Plant Ecology PDF

PLANT ECOLOGY Dr. Laila Mohamed  PLANT ECOLOGY Introduction Environmental factors Ecosystem Vegetation Human effect in ecosystem  Ecology Is the scientific study of the relationship between organisms and their environment There is interrelationship between...

PLANT ECOLOGY Dr. Laila Mohamed  PLANT ECOLOGY Introduction Environmental factors Ecosystem Vegetation Human effect in ecosystem  Ecology Is the scientific study of the relationship between organisms and their environment There is interrelationship between plants and their environment , were plants affect their environment and the environment affects the plants that live in it interrelationship land plants water microorganisms animals air  plant Ecology Is the scientific study of the relationship between plants and their environment interrelationship 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..  Autoecology Synecology..  Branches of plant ecology There two main branches 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  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 ( land , water or air)  Environmental factors Environmental factors could be classified into: *Climatic factors *Edaphic 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  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 plants Effect of light on plant 1- Light affecst the formation of chlorophyll ( ch. Is a green pigment and mainly formed in light) 2- Light affect the number of chloroplasts. At high light intensity ,production of chloroplast decreases and thus the number of chloroplasts decreases and vice versa. 3- Light affect the position of chloroplasts. At low light intensity the chloroplasts become close to the surface of leaf and vice versa , but at high light intensity the chloroplasts become far away from the surface of leaf  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 these plants can grow under direct sunlight for a these plants can grow under long time indirect sunlight for a long time 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 in 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.