TABLE OF CONTENTS INTRODUCTION Page Unit 1: FORESTRY Page 2-6 Unit 2: TREES AND FOREST Page 7-12 Unit 3: IDENTIFICATION OF TREES (Part I) Page 13-17 Unit 4: IDENTIFICATION OF TREES (Part II) Page 18-23 Unit 5: TREE SIZE AND TYPE CLASSIFICATION Page 24-27 Unit 6: THE ANATOMY OF A TREE (PART I) Page 28-32 Unit 7: THE ANATOMY OF A TREE (PART II) Page 33-36 Unit 8: TREES ARE CHEMICAL MACHINES (PART I) Page 37-42 Unit 9: TREES ARE CHEMICAL MACHINES (PART II) Page 43-47 Unit 10: FOREST TREES DISEASES Page 48-53 Unit 11: CONTROL OF TREE DISEASES Page 54-57 FURTHER READING Page 58-59 FURTHER READING Page 60 FURTHER READING Page 61-63 FURTHER READING Page 64-65 FURTHER READING Page 66-70 REFERENCES Page 71 INTRODUCTION This course has three purposes It is intended: To introduce students to the contents of Forestry To provide examples of authentic texts written in the language typical of the subject To help students to practise the skills they will need in order to study the subject via English and to use it when they have learned it In this course, the designer doesn‟t intend to give comprehensive coverage, but the materials does embrace most of the basic concepts It in sense is a basic course book of Forestry All the texts in this course are selected from many different sources They are not simplified for students of English: the language the students encounter in these texts is exactly what they will meet in real life The most important aim of this course is to help the students to acquire and develop the skills they will need in order to learn their subject and when they have finished the course, to use what they will have learned Unit : FORESTRY A READING & COMPREHENSION I Reading text Principle of Forestry Since the primary task of the forester is centered on producing trees, understanding trees and their growth is essential Although certain special terms may be used for convenience, the principles underlying the growth, development, and reproduction of trees of the forest are the same as those for other crop species Thus, forestry must be based on a sound understanding of botanical principles One critical point to keep in mind is that trees are generally managed for wood production, i.e., stem tissue Compared with most horticultural and agronomic crops, forests represent long-lived, perennial plants Classification In United States forests, all trees are spermatophytes, or seed plants They are classified formally as either gymnosperms (cone-bearing plants) or angiosperms (flowering plants) This formal classification is accepted scientifically, but others are routinely used by foresters The most common general classification identifies a tree according to its leaf form as a hardwood or softwood tree Hardwoods are broad-leaved, generally deciduous, flowerbearing trees Softwoods are needled-leaved, mostly ever-green, cone-bearing trees This broad classification is far from perfect: the southern long-needled pine is classified as a softwood species although its wood is harder than that of many of the hardwoods, and several deciduous broad-leaved species yield softwood, e.g., basswood, willow, and aspen This leads to the confusing terms hard hardwoods, and soft hardwoods Some senses can be made from this when it is remembered that the terms were established early, when the demand was for the soft white pine and the very hard white oaks only Later use of numerous species of widely varying hardness or softness could not erase the old established usage Morphology and Anatomy Although a forest may contain annual, biennial, and short-lived perennial plant species, trees are generally considered to be the major vegetation: they are long-lived perennials that usually produce a single central stem and attain a height of m or more Rarely does a forest tree maturity in less than 15 to 20 years: some trees may grow continuously for centuries though generally very slowly after the five hundred years In considering the growth of trees, increases in both height and diameter, or girth, are important in determining the yield of lumber or other products In terms of gross morphology, as a rule, tree growing in a typical forest environment are taller and have smaller root systems than those growing separately or under widely spaced, ornamental-settings The apical or top portion of the tree, the crown, is also smaller under crowded conditions Note that the word crown has a different meaning in forestry than in horticulture and agronomy In forestry, the crown is that portion of the tree which has branches Since shade decreases the ability of branches to survive, the trees in crowded forests tend to shed their lower branches and thus have less crown in proportion to clear stem Roots Roots serve the same general function as for other plants: anchorage, absorption of water and essential minerals, and storage of photosynthate The storage function is less important in forest trees than for most perennial field crops since stem tissue takes over much of the storage function in trees Trees species differ markedly in the extent of their roots systems, differences that may affect how the species are managed in a forest For example, most oak, hickory, and walnut trees have deep and extensive taproot systems which provide extremely solid anchorage Thus, these and other trees