Plant Ecology PDF

PLANT ECOLOGY introduction environmental factors Ecosystem plant vegetation Human effect in ecosystem  Alternate relationship water land plants animals air micr...

PLANT ECOLOGY introduction environmental factors Ecosystem plant vegetation Human effect in ecosystem  Alternate relationship water land plants animals air microrganisms  Plant Ecology Is the scientific study of the relationship between plants and their environment Alternate relationship Note that The term ecology has been drived from the Greek words : Eikos, meaning house and logos, meaning "the study of ". This denotes the study of the relationships between organisms and their natural surroundings.. Branches of plant ecology There two main types of plant ecology:- A) Autoecology, including the study of certain plants (each separate) in their natural habitats to indicate the effect of environmental factors on the plant. B) Synecology (Phytosociology), including the study of plant societies in an area to elucidate their structural members, their origin, their development, and to detect the various factors affecting these societies and controlling their distribution Draw  Relationship between plant ecology and other branches of Botany The field of plant ecology is closely related to other branches of Botany is well as to some branches of science. Such branches may be summarized as follows ; 1.Morphology and Anatomy: This is because morphology and anatomy of plants is usually linked with environmental changes. Deviation of morphological or anatomical feature of a plant is mostly a mean of adaptation to environmental conditions. 2.Physiology: It forms a necessary, background to the ecologist since physiological processes are widely affected by ecological factors (as osmotic pressure ; transpiration ) 3.Taxonomy: The ecologist must have a grasp of the classification and structure of plants in order to identify and draw actual idea of a society or a member in the region under study..  4.Meteorology: In order to give full explanation concerning certain, plant society or ecological study, meteorological conditions must be recorded accurately. 5.Pedology: This includes the study of soil conditions which affect the growth of roots of plants and represent their source of minerals and later. If soil nature is not favourable, plant growth is impossible. 6.Hydrology: This branch of science is quiet important for ecological studies particularly with studies on hydrophytic plants where the depth of water, water currents means of irrigation, ground water...etc. are different factors to be recorded. 7.Topography: Topography includes the study of differences in altitude and depth of soil surface. This factor affects widely, the growth of plants due to clear differences of high regions from lower ones. When certain region is ecologically studied, a topographic map is constructed to participate in illustrating full idea In pla  8. Geography : In plant geography , the distribution of plants among the world or within certain region is studied. This branch of science provide also ideas concerning the origin of different plants of the world and their classification into kingdoms , provinces , and phytogeographical regions. 9. Geology : The study of layers of earth and its effects on plants within certain region. On the other hand , the study of old layers and formations of earth helps in elucidation of old plants and study of evolution Definition of environment : this means All factors that affect plants ( growth, reproduction ,………etc ) so this factors named environmental factors - But habit or habitat refers to the location in which a plants live  Environmental factors Environmental factors could be classified into: *Climatic factors *Edafic factors *Physiographic factors *Biotic factors  Climatic factors These factors include: temperature, light,, wind, humidity, and evaporation These factors affect the plant life directly and indirectly. They are influenced by other environmental factors. Also, the climatic factors affect other environmental factors. Light and temperature factors are the most important factors playing an important role of plant life Climatic factors  Number of chloroplasts formation position of of chloroplasts chlorophyll Light The plants divided into types according to light as follow:- 1- Sun plants (that grow under sunlight directly) 2- shade plants(that grow under sunlight indirectly)  plants grow under sunlight grow under indirect sunlight directly  Environmental factors Environmental factors could be classified into: *Climatic factors *Edafic factors *Physiographic factors *Biotic factors  1- Climatic factors These factors include: temperature, light,, wind, humidity, and evap These factors affect the plant life directly and indirectly. They are influenced by other environmental factors. Also, the climati affect other environmental factors. Light and temperature factors are the most important factors playing an role of plant life Climatic factors  Temperature The temperature of plants follow to its growth media The plant divided into - Shoot system ( this follow to air temperature) - Root system (this follow to soil temperature) The shoot system is the most exposure to the different environmental factors , So it is the most change in temperature than the root system Effect of temperature on plant In general - All metabolic processes increase by increase plant temperature As (germenation , growth , reproduction, transpiration,) - Each plant has heat range to grow ,the heat range is between minimum temperature and maximum temperature Shoot system Root system Before (min.t) and above ( max.t )the plant growth stopped , this process tack place gradually The best growth tack place at optimum temperature Show the growth curve as follow. growth 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.5 1 1.5 2 2.5 3 temp3.5 Effect of Temperature on Transpiration There are 2 main types of transpiration:- 1- Stomatal transpiration This tack place in natural condition of temperature The water vapor exit from plant stomata ,that present on plant leaf 2- Cuticular transpiration This tack place at high temperature In This case most stomata are closed to decrease the transpiration.And the ratio of Cuticular transpiration more than Stomatal transpiration and vice versa Stomata  Light Light is one of the most important factors affecting the growth of plants and the development of the vegetation. The sun is the main source of light and energy for plant - Light affect the formation of chlorophyll - and the number and position of chloroplasts. In high light density the number of chloroplasts are decreased and vice versa. In low light density the chloroplasts become near the leaf surface and vice versa.  