Ecology: Ecosystems and Environmentalism

• Ecology studies the interactions between organisms and their environment.

Ecosystem Components

• Biotic factors are living components (plants, animals, fungi).
• Abiotic factors are nonliving components (temperature, sunlight, water, fire).
• Ecosystem involves all living and nonliving components in a specific area.

Environmentalism

• Environmentalism is a philosophy and social movement focused on environmental protection.
• Ecology is a science and environmentalism is a social and political movement.
• Ecology informs environmentalism.

Levels of Ecological Study

• Ecology is studied at multiple levels, each including the previous one.
• Organismal ecology studies individual organisms and their adaptations.
• Population ecology studies groups of individuals of the same species, examining factors affecting size, growth, and density.
• Community ecology examines interactions between different species.
• Ecosystem ecology studies energy flow and chemical cycling.
• Global ecology (biosphere) examines the global ecosystem and the influence of energy and matter across the planet.

Ecosystem Processes

• Ecosystems depend on energy flow and chemical cycling.

Energy Flow

• Energy enters as sunlight, is converted by producers, and flows through trophic levels.
• Energy is lost as heat at each transfer.

Chemical Cycling

• Elements cycle through ecosystems between abiotic reservoirs and biotic components.
• Biogeochemical cycles are the cycling of chemical elements through biotic and abiotic components.

Population Measurements

• Key population measurements are used in Ecology studies.
• Population density is the number of individuals per unit area or volume.

Dispersion Patterns

• Dispersion patterns describe how individuals are spaced in a habitat.
• Clumped dispersion: Individuals aggregate in patches.
• Uniform dispersion: Individuals are evenly spaced.
• Random dispersion: Individuals are distributed unpredictably.

Survivorship Curves

• Survivorship curves are graphs showing the percentage of individuals surviving to a particular age.
• Age structure is the proportion of individuals in different age groups, useful for predicting population growth.

Population Growth Models

• Exponential growth occurs under ideal conditions, resulting in a J-shaped curve.
• Logistic growth incorporates limiting factors, resulting in an S-shaped curve.
• Carrying capacity is the maximum population size an environment can sustain.

Limiting Factors

• Environmental constraints limit population size.
• Density-dependent factors' influence increases with population density (e.g., competition, disease).
• Density-independent factors' influence is unrelated to population density (e.g., weather, natural disasters).

Interspecies Interactions

• Species interact in various ways within a community.
• Antibiosis is when two species interact and one is harmed.

Competition

• Competition is a mutually harmful interaction where species compete for resources.
• Competitive exclusion principle: Species requiring identical resources cannot coexist indefinitely.
• Predation is when one species (predator) kills and eats another (prey).
• Herbivory is when an animal consumes plant parts, harming the plant.
• Parasitism is when one species (parasite) lives on another (host), obtaining nutrients.
• Pathogens are disease-causing microorganisms.
• Amensalism is when one species is harmed and the other is unaffected.

Symbiosis

• Symbiosis is where two species interact, with one or both benefiting but neither are harmed .
• Mutualism is when both species benefit (e.g., pollination, mycorrhizae).
• Commensalism is when one species benefits and the other is unaffected.

Trophic Structure

• Trophic structure is the feeding relationships, expressed as a food chain or food web.
• Arrows point toward the organism doing the consuming, indicating energy flow.
• Food chains are linear sequences of who eats whom.
• Food webs are interconnected food chains.

Trophic Levels

• Trophic levels are levels in a food chain or web.
• Primary producers are autotrophs (e.g., plants) that convert solar energy via photosynthesis.
• Primary consumers are heterotrophs that consume producers.
• Primary consumers may be herbivores or omnivores
• Secondary consumers are carnivores or omnivores that eat primary consumers.
• Tertiary consumers are carnivores or omnivores that eat secondary consumers.
• Quaternary consumers are typically carnivores that eat tertiary consumers and may or may not be apex predators.
• Apex predators are top predators without natural predators.
• Decomposers break down dead organic matter.
• Detritivores are a type of decomposer that ingest dead organic matter.
• Parasites and pathogens that are quaternary consumers are not apex predators since they have natural predators

Energy and Biomass

• Energy decreases at each level (approximately 10% transfer efficiency).
• Biomass is the total mass of living material in an ecosystem.
• Primary production is the rate at which solar energy is converted to biomass by producers.

Biodiversity

• Biodiversity is the variety of life on Earth at all levels.
• Species richness is the number of different species in a community.
• Species abundance is the number of individuals of each species.
• Keystone species have a disproportionately large effect on their environment.
• Native species are in an ecosystem.
• Removal of native species leads to an imbalance in the ecosystem

Ecological Succession

• Ecological succession is the gradual change in species composition over time.
• Primary succession occurs in lifeless areas with no soil and can take decades or centuries.
• Secondary succession occurs after a disturbance that leaves the soil intact and recovers more quickly.
• Invasive species are non-native species that spread rapidly and disrupt ecosystems.
• Biological control involves using natural enemies to control invasive species.

Integrated Pest Management

• Integrated pest management uses multiple methods to control pest species.

Biomes

• Biomes are large-scale ecological communities classified by vegetation and climate.
• Examples include forests, grasslands, deserts, tundra.
• There is a particular temperature and rainfall level with the ammount of biomass found in each biome
• Aquatic biomes are defined by salinity.
• Freshwater biomes such as lakes, ponds, rivers, streams, wetlands.
• Intermediate aquatic biomes such as estuaries, intertidal zones.
• Marine biomes such as oceans, coral reefs.
• The photic zone is the sunlit upper water layer with photosynthesis.
• Phytoplankton are microscopic photosynthetic organisms forming the base of aquatic food webs.
• The aphotic zone is the dark, deeper water layer where photosynthesis cannot occur.
• Hydrothermal vents are unique ecosystems in the deep ocean supported by chemosynthesis.

Biogeochemical Cycles

• Biogeochemical cycles describe nutrient cycles and the movement of chemical elements.
• Carbon cycle: Carbon cycles through the atmosphere, oceans, and living organisms.
• Human activities (burning fossil fuels) are significantly altering the carbon cycle.
• Carbon in an ecosystem is constantly recycled, unlike energy.
• Nitrogen cycle: Nitrogen cycles through the atmosphere, soil, and living organisms.
• Nitrogen fixation by bacteria is crucial for plant nitrogen availability.
• Human activities (fertilizer use) are significantly impacting the nitrogen cycle.
• Water cycle: Water cycles through evaporation, transpiration, precipitation, and runoff.

Ecological Footprint

• Ecological footprint is an estimate of the amount of land and water required to sustain one person.

Human Impacts

• Human impacts include habitat destruction, freshwater shortages, species decline and extinction, pollution, and climate change.
• Conservation biology studies how to protect biodiversity.
• Restoration ecology uses ecological principles to repair degraded ecosystems.
• Sustainable development meets present needs without compromising future needs.
• Greenhouse gases trap heat in the atmosphere (CO2, CH4, N2O).
• The greenhouse effect is the natural process by which greenhouse gases trap heat.
• Increased greenhouse gas concentrations are causing global warming and climate change.