with similar roots systems are not prone to uprooting by severe winds In harvesting a forest, wind damage is a minor concern with these trees Spruces and balsam, on the other hand, have shallow roots system and can be uprooted even by moderate winds In planning the harvest, such trees must be removed or allowed to remain in a pattern that will ensure adequate wind protection Most forest trees fall somewhere between these extremes Generally, the root systems provide sound anchorage except in relatively extremely conditions Of course, even deep-rooted species can be up-rooted under severe conditions, such as prolonged heavy rains before or during high winds Hurricane conditions can level extensive areas of forest In addition, trees that normally produce taproots may develop shallow root systems because of poor soil conditions, e.g., only a thin layer of a soil above the bedrock In such cases trees may be not only stunted but also easily blown over This text was taken from Barden et al., Plant Science, Mc Grav-Hill II Comprehension questions: Now read the text carefully, and try to answer the following questions: 1.Why are forests usually managed? 2.What is the difference between an angiosperm and a gymnosperm? How are hardwoods and softwoods differenciated? What kind of tree is the aspen? How long does it take for a forest to mature? How you assess the amount of wood you will get from a tree? What is a crown? Why is the storage function of a tree‟s roots less important than those of a field crop? Why is an oak less likely to be uprooted than a balsam? 10 When is the root system inadequate to anchor a tree? III Vocabulary Look at the first paragraph again What words have the same meaning as: well-informed main, most important Look at paragraph again What words have the opposite meaning to: straightforward; easy to understand as an exception Look at paragraph again Can you explain the words: hard hardwood hard softwood Look at paragraph again What words have the same meaning as: go on living deciding hundreds of years part all the time seldom Look at paragraph and again Which words correspond to these definitions: holding something down so that it is not blown over liable or inclined to going on for a long time poorly developed qualities which are as wide apart as possible B GRAMMAR Some verbs in English must be followed by the - ing form: He admitted taking my book Others are followed by the infinitive, “to”: He agreed to lend me his book Verbs followed by a particles like „in‟, „from‟, ect are followed by the -ing form: He insisted on going to a film last night Some verbs are followed by either gerunds or infinitives: It began raining It began to rain COMMON VERBS FOLLOWED BY GERUNDS COMMON VERBS FOLLOWED BY INFINITIVES Enjoy: I enjoy working in my gardent want refuse Finish: Bob finished studying at midnight need appear Stop: It stooped raining a few minutes ago would like pretend Quit: David quit smoking would love forget Mind: Would you mind opening the window? hope can’t afford Postpone: I postponed doing my homework expect Put off:I put off doing my homework plan Keep: Keep working Don’t stop intend Keep on: Keep on working Don’t stop mean Consider: I’m considering going to Hawaii decide Think about: I’m thinking about going to Hawaii promise Discuss: They discussed getting a new hat offer Talk about: They talked about getting a new car agree Make sentences from the following notes Think whether you should use the infinitive or the – ing form after the verbs He/suggest/read/chapter 5/before/we/go/lecture The rain/not stop/fall/until yesterday evening He/wants/spend/more time/study A good farmer/try/set/objectives Peter/prevent/harvest/his crop/bad weather I enjoy/listen/music He/not mind/work/weekends He/forget/hand in/essay/ last night There/nothing/that shop/worth/buy It/no use/leave/your work/last minute I/miss/watch/college football match/last week He/ hope/get/ good results/his examination I/expect/grow/more vegetables/next year I/not want/risk/fail/my exams Asking question You want to find out about the oil palm Find out about the oil palm by asking questions Note down the answers Asking about the following points: Botanical name: Family: Varieties: Seed rate: Planting out: Spacing: Maturation: Harvest: Yields: Composition percentage Diseases: Processing: Paragraph Writing: Now write a short paragraph on the oil palm, using the information you have noted above Unit 2: TREES AND FORESTS A READING & COMPREHENSION I Reading text A mature forest cannot be precisely measured nor cost However, it is clear that forests have special functions In addition to providing habitats for animals and contributing to environmental stability, forests influence wind patterns, rainfall and nutrients turnover The Function Of A Forest The waru The trees are the fixed elements of a forest and the associates of trees- fungi, bacteria, squirrels, possums, insects, birds, and other animals- can be seen as the mobile elements The whole- the tree and its associates- can be imagined as a guild or waru (the Australian Aboriginal word waru expresses the sense of all organisms belonging together and working co-operatively.) the tree provides habitat for the animals (shelter, food, nesting materials); in return animals carry out the tree‟s needs for pollination, seed