Sustainable Ecosystems Unit Review Flashcards
Populations and Resources (Topic 5: 2.1)
Population Definition: A population is defined as a group of individuals belonging to the same species that live in the same geographic area at the same time and are capable of interbreeding.
Exponential Growth: This refers to a pattern of population growth where numbers increase at a constant rate over a specific time interval. This typically occurs in environments with unlimited resources and no limiting factors, resulting in a "J-shaped" curve on a graph. The population size increases slowly at first and then extremely rapidly.
Carrying Capacity: The carrying capacity is the maximum population size of a particular species that a given environment can support sustainably over the long term without degrading the ecosystem's resources for the future.
Population Equilibrium: When a population reaches equilibrium, it has balanced its numbers with the available resources. At this point, the birth rate () is approximately equal to the death rate (), resulting in a stable population size that fluctuates slightly around the carrying capacity.
Limiting Factors: A limiting factor is any resource or environmental condition that restricts the growth, abundance, or distribution of a population in an ecosystem.
Abiotic Example: Availability of water, light, temperature ranges, or soil nutrients.
Biotic Example: Competition, predation, or the spread of infectious disease.
Predator Regulation: Predators limit population growth by consuming prey individuals. This keeps the prey population from exceeding the environment's carrying capacity, prevents overgrazing or overconsumption of primary resources by the prey, and often removes the sick or weak from the gene pool.
Human Increase of Carrying Capacity: Humans can artificially raise the carrying capacity for specific species through agricultural practices (increasing food supply), habitat restoration, medical interventions, or the removal of natural predators.
Human Decrease of Carrying Capacity: Carrying capacity is reduced by human activities such as pollution, deforestation, habitat fragmentation, and the depletion of natural resources which makes the environment less habitable for native species.
Urban Sprawl: This is the unplanned, low-density expansion of urban development (housing, roads, and commercial areas) into the surrounding rural or natural lands, often resulting in increased reliance on automobiles.
Environmental Impact of Urban Sprawl: One major impact is habitat fragmentation, where large, continuous ecosystems are broken into smaller, isolated patches, making it difficult for wildlife to find food, mates, or migrate.
Intensification: This is an urban planning strategy that focuses on increasing the population density within existing urban boundaries (e.g., building high-rise apartments or redeveloping empty lots) to reduce the pressure for outward expansion and save natural ecosystems from sprawl.
Interactions Among Species (Topic 6: 2.2)
Ecological Niche: This describes the specific role and position a species has in its environment, including its habitat, what it eats, its behavior, and how it interacts with other biotic and abiotic factors.
Competition: This is an interaction between organisms or species in which both the organisms or species are harmed when they contend for the same limited resource.
The Cause of Competition: Competition occurs because resources such as food, water, light, territory, and mates are finite and cannot support an unlimited number of individuals.
Competition Example: Two species of birds, such as wood warblers, may compete for the same type of insect or for the best nesting sites in a specific forest canopy.
Bottom-Up Population Regulation: This occurs when the population size of higher trophic levels is controlled by the productivity and abundance of organisms at lower trophic levels (e.g., restricted nutrients in soil limiting plant growth, which in turn limits herbivore populations).
Top-Down Population Regulation: This is a control mechanism where the abundance of lower trophic levels is regulated by consumers at higher trophic levels (e.g., wolves preying on elk to prevent the elk from overgrazing the local vegetation).
Predator Utility in Ecosystems: Predators serve as regulators that maintain biodiversity by preventing any one single species from becoming overly dominant and exhausting the ecosystem's resources.
Symbiosis: A close, prolonged physical relationship between individuals of two different species. This interaction can be beneficial, harmful, or neutral to the participants.
Mutualism: A type of symbiotic relationship where both species involve benefit from the interaction ().
Parasitism: A symbiotic relationship where one organism (the parasite) benefits at the expense of the other (the host), which is harmed but usually not killed immediately ().
Commensalism: A symbiotic relationship in which one species benefits while the other is neither helped nor harmed significantly ().
Mutualism Example: The relationship between bees and flowers; bees collect nectar for food, and in the process, they pollinate the flowers, allowing the plants to reproduce.
Parasitism Example: A tapeworm living inside the intestines of a mammal; the tapeworm absorbs nutrients directly from the host's digested food, depriving the host of nutrition.
Host Definition: In a parasitic relationship, the host is the organism that provides the environment and nutrients for the parasite and is generally harmed by the interaction.
Parasite Definition: An organism that lives on or in a host organism and gets its food from or at the expense of its host.
