Ecosystems Week 4

What is Ecology Ecology is the study of how organisms interact with one another and with their physical environment of matter and energy

Ecosystem Ecology comes from oikos (living space) and logos (the science of) used by Ernst Haeckel in 1869 Organisms is a living substance on surface layer of earth (biosphere), air (atmosphere), land( lithosphere), and water (hydrosphere) The ecosystem is composed of various of inputs, processes or stores and outputs. It should maintains its dynamic equilibrium.

Ecosystem definitions A.G. Tansly definition: A particular category of physical systems consisting of organisms and inorganic components in a relatively stable equilibrium, open and in various kinds and sizes I.G Simmons definition: A unit of space-time containing living organisms interacting with each others and with their abiotic environment by the interchange of energy and materials

What keep organisms alive Life is sustained by the flow of energy from the sun though the biosphere, the cycling of nutrients within the biosphere, and gravity.

Major component of an ecosystem Ecosystems contain living (biotic) and nonliving (abiotic) components.

Energy and matter in an Ecosystem Energy flows through ecosystems in food chain and webs As energy flows in food chain the amount of chemical energy available to organisms at each succeeding feeding level decreases. Matter, in the form of nutrients, cycles within and among ecosystems and biosphere, and human activities are altering chemical cycles.

Organisms : an individual living begins Atom: the most smallest of matter in which an element can be divided and still retain its chemical properties. Molecule: a combination of two or more atoms of the same or different elements held together by forces called chemical bonds. Organisms : an individual living begins Cell: the fundamental structure unit of life Population: A group of the same species living in a particular place Community: Population of different species living in a particular place, and potentially interacting with each other Nature Ecosystem: a community of different species interacting with one another and with their nonliving environment of matter and energy Biosphere: Parts of the earth’s air, water, and soil where life is found.

Ecology classification Ecology contains: Organisms; Spaces: A set of individuals that can mate and produce fertile offspring. Every organism is a member of certain species with certain traits. Population; Genetic diversity: variation in a population, don’t all look or act alike Habitat: a place where population or an individual organisms live and has its certain resource such as water and environmental conditions such as temperature and light. Community; Biological community: consist of all populations of different species that living in the particular place and many of them interact with one another in feeding and other relationships. Ecosystem; It can range in size, natural and artificial, has no clear boundaries and are not isolated from one another. Matter and energy move from one to other ecosystems Biosphere; A global ecosystem in which all organisms exist and interact with one another.

Life-support system Four major components Atmosphere: it(air) is a thin spherical envelope of gases surrounding the earth’s surface. Hydrosphere: it(water) consists of all water on or near the earth’s surface and covers 71% of the globe. Geosphere: it(rock, soil, sediment) consists of the earth’s intense. Biosphere: it(living things) occupies those parts of other 3s where live exists.

Atmosphere Troposphere: is the inner layer of atmosphere with the extension of 17 km above sea level at tropics and 7 km at poles. Greenhouse gases: are the 1% of remaining gases (H2O, CO2, CH4) out of 68% N2 plus 21% of O2 which make up air in troposphere. Stratosphere: is the upper layer next to T stretching 17-50 km with O3 to filter harmful ultraviolet radiation of sun and allows life to exist

Hydrosphere Liquid water: exist on the surface and underground Ice: in form of polar ice and iceberg Permafrost: the ice frozen soil layer Water vapor: the water which exist in the air saline water: exist in the seas and oceans and cover 71% of the globe

Geosphere and Biosphere Geosphere consist of hot core, a thick mantle, and a thin outer crust. Biosphere is a thin layer of the combination of A, H, and G extended from 9km above earth surface to bottom of the ocean where life exist. Biomes: a large region of terrestrial part of biosphere such as forest, desert, grasslands etc with distinct climate and certain specious Aquatic life zones: watery part of biosphere which consists of freshwater life zone and marine life zone. The goal of ecology is to understand the interactions in this thin layer of air, water, soil, and organisms.

Sustaining life on Earth One-way flow of high-quality energy from sun for feeding interactions of organisms. It cannot be recycle. (First and 2th laws of thermodynamics) Cycling of matter or nutrients through part of Biosphere. Earth is closed to space matter. (law of conservation of matters) Gravity enable the movement of chemicals through air, water, soil, and organisms.

Ecosystem components Abiotic consists of nonliving components such as water, air, nutrients, rocks, heat, and solar energy. Biotic consists of living and once living biological components such as plants, animals, microbes, dead organisms, dead part of organisms, and the waste products of organisms.

Ecosystem and population growth Range of tolerance: each population in an ecosystem has a range of tolerance to variations in its physical and chemical environment. Ecological principal of limiting factors: Too much or too little of any abiotic factors can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance. Main abiotic limiting factors: include temperature, sunlight, nutrient availability, low solubility of O2, and salinity.

Ecosystems’ producers & consumers Trophic level: is the feeding level of every organisms in an ecosystem that transfer energy and nutrient from one to another level and can classify to P & C. Authotrophs: or producers or self-feeders make the nutrients they need from compounds and energy obtained from their environment such as green plants, algae, and phytoplankton. Heterotrophs: or consumers or other-feeders obtain their nutrient by feeding on other organisms, producers or other consumers, or their remains and not produce their needs though photosynthesis.

Energy cycle and photosynthesis Carbon dioxide + water + solar energy = glucose (carbohydrate) + oxygen 6CO2 + 6 H2O + solar energy = C6H12O6 + 6 O2 AND C6H12O6 + 6 O2 = 6CO2 + 6 H2O + energy

Heterotrophs or consumers Primary consumers or herbivores: plant eaters Secondary consumers or carnivores: meat eaters Higher-level consumers: carnivores that feed on the other carnivores Omnivores: feeding on both plants and animals Decomposers: release nutrient from dead body of plants and animals to soil for reuse Detritivores: feed on waste or dead body of other organisms.

Food chain in Ecosystems Food chain determines how chemical energy and nutrients move from one form of organisms to another through the trophic level in an ecosystem. Food web is a complex network of interconnected food chain which shows how a consumer organism feed on one or more type of producer organisms in the natural ecosystems. Food chains and webs demonstrate how producers, consumers, and decomposers are connected to one another as energy flows through trophic levels of E,s

Differentiation of Ecosystems by Energy usage Loss of energy in organisms; the more trophic levels there are in food chain, the greater is the accumulative loss of usable chemical energy as it flows through the T.L. Ecological efficiency of energy ranges from 2-40% (loss of 60-98%), depending what type of species and ecosystems are involved, but 10% is typical. Gross Primary Productivity (GPP) is the rate at which an ecosystem’s producers (plants) convert solar energy into chemical energy as biomass found in their tissues. (kcal/m2/yr) To stay alive, grow and reproduce, producers must use some of chemical energy stored in the biomass they make for their respiration. Net Primary Productivity (NPP) is the rate at which producers use photosynthesis to produce and store chemical energy minus the rate at which they use some of this stored chemical energy though aerobic respiration. NPP = GPP – R R is energy used in respirations Ecosystems differ in their NPP and decrease from equator toward poles

Ecosystems classification Terrestrial Ecosystems swamps and marshes (9600 kcal/m2/yr) مرداب و باتلاق Tropical rain forest (8800) Temperate forest (5600) Savanna (3200) Agricultural lands (3000) Woodland and shrub land (2800) بیشه Grasslands (2400) Alpine and Tundra (700) Desert (250) Extreme Desert (100) Aquatic Ecosystems Estuaries ( 8800) مصب Lakes and streams (2300) Continental shelf (1500) Open ocean (1100)