Introduction and details of eucalyptus

Morphological characteristics of shady trees, 20 meters high; Bark is persistent, dark brown, 2 cm thick, slightly soft and loose, with irregular oblique cracks; The shoots are angular.

Eucalyptus young leaves are opposite, thick leathery, oval, long 1 1 cm, wide 7 cm, with stalks; Mature leaves are ovate-lanceolate, thick leathery, with unequal sides, 8-17cm long and 3-7cm wide. The lateral veins are numerous and obvious, with an angle of 80 degrees and gently inclined to the edge, with glandular points on both sides, and the lateral veins are 1- 1.5 mm away from the edge. Petiole length 1.5-2.5 cm.

Umbellies are stout, with 4-8 flowers, and the total peduncle is squashed, less than 2.5 cm long; Pedicel short, but not more than 4 mm long, sometimes longer, thick and flat; The flower bud is1.4-2cm long and 7 7- 10/0mm wide; The container is hemispherical or inverted conical, with a length of 7-9 mm and a width of 6-8 mm; The cap is about the same length as the calyx tube, and the top end shrinks into a beak shape; Stamens are 1- 1.2 cm long, anthers are oblong and dehiscent longitudinally.

Capsule ovoid, pot-shaped, long 1- 1.5 cm. The upper part is slightly contracted, the capsule mouth is slightly enlarged, and the fruit petals are 3-4 pieces, which are deeply hidden in the calyx tube. The flowering period is from April to September.

Born in sunny plains, hillsides and roadsides. Recyclable holidays every year. It is cultivated in the south and southwest of China. The trunk is tall, the root system is developed and the transpiration is large. Calling a water pump is easy to cause soil desertification and is not conducive to the growth of other plants. Generally, it can grow in areas with annual precipitation of 500 mm, and it grows better when the annual precipitation exceeds1000 mm.

It is suitable to grow in acid red soil, yellow soil and alluvial soil with deep soil layer, but it grows well in places with deep soil layer, loose soil layer and good drainage. The main root is deep and has strong wind resistance. Most roots and necks have wood tumors, which can store nutrients and germinate and renew. Generally, it can blossom and bear fruit in 3~4 years after afforestation.

Distribution: Eucalyptus mostly grows in the Australian mainland, with a few in neighboring new guinea, Indonesian and Philippine Islands. /kloc-was introduced to all parts of the world in the 0/9th century. By 20 12, it has been cultivated in 96 countries or regions. The main distribution center is in Oceania, and it is also distributed in Fujian, Guangxi, Guangdong, Yunnan and Sichuan.

Eucalyptus has many kinds, strong adaptability and wide uses. It grows in a wide range of environments, from tropical to temperate, including Eucalyptus bicolor, Eucalyptus gunnii and Eucalyptus humilis. They are tolerant to-18℃ and -22℃. From coastal areas to inland areas, from plains to mountainous areas (2000m above sea level), areas with annual precipitation of 250-4000mm can grow. Its shape has also undergone great changes, including rare trees with a height of 100 meters in the world, short and overgrown shrubs, and some tree species with drought and waterlogging tolerance.

Species classification includes dry broadleaf forest type, wet broadleaf tree type, savanna type, dry broadleaf tree type and alpine meadow type.

There are 522 species of eucalyptus, 150 species. Eucalyptus globulus,

There are 5 species of eucalyptus citriodora, eucalyptus grandis and eucalyptus cupressa.

Propagation methods include sowing, grafting, cutting and shoot tip tissue culture.

Eucalyptus photo (3) Cultivation techniques are usually manual, and mechanized land preparation has been greatly promoted, which has obvious effects on improving the efficiency and effect of land preparation. However, it also has a certain impact on the ecological environment of eucalyptus forest, and many beneficial organisms have been eliminated in the process of eliminating weeds. Soil preparation can improve the physical and chemical properties of soil, make the soil transparent, effectively remove weeds and enhance the water storage capacity of soil, especially for hardened soil. In the young forest stage, soil preparation can improve the conversion rate of soil fertilizer, reduce the growth resistance of roots, and thus improve the growth rate of seedlings.