Human Niches and Population (Topic 7: 2.3)
The Human Niche: Humans occupy a uniquely broad niche. Unlike most animals, humans use technology and social organization to adapt to and inhabit almost every ecosystem on Earth, from deserts to the Arctic.
Expansion through the Human Brain: Brain expansion allowed for complex language, problem-solving, and the development of tools and fire. This enabled humans to modify their environment and extract energy more efficiently, effectively expanding their niche beyond their biological constraints.
Sustainable Use: This refers to the utilization of components of biological diversity in a way and at a rate that does not lead to the long-term decline of biological diversity, thereby maintaining its potential to meet the needs and aspirations of present and future generations.
Importance of Sustainable Use: It is critical to ensure that natural resources (like fresh water, forests, and fisheries) are not exhausted, ensuring the survival of the human species and the health of the biosphere.
Ecological Footprint: A measure of human demand on Earth's ecosystems, represented as the amount of land and water area required to produce the resources an individual or population consumes and to absorb the waste they generate.
Factors Increasing Footprint: High levels of meat consumption, excessive use of fossil fuels (for heating or transportation), high electricity usage, and high waste production (single-use plastics).
Technology and Carrying Capacity: Technology has increased the human carrying capacity significantly through the development of fertilizers (Haber-Bosch process), irrigation, modern medicine (antibiotics and vaccines), and sanitation systems, all of which reduce mortality and increase food security.
Industrial Revolution Effects: The Industrial Revolution marked a shift from manual labor to machine-based manufacturing. This led to a massive spike in human population growth due to the mass production of food, improved transportation for resource distribution, and advancements in public health.
Ecosystem Services (Topic 8: 2.4)
Ecosystem Services Definition: The variety of benefits that humans freely gain from the natural environment and from properly functioning ecosystems, including provisioning, regulating, cultural, and supporting services.
Forest Ecosystem Services: Forests provide a source of timber and fuel, produce oxygen through photosynthesis, and provide habitat for thousands of species.
Climate Regulation by Forests: Forests act as huge carbon sinks, absorbing carbon dioxide () from the atmosphere. They also influence local weather through transpiration, which adds moisture to the air and helps regulate rainfall and temperature.
Importance of Pollination: Pollination is essential for the reproduction of many plants, including approximately of the world’s food crops. Without pollinators (bees, birds, bats), food security would be severely compromised.
Decomposition: The biological process where organic substances are broken down into much simpler matter. This is primarily performed by bacteria and fungi.
Role of Decomposers: Decomposers are essential for nutrient cycling; they return vital elements like nitrogen () and phosphorus () back to the soil, making them available for primary producers to use again.
Impacts of Deforestation:
Loss of Biodiversity: Destruction of habitats leads to the extinction or displacement of many species.
Increased Greenhouse Gases: Fewer trees means less is removed from the atmosphere, accelerating climate change.
Measuring Biodiversity (Topic 9: 3.1)
Biodiversity Definition: The variety of life found in a particular habitat or ecosystem, often measured at the genetic, species, and ecosystem levels.
Species Richness: A simple count of the total number of different species represented in an ecological community, landscape, or region.
Importance of Biodiversity: High biodiversity increases ecosystem resilience, ensuring the system can recover from disasters. It also provides humans with untapped medicinal resources, food variety, and aesthetic value.
Biodiversity Hotspot: A biogeographic region with significant levels of biodiversity that is under threat from human habitation and destruction. To qualify, a region must contain a high number of endemic species (found nowhere else).
Quadrat Sampling: This method involves placing a square frame (often ) on the ground to count the individuals belonging to different species. It is best used for stationary or very slow-moving organisms, such as plants, fungi, or snails.
Transect Sampling: Scientists use a line (like a measuring tape or rope) across a specific habitat. They count and record the organisms that touch or reside within a specific distance from the line. This is useful for studying changes in species composition along a gradient (e.g., from a shoreline into a forest).
Canopy Fogging: This technique involves spraying a light mist of biodegradable insecticide into the top of a tree. The insects then fall onto a collecting sheet below, allowing scientists to study the vast biodiversity found in forest canopies.
Netting: Fine-mesh nets (like mist nets) are used to safely capture mobile animals such as birds, bats, or butterfly species, or dragged through water to sample aquatic organisms.
Why Scientists Measure Biodiversity: Scientists measure biodiversity to monitor the health of ecosystems, identify species at risk of extinction, assess the effectiveness of conservation efforts, and track the impacts of climate change or pollution over time.