Number of chloroplasts formation of position of chlorophyll chloroplasts Light The plants divided into types according to light as follow:- 1- Sun plants (that grow under sunlight directly) 2- shade plants(that grow under sunlight indirectly) grow under sunlight grow under indirect sunlight directly The characters of plants grown under full sunlight Morphologic features: 1-Thicker stems with developed xylem and supporting or mechanical tissues than shade plants 2-Shorter stem 3-Small leaf 4-More branching than shade plants 5-Smaller cells in leaf blades which usually result in: a) usually smaller but thicker leaf blades b)stomata closer and close together c) Smaller vein islets d) More hairs per unit area, provided the leaves are pubescent 6-Thicker cuticle and cell walls 7-Chloroplasts fewer and smaller 8-Better developed palisade, which frequently occur on both sides of the blade. 9-More weakly developed sponge mesophyll 10-Smaller intercellular spaces. 11-Greater ratio of internal to external leaf surface. 12-Lateral walls of epidermal cells less wavy. 13-Roots longer and more branched with a higher ratio of roots to shoots. 14-Greater dray weight Physiologic features: 1-Usually a lower chlorophyll content and leaves greenish yellow. 2-Higher photosynthesis rate per unit surface in bright light but a lower rate weak light. 3-High respiration rate and consequently high compensation point. 4-Lower percentage of water on a dry weight basis. 5- More rapid transpiration. 6-Higher salt content , sugar content and therefore higher osmotic pressure. 7-High carbohydrate /N ratio Low K, ca and p content Greater Vigor of flowering and Fruiting. Earlier appearance of flowers.Greater resistance to temperature injury, drought and parasites.  HUMIDITY The moisture of the air which is in the form of vapor is termed humidity. Types of humidity There two types of humidity:- 1- Absolute humidity The actual amount of water present in the air is called the absolute humidity. It is expressed as grams per cubic foot or grams per cubic meter of air. The amount of water vapor in the atmosphere taken by itself does not determine the dryness or wetness of a climate. e.g Humidity is 50 g / m3 This is not determine the dryness or wetness of air 2- Relative humidity This is the ratio between 𝒕𝒉𝒆 𝒂𝒎𝒐𝒖𝒏𝒕 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝑰𝒏 𝒂𝒊𝒓 (𝒂𝒕 𝒄𝒆𝒓𝒕𝒂𝒊𝒏 𝒕𝒆𝒎𝒑𝒆𝒓𝒂𝒕𝒖𝒓𝒆𝒂𝒏𝒅𝒄𝒆𝒓𝒕𝒂𝒊𝒏 𝒑𝒓𝒆𝒔𝒔𝒖𝒓𝒆) 𝒕𝒉𝒆 𝒂𝒎𝒐𝒖𝒏𝒕 𝒐𝒇 𝒘𝒂𝒕𝒆𝒓 𝒕𝒉𝒂𝒕 𝒏𝒆𝒔𝒔𝒆𝒔𝒂𝒓𝒚 𝒇𝒐𝒓 𝒂𝒊𝒓 𝒔𝒂𝒕𝒖𝒓𝒂𝒕𝒊𝒐𝒏 𝒂𝒕 𝒕𝒉𝒆 𝒔𝒂𝒎𝒆 𝒄𝒐𝒏𝒅𝒂𝒕𝒊𝒐𝒏 e.g 50 × 100 = 50 % 100 This means that 50 %of air molcules size is filed with water By this type we can determine the dryness or wetness of air Factors affecting humidity There 2 main Factors affect humidity Temperature Wind By increase temperature the humidity is By wind the adjacent air is decreased and vice versa removed and new air occupy this area Dry wind Wet wind By dry wind the By wet wind the humidity is humidity is decreased increased Effect of humidity on transpiration By increase. humidity the transpiration is decreased and vice versa ‫رسم نبات وحول جزيئات هوااء وهبوب رياح رياح رياح ربة واخرى جافة‬  EVAPORATION Exit of water from any surface (as s0il ,sea , ………) Special case Water out from plant is named transpiration There are main factors affect evaporation or transpiration as temperature , humidity and transpiration.  Wind Wind is motion (moving) air Effect of wind on plants - ve effect + ve effect - (harmful) (useful) Wind pollination Harmful influences (effects) of wind 1-Desiccation 6- Erosion and deposition 2-Dwarfing 4-Abrasion 3-eformation 1-Desiccation When the plant exposed to wind the transpiration increased. This wind characterized with : 1- drying wind 2- Continuous for long time 3- After mature stage With Continuous of transpiration this plant retches to wilting state ,and gradually may be die 2-Dwarfing When the plant become in subnormal size , this plant named dwarf plant, this is due to : The dwarf plant cells never reach to complete hydration, and hydration, and consequently of turgidity, So this dwarf plant cells never expose to complete turgid pressure on inner surface of cell wall , not complete cell expanding tack place. By repeating this process the cells never reache to the normal sizes, so after maturing this plant remains in subnormal size wind characters 1- drying wind 2- Continuous for long time 3-blow before mature stage Not that : In normal plant by repeating of hydration, and turgidity this plant reaches to the normal size  Normal plant Turgid pressure _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ -- _ _ _ _ _ _ Hydration Normal size (turgidity) Cell expanding (final size) Before maturing stage  Dwarf plant Plant cell _ _ _ _ _ _ _ _ _ _ _ _ _ __-__ _ _ _ _ _ _ (3) (1) (2) Subnormal size (final size) After maturing stage 3-Deformation Change of shoot system form and position This tack place when the plant exposed to : 1- strong wind 2-Blow ( come ) from constant direction 3- For long time This wind act as force  4-Abrasion When wind carries particles of soil or ice, it act as abrasive force and removes the outer layer of plant Effect of this wind Leaves Stem ArK and buds are Cutting zone on Stomata are closed eroded away woody plant By Pores in leaves removing the outer layer of trunk Leaves cutting gradully forming pits 6-Erosion and deposition. Erosion Removing of outer layer of soil (gradually ) by strong wind. So the root may be exposed to all environmental factors specially the light factor As a result of this death of root tack place. Deposition The soil particles transfer from place to anther place by strong wind. And deposit on anther plants These plants must be weak plants as ( herbs , seedlings )  Edafic factors The edafic factor include all physical and chemical properties of soil affecting plants growth - The physical properties as (soil texture, profile, moisture ,...etc. ) - The chemical properties as( organic matter, soil reactions, mineral content...etc.. Plant communities that are mainly affected by edaphic factors are referred to as "Edaphic plant communities." Examples are "saline communities" where edaphic factors become limiting to plant growth. These plants are usually characterized by special morphological and anatomical features as well as physiological properties. importance of soil 1 - Fixation Plants are fixed via their roots in soil. Roots branches in different directions 2. Supplying plants with water and mineral salts. Water and mineral salts are absorbed from soil. Both are utilized in the different biochemical activities of plants. 