The planting density of digging holes has a very important influence on the final output of eucalyptus, and digging holes determines the final planting density. When digging holes, the spacing of digging holes should be determined according to the planting years and variety growth characteristics of fast-growing eucalyptus trees, so as to ensure the reasonable permeability of eucalyptus growth and avoid wasting soil fertility because of too small planting density. Generally, the digging density between rows can be 3m×2m, and the digging specifications are1250px1250px1000px, which are arranged in zigzag. In addition, it is also necessary to prevent soil erosion caused by digging a pit, so as to prepare the soil before digging the pit, and the depth of the pit bottom should be greater than 1000px.

Fertilized fast-growing eucalyptus trees grow fast and have a great demand for fertilizers. Therefore, reasonable fertilization is very important to improve the growth rate of eucalyptus. When applying fertilizer, we must grasp a basic principle: under the premise of satisfying the growth of eucalyptus, we must pursue the least amount of fertilization. Therefore, when studying fertilization technology, we should not only study the specific methods of fertilization, but also determine the fertilizer needed by plants.

First of all, we should pay attention to the use of base fertilizer, which is generally fermented municipal solid waste or manure. These fertilizers have slow release, and can be applied before planting 1 month, and ammonium, phosphorus, potassium fertilizer and organic fertilizer can be mixed and applied to people when backfilling. It should be noted that the root system of eucalyptus seedlings is fragile, so it is necessary to avoid direct contact between fertilizer and root system of eucalyptus seedlings, resulting in root burning. Fast-growing eucalyptus needs more fertility in the first three years, so the first topdressing can be carried out 40 days after the first fertilization. If the nitrogen content of the previous fertilization is high, the first topdressing time can be postponed appropriately. In the future, the timing and dosage of topdressing should be determined according to the growth of eucalyptus, especially the canopy density. In addition, in order to prevent weeds in the forest from competing for fertility, weeding should be done in time.

Appropriate planting time should be selected after soil preparation and base fertilizer planting. Spring is an ideal afforestation time, because the temperature is suitable, the rainfall is abundant and the survival rate of eucalyptus seedlings is high. When planting, we should first choose strong seedlings, and carry out disease prevention and insect prevention treatment to keep the seedlings moist. When planting, we should take off bags, deeply plant and compact them. Then replanting should be carried out according to the survival rate of eucalyptus seedlings.

The growth of cultivated seedlings is still weak within 3~6 months after successful planting. In order to ensure that seedlings can have sufficient light and nutrients, attention should be paid to weeding to avoid competing with seedlings for growth elements. Spring is the peak season for weed growth, so weeding is necessary. At the same time, in order to ensure the release of soil fertility, it is necessary to loosen the soil, and pay attention to keeping a certain distance from the roots of seedlings during operation to avoid damaging the roots.

Picture of Eucalyptus (4) Pest Control

Scorch, bacterial wilt, stem rot and gray mold are common diseases of fast-growing eucalyptus trees.

The scorch disease is mainly characterized by gray-green water stains at the junction of healthy tissues and diseased spots, and leaves are dry and fall off. Bacterial wilt can occur in the whole growth cycle of fast-growing eucalyptus trees, which mainly shows that some or all leaves wilt, dry and droop in the form of water loss, and will die within a few days. Stem rot is characterized by white waterlogging at the base of the stem, which then turns brown and black. Gray mold is characterized by the formation of fungal mold on the surface of plants. The prevention and control of diseases of fast-growing eucalyptus trees should adhere to the principle of giving priority to prevention and combining prevention and control. First of all, thorough disinfection should be carried out during the planting process to prevent germs from being brought in with the seedlings, and the drainage system in the planting area should be kept normal to cut off the transmission route of germs. Also pay attention to rational fertilization. In addition, chemical agents such as Bordeaux mixture, chlorothalonil and thiophanate methyl can also be used for sterilization.

