Ecology Summer Study Material PDF

ECOLOGY SUMMER STUDY Material Green Generation Summer Study Ecology is the study of how organisms interact with one another and with their environment. Environment can be split into two components; the living portion, termed the biotic component (e.g., organisms), and the nonliving portion, termed...

ECOLOGY SUMMER STUDY Material Green Generation Summer Study Ecology is the study of how organisms interact with one another and with their environment. Environment can be split into two components; the living portion, termed the biotic component (e.g., organisms), and the nonliving portion, termed the abiotic component (e.g., air, soil, water, etc.). Ecologists organize the biosphere into several levels. A population is a group of individuals of the same species occupying a common geographic area. A community is formed when two or more populations reside in the same geographic location. An ecosystem is comprised of a community and its surrounding abiotic factors. A biome is a collection of ecosystems with similar climates and communities. Energy Flow Food webs describe the flow of energy within an ecosystem by linking together several food chains. Each food chain begins with an organism that uses energy from light or chemical reactions to produce organic compounds from inorganic compounds through photosynthesis or chemosynthesis, called an autotroph (also referred to as a producer). Any organism that can't produce its own organic compounds and must consume other organisms to obtain them is called a heterotroph (also referred to as a consumer). Heterotrophs can be further organized based on what they consume: ● ● ● ● ● Herbivore-a heterotroph that only consumes plants Carnivore-a heterotroph that only consumes animals Omnivore-a heterotroph that consumes both plants and animals Detritivore-a heterotroph that consumes detritus (dead and decaying organic matter) Decomposer-a heterotroph that breaks down dead and decaying organic matter using biochemical reactions Note that as opposed to detritivores, decomposers break down dead and decaying organic matter using biochemical reactions without ingesting it. Each "step" in a food chain is called a trophic level. For example, autotrophs comprise the first trophic level of a certain food chain, the heterotrophs that consume those autotrophs make up the second trophic level, and so on. Within each food chain, only about 10% of the amount of energy that is initially available to one trophic level is available to the organisms in the next trophic level. 1 Biogeochemical Cycles A biogeochemical cycle is a description of the pathways a chemical substance takes to recycle itself. Some of the most important biogeochemical cycles are depicted in the table below. Cycle Description Hydrologic Cycle The cyclic movement of water between Earth's hydrosphere, atmosphere, cryosphere, biosphere, and lithosphere. Click on the diagram to the right for a better view of it. Carbon Cycle Picture The cyclic movement of carbon in different chemical forms from the environment to organisms then back to the environment. 2 Nitrogen Cycle The cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment. Phosphorus The cycle that Cycle involves the uptake of phosphorus by organisms. Phosphorus in the environment is mainly found in rocks, but natural weathering processes can make it available to biological systems. Phosphorus is an essential nutrient for plants and animals in the form of the ions PO43and HPO42- . (phosphate ion, hydrogen phosphate ion, respectively) It is a constituent of DNA-molecules and RNA-molecules, which store energy,(in the form of ATP and ADP) and of fats of cell membranes. (lipids) Community Interactions 3 Table of community interactions Within a community, species will interact in multiple different ways. The term symbiosis is usually defined as the interaction between two or more species. There are many different types of symbiosis which are defined by whether or not the interaction is beneficial, detrimental, or without effect to the species in the interaction, and they are described below; ● ● ● ● ● Commensalism-an interaction which is beneficial to one species, but has no effect on the other species Amensalism-an interaction that is detrimental to one species, but has no effect on the other species Antagonism-an interaction that is beneficial to one to one species, but detrimental to the other species ● Predation-a form of antagonism in which a predator feeds on its prey, and the prey is killed in the process ● Parasitism-a form of antagonism in which a parasite feeds on its host, but the host is not usually killed Mutualism-an interaction that is beneficial to both species Competition-an interaction that is detrimental to both species (described in more detail below) In addition, two species that don't have an effect on each other are referred to as neutral. Ecological succession is a series of progressive changes in the species that make up a community over time. Ecologists usually identify two types of succession, which differ in their starting points: In primary succession, newly exposed or newly formed rock is colonized by living things for the first time. 4 In secondary succession, an area that was previously occupied by living things is disturbed, then re-colonized following the disturbance. Primary succession occurs when new land is formed or bare rock is exposed, providing a habitat that can be colonized for the first time. For example, primary succession may take place following the eruption of volcanoes, such as those on the Big Island of Hawaii. As lava flows into the ocean, new rock is formed. On the Big Island, approximately 32 acres of land are added each year. What happens to this land during primary succession? First, weathering and other natural forces break down the substrate, rock, enough for the establishment of certain hearty plants and lichens with few soil requirements, known as pioneer species, see image below. These species help to further break down the mineral-rich lava into soil where other, less hardy species can grow and eventually replace the pioneer species. In addition, as these early species grow and die, they add to an