3. Supplying Plants with organic matter. Soil is the source of organic matter required by plants. The percent of organic matter increases with increase in density of vegetation. The highest value of organic matter is recorded in forests due to increase of plant remains. The reverse is true in desert regions which are poor in vegetation. 4- Soil as a medium of root-respiration Soil is the medium of respiration of plant roots. Consequently, aeration of soil is one of the important factors controlling the growth of plants. For this reason, the porosity of soil is too important since it controls soil acration. So, loamy soil is most suitable for the growth of roots.  Origin of Soil There are mainly two types of soil which are different in origin. 1. Residual soil Consisted of the original rocks of the same place by disintegration. In this case, original rocks disintegration must be subjected to long weathering factors. 2.Transported soil This soil is not formed in the same place but transported from another place where the rocks have been exposed to disintegration. Transportation may be achieved by one or more of the following factors as:( wind – water -. Gravity ) Not that :- Residual soil has the same chemical composition of original rocks but transported soil has not the same chemical composition of original rocks Not that :- Residual soil has the same chemical composition of original rocks but transported soil has not the same chemical composition of original rocks Residual soil Residual soil Original rock  Soil Formation Soil is formed from the outer layer of earth’s crust There are 2 main processes of soil formation as follow: 1. Disintegration (Mechanical processes) Soil is formed by physical processes (forces) or by (weathering factors) disintegration processes alter the shape and size of rocks and without affecting their chemical composition. physical processes are:- a-. Temperature changes: a rock composed of different minerals If these minerals heated and Cooled this leads to changes of the minerals volume due to contracting and expanding of minerals Thus repetition of changes in temperature during the day and night and allover the year (in different seasons) causes disintegration b-. Water effects: Water falls, rains, glaciers sea-waves... etc. are main factors causing physical erosion). Some rocks are porous so they imbibe water and increase in volume leading to imbibitional pressure. By repetition of this process causes disintegration they imbibe rain-water and increase in volume causing splitting and decay. In general this water leads to changes in rock temperature so this is an important factor in disintegrating process. This water leads to rock wetting , after time this rock become drying so contracting and expanding tack place, respectively So Small cracks are formed , and By repetition of this process the rock disintegration tack place (part of rock split and fall down) c-. Wind and Volcanoes: Wind and volcanoes are considered among the physical factors carrying out disintegration 2. Chemical Processes of soil formation (decomposition) Processes which change the chemical composition of soil material are termed the chemical forces of weathering. Such changes are.The most active chemical forces are considered as follows:- A. Oxidation: The atmosphere includes about 20% oxygen. An example is the oxidation of ferrous iron in a mineral into ferric iron where CO₂ is split off: 4FeCO3 + O₂ → 2Fe₂O3 + 4CO₂ B. Reduction: It occurs when the supply of oxygen is Quite limited. Therefore, the most suitable conditions of reduction are at lower depths in the carth's crust. Also under poorly drained conditions where aerations limited. The evolution of CO₂ from rapidly decaying organic matter may also result in reduction due to lowering oxygen supply. C. Hydration: This is the union of water with soil minerals as shown below: 2Fe₂O3 + 3H₂O → 2Fe₂O3.3H₂O Other compounds like SiO2, AL₂O3 and aluminosilicates, as well as organic substances become hydrated. c. Hydrolysis: This process goes on extensively with minerals containing strongly basic elements, parts of which are exchanged for Hi thus, Ca SiO3 + 2H.OH → H₂SiO3 + Ca (OH)2 Calcium silicate Silicilic acid Formation of such acids or the change in structure of elements aids in rock-dissociation and soil development.  d. Carbonation: This process results from the combination of CO₂ with bases in soil forming carbonates and bicarbonates. CO₂ results from the decomposition of organic matter in the soil and the respiration of plant roots. Examples are shown in the following: Ca(OH)2+ 2C02 → Ca (HCO3)2 2KOH + CO2→ K2CO3 +H20 f. Solution: Acids may be formed in soil as a result of chemical and biological processcs. These acids are more effective than water in the decomposition of rocks and minerals.  