control of insect

Soil-dwelling termites are common pests of fast-growing eucalyptus trees, which usually occur in the young forest stage. Termites first harm the roots of young trees, then turn to the ground and peel off the main roots and roots along the topsoil, and finally make the seedlings unable to transport nutrients and die. Mainly to prevent and control ant damage, using drug bait to trap and kill. During afforestation, 3 ~4g carbofuran can be placed in the hole and mixed with soil-based fertilizer to fill the hole, and the dosage can be 0.35kg per 667m2. After afforestation, 2g carbofuran can be placed at a distance of 5m from the tree pocket, and 0.22kg should be used every 667m z, and attention should be paid to avoid phytotoxicity caused by powder contact with young trees. Fast-growing eucalyptus is one of the fastest growing tree species in the world. Reasonable cultivation techniques are of great significance to improve the output of eucalyptus. Every step of planting and management of fast-growing eucalyptus will affect its final yield. Using scientific planting techniques and strengthening pest control will surely achieve the goal of increasing production quickly.

Weed control: artificially spread a black film with a thickness of 5 lines 1 m2, and then press the surrounding edges with soil, subject to the wind. Or use thinner agricultural film (1× 1 or 1.5× 1.5). It is suggested to use the agricultural film with the width of 1.2~ 1.5 meters to lay in strips, which saves labor and time. It is estimated that the cost of black film (non-degradable) per plant 1 m2 is 0.35 yuan; The price of agricultural film (degradable) for each plant is 0. 16 yuan, and its life span can generally reach 10~ 12 months. The method of using agricultural film does not need weeding for one year, and has good functions of heat preservation, water retention and insect prevention.

Eucalyptus is a substitute tree species for eucalyptus, which grows fast and has a wide range of wood uses, but its biological characteristics have been criticized by experts and scholars in the forest industry. The rapid growth of eucalyptus is accompanied by the deterioration of local ecological environment, which requires a lot of water resources. Large-scale planting will lead to the decline of local groundwater level and the decrease of soil water-holding capacity, which will lead to soil hardening and even soil desertification in the long run. Eucalyptus has a great demand for fertilizer in the soil. Where eucalyptus has been planted, soil fertility will decline or even dry up to varying degrees, so eucalyptus is nicknamed "overlord tree". New varieties are needed to replace eucalyptus planting.

Eucalyptus is used instead of eucalyptus, such as fir, pine and acacia.

Introduce alternative tree species

fir wood

The plants of this family are evergreen, semi-evergreen or deciduous trees, with straight trunk ends, large branches in whorls or near whorls, longitudinal split bark and long strips falling off; Leaves, bud scales, stamens, bract scales, pearl scales and seed scales are all arranged in a spiral shape and rarely interact with each other (Metasequoia glyptostroboides). The leaves are lanceolate, subulate, scaly or linear, and the leaves on the same tree are of the same type or two types. Cones are unisexual and monoecious; Male cones are small, solitary or clustered, with occasional leaf axils, or arranged in terminal racemes or panicles. Stamens have 2-9 (usually 3-4) anthers, the pollen is spherical or slightly flat, there is no air sac, and there is an obvious or inconspicuous * * * protrusion on the far pole surface; The female bulb is terminal, and most of the pearl scales are combined with the bract scales, or the pearl scales are very small or the bract scales are degraded. There are 2~9 upright or inverted ovules at the ventral base of the pearl scale. Cones mature and crack in the same year or the following year, and the seed scales (or bracts) are flat or shield-shaped, wood or cortex; Seeds are flat or triangular, with narrow wings around or on both sides, or long wings at the lower part; Embryo has 2~9 leaflets. Chromosome bases are mostly x= 1 1, sparse 10 or 33.

