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Although eucalyptus grows rapidly and its wood is widely used, 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 huge demand for fertilizer in the soil, and soil fertility will decline in different degrees in areas where eucalyptus has been planted.
Even dried up, so eucalyptus was nicknamed "overlord tree". New varieties are needed to replace eucalyptus planting.
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 spirally, and rarely cross 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 axillary leaves 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 papilla on the far pole. 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. The cones mature and crack in the same year or the following year, and the seed scales (or bracts) are flat or shield-shaped, woody or leathery; 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 [5]
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 flowers, very fragrant, densely forming a raceme, drooping, long 10-20 cm, hairy in floral axis, pedicel 7 mm long, 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.
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 exposed and 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 China 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 rice for future generations". For example, he said that planting eucalyptus is an "immoral tree". [7]
Guangdong quasi-legislative reservoir
Measures for the Implementation of People's Republic of China (PRC) Water Law and National Water Law (Draft) in Guangdong Province. No unit or individual is allowed to renew afforestation by burning mountains, reclaiming land, or planting 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. [8]
Pearl River Delta
Planting eucalyptus in a large area 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. [9]
Sanshui
Sanshui District started the forest right reform, and made it clear that the ecological public welfare forest in the collective forest land was 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.
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%. [ 1 1]
Eucalyptus not only brings value to industry, but also brings economic benefits to other industries. [ 1 1]
Paper 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.
refine petroleum
Eucalyptus varieties 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 irritating and 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.
golden
Australian scientists used X-rays to find a trace of gold in eucalyptus leaves, which is considered to be the first time that humans have found naturally occurring gold in organisms. [ 12]
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. [ 13]
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. [ 12]
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. [ 12]
Edible
The roots of eucalyptus can be used as food or water. Some places also use eucalyptus as fuel. There are many eucalyptus leaves that can be used as feed.
Medicinal value
Fresh eucalyptus leaves can be distilled with water to produce 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 attribute
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 graceful posture, evergreen seasons, rapid growth and strong drought resistance, and is suitable for street trees, windbreak and sand fixation 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.
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, and can be used in buildings, sleepers, columns, piles, furniture, matches, farm tools, poles, fences, carbon materials and so on.
harm
Based on the opinions and objective reports of many experts, scholars and media organizations such as the Institute of Ecological Environment of China Academy of Sciences, Southwest Forestry College of China, State Forestry Administration and CCTV, the harm of planting eucalyptus in large areas 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 decadent and degraded, 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 the toxic effect lasts for a long time. Eucalyptus gas has irritating 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 is irritating and toxic to human body, which will threaten the health of local people. [ 14- 15]
Question 1: Eucalyptus is a "water pump", which will absorb water and cause drought.
This is the most common problem about eucalyptus: due to the large transpiration, the groundwater of eucalyptus drops obviously, just 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.
Question 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.
In Yunnan, where eucalyptus is planted in a large area, the government quickly held a press conference on this rumor, saying that there was no scientific basis to prove that eucalyptus forests and rubber forests caused the drought. People's Daily also published an interview with official forestry scholars to clarify 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 government and official scholars and experts sitting on eucalyptus trees. Even if these environmental protection organizations and media lack on-the-spot investigation, and the attitude of scientific falsification is even just an opinion, the balance in people's minds naturally tends to the non-government side. 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 has a blue-gray wax layer on young and mature leaves, branches and sometimes trunks. 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? Small trees and shrubs.
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.