Soil Organic Matter (Humus) An essential difference between fertile soil and unfertile soil is that the former contains some organic matter: The nature of soil humus: Soil Humus (Soil Organic matter) - Is the end product, of organic matter decomposition. -Humus is dark colored organic compounds resulting from plant and animal organic matter -Humus is resistant to decomposition (humus decomposition is very slow an difficult) because it formed from long branched chains. Complex chain - Simple chain long &branched chains Composition of humus High ratio of Lignin about ( 40- 45 % ) High ratio of proteins about ( 30 – 35 % ) Small ratio of elements as p , k, ca , Al , Mg ,……) Lignin and proteins form a new complex that resists decomposition by microorganism. Importance of humus - Source of N in soil because it contains proteins in its composition - Humus increase the water holding capacity of soil , because it contains colloids - Humus increase the soil aeration , due to aggregation of fin soil particles to each other ( by colloids ) forming compound particles leaving (forming ) large spaces between the soil particles.  Soil Texture The physical properties of soils are dependent mainly on the particle-sizes So , study 0f size of soil particles is very importance , this tack place by mechanical analysis of soil There are many method of soil mechanical analysis , one of this method is sieves method sieves method In this method : - Set of sieves are arranged in descending arrangement - The soil is put in the upper sieve - By this method the soil particles are separated into groups according to its soil particle sizes. The main groups are gravel , sand , Silt , Clay Determining the % percentge of each group Soil Particles Diameter (mm) Coarse gravel more than 2.00 ** Fine gravel 2.00 - 1.00 Coarse sand 1.00 - 0.50** Medium sand 0.50 - 0.25 Fine sand 0.25 - 0.10 Very fine sand - 0.10 - 0.05 Silt 0.05 - 0.002** Clay less than 0.002 ** Soil separates range between coarse gravels, of large sizes, and fine particles which are difficult to be shown by microscopes. Note that :- - gravel and sand are named large particles - gravel and sand have no colloidal properties. Therefore, they are not active in absorption of water or soluble nutrients - Silt and clay are named small particles - Silt and clay have colloidal properties. Therefore, they are active in absorption of water or soluble nutrients The soil divided into the 3 main types of soils (according to Soil Texture) types of soils Mud soil Sandy soil Loamy soil  Effect of Soil Texture on its Features 1.Water holding capacity In soil with high ratio of fine particles ( colloidal particles) can absorb high amount of water (around them as fin film or soluble nutrients by strong surface force , and vice versa In soils with high ratio of large particles these particles have no colloidal properties so the water around these particles leached in case of sandy soils draw 2- Infiltration of water Rain water represents the main source of water in soil. The ability of soil to capture water is dependent on texture. Thus most of rain water penetrates sandy soil ( light soil ) ; and infiltration of water is relatively Rapid and easy whereas in heavy clay soil infiltration of water is relatively difficult and slow causing great loss of water by run-off and evaporation from surface area. 3- Fertility Soil containing relatively large amounts of fine particles (clay specialy) is more fertile than sandy soil with coarse (large ) particles. This is because ions required for plant growth and development are adsorbed at the surfaces of clay particles. This explains why the fertility of soil is increased with increase in the percentage of clay particles 4-Mechanical resistance to root penetration Heavy soil consisted of high content of fine and clay particles is most resistant to penetration by roots of plants. Heavy soil contain narrow pores and cementing layer. light soil is, on the other hand, less resistant. This explains the retarded penetration and branching of root systems of plants in heavy soil. So , root system is more longer branching in sandy soil and vice versa in mud soil.  6- Rate of water movement in soil: Movement of water in soil is no doubt dependent upon the texture of soil. It is logic that the rate of water movement reaches in maximum in sandy soils with loose particles. This explains the point that successful plants on sandy soils are those with long roots reaching the deeply accumulated water Determination of water Infiltration time in soil. - In sandy soil , rate of water movement is maximum (hours) - In mud soil , rate of water movement is minimum ( days ) - In loamy soil ; rate of water movement is moderate rate 5- Soil aeration: Aeration is increased with increase in large particles or in soils where fine particles aggregate in large particles. This is due to the fact that large particles include within large air spaces which facilitate the release of CO2 resulting from respiration of roots and microorganisms and its substitution with (replacing by ) fresh air containing oxygen. So , sandy soil is good aeration. The reverse is true in heavy soils with bad aeration.  Soil Profile a vertical section in soil shows that different layers are present with different forms. Such section is termed "Soil Profile"; whereas the different layers are called horizons Soil is consisted of particles of different sizes, different chemical structure and solubility These properties of soil particles may be changed by other factors which are mainly climatic and biotic. For example in rainy countries calcium carbonate is dissociated and soluble salts are leached down with rain water from upper to lower layers of soil. Relatively fine clay particles may be brought also to deeper layers by rain water. Therefore,. The horizons can be differentiated as follows:  A. Zone of extraction (horizon A) It is the 'upper, surface layer characterized by: 1- Particles with large sizes relatively. This is due to Relatively fine clay particles may be brought to deeper layers by rain water 2- Poor in soluble substances(salts). This is due to the soluble salts are leached down with rain water from upper to lower layers of soil. 3- Root penetration to this layer is easy. Because of most Particles with large sizes 3- Its particles usually aggregate in the form of compound particles. This is due to presence of disintegrated organic matter al this layer which results from the decay of the remains of plants and animals. Such organic matter is colloidal in nature causing aggregation of soil particles. For this reason the roots of plants can easily inter this layer  B.Zone of concentration (horizon