Hong senhuai

Tall trees, narrow crown type, its dry shape rate can reach 0.78; The trunk is straight, the crown is compact and complete, the branch angle is 30-45, and the branches are evenly distributed in the crown to form a complete crown. It is about 25 meters high, with brown or light gray bark, odd pinnate compound leaves and a length of 25-40 cm. Leaves alternate; 7- 12CM long, petiole 1-3 cm, leaf width 4-7CM, and enlarged base; Oval to oblong, or oblong-lanceolate, with rounded or obtuse apex, sometimes slightly concave, with small spines at the top, entire, smooth or pubescent when young, thick and bright green leaves. Inflorescence axillary, with white and fragrant flowers, densely forming racemes, drooping,10-20cm long, floral axis hairy, pedicels 7mm long and densely hairy; Corolla butterfly consists of flag flap, wing flap and dragon bone flap, in which there is a yellow spot at the base of flag flap; Stamens102; The ovary is cylindrical and stigma-shaped, and it blooms in early summer.

Hongsenhuai pine tree

When the pine tree is young, the crown is pyramid-shaped and the branches are mostly wheel-shaped. When the seedlings are unearthed and the cotyledons are unfolded, the primary leaves appear first, which are solitary, spirally arranged, linear and lanceolate, and the leaf margin is toothed. It takes 1~3 years for primary leaves to function as leaves, and then there are needles, usually 2, 3 or 5 bundles, which are inserted at the top of short branches. Each bundle of needles has a leaf sheath at the base, which falls off or exists early. The position of resin channel in mesophyll tissue is relatively constant in adult plants, which can be divided into three types: exogenous, mesophyll and endogenous. There are 1 or 2 vascular bundles in the cross section of pine needles, and the vascular bundles can be combined in the double vascular bundle pine under special circumstances. These cones are monoecious and monoecious. Most cones are composed of seed scales and lignified when they mature. The thickened part of the seed scale is called the scale shield, and the tumor-like process at the top of the scale shield is called the scale navel. Some tree species have thorns on their scales and umbilicus, while others don't. When the cone is mature, the seed scales open and the seeds fall off; But the scales of some trees remain closed for a long time. Each seed scale has 2 seeds, the upper part has long wings, and a few have short wings or no wings.

Populus guanhong

The leaf color of Populus guanhongyang gradually changed from bright red in the germination stage in March to purple and orange, and the lower leaves turned to emerald green, and then changed to bright red and orange in the defoliation stage in June165438+1October every year. Petiole, vein, stem and new shoot are all purple, and a tree can keep three colors throughout its growth period.

When Xu Weizhong, member of Huidong County Committee of CPPCC and chairman of Huidong Branch of Democratic Progressive Party, suggested banning eucalyptus planting, Xu Yi, deputy secretary of Huidong County Committee and county magistrate, said that people who plant eucalyptus in Huidong should "save some food for future generations". For example, he said that planting eucalyptus is an "immoral tree".

Measures for the Implementation of People's Republic of China (PRC) Water Law in Guangdong Province (Draft) No unit or individual may adopt Yamakaji or the method of reclaiming wasteland for afforestation, and may not plant eucalyptus and other tree species that are not conducive to water conservation and protection. The staff of the Water Resources Department at the scene said that eucalyptus has a great influence on water sources, so eucalyptus was specially added to the draft. Some delegates also supported this practice, thinking that eucalyptus leaves are easy to rot and produce cyanobacteria in reservoirs, which is a great threat to drinking water. Many members also support the idea that the scope should be expanded and it is not appropriate to plant tree species that are not conducive to water conservation and protection.

Planting eucalyptus on a large scale in the Pearl River Delta is very harmful, which will lead to land desertification, fertility decline and inhibit local protozoa. The representative meeting in Shenzhen submitted a proposal calling for banning eucalyptus planting.

