Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Ecology Ecology is the study of how plants and animals interact with each other and their (nonliving) environment. Biotic factors living parts of the environment e.g. predation, bacteria food availability, competition Abiotic factors non-living parts of the environment e.g. rainfall, temperature, soil pH Community – made up of all the different plants and animals in a given area (i.e. habitat). Energy is the basis of every community. Of course, the origin of all energy is the sun. The soil depends on organic matter for minerals (e.g. decomposing plants or animals) An ecosystem consists of all the organisms in a community and the non-living part of the environment and their interaction. Many individuals of same species = Population + Population of other species = Community + = ECOSYSTEM Non-living part of the environment The environment is the surroundings of an organism and everything that influences it The habitat is where an organism usually lives The population is the number of single species in a given area. All ecosystems contain: producers (green plants) consumers (animals) decomposers (bacteria / fungi) Energy flow in an ecosystem The source of all energy in an ecosystem is the sun. Energy from the sun is trapped in chlorophyll in green plants to produce carbohydrates (e.g. glucose) in the process of photosynthesis. The carbohydrates produced provide a source of energy for animals. A lot of energy is lost to the environment by transfer of one species to another. Therefore, the flow of energy in an ecosystem is always linear (i.e. degrades progressively) but the flow of matter is cyclic (i.e. re-occurs). Matter within an ecosystem The material for living organisms is derived from the soil, rock and the atmosphere. It has a limit. It is recycled by the process of growth and decay. Therefore, the flow of matter is cyclic. Cycles Materials are continuously exchanged between the earth and the space surrounding it. The exchanges occur in cycles between organisms and the physical environment. For example, oxygen, carbon dioxide, water and minerals are all exchanged between organisms as well as the environment. These are constantly absorbed by organisms and replaced by natural processes such as photosynthesis, excretion, respiration and decomposition. The losses = the replacements – so it is all balanced. Recycling in an ecosystem CONSUMERS (animals) die eaten light energy die PRODUCERS (green plants) DECOMPOSERS (bacteria, fungi) decomposition water and minerals Food chains - SOIL (minerals and humus) series of eaters and things that are eaten summarises the feeding relationship between organisms begins with a green plant (producer) ends with a carnivore arrow shows flow of energy – it points to the eater Generalisation food chain Green plant → die Herbivore die → Carnivore die → Top carnivore die and decompose (by saprophytes) Sapprophytes live on dead decaying organic matter (e.g. bacteria / fungi) they break down decaying matter into ammonium compounds There are rarely more than 5 stages in a food chain because energy is lost at each stage. The energy transfer from producer to herbivore is low because we do not have the enzymes to break down xylem (fibre) and cellulose. Food webs are a series of interlocking food chains. The disruption of any one chain can effect the whole food web. Pyramid diagrams - used to represent feeding relationships. The sun is the ultimate source of energy. All plants are the basic food supply for all animals – directly or indirectly. (a) Pyramid of numbers Problems - scale is unmanageable accuracy of the count at each trophic level is not accurate many eat more than one food source Example: 1 sparrow hawk 4 birds 100’s of invertebrates 100’s of green leaves relative number (b) Pyramid of biomass dry-mass at each trophic level water variable dry the organism / sample in oven at 100ºC biomass – biological material – more likely to indicate energy at each trophic level energy lost by: Advantages - energy respiration movement heat conversion into mass (So, obviously, energy loss can be reduced by keeping at warm temperature and also restricting the movement of some of the animals) manageable scale efficiency of energy transfer between trophic level can be calculated energy wasted at each level can be seen gives more information: indicates energy present Disadvantages sampling is destructive (sample has to be dead) all organisms contain dead material that would not be eaten not actually energy (but an estimate)