B) It is the following lower layer to horizon (A). In this layer fine clay particles, and soluble salts, leached down with rain water ,are accumulated. Therefore , soil particles are more compact ; ( duo to presence of is colloidal substances So the layer resist penetration and branching of roots as compared with root growth at horizon (A). However, it must be noted that horizons (A) and (B) represent the soil layers occupied by plant roots. C. Zone of weathered parent material (horizon C) This layer is consisted of the parent rock material which is usually disintegrated by decomposition and weathering factor. D.Bed-rock zone (horizon D) This layer is consisted from the original rocks draw  Water Content of Soil Soil-Water Soil-moisture Water is a vital factor for living organisms because it the main constituent in all biological approxmatly ( germination , germination , protoplase , …… etc ) Classification of Soil Water Soil-water can be divided into four types: 1. Gravitational water: It is water occupying non-capillary pores; which is leached down with gravity. After rain-fall or irrigation soil the capillary non capillary pores filed with so this soil becomes saturated with water Then (gravitational water) passes down rapidly and after short time all (gravitational water) leached down. these non capillary pores filled with air which play an important role in soil aeration. If gravitational water was faced by a solid layer of soil it is accumulated on this solid layer forming free water table or (ground water) In general, free water table is deep, far from soil surface so that absorption of gravitational water by plant-roots is either impossible or limited. 1. Gravitational water: It is water occupying non-capillary pores; which is leached down with gravity. After rain-fall or irrigation soil the capillary non capillary pores filed with so this soil becomes saturated with water Then (gravitational water) passes down rapidly and after short time all (gravitational water) leached down. these non capillary pores filled with air which play an important role in soil aeration. If gravitational water was faced by a solid layer of soil it is accumulated on this solid layer forming free water table or (ground water) In general, free water table is deep, far from soil surface so that absorption of gravitational water by plant-roots is either impossible or limited. 2. Capillary water: This represents relatively large amounts of water that present in capillary spaces (fine spaces) between the fine soil particles and as thin films surrounding the particles that absorbed by the soil colloids. So , infiltration of capillary water is difficult and slow. This water is available to plants It must be noted that: the amount of capillary water differ according to the type of soil. Thus, highest amount is recorded in heavy clayey (mud ) soil and lowest values in light sandy soil. 3. Hygroscopic water: It represents the relatively small amount of moisture (water vapor) absorbed by dry soil from the atmosphere. It is held so tightly by the soil colloids H w present as thin film (layer) around soil particles , These soil particles held this water by strong force due to soil colloids. This hygroscopic water libarated at 105 This type of water released at high temperatures reaching 105° C. So it is unavailable to plants. The amount of hygroscopic water varies with variations of humidity and temperature. Thus it is higher in cold- humid weather, relatively low in humidity. And decreases in hot climates and vice versa. 4. Combined Water: It represents water of crystallization of certain mineral salt. as oxides of silicon, aluminium, and iron. This type of water cannot be released even at high temperatures reaching 105° C. ‫ جزىئات ماء) حديد متمىأ‬3 ‫مثال الفريك زائد ماء بتدى يلورة (حديد ح و‬ In addition to the above mentioned types, water may be also present in gaseous state as water vapor in the air occupying the pores between soil particles, as air component  Topographic factors physiographic factors These factors are controlled by the topographic features and the geological formation. They include: altitude, slope, exposure, silting and erosion. Through their influence on the other environmental factors, specially climatic and edafic factors forming local climate so particular habitat is formed in general habitat the physiographic factors play an important role in the distribution of vegetation, its density and the kind of plants growing in a particular habitat. e.g  Topographic factors physiographic factors These factors are controlled by the topographic features and the geological formation. They include: altitude, slope, exposure, silting and erosion. Through their influence on the other environmental factors, specially climatic and edafic factors forming local climate so particular habitat is formed in general habitat the physiographic factors play an important role in the distribution of vegetation, its density and the kind of plants growing in a particular habitat. e.g particular general particular habitat has habitat habitat General climate  Biotic factors Effect of living organisms on another organisms Green plants are influenced by other organisms.. Though the physical environmental factors affect the plant life to a great measure, one organism may affect another organisms by modifying the physical environment. ( indirect effect) As example, shading of small herbs by shrubs and trees modifies the environment of these herbs. Some other biotic influences are clear, e.g. grazing, animal pollination and animal dissemination. Organisms living together have alternate relationships to each other and to their environment.  