dispersal, pruning, cultivation and fertilising In permaculture, you are aiming to create landscapes and ecosystems that function with the wonder, diversity and efficiency of a waru Trees and wind Trees are “pruned” or deformed by prevailing winds and from this you can predict local wind direction and intensity, and assess the need for windbreaks Heavy trees with large canopies, such as oak trees, rely mainly on their weight to withstand severe winds Trees with lighter canopies insert roots deeply into the ground to anchor themselves It is important to use anchoring trees in cyclone areas Wind carries a “load” It carries ice particles, sand, dust, bacteria, viruses and seed Trees with small fine leaves can “trap” the load and deposit the nutrients for their own growth Because fine-leaved trees are often found on the edges of forests, you will sometimes find that the edge facing the prevailing wind has richer soils than the edge on the leeward side Typically, in a forest about 60% of the windstream is deflected up and over the trees The remaining 40% that enters the “edge” or forest closure is absorbed and warms the forest with its energy Within 100m the wind dies At this point in the forest the air is clean, warm, still and slightly humid This is a perfect growing place The deflected wind is compressed in a region up to 20 times the height of the tree canopy If the air is humid, it will be compressed and cooled, and it will rain The forest edge is essential to the lift of the wind The species growing on the edge are dense, small-leaved and thick-stemmed, and can withstand the force of the wind The edge must be kept intact because if it is destroyed the plants in the forest may suffer from windburn and abrasion, and diseases and weeds can enter the forest and destroy its integrity Trees and temperature Forests can be seen as nature‟s air conditioners because they clean the air and modify extremes of humidity and temperature Trees absorb the sun‟s light energy and turn it into chemical energy If leaves are dark green or reddish in colour, as often found in the tropics, more light as absorbed and local temperatures are reduced Trees transpire water into the atmosphere as humidity (one medium-sized elm will transpire 7000 litres of water on a clear day.) this evaporation is accompanied by cooling so that by day it is cooler in and near a forest than it is in unvegetated areas At night, in humid conditions, water condenses on the leaves and warms the surrounding air In very dry areas, the evapotranspiration from trees will humidify air which is uncomfortably dry; in very damp areas, water captured by trees dehumidifies the air by absorbing water Trees and precipitation Where the air stream is very humid (i.e coasts and islands), air flows rapidly and condenses on leaf surfaces In these conditions dense rainforests will grow and the condensation from leaf surface can be 80-86% of the total precipitation Trees pump moisture into the air as they transpire- up to 75% of precipitation is returned to the atmosphere in this way The Tasmanian Blue Gum, Eucalyptus globulus, which averages about 60 trees to a hectare in a natural mixed forest, pumps 4000 litres/ day This is a huge return of moisture to the airstreams The environmental effects of forest removal are dramatic, both in the local area and further field It has been calculated that as much as 60% of inland water comes from forest transpiration Hence, forest removal in one area may relate directly to drought in another area Forests protect the soil from erosion In one heavy deluge up to 80 tones/ hectare of soil can be lost from bare earth In addition, the topsoil and subsoil start to dry out if water runs across the surface and off the land into waterways Dams and rivers silt up and eventually flood, carrying the valuable topsoil downstream When it rains……… 59 FURTHER READING Classification schemes The most important of several broad ecological classification of trees for forest management is shade tolerance A shade-tolerance tree can generally with-stand closer planting or more competition for light than nontolerant type This becomes a major consideration in planting, thinning, or harvesting operations and schedules Forest trees are classified under three broad headings with regard to light requirements: Shade-tolerant species- e.g., balsam fir, hemlock, redwood, basswood, spruce, birch, and maple Intermediate- e.g., Douglas fir, ash, elm and many oaks Shade-intolerant- e.g., cypress, eastern red cedar, larch (tamarack), pine, aspen, black cherry, black walnut, cotton wood, hickory, locust, red gum, sycanore, yellow poplar, and willow Species in these three groups presumably differ in basic physiological processes related to photosynthesis The most common explanation is that the differences in shade tolerance are related directly to differences in the amount of light required to reach light compensation, or the amount of light a plant needs for net photosynthesis to occur, as well as light saturation It is important to note that these classifications are broad Within any species are genotypes which may be more or less tolerant to shading than the average Since a common cause of shading is crowding or dense planting, trees that tolerate shading are, within limits, also expected to