Sanshui Sanshui District has started the forest right reform, and it is clear that the ecological public welfare forest in the collective forest land is managed and operated by the village collective to maintain its ecological function. For commercial forests, it is forbidden to plant eucalyptus and other trees that destroy the ecology.

Main Value Economic Value China has successfully developed manufacturing technologies such as high-performance eucalyptus reconstituted wood, eucalyptus veneer laminated wood, bamboo-eucalyptus composite material, thick-core eucalyptus solid wood composite board and aldehyde-free eucalyptus plywood. The comprehensive utilization rate of eucalyptus can be increased to more than 90%.

Eucalyptus not only brings value to industry, but also brings economic benefits to other industries.

Papermaking and pulp eucalyptus papermaking began as early as the early 20th century. The average fiber length of eucalyptus is 0.75- 1.30mm, and its color, density and ratio of extractives are all suitable for pulping. There are also many large paper mills that use eucalyptus to make kraft paper and printing paper. Cellulose in eucalyptus wood can be made into dissolved wood pulp and then processed into rayon, which has achieved considerable success.

Eucalyptus varieties used for oil refining include Eucalyptus globulus, Eucalyptus erectus, Eucalyptus Smith, Eucalyptus macrophylla, Eucalyptus microphylla and Eucalyptus rubra. Eucalyptus globulus and Eucalyptus globulus are the main varieties for extracting eucalyptus oil. Eucalyptus leaf oil contains eucalyptol, which is a colorless or yellowish liquid with a cool fragrance. Mainly used in toothpaste, mouthwash, food and medicine. Eucalyptus globulus and Eucalyptus verticillata are excellent tree species, and eucalyptus oil is extracted from their branches and leaves with the best texture.

Australian scientists used X-rays to find trace gold in eucalyptus leaves. It is believed that this is the first time that human beings have found natural gold in living things.

Through research, scientists found that eucalyptus and acacia trees in western and southern Australia have deep and extensive roots. During drought, their roots dig three feet to find water, and some roots touch gold veins, from which they suck a tiny part of gold. Then, the roots will dilute the gold and conduct it to the venous system of trees. After a large amount of gold material accumulates at the top of the blade, it can form larger crystals.

Scientists further pointed out that gold is toxic to plants, so gold can be transported to the ends of plants such as leaves, which can reduce destructive biochemical reactions.

In addition, the researchers said that the amount of gold contained in leaves is very small, and the gold content in 500 eucalyptus leaves grown in gold mining areas may be enough to make a wedding ring, so this discovery will not bring wealth to gold diggers. However, scientists point out that this discovery will help people explore gold in a more environmentally friendly and cheap way.

Edible eucalyptus roots can be used for food or water. Some places also use eucalyptus as fuel. There are many eucalyptus leaves that can be used as feed.

Fresh eucalyptus leaves can be distilled with water to produce medical eucalyptus oil (the oil yield is 0.5- 1.8%). Eucalyptus mainly contains cineole (65-75%). Terpene, isoprene leaf oil, carvone, menthone, piperidone, etc. It can also be used as medicinal raw materials for oral cavity, rhinitis, expectorant, cooling oil, Qufeng ointment, etc.

Traditional Chinese Medicine This product is slightly pungent, slightly bitter and flat in nature. Has the effects of expelling pathogenic wind, relieving fever, inhibiting bacteria, diminishing inflammation, preventing corrosion and relieving itching. Mainly used to prevent influenza and epidemic diseases.

Meningitis, upper respiratory tract infection, pharyngolaryngitis, bronchitis, pneumonia, acute and chronic pyelonephritis, nephritis, dysentery and filariasis; Externally used for treating burn, cellulitis, mastitis, furuncle, erysipelas, paddy field dermatitis, skin itching, beriberi, etc. Unilateral prescription

1. Treatment of intestinal mycosis: Take Eucalyptus grandis leaves, Sapium sebiferum leaves, Zingiber officinale leaves and Sophora japonica leaves 15-30g and decoct them in water twice a day for 7 days as a course of treatment.