Biotic factors Effect of Plant on plant Animal on plant -shading of small herbs by shrubs and trees 1- animal pollination modifies the 2- grazing environment of these (The animals feed on plans) herbs Increase in light density , Increase in humidity , decrease in temperature So , disappearance of these herbs and appearance of new types gradually (This indirect effect)  Ecosystem Defination Components of ecosystem : All ecosystems divided into Components according to function or stracure ( A ) Components of ecosystem according to its function. have two basic components: (1) Autotrophic component, and (2) Heterotrophic component. The autotrophic components can prepare and its food from simple inorganic substances in presence of source of energy via photosynthesis process. As green plants ,algae , hydrophytes The heterotrophic component cannot prepares its food from simple inorganic substances and take its food from autotrophic, rearranges it and finally decomposes the complex organic materials into simple inorganic forms. As , all animals fungi. In the forest ecosystem, the autotrophic metabolism is maximum in the canopy and in the water ecosystem it is in the surface water where mostly autotrophs are concentrated because of maximum availability of light. The heterotrophic activity is maximum in the lower layer where organic matter accumulates. In the land ecosystems the heterotrophic stratum is the top layer of soil and in aquatic ecosystem it is the bottom sediments.  (B ) Components of ecosystem according to its structure. The ecosystems have two basic structural components. These are as follows: ( 1) Abiotic components (2) Biotic components: (a) Producers (b) Consumers (c) Decomposers  (B ) Components of ecosystem according to its structure. The ecosystems have two basic structural components. These are as follows: ( 1) Abiotic components (2) Biotic components (a) Producers (c) Decomposers (b) Consumers consumers: a)Primary consumers These are mainly herbivorous animals that feed on producers or green plants. Such as, Insects, , rabbit, deer, cow, buffalo, goat are some of the common herbivores in the terrestrial ecosystem, and small crustaceans mollusca ,fish etc. in the aquatic habitat. (b)Secondary consumers: These are carnivores and omnivores. Carnivores are flesh eating animals, that are consume herbivores. Omnivores are the animals that are consume herbivores as well as plants as their food. Examples of secondary consumers are sparrow, crow, fox, wolves, dogs, cat, snakes etc. Draw of food chan  (c) Tertiary consumers: These are the top carnivores which prey upon other carnivores, omnivores and herbivores. Lions, tigers, hawk, vulture, etc. are considered as tertiary or top consumers. Anther types of consumers Parasites, scavengers and saprobes are also included in the consumers. The parasitic plants and animals utilize the living tissues of different plants and animals. The scavengers and saprobes utilize dead remains of animals and plants as their food  Decomposers and transformers. Decomposers and transformers are the living components of the ecosystem and they are fungi and bacteria. Decomposers attack the dead remains of producers and consumers and degrade the complex organic substances into simpler compounds. The simple organic matters then are attacked by another kind of bacteria, transformers which finally change these organic compounds into the inorganic forms that are suitable for reuse by producers or green plants. The decomposers and transformers play very important role in maintaining the dynamic nature of ecosystems Draw decom &trans  Fundamental (principal) steps in the operations of ecosystem The principal steps in the operation of ecosystem are as follows: (1) Reception of radiant energy of sun. (2) Manufacture of organic materials from inorganic ones by producers. (3) Consumption of producers by consumers and further elaboration of consumed materials. (4) After the death of producers and consumers, complex organic compounds are degraded and finally converted into such forms that are used by producers. ► The principal steps in the operation of ecosystem not only involve the production, growth and death of living components but also they influence the abiotic aspects of habitat. ► It is now clear that there is a transfer of both energy and nutrients from producers to consumers and finally to decomposer and transformer level. In this transfer there is a progressive decrease of energy and cycling from abiotic to biotic and vice versa. ►. The two ecological processes, energy flow and mineral cycling between biotic and abiotic components lead to dynamics of ecosystem.  MAJOR ECOSYSTEMS There are two major types of ecosystems. 1- Terrestrial ecosystem , operates on the land habitat. 2- Aquatic ecosystem , operates in the aquatic habitat. Terrestrial ecosystem divided into the following types: (1) Forest ecosystem. (2) Grassland ecosystem. (3) Desert ecosystem. Aquatic ecosystems divided into the two types (1) Fresh water ecosystems,as (river lake,pond) (2) Marine ecosystems,as ( sea, ocean ) Aquatic ecosystems divided into the two types (1) Fresh water ecosystems,as (river lake,pond) (2) Marine ecosystems,as ( sea, ocean )  Food chain chain, producers represent the first trophic level, herbivores represeThe producers and consumers in ecosystem can be arranged into several feeding groups, each known as trophic level ( feeding level). In Food nt the second trophic level, primary carnivores represent the third trophic level and top carnivores represent the last level. In the ecosystem, green plants alone are able to trap in chemical energy is stord in the various organic compounds, such as carbohydrates, fats and proteins, present in the green plant solar energy and convert it into chemical energy. the green plants is utilized by herbivores. Then herbivores eaten by carnivorous animals. In. Thus, food from one trophic level reaches to the other trophic level and in this way a chain is established. This is known as food chain  Food chains are of three types: 1- Predator chain: which starts from plant and goes from smaller to larger animals. 2- Parasitic chain: it goes from large to smaller organism. 