tolerate more crowded conditions than nontolerant species Tolerance is obviously a major consideration in deciding whether to manage trees as even-aged stands or as unevenaged, stands where regeneration and growth must take place in the shade of several older age classes This text was taken from Barden et al., Plant science, McGrawII COMPREHENSION CHECK Look at paragraph again Are these statements correct or incorrect? A hemlock tree can stand more shade than an aspen A tamarack needs more light than a red wood Look at paragraph again Which words correspond to these definitions: growing again 60 the genetic makeup of an individual, determined by the assemblage of genres it possesses thick supposed Look at paragraph again Which words have the same meaning as: showing what something is having meaning or importance have control or influence over an overhanging covering Look at paragraph again Can you explain in your own words the differences between dominant, codominant, intermediate and overtopped trees? Look at paragraph again Can you explain: habitat swamp FURTHER READING 2: The Science known as Ecology 61 For a long time people have realized that living things are greatly affected by other living things and by their surroundings, their environment, and that organisms also tend to affect their surroundings In the present century, such interrelationships have been studied very seriously, and that study has developed a division of science called ecology The science as ecology as a whole is concerned with the interrelationships of organisms and their physical environments and with other organisms The word ecology is also applied to a specific organism, for example, the “ecology” of loblolly pine, which refers to all the relations between that species and other organisms and its environment Our study of forestry will include the ecology of various organisms An example is the ecology of forest game, where hunting is utilized to forestall animal overpopulation, thus preventing over-browsing and wintertime starvation This may be compared with the study of human ecology, which is very important because of the prospect of word over-population and worldwide insufficiency of food and energy Human activities affect the natural world; a simple example is that sewage can kill fish As the population continues to grow and material productivity increases, the impact of human activities will become progressively greater People cannot live apart from the natural world because they rely on it for food, materials for shelter and clothing, and recreation Thus human survival depends on maintaining the natural world in a state of vigor and productivity One of the most visible examples of a vigorous productive environment is the forest So we will discuss the basics of forest ecology Forest ecology is a growing science with new knowledge coming both from research and from the results of forest management experiences The stockpile of accumulated ecological knowledge is often tapped by foresters and legislators for methods and ways to improve our environment Tree leaves employ the energy of sunlight to convert carbon dioxide from the air and water and minerals from the soil into woody material Tree leaves also collect dust, which is washed off by rain and falls to the ground, where some of the dust particles enter and become part of the soil Runoff water from a forest carries some of the dust particles into streams, where part of it may be consumed by organisms, including fish If the dust happens to have come from an industrial plant manufacturing a poison, it could harm the fish or a person who eats the fish For a tree to live, it must have water The availability of water depends upon the amount of precipitation, the natural of the soil, and the level of the water table (the upper limit of the ground wholly saturated with water, as indicated by the level at which water naturally stands in a well) The water table fluctuates with precipitation and surface use Some forests (evergreen) are not noticeably affected by seasonal changes in the weather; others (deciduous) are drastically affected, losing all the leaves each autumn The growth rate of forest trees depends upon a number of factors, mainly amount of sunlight, type of soil, availability of water, temperature, and the genetic potential of the trees Most of these factors are related to climate, directly or indirectly 62 FURTHER READING Soil structure and texture A READING COMPREHENSION I TEXT Soil Texture Soil texture is that characteristic which is determined by the amount of clay, silt, sand and organic matter which soil contains This property normally can not be altered by the farmer soil texture can be measured by a mechanical analysis of a sample in the laboratory and classified accordingly and also by a „feel‟ test Soil Structure Soil structure is the arrangement of the soil particles individually (e.g grains of sand), in groups (e.g crumbs or clods) or as a mixture of the two It can be altered by : weather conditions (e.g lumps changed to crumbs by frost action or alternate wetting and drying), penetration of plant roots, cultivations, ect It is not possible to measure soil structure satisfactorily, but an experienced person can easily assess its quality at any one time by its appearance and „feel‟ It is