pterocarya stenoptera, Sapium sebiferum, Fraxinus mandshurica, oleander, banyan, calla lily, Metasequoia glyptostroboides, begonia and Guangdong Evergreen. 3) xerophyte landscape xerophytes are mostly native to tropical drought or desert and desert areas, and have strong drought resistance. Common drought-resistant tree species in China are cactus, Populus simonii, Caragana korshinskii, Cedar, Poplar, Elm, Elaeagnus Elaeagnus, Platycladus orientalis, Sabina vulgaris, Pistacia chinensis, Schizonepeta, Amorpha fruticosa, Wisteria, Gleditsia sinensis and so on. These plants are good trees for arid landscape. Fourthly, the influence of air on garden plants is various. Carbon dioxide and oxygen in the air are the main raw materials and material conditions for plant photosynthesis, which directly affect the healthy growth and flowering of plants. In garden practice, some harmful gases have a great influence on plant landscape and directly threaten the growth and development of garden plants. Therefore, in the configuration and landscaping of garden plants, we should choose garden plants resistant to harmful gases according to local conditions. 5. Soil is the substrate for the growth of garden plants. Generally, the soil used to cultivate garden plants should be good in aggregate structure, loose and fertile, good in drainage and water retention, rich in humus and suitable in pH value. 1, the influence of soil physical properties on plants. Physical properties of soil mainly refer to the mechanical composition of soil. The ideal soil should be "loose, rich in organic matter, with strong water and fertility retention and granular structure"? Urban soil has great particularity. (1) Due to the large flow of people in cities, people step on cars, which increases soil density and reduces soil permeability and water retention capacity; (2) After the soil is compacted, the pores in the soil are reduced and the air permeability of the soil is poor, which inhibits the elongation and growth of plant roots; (3) Some floors in the city are paved with cement, asphalt and paving bricks. , are closed, leaving a small tree pond, which also causes poor soil permeability and high hardness; (4) In summer, most bare land absorbs heat strongly, which makes the soil temperature rise. These factors are not conducive to plant growth. 2. Effects of different soil pH values on garden plants. In nature, soil pH is influenced by climate, inorganic and organic components in parent rock and soil, topography, groundwater and plants. According to soil acidity and alkalinity in China, soil acidity and alkalinity can be divided into five grades: pH