3- Saprophytic chain: it goes from dead matter to microorganisms  Food web Many food chains exist in an ecosystem, in fact, these food chains are not independent. In ecosystem, one organism does not depend wholly on another (one type only. I.e the one organism may feed on more than one kind of food. the one organism are eaten by diffrrent variety of consumers. The marsh plants are eaten by variety of insects, birds, mammals and fishes. and some of the animals are eaten by several predators. grasses → mouse → snakes → owls, some times mice are not eaten by snakes but directly by owls. so types of interrelationships and interlinks between individuals tack place.. In this way, food chains become interlinked. So complex of interrelated food chains are formed ,forming food web. Food web maintains the stability of the ecosystem. Draw food web  Vegetation Vegetation is the sum total plants covering an area. e.x Vegetation conssist of basic units Each basic unit of vegetation is called plant community  PLANT COMMUNITY Plant community is the basic unit of vegetation Plant community is group of plans that persent in the same habitat and its growth controlled by the same environmental conditions Plant community orders: (1) Plant formation (2)Association (3) Consociation (4) Societies (1) Plant formation Plant formation is, a group of plans that presnt in the same habitat,and its growth controlld by climatic factors or edafic factors. Plant formation is characterized by the life form of dominant plants ( vegetative form or the shoot system) Types of plant formation : -a) Climatic plant formation -b) Edafic plant formation -a) Climatic plant formation The growth of this plants contrroled by climatic factors E.X of climatic plant formation 1 ) Evergreen tropical rain forest This is characterized by:- Life form (l.f ) - high trees , and evergreen all the year Climate - Very high Temperature - high amount of rain all the year 2)Summer deciduous forest This is characterized by:- Life form (l.f ) - high trees with large leaves.and with deciduous leaves in summer Climate - Cold Climate 3) Needle leaf evergreen forest (coniferous ) This is characterized by:- Life form (l.f ) - high trees with needle leaves. Climate - Very cold Climate 4 ) Savanna formation This is characterized by:- Life form (L.f ) -very tall grasses, about (7 -5 ) meter Climate - high Temperature - high amount of rain 5) Desert formation This is characterized by:- Life form (l.f ) -herbs , subshrubs. Climate - very high Temperature in day -very cold in night -very low amount of rain -b) Edafic plant formation The growth of this plants controlled by edafic factors E.X of climatic plant formation  1) Reed swamps This is characterized by:- Life form (l.f ) -Reed plants with long stem , linear leaves Soil properties -soil covered wit shallow water 2) Sand dunes This is characterized by:- Life form (l.f ) -Small and little herbs Soil properties -soil contain very low amount of water ( the water infiltrated rapidly ) Salt marshes This is characterized by:- Life form (l.f ) -Small and little subshroubs - small leaves covered with salt Soil properties -soil contain high amount of salt Associatoin The plant community divided into sub order that named associatoin Each associatoin characterized by more than one dominant species -Determine the dominant species in and subordinate species in plant community -Each associatoin is named by name of dominant species -the dominant species that have the largest numbers of indevidules Example dominant species ( Oak ,Beach ) subordinate species ( Typha ,Cyperus,…….etc ) Oak ,Beach associatoin Consociatoin If plant community contain one dominant species only this named consociatoin Societies -Determine the subordinate species , then determine the dominant species in this group. Each associatoin is named by name of dominant species. If dominant species is (Typha) This named Typha society  STUDY OF PLANT COMMUNITY STRUCTURE Meth0d of vegetation analysis To STUDY OF PLANT COMMUNI ty we study the plant species at different places in this area Each plasce named sample area or sample plot Methed of vegetation analysis There are several methods have been used by ecologists for this purpose which are as follows: (1) Quadrate method (2) Transect method (1) Quadrate method In this method the sample plot is determind as square **Kinds of quadrats: Quadrats are named according to the use. These are of the following types: (i) List quadrate - Name of species that present in sample –plot are determined - Then these species are listed  Sp. Sp. No. 0f individuals Zea Zea -500 Vicia Vicia --300 Rosa Rosa -100 (ii) Count quadrate or list-count quadraet: - Species that present in sample –plot are named - The number of each are recorded - the species name and the number of individuals of each species found in the sample area are recorded in list - list-count quadrate and list-count quadrate are usually used in forest survey work - (iii) Cover quadrat: The percentage of the sample area covered or shaded by vegetation is determined or recorded as follow: relative coverage Shaded area( that covered with plants ) Total area (iv) Chart quadrate: In this method the sample plot is determind as square (large square ) - The large square divided into small equal sized squares - Horizontal and vertical chains or ropes are strached - Each small square is numberd - number of individuals of each species found in each small squares This sample –plot is represented on graph paper as map Not that, put the key under this map ,include , symbol of each species This method shows the location of individuals of each species Individuals We can determined the following The shaded area , hollow area , density of each species , frequen …….etc This method is very accurate than the other quadrates of their individuals  (2) Transect method In this method the sample – plot is like a cross-section used as a sample for recording, mapping or studying vegetation is called transect. It may be a strip, belt or a line across the area of study. The species occurring along this transect is recorded The are of two types transects : (i) Belt transect, (ii) Line transect. (i) Belt transect: the sample – plot is is like strip , this strip has width and length - Each strip may be divided into equal sized segments - Each segment has equal width and length - ( i.e Each segment is square ) - Names of species and number of individuals of each species in each unit are recorded. The belt transect method is used to obtain anther informations as abundance, frequency, density and distribution of species in the community.  