possible to classify the texture of a soil clay by rubbing a moist sample of it between the thumb and fingers Clay is sticky, will take a polish, and can be moulded Silt feels silky, smooth and slightly sticky Sand feels gritty Organic matter usually feels soft and slightly sticky The dominant „feel‟ indicates the texture group of the soil; if there is no dominant feeling then the soil is a loam Soils are often classified by farmers and others as heavy, medium and light (not a weight measures) The terms “heavy” and “light” refer to the amount of power required to draw a plough or cultivator through the soil A heavy (clayey) soil consists mainly of large particles which pack tightly together whereas a light (sandy) soil consists mainly of large particles which loosely held together because of the relatively large pore spaces Crumb structure is formed by the grouping together (aggregation) of the particles of clay, sand and silt This aggregation is possible because there are positive and negative electric charges (forces) acting the surface of the particles These forces are strongest in clay and very weak in sand This strong adhesive property of clay particles makes clay soils more difficult to work than sandy soils but it also enables them to form crumbs easily Water has special electric properties and its presence is necessary for the grouping (crumbing) of soil particles The electric forces in the water and in the soil particles make the 63 water sticks as a thin film around the particles of soil As this film becomes thinner (e.g when soil is drying out) the particles are drawn closer together to form groups (crumbs) The particles in the crumbs may come apart again if the soil becomes very wet There must be lime present in the water if clay particles are to tick together to form porous crumbs This partly explains why liming benefits the soils If organic matter or an iron compound (ferric hydroxide) is present then the particles in the crumbs may remain cemented together and have a more lasting effect on soil structure Too much ferric hydroxide can have a harmful effect because tightly cemented crumbs are very difficult to wet again after they have dried out Where there is very little organic matter or ferric hydroxide the stability of the crumbs depends mainly on the amount of clay present The more clay there is, the stronger will be the forces holding the particles together 10 Some soil structures are more stable than others, e.g clays usually have a more stable structure than silts Soils containing fine sand and silt easily lose their structures and are difficult to work if they are low in organic matter This is because under wet conditions the sand and silty materials flow very easily and block the aeration and drainage channels in the soil 11 Tilth is a term used to describe the condition of the soil in a seed bed For example, the soil may be in a fine-divided state or it may be rough and lumpy; also, the soil may be damp or it may be very dry Whether a tilth is suitable or not partly depends on the crop to be grown In general, small seeds require a finer tilth than large seeds Soil fertility and productivity 12 Soil fertility is a rather loose term used to indicate the potential capacity of a soil to grow a crop ( or a sequence of crops) The productivity of a soil is the combined result of fertility and management 13 The fertility of a soil at one time is partly due to its natural make-up (inherent or natural fertility) and partly due to its condition (variable fertility) at that time 14 Natural fertility has an important influence on the rental and sale value of land It is the result of factors which are normally beyond the control of the farmer, such as: The texture and chemical composition of the mineral matter, The topography (natural slope of the land) - this can affect drainage, temperature and workability of the soil, 64 Climate and local weather - particularly the effects on temperature, and rainfall (quantity and distribution) 15 Soil condition is largely dependent on the management of the soil in recent times It can be built up by good husbandry but if this high standard is not maintained the soil will soon return to its natural fertility level The application of fertilizers can raise soil fertility by increasing the quantities of plant food in the growth and decay cycle 16 Management can control the following production factors: The amount of organic matter in the soil Artificial drainage and irrigation Erosion (removal of soil by wind and water) pH of the soil and the plant nutrients applied Cultivations and time of planting Variety and plant spacing Sequence of cropping weeds, pests and diseases 17 Good management of the above factors should maintain or increase soil fertility and at the same time be commercially profitable II COMPREHENSION CHECK Explain in your own words the terms: Soil structure Soil texture What factors can change the structures of a soil? Can you explain what is meant by the „feel‟ of a soil? Can you explain why clay soils are harder to work than sandy soils? What is „tilth‟? What two factors decide the productivity of a soil? Can you explain the term „natural fertility‟? Explain in your own words why management of the soil can affect soil condition 65 FURTHER READING 4: WINDBREAKS When you design