ever-growing layer of decomposing organic material and contribute to soil formation. This process repeats multiple times during succession. At each stage, new species move into an area, often due to changes to the environment made by the preceding species, and may replace their predecessors. At some point, the community may reach a relatively stable state and stop changing in composition. However, it's unclear if there is always—or even usually—a stable endpoint to succession, as we'll discuss later in the article. In secondary succession, a previously occupied area is re-colonized following a disturbance that kills much or all of its community. A classic example of secondary succession occurs in oak and hickory forests cleared by wildfire. Wildfires will burn most vegetation and kill animals unable to flee the area. Their nutrients, however, are returned to the ground in the form of ash. Since a disturbed area already has nutrient-rich soil, it can be recolonized much more quickly than the bare rock of primary succession. Before a fire, the vegetation of an oak and hickory forest would have been dominated by tall trees. Their height would have helped them acquire solar energy, while also shading the ground and other low-lying species. After the fire, however, these trees do not spring right back up. Instead, the first plants to grow back are usually annual plants—plants that live a single year—followed within a few years by quickly growing and spreading grasses. The early colonizers can be classified as pioneer species, as they are in primary succession. Over many years, due at least in part to changes in the environment caused by the growth of grasses and other species, shrubs will emerge, followed by small pine, oak, and hickory trees. Eventually, barring further disturbances, 5 the oak and hickory trees will become dominant and form a dense canopy, returning the community to its original state—its pre-fire composition. This process of succession takes about 150 years. The path and endpoint of succession The early ecologists who first studied succession thought of it as a predictable process in which a community always went through the same series of stages. They also thought that the end result of succession was a stable, unchanging final state called a climax community, largely determined by an area's climate. For instance, in the example above, the mature oak and hickory forest would be the climax community. Human Impacts There are many visible human impacts on the environment. However, not all of them are easy to see, and there are many different ways that humans can negatively affect the world around them. Population Growth People are organisms, and like any organism, they need resources to live. However, humans are unique in that we have built a large, organized civilization with advanced infrastructure, which takes up significantly more resources than other beings whose main concerns are survival and procreation. As the human population continues skyrocketing past 7 billion, there are several ways this can affect the environment ● ● ● Rise in Carbon Emissions - the current human population is based around non-renewable energy sources that release greenhouse gases when burned. Until humans make a commitment to renewable energy sources, the release of gases will only increase with more population. In addition, the greater the population, the faster these resources will run out Destruction of Habitat - As humans continue building, they have to develop undeveloped areas, which destroys the habitats of that area. Deforestation is a common issue (more on deforestation below), and ocean habitats are also affected due to the large concentration of people living along coastlines. Pesticides and Fertilizers - People need food to live, so farmers are key to sustaining the human population. Unfortunately, most farmers use pesticides that can seep into the soil, polluting it, and can run off into nearby waterways, which pollutes the water for ecosystems downstream. VOCAB Deforestation - the permanent removal of trees to make room for something besides forest. Desertification - the process by which fertile land becomes desert, typically as a result of drought, deforestation, or inappropriate agriculture. Bioremediation - the use of either naturally occurring or deliberately introduced microorganisms or other forms of life to consume and break down environmental pollutants, in order to clean up a polluted site. Perpetual - so frequent as to seem endless and uninterrupted Inexhaustible - unable to be used up because existing in abundance. limiting factor - anything that constrains a population's size and slows or stops it from growing 6 carrying capacity - the number or quantity of people or things that can be conveyed or held by a vehicle or container. greenhouse effect - the trapping of the sun's warmth in a planet's lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface native species - one that is found in a certain ecosystem due to natural processes, such as natural distribution and evolution invasive species - organism not native to an ecosystem and causes harm acid rain - rainfall made sufficiently acidic by atmospheric pollution that it causes environmental harm, typically to forests and lakes. The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulfur and nitrogen oxides, which combine with atmospheric water to form acids. Extinct - termination of a kind of organism or of a group of kinds, usually a species Extant - organism that still has living species indicator species - an animal or plant species that can be used to infer conditions in a particular habitat keystone species - a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically. Eutrophication - excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen. red tides - It is a common name for harmful algal blooms occurring along coastal regions, which are resulted from large concentrations of aquatic microorganisms, such as protozoans and unicellular algae Hypoxia - deficiency in the amount of oxygen reaching the tissues dead zone - an area of hypoxic (less than 2 ppm dissolved oxygen) waters at the mouth of the Mississippi River that are caused by algae blooms 7