Ecosystem Components and Interactions

Ecosystem Components and Interactions

• An ecosystem comprises living organisms and their physical environment.
• The biosphere is the life-supporting portion of Earth.
• Crucial factors for life on Earth are not entropy, but rather interconnected elements like the sun's energy, water, and nutrients.
• Solar energy, mostly converted to infrared, drives ecosystems.
• Dissolved oxygen is a vital limiting factor for aquatic life.
• Producers (like phytoplankton) in open water ecosystems harness energy from the sun.
• Decomposers are detritivores, breaking down organic matter.
• Gross primary productivity measures total energy conversion by producers, while net primary productivity assesses energy stored as biomass by producers.
• The carbon cycle is involved in fossil fuel formation.

Biogeochemical Cycles

• The hydrologic cycle is altered by human activities like over-extraction of water resources, increased fossil fuel use, and wetland degradation.
• The phosphorus cycle does not involve the atmosphere.
• The stratosphere houses the ozone layer.
• The biosphere includes the atmosphere, hydrosphere, lithosphere; not the hemisphere.
• Nitrification in soil involves bacterial action converting ammonia to nitrate.
• A biogeochemical cycle summarizes the pathway of particular elements through various reservoirs.

Ecosystem Structure and Function

• Abiotic factors are the non-living components of ecosystems.
• A food chain illustrates the energy flow from a source (sun) through various trophic levels.
• A species' niche is its role, while its habitat is its address.
• Organisms with narrow niches are specialist species, and those with broad niches are generalists.

Evolution and Adaptation

• Natural selection fosters traits enhancing survival and reproduction in a changing environment.
• Speciation begins with geographic isolation leading to reproductive isolation and divergence of gene pools.
• Microevolution encompasses small genetic modifications in populations; macroevolution involves larger, long-term changes potentially leading to new species.
• Mutations and genetic drift cause genetic variability.
• Differential reproduction plays a critical role in natural selection, as organisms with advantageous traits reproduce more successfully.
• In stable environments, specialists have fewer competitors, but generalists fare better during rapid change.
• Three fundamental aspects of natural selection are heritable traits, differential reproduction, and variability within a population.
• Evolution describes changes in a population's genetic makeup over generations, driven by natural selection.
• Macroevolution results in populations incapable of interbreeding with parent populations, defining a new species.
• Geographic isolation allows populations to diverge genetically, potentially leading to speciation.

Population Ecology

• A species' carrying capacity represents its maximum sustainable population size in a habitat.
• J-curves describe exponential population growth, while S-curves describe logistic growth leveling off at the carrying capacity.
• K-selected species typically exhibit slow reproduction rates and raise relatively few offspring; R-selected species reproduce rapidly with many offspring.
• Species with high intrinsic rates of increase tend to be generalists, producing numerous offspring, and often R-selected.
• Limiting factors are elements constraining population growth.
• Ecological succession describes the gradual species replacement in an area following disturbance.
• Primary succession re-establishes life in lifeless areas, whereas secondary succession follows a disturbance in an area previously supporting life.
• Population density refers to the number of individuals in a specific area.

Community Interactions

• Interactions like predation, commensalism (one benefits, other unaffected), and mutualism (both benefit) define communities.
• Interspecific competition occurs when species interact over resources.
• Coevolution occurs when species interact over a long duration, driving reciprocal adaptation.
• Resource partitioning describes how species divide shared resources to reduce competition.

Ecosystems and Human Impact

• A biome describes a major terrestrial region with characteristic organisms adapted to its climate.
• Climate encompasses average temperature and precipitation.
• An eutrophic body of water is one with excessive nutrients and high algal growth. An oligotrophic body of water is one with low nutrients and little algal growth.
• Water pollution sources include point sources (identifiable) and non-point sources (diffuse).
• Desalination of ocean water is a technique to achieve freshwater augmentation.
• Water scarcity stresses, use, and pollution problems result from human activities.
• Important conservation and management activities include water use efficiency/protection, water resource protection/augmentation, water pollution control.
• Protecting ecosystems with natural water storage and reducing waste are important for improving water availability and quality.

Biodiversity, Conservation, and Threats

• Human activities are the leading cause of species endangerment and extinction.
• The Convention on Biological Diversity (CBD) aims to reduce biodiversity loss and share genetic resources.
• Biosphere reserves are protected areas intended to preserve biodiversity.
• Habitat destruction, fragmentation, and degradation are major threats to biodiversity.
• "HIPPO" – Habitat loss, invasive species, pollution, population (human), overexploitation – are contributing factors to biodiversity loss.
• Overgrazing, unsustainable agriculture, and resource extraction (mining, clearcutting) damage ecosystems.
• Deforestation and habitat fragmentation threaten biodiversity.
• Soil erosion is a significant factor in land degradation.
• Clearcutting reduces biodiversity, increases timber yield but can damage ecosystems.
• Sustainable forestry practices such as selective cutting conserve biodiversity.

Other Relevant Issues

• Colonization/introduction of alien species disrupts the existing food web and ecological balance.
• Exponential population growth is a strong driver for issues such as overuse of resources and habitat destruction contributing to a decline in biodiversity.

Human Population Dynamics

• Birth rates, mortality rates, and migration influence population growth or decline.
• Age structure diagrams can predict future population trends.
• Total fertility rate (TFR) represents the average number of children born per woman in a population.
• Factors influencing human population growth include economic development, healthcare, and family planning.