windbreaks you call on your knowledge of how forests function Well-designed windbreaks modify climate, reduce erosion, and hold water on land Wind is a fluid, and like water it can be deflected sideways or upwards It naturally forms into layers with hot air rising and cooler air flowing underneath You can use the natural characteristics of winds to achieve specific planting effects including: Suntraps Firebreaks/ fire-retardants Increased wind velocity (for energy) Erosion control Shelterbelts for stock Dust filtration Nutrient traps (wind and water) Every site has a predictable wind pattern Sometimes you can find this out from weather records; otherwise you will use your observations of how tree shapes are deformed (wind pruned) and the amount of wear on buildings Every windbreak should be designed to work many ways, and to yield a variety of products such as mulch, bee folder, animal browse, firewood and building timber It should be noted that a line of pine trees is not an efficient windbreak Once the lower branches fall off, the wind velocity under the trees is increased Also, the long black shadows cast by the trees reduce the land‟s productivity How windbreaks work There must be some movement of air through a windbreak or the wind forms into eddies, which can be quite destructive, on the other side of the barrier The principle is to create the equivalent of the forest “edge” which will lift the wind up and over the area you wish to protect The wind can then be “shaped” so it tapers off at the ends and wind velocity is reduced The most effective shape for a windbreak planting is a boomerang or parabola shape This allows the wind to be diverted around the site In addition these windbreaks work as suntraps 66 How to design your windbreak The design is based on the concept of succession You start off your windbreak with smaller-growing plants and nurse species which prepare the environment for the final (climax) species Plants with the following characteristics should be included in the windbreaks: Hardy species with deep anchoring root systems Plants with fibrous stems and fleshy leaves- these are more likely to be wind and fire resistant Plants with fast early growth, i.e pioneer species Nitrogen-fixing plants Self-mulching plants, i.e plants which have good leaf fall Windbreaks for orchards: Several parabola-shaped windbreaks can be planted in the orchard to protect individual trees or small groups of fruit trees Windbreaks for small areas: These are very important an need not be permanent For example, Jerusalem artichokes make an excellent summer windbreak or suntrap in cool climate- they may be just what is required to collect and focus sun on ripening tomatoes Even knee-high windbreaks, such as small hedges or herbs, can provide protection for plants growing nearby 67 FURTHER READING 5: TREE DISEASES A READING & COMPREHENSION I Reading text Trees, like people, are vulnerable to many diseases Like people, trees are attacked in various places by different kinds of diseases Forest pathology is the study of diseases of trees Some foes work on the main body trunk, some on the roots, and some on the leaves Vigorous trees are attacked less by diseases The older, weak trees or young seedlings that are struggling to become established trees are the most susceptible If a forest is managed correctly, seldom will disease be serious enough to require overt control Well-managed forests are healthy and comparatively devoid of disease Tree diseases are of two main types: nonparasitic and parasitic, often called environmental and organic The nonparasitic diseases are caused by drought, sunscald, winter injury as from heavy ice storm and snow, improper nutrition of the trees, air pollution by smoke and gases, flooding, and soil pollution The salt laid on the highways during winter months pollutes the nearby soil and in some instances kills trees Ocean spray, which feels so good on one‟s face, is a prime cause of disease in the coastal area This sea spray can be blown inland by hurricanes and result in tree damage far from the coast The parasitic diseases are caused by organisms that live within various parts of nutrients from it while contributing nothing to the well-being of the tree There are five groups of such organisms: viruses, bacteria, nematodes, mistletoes, and fungi Viruses cause minor gall, a condition known as witches-broom, and the serious phloem necrosis in elms and locusts A number of bacteria that are involved in many serious diseases of agricultural plants are of little importance in forest trees Nematodes, a group of parasitic worms, can be a problem for tree seedlings Mistletoes, parasitic seed-bearing plants, are widespread and cause serious damage, the dwarf mistletoes of the West in particular The most important cause of tree disease are the parasitic fungi Saprophytic fungi decay dead tree and are important in the recycling of nutrients within the forest ecosystem The parasitic fungi attack living trees and are serious problems in all forest regions Considerably more timber is lost annually to fungal disease than is lost to fire The life cycle of a typical fungus consists of two basic stages, the vegetative and the reproductive The vegetative stage begins with the germination of a spore, the fugal equivalent of a seed Out of