2. Treatment of acute gastroenteritis: Eucalyptus grandis leaves 15g, root leaves 10g, decocted in water.

3. Treatment and prevention of influenza and meningitis: eucalyptus grandis 15g, decocted in water.

4. Treatment of rice field dermatitis, skin eczema and foot rot in the distant years: eucalyptus grandis leaves, neem leaves, lacquer aunt leaves and pine and cypress leaves are all suitable for frying and washing.

5. Cure cervical erosion: Calcined and ground eucalyptus grandis leaves to the affected area. (Take medicine according to gynecological routine).

6. Treatment of pustular herpes and eczema: eucalyptus grandis leaves and neem bark are suitable. Wash with boiling water twice a day.

The usual dosage of this product is 9- 15g (fresh 15-30g), so it is not advisable to take it in excess. Appropriate amount for external use, decoction and external washing.

Natural value Eucalyptus has beautiful posture, evergreen seasons, rapid growth and strong drought resistance, and is suitable for street trees, windbreak and sand-fixing forests and landscaping trees. The leaves contain aromatic oil, which can sterilize and repel mosquitoes and can be used to extract sesame oil. It is also a good greening tree species in convalescent areas, residential areas, hospitals and public green spaces.

Eucalyptus plantation is also a huge carbon pool. According to research, eucalyptus can absorb 9 tons of carbon dioxide per hectare and release oxygen at the same time. Planting eucalyptus on degraded land can improve soil structure, increase soil biomass, improve microclimate and change the ecological environment of afforestation area. Leizhou Peninsula used to be thousands of miles away, the environment deteriorated, and the forest coverage rate was only 8%. Since 1954, a large number of eucalyptus plantations have been built, with nearly 3 million mu of eucalyptus and a forest coverage rate of 24%. The ecological environment has obviously improved and it has become an important agricultural city in the south subtropical zone.

Development trend of eucalyptus mixed forest

The mixed forest of eucalyptus, Sophora japonica and poplar can make full use of land resources and light energy resources to maximize economic benefits.

Mixed forests are mixed and matched according to the characteristics of plants like light and shade tolerance, root rooting depth, plant growth cycle, and fertilizer preference, so as to make full use of land resources and rationally distribute light, water and nutrients at different levels. Another feature of the mixed forest is that the light in the forest is weakened and the water evaporation is reduced, which can form a microclimate mixed forest with more developed roots and more effective water conservation, wind prevention and sand fixation. Mixed forest has thick crown, more litter and more leaves per unit area, which can improve soil fertility more than simple forest. Mixed forest has many varieties, good habitat and many natural enemies of pests and diseases, which can effectively inhibit the propagation and spread of pests and diseases; Because of the low temperature, high humidity and low wind speed of mixed forest, the risk factor of fire is low; The main tree species of mixed forest, with the help of associated tree species, grow more generally and roundly, and have better dry wood quality.

High-quality wood Eucalyptus wood is heavy and hard, with strong corrosion resistance, which can be used in buildings, sleepers, columns, piles, furniture, matches, farm tools, poles, fences, carbon materials and so on.

Harm comprehensive China Academy of Sciences Institute of Ecological Environment, Southwest Forestry College of China, State Forestry Administration, CCTV and many other experts and scholars' opinions and objective reports, the harm of planting eucalyptus in a large area is mainly reflected in the following aspects:

1, eucalyptus is a "fertilizer extractor"

Eucalyptus has a great demand for fertilizers and nutrients in the soil. Where eucalyptus is planted, the fertility of the land will decline or even dry up, and the original vegetation will be seriously damaged because of insufficient fertilizer and nutrients, leading to land degradation, soil and water conservation deterioration and barren land. It is impossible to survive by introducing other plants. The proportion of soil strength erosion has increased year by year, and landslides and floods have increased.