ii) Line transect: It is one dimensional transect. In this method, observation is taken on lines that are laid over the study area. The procedure is as follows: (a) A metric steel steel chain is stretched between two stalks (33.5 metres or one chain apart). (b) The observer moves along the lines and records name and individuals number of each plant species (density ,…etc) along the line transect. The trees. Shrubs , tall..., etc are measured at high level of ground , but herbs, small grasses, small…., etc are measured at low level of ground. (d) many number of lines may be present in sample-plot or over the study area Succession: composition and shape of community remains in changing state. This is called succession The changes take place due to continuous of death and migration of some plant species The changes in the community go on taking place until a complete balance is established between plant community and environment. This is called succession. As vegetation develops, the same area becomes successively occupied by different plant communities. This process results from series of successive steps or stages This succession process take place : -Gradually -at long time Types of succession There two main types of succession : According to start point. (1) hydrosere (2) Xero sere (1)Hydrosere Successions beginning in water as ( ponds, lakes, marshes, …….) are termed hydrosere. This process results from series (sere) of successive steps or stages. The different stages of the series (from initial stage to climax stage) constitute a hydrosere.  (2) Xerosere Successions beginning in land that contian very low amount water contant as ( desert , rock ) This process results from series (sere) of successive steps or stages. So this type of Succession is termed serosere  Hydrosere (1)Submerged stage The start point in water ( begining in water ) the water depth is less than 20 feet ( 18-20 ) near the shores of a lake The plants species that grow in this place must be entirely submerged in water. These are the pioneers of the hydrosere - The remains of plants and animals and other substances that carried by water current are sedimented on water bottom and repetation of this process and by the time. - This leads to :- - Increase of soil thickness (due to the building water bottom ) - Decrease of water depth - So the water depth become unfavorable to submerged species (gradually) , and Suitable for a new species ( invaders) - e.g - Elodea , Ceratophyllum (2)Floating stage the water depth is (8-6 )feet When the water depth is (8-6 )feet , appearance of floating plants take place These plants grow in water and air , most plant grow in water and small part grow in air ( leaves specially ) Characters of floating plants : - have rhizome, broad leaves with long petioles to float on the surface So this water contain submerged plants mixed with floating plants By reproduction of floating plants these plants become dominant and submerged plants disappeared gradually , and after long time the sedimentation process is increased - This leads to :- - Increase of soil thickness (due to the building water bottom ) - Decrease of water depth So the water depth become unsuitable for floating species (gradually) , and Suitable for a new species ( invaders) e.g Echhornia , Nymphaea 3)Reed-swamp stage ( the water depth is (8 to 6 )feet. This area becomes soil covered with shallow water. These plants grow in water and air , most plant grow in air and small part grow in water ( root and small part of stem) Characters of floating plants : - have rhizome, long aerial stem ,linear leaves and supporting tissue So this water contain floating plants mixed with Reed-swamp plants By reproduction of Reed-swamp plants these plants become dominant and floating plants disappeared gradually and after long time the sedimentation process is increased - This leads to :- - Increase of soil thickness (due to the building water bottom ) - Decrease of water depth So the water depth become unsuitable for these species (gradually) , and Suitable for a new species ( invaders) e.g Typha, and Phragmites (4)Sedge-meadow stage: In this stage the soil area becomes saturated with water. So this becomes unfit to Reed-swamp plants and are disappeared gradually By disappearance of Reed-swamp plants this soil is exposed to high amount of light so this area is Suitable for Sedge-meadow plants Characters of Sedge-meadow plants : - Small herbs with long slender rhizome and fibrous root. - By reproduction of Sedge-meadow plants these plants become dominant and Reed-swamp plants disappeared gradually and after long time the sedimentation process is increased - This leads to :- - Increase of soil thickness (due to the building water bottom ) - Decrease of water depth So the place becomes unsuitable for these species (gradually) , and Suitable for a new species (new invaders) e.g Juncus, and Carex (5) Woodland stage: In this stage the soil is unsaturated with water ,but this soil is saturated sometimes (in spring and early summer), So certain species of shrubs and trees may appear. These species can tolerate waterlogged soil around their roots. By reproduction of woodland species these plants become dominant and gradually The drier, shaded soil is a very unsuitable for sun-loving, sedge- meadow species, which gradually disappear. This shading habit leads to - Increase of microrgnisms (Increase of humidity) - Increase of soil fertility ,due to Increase of humus as a result of decomposition plant remains by microrgnisms Decrease of soil water content at last e.g - Salix , Populus (6)Climax forest: This is the final stage of hydrosere succession Characters of this stage soil - decrease of soil water content - Soil is more drought ,so the plant expands its root to obtains its water requarementes - Increase of soil aeration - Increase of s oil fertility - This soil becomes filled with bacteria and fungi and other organisms This habit is Suitable for many species especially trees , shrubs and subshrubs these plants become dominant and woodland species plants disappeared gradually In the final, This habit is Suitable for all mesophyte species these need moderate water amount ( As forest defferent types of plants ) Note that:these plants include trees , shrubs and subshrubs ,herbs, grasses and ………..etc.