the spore grown a microscopically fine hollow filament called a hypha, which penetrates into wood or foliage and grows very rapidly, branching and rebranching to produce a gossamer, interwoven network known as a mycelium These mycelia dissolve the tree‟s cell walls and convert them and the contents of the cell into food The second stage is the reproductive stage in which hyphae grow to the surface and produce fruiting bodies, which split and release spores to be carried away by the wind The form, 68 texture, colour, and location of these fruiting bodies are how most fungi are recognized Familiar examples are mushrooms and conks For convenience the fungal diseases can be sorted into three large groups: the foliage diseases, the stem diseases, and the rotting diseases Although widespread and of great importance in horticulture, foliage diseases are problems in forest trees only in that they can reduce the rate of growth of the infected trees Stem diseases can in turn be broken into three groups, the cankers, the rusts, and the wilts Among these are the epidemic diseases, which can result in rapid and widespread loss of forest trees The chestnut blight is an example of a stem canker diseases The American chestnut once was one of the most important and useful eastern trees Very widespread, it often accounted for as much as one half of the trees in many forest stands The fungus was introduced into New York probably prior to 1900 on imported Chinese chestnuts, and the native species had no resistance The windblown spores from an infected tree could travel great distances to enter tiny cracks or breaks in the bark of other chestnuts The stem is killed by girdling as the cambium is destroyed By 1950 a living noninfected chestnut tree was a rarity Today the American chestnut is no longer a viable species The potential threat of similar epidemics of exotic disease to other native species is source of anxiety for many foresters The Dutch elm disease is an example of the wilt disease This fungus, probably native to the Orient, was introduced into this country from Europe around 1930 The disease is spread by the elm bark beetle, which upon emerging from an effected tree is covered with spores When the insect burrows under the bark of an uninfected tree, it is effectively inoculated The fungus grows rapidly within the vascular tissue of the elm, and death is caused by physical blocking of the movement of moisture and nutrients to the foliage and perhaps by the production of a poison that kills living cells The spread of this disease has been rapid Many feel that the future of elms, particularly in the northern sates, is in jeopardy There are a number of serious ruts of fruit trees White pine blister rust and the fusiform rusts of the southern pines are the most important These rusts have an unusual and complex life cycle involving the infection of two widely different species of plants known as alternate hosts and the production of more than one type of spore The fungus moves from one host, species A, to a second host, species B, and then back to species A again White pine blister rust, another disease introduced from Europe, is and extremely destructive disease of eastern and western white pines and of sugar pine of California and Oregan Simply put, the disease is spread by the movement of spores from infected currant or gooseberry bushes to the needles of the pines The fungus moves from the needles into the phloem and cambium of limbs and stem The name is from the orange-yellow spore- filled blisters formed on the bark Whenever infection reaches the main stem the tree is doomed, for 69 destruction of phloem continues until the stem, no matter how large, is girdled Infection can be severe and often entire stands are killed The southern fusiform rust, which infects a number of the southern pines, has as its alternate host any of the numerous red oak species of the region While not as destructive as the white pine blister rust, this disease is of increasing concern to forest managers It is most virulent on loblolly pine, which is being intensively managed with costly site preparation and fertilization The rotting fungi, while they rarely cause death directly, are responsible for rendering great volumes of wood worthless There are two major types, the root-decaying fungi and the heart-rotting fungi The Fomes root rots typify the first category Though they attack a variety of species, they are most troublesome in eastern white pine and in plantations of the southern pines Working in the roots and butt of the tree, they weaken the tree, making it susceptible to windthrow, and reduce its growth The heart-rotting fungi destroy the nonliving heart wood of the tree and, aside from leaving it mechanically weaker, not otherwise influence its health and vigor The rotten wood of course valueless Spores of the heart-rotting must enter through breaks in the bark Once they have germinated, the disease develops very slowly, and rot is rarely a problem in young stands In the oldgrowth conifer forests of the West, a 50 to 60 percent loss of volume to rot is not common II Comprehension questions 1.What are trees vulnerable to? What does “ Forest pathology “ study? What parts of a tree can be attacked by different diseases? Which trees are the most susceptible to diseases? What are the two main types of tree diseases? What are the non-parasitic diseases caused by? By how many agent are the parasitic diseases caused by? How organisms destroy the trees? How are the organisms classified? 