2. Eucalyptus is a "overlord tree"

Eucalyptus has a great inhibitory effect on local native, native and native species. When it grows, other species can't grow, and it will slowly shrink back. Finally, the ground of eucalyptus forest is bare, without grass and shrubs (such as mud trees, milk roots, chicken manure vines, honeysuckle, etc. ) the ground is covered, and there are no small trees and various Chinese herbal medicines. No other species can coexist with it. The original biological species are decaying and degenerating, and the plant species are very single, which can not provide food or suitable habitat for most animals. Animals in the forest are very rare or even extinct, the level of biodiversity is extremely low, the biological food chain is broken, the ecology is very fragile, and there is no natural enemy to control pests, which is easy to cause disaster to the disease-causing people and will cause large-scale destruction. Cutting down natural forests and planting large-scale artificial forests with single tree species and similar age will lead to "green desert"; Dry and easy to catch fire; It will also lead to serious ecological crises such as microclimate change. The ecology will suffer subversive damage and it will be difficult to recover. And it may not appear for two or three years.

3. The chemical products used in eucalyptus are highly toxic and have a long toxic effect. Eucalyptus gas has * * * and toxic effects.

When planting eucalyptus, some chemical products with strong toxicity and long toxic effect will be applied. Once the product is applied to the land, it is difficult to clean it up. After drinking, it will cause great pollution to the water quality and immeasurable harm to people and animals. In addition, the smell of eucalyptus has a toxic effect on human body and will threaten the health of local people.

Question 1: Eucalyptus is a "water pump", which absorbs water and causes drought.

This is the most common question about eucalyptus: because of the large transpiration, the groundwater of eucalyptus drops obviously, like a "pump", resulting in land drought and water depletion. In this regard, the results of scientific research prove that the water use efficiency of eucalyptus is quite high compared with other conifers, and the role of eucalyptus forest in water conservation, soil and water conservation and climate regulation is not inferior to other tree species. A large number of field observation experiments also show that eucalyptus does not directly cause drought. The observation data of scientist Bailly and others for 8 years also show that most of the water in Eucalyptus grandis forest has penetrated into the soil, but it can effectively maintain water and soil.

Doubt 2: Eucalyptus is a "fertilizer absorber", which will lead to "soil fertility failure"

Many people who have been to eucalyptus forests or planted eucalyptus in person said that eucalyptus has a great demand for soil fertilizers and nutrients, but the fertility of the land where eucalyptus is planted has declined or even dried up, and other plants reintroduced into the soil where eucalyptus is planted cannot survive at all. In China, Bai Jiayu, a scientist who has been engaged in eucalyptus research for many years, found that eucalyptus uses nutrients more efficiently than other tropical tree species by measuring its nutrient absorption. In foreign countries, scientist Liani also found through the observation of eucalyptus forest soil that eucalyptus will return the nutrients absorbed in the rapid growth period to the soil. In fact, most of the negative effects such as "water pump" and "fertilizer pump" only occur in the early stage of afforestation (the first 8- 10 years), and then the water storage and fertilizer storage functions of eucalyptus will gradually be reflected.

Question 3: Eucalyptus is a "overlord tree", which will inhibit the growth of other species.

It has been pointed out that eucalyptus has a great inhibitory effect on local native, native and native species, and other species cannot coexist with it. Indeed, according to scientific common sense, alien species may indeed do harm to the local ecological environment. However, scientific research has also found that almost all harmful exotic plants are herbs, and the ecological harm of eucalyptus as a tree has not really been confirmed. In addition, the phenomenon that some tree species are sensitive to sap or rotten leaves of another tree species is also a normal phenomenon in nature. An investigation was conducted in Leizhou Peninsula, Guangdong Province, and the results also showed that planting eucalyptus did not reduce the diversity of local forest plants.

The discussion mechanism is not complete, and environmental organizations become spokespersons.

Since then, the "harm" of eucalyptus has been continuously amplified, and the report and data of "Greenpeace" have been widely quoted by many "popular science writers", public figures and the media. The latest version is the "Eucalyptus Drought" in the southwest drought.

