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Ecosystems and Environments (7.10ABC) Student Expectation The student is expected to observe and describe how different environments, including microhabitats in schoolyards and biomes, support different varieties of organisms, describe how biodiversity contributes to the sustainability of an ecosystem, AND observe, record, and describe the role of ecological succession such as in a microhabitat of a garden with weeds. Key Concepts Key Concept 1: Earth’s biomes, including freshwater, marine, desert, forest, grassland, and tundra and their main vegetation type support organisms that are adapted to that particular environment. Key Concept 2: Like a habitat, a microhabitat is a specialized space with food, water, and shelter for organisms to survive and interact with biotic and abiotic factors. An example of a microhabitat includes a garden or the space between two rocks. Key Concept 3: Biodiversity, or biological diversity, is the variety of life and the intricate interactions that support and link organisms together in a geographical region. Key Concept 4: Biodiversity includes a variety of genes, species, and ecosystems. The higher the biodiversity of an ecosystem, the better that ecosystem can withstand environmental stress. Hence, if biodiversity is lost, that ecosystem has less ability to withstand the same environmental stress. Key Concept 5: The biodiversity of an ecosystem depends on limiting factors, or factors that limit the ability of that habitat to sustain a population. Key Concept 6: Ecological succession is the dynamic and predictable transition of organisms that make up a community after a disturbance (either natural or human-caused) as it reaches its climax community. Key Concept 7: Succession can be primary, beginning with rock exposed by geologic activity, or secondary, where the existing community’s soil is intact. Key Concept 8: A microhabitat’s transition over time can be observed and recorded to identify the role of ecological succession as new habitats and niches are created Teacher Background Objective(s): 7.10A Observe and describe how different environments, including microhabitats in schoolyards and biomes, support different varieties of organisms. 7.10B Describe how biodiversity contributes to the sustainability of an ecosystem. 7.10C Observe, record, and describe the role of ecological succession such as in a microhabitat of a garden with weeds. Foundation: Organisms are well-adapted to the environments in which they live. Earth's biomes, including desert, forest, grassland, marine, freshwater, and tundra, support different varieties of organisms. Even in America's national parks, habitats vary and different types of animals live in different areas within the same park. On the microscopic scale, there are also environmental variations that differentiate types of habitats. Microhabitats exist in gardens and in the spaces between rocks, for example. A variety of organisms live in these microhabitats, where they interact with different biotic and non-biotic factors (resources) such as water, food, and shelter. Biodiversity is a shortened term for biological diversity, and it can be observed and measured on a large scale — such as in the ocean or a national park or on a smaller scale, such as in a microhabitat. In a certain geographical region, the variety of life and the intricate interactions between them indicate the level of diversity present in an area. A variety of genes, different kinds of species, the ecosystems and the relationship between all of these factors form biodiversity. The stability of the ecosystem is tightly linked to its diversity. Simply put, the lower the biodiversity of an ecosystem, then the more vulnerable it is to environmental change and imbalance. If an ecosystem has a higher biodiversity, which means more genetic diversity, more varieties of species and so on, then the ecosystem can withstand more environmental stress. Thus, if certain genes or species are lost permanently, then the biodiversity is reduced. With the same environmental stress, this ecosystem will have less ability to withstand. The biodiversity of an ecosystem depends on those factors that limit the ability of the habitat to sustain a population. Following a major disturbance, such as natural disaster, a progression of re-building occurs. Weeds, small insects, and other pioneers will move into the disturbed area first. This literally lays the foundation for other species to move into the area, and the progress continue. This is referred to as ecological succession. Based on F.E. Clement’s theory, succession is a dynamic process with several steps, such as the bare site, migration, habitation, competition, reaction, and stabilization. Stabilization is the process of reaction, when an area reaches a climax community. There are different types of climaxes, such as Catastrophic Climax, Pre-climax and Post-climax, and Climatic Climax. The Climatic Climax means the climax community’s progress is solely controlled and influenced by the local climate. There are also different kinds of successions. Generally, if the development happens on a bare site, which has not been occupied before, it is considered as primary succession. A succession which begins on the rock exposed by geologic activity would be this kind. On the other hand, if the community develops and proceeds on a site from which another community was removed, it is secondarysuccession, as it develops on the existing soil. The transitions of microhabitats can be a record to recognize the role of ecological succession. New habitats and niches are created, and the microhabitat is transformed. The observation of a microhabitat’s transition could potentially tell the history of ecological succession. This philosophy is to make use of a small sample to identify what happens for the whole system. Entire species, populations, and individual organisms are directly and indirectly dependent on their environment. Thus, if environmental conditions change, then these changes will affect the animals and plants living there. There are generally two types environmental change, short-term and long-term. Climate change is considered long-term change. Many scientists have concluded that the Earth’s average temperatures are rising and predict that they will continue to do so. One consequence of this, many believe, is that terrestrial ecosystems generally experience an earlier arrival of spring. Such dramatic shifts in seasonal conditions may lead to extinctions. Existing food chains or food webs may become broken. However, this is still a gradual change over a long period of time during which the genetic variations could become more or less favorable towards the new environment. Although this long-term change may permanently alter an ecosystem, depending on which those living things may not be able to survive, adaptation to these changes may allow some species to survive. Short-term change happens in a relatively short period of time, and commonly forces populations to move or perish. Along marine coastlines, populations and entire species often suffer from floods, hurricanes, tsunamis, and human-caused disasters. Many Texans may still remember Hurricane Katrina's devastation in 2005. Millions of people were evacuated. This short-term environmental change not only affected humans, but also other species. Those who could not flee, such as reptiles, may have their population numbers reduced. If the populations were small and the species isolated to that area, then an entire species could go extinct from one catastrophic, short-term event. In addition to natural forces influencing environmental change, human activities are also often responsible for both short-term and long-term environmental changes. Burning fossil fuels, cutting large tracts of forest, and unsustainable agricultural practices all affect the natural environment. Over-consumption and waste also harm the environment. Plastic bags, for example, are used and discarded daily by the millions and may take hundreds of years to decompose. Such waste degrades the environment quality and harms food webs.