10 What does each type of organisms damage? 11 Which fungi are the most important cause of tree diseases? 12 What parasitic fungi attack? 13 What are the two basis stages in the life cycle of typical fungus? 14 What are the characteristics of each stage? 15 What are the large groups of the fungal diseases? 16 What are the groups of stem diseases? 17 What is the life cycle of the rusts like? 18 How these rusts regenerate and develop? 19 Which fungi make great volumes of wood worthless? 20 What are the two types of rooting fungi? 21 What root-decaying fungi attack and cause? 22 What heart- rotting fungi destroy? 23 How spores of the heart-rotting fungi enter the heart wood? III Vocabulary Find out the word that means 70 k the science that studies forest tree diseases l can be attacked m strong n easily affected by …… o enters p without q taking place r single cell by which a fungus reproduces itself s all t main Find out an appropriate word to fill the blank a These houses are …… ……… to storm b Next term, we will study forest ……………… …… c The …………… … diseases are caused by organisms d ………………… often destruct seedlings e ………………… fungi help the recycling of nutrients within the forest ecosystem f The vegetative stage of the life cycle of a typical fungus starts with the ………………of a spore g The rotting fungi ………… …… great volumes of wood worthless h The pain in his leg has been ……………………… i Due to over forest exploitation for export, several valuable tree species are in danger of ………………… j His speech ……………………… the thinking of the young generation B EXERCISE I Checking your understanding As a matter of fact, there are ……… …… tree diseases A four B some C a lot of D six ………… can be attacked by different kinds of diseases A Only the trunk B Only the leaves C Only the roots D All the parts of a tree Trees diseases fall in ………… …… classes A three B two C four D five Organisms that cause the parasitic diseases are of ……… …… Types A four B two C three D five 71 The life of a fungus undergoes ………………… periods A four B two C three D five ………… rendered great volumes of wood worthless A The foliage fungi B The stem fungi C The rotting fungi D None are correct Rooting fungi can be sorted in ………………….…… A three major groups B two major groups C four major groups D five major groups Heart-rotting fungi usually attack ……………… … A young stands B primitive forests C old stands D pine stands The most important cause of tree diseases are: A fungi & viruses B bacteria & nematodes C mistletoes D All of these are correct Reading text Read the text carefully and answer the following questions: For hundreds of years people have planted trees to serve the needs of future generations for timber and tree products In Europe and Asia forests were planted by rulers, church leaders and farmers – for the people By planting trees they particularly and symbolically showed faith and hope for the future Trees are fundamental to life and the processes that maintain healthy soil, and clean air and water There is evidence which shows that in regions where the trees are cleared to less than 30% of their original surface area, other sustainable life processes begin to collapse Rivers silt up, soils wash away, and air quality declines James Lovelock, a renowned ecologist, claimed these breakdowns in natural systems will in turn affect other word bioareas continent or cyclones may occur more frequently It will be sad if these things happen before we change from consumers to producers What people plant trees for? What European and Asian people want to show by planting trees? What are fundamental roles of trees? What will happen to the area when the trees are cut down? 72 REFERENCES Lê Thị Thanh Chi 2004 A course of English for students of agricultural extension and rural development Võ Thị Kỳ 2001 English in agriculture for students of animal husbandry Nguyễn Văn Tú.1992 English for forestry students NXB Đại Học Quốc Gia Hà Nội, Hà Nội Stephen Denny, Lewis Kerr, Martin Phillips, Clarence Shettlesworth 1985 Science and technology: Agriculture Longman, Hongkong Rosemary Morrow 1993 Earth user‟s Guide to Permaculture Kangaroo Press, Australia C St J Yates 1990 English for academic purposes series: Agriculture Oxford, England www.fallrivertrees.org www.dnr.state.oh.us/forestry www.woodlands.co.uk 73 THÔNG TIN CÁ NHÂN HỌ VÀ TÊN: TRẦN PHẠM MINH ĐỨC NGÀY SINH: 12/04/1968 NƠI CÔNG TÁC: ĐẠI HỌC NGOẠI NGỮ NĂM TỐT NGHIỆP ĐẠI HỌC: 1991 NĂM TỐT NGHIỆP CAO HỌC: 2001 TRÌNH ĐỘ: THẠC SỸ - GIẢNG VIÊN CHÍNH ... (paragraph 1) types (paragraph 2) definite (paragraph ) accurate (paragraph 1) the same (paragraph 1) sawn wood (paragraph 4) 20 before (paragraph 2) easily to be seen, bought (paragraph 1) classified... Look at paragraph again What words have the opposite meaning to: straightforward; easy to understand as an exception Look at paragraph again Can you explain the words: hard hardwood hard softwood... than a balsam? 10 When is the root system inadequate to anchor a tree? III Vocabulary Look at the first paragraph again What words have the same meaning as: well-informed main, most important