Yunnan, which has a large area of eucalyptus planting, once held a press conference on this rumor, saying that there is no scientific basis to prove that eucalyptus forest and rubber forest caused the drought. People's Daily also published an interview with official forestry scholars to clarify the doubts.

On the one hand, it is questioned by environmental protection organizations and media who are used to exposing problems, on the other hand, it is questioned by scholars and experts with eucalyptus and official status. Even if these environmental protection organizations and media lack field investigation, and the attitude of scientific falsification is even just a point of view, the balance in people's minds naturally tends to be non-square. But in the end, Greenpeace's report, or the public's understanding, blamed the initial review of human behavior on the existence of natural species in the continuous discussion between NGOs and the media.

plant culture

Eucalyptus is the general name of eucalyptus in Myrtaceae, which may have originated in the late Cretaceous, because there were oblique vein species in Eocene and early Miocene. Its original type has Mesozoic structural characteristics, and its evolution mainly follows the changes of Australian geological history, and also depends on its adaptation to drought, drought and semi-arid conditions, mainly xerophytes, mesophytes and ice-loving systems.

The adaptation of eucalyptus to drought conditions led to the formation of a series of morphological and anatomical structures. One of the earliest adaptation types is the formation of colloid, fluff or bristles on leaves, but when the drought intensifies, this protective effect is not very effective, so it is only preserved in the young stage of plants, and wax layer epidermis is formed in the later stage. Eucalyptus growing in mountainous and arid areas, young leaves and mature leaves, branches, and sometimes the trunk has a blue-gray wax layer. In the modern development stage, the cuticle of eucalyptus thickens, which is beneficial for it to adapt to dry conditions most safely. It should be said that the regeneration characters of eucalyptus are all developed on the basis of the mesogenetic evolutionary system.

All species in the humid areas of northern Australia, and many trees in the humid coastal areas and humid mountainous areas of southeastern Tasmania should be classified as mesophytes. Ice-loving evolutionary system is an evolutionary system adapted to alpine ecology, including some species growing in arid areas of central Australia. The living conditions in this area are sharp changes in the temperature difference between day and night, often high (hot) during the day and low (cold) at night. The evolution of eucalyptus here is essentially a kind of degradation, and its evolution process is arbor-sub-arbor-Shy small tree. Shrub.

During the period of 1982, the paleobotany team of the Qinghai-Tibet Plateau Comprehensive Investigation Team of China Academy of Sciences collected more than 40 eucalyptus fossil specimens in the strata of Litang County at an altitude of 3,700 meters in the west of Sichuan Province in the late new century. Among these fossils are eucalyptus leaves, fruits and flower buds. The fossil was preliminarily identified as Eucalyptus religiosa, which is similar to Eucalyptus tenuifolia and Eucalyptus rubra in China.

More than ten years ago, eucalyptus angustifolia fossils were also found in Xigaze area and Jinggangshan in Tibet. From the perspective of phytogeography, it can be imagined that in the late Eocene, 400-500 million years ago, a large area of eucalyptus evergreen broad-leaved forest was distributed in western Sichuan and Tibet. At that time, the climate in these areas was warm and dry, which was very suitable for eucalyptus growth. Later, about millions of years ago, the strong Himalayan orogeny caused the crust of western Sichuan and Tibet to uplift, and eucalyptus plants disappeared because they could not adapt to the cold climate. Eucalyptus gradually moved south to Oceania via Malaysia, and now Australia has become the main distribution center of eucalyptus plants.

These fossils found in China stratum at the end of 2 1 century are about 654.38 billion+0 billion years earlier than the earliest eucalyptus fossils found in Australian stratum in the new century. This questions the traditional view that eucalyptus originated in Australia. It has important academic research value and provides a basis for establishing geological age and studying paleogeography, paleovegetation and paleoclimate.