Environmental Systems and Ecosystem Ecology

Ecosystem Ecology Examines Interactions Between the Living and Non-Living World A particular location on Earth distinguished by its particular mix of interacting biotic and abiotic components. A community of organisms and their nonliving (abiotic) environment.

Ecosystem Boundaries Some ecosystems, such as a caves and lakes have very distinctive boundaries. However, in most ecosystems it is difficult to determine where one ecosystems stops and the next begins.

Ecosystem Processes Even though it is helpful to distinguish between two different ecosystems, ecosystems interact with other ecosystems.

Energy Flows through Ecosystems

Photosynthesis and Respiration Producers (autotrophs) are able to use the suns energy to produce usable energy through the process called photosynthesis.

Photosynthesis and Respiration Cellular respiration is the process by which organisms gain energy (ATP) from consuming organic molecules such as glucose (C6H12O6)

Trophic Levels, Food Chains, and Food Webs Consumers (heterotrophs)- obtain energy by consuming other organisms. Primary Consumers (herbivores)- consume producers. Secondary Consumers (carnivores)- obtain their energy by eating primary consumers. Tertiary Consumers (carnivores)- eat secondary consumers.

Food Chain- The sequence of consumption from producers through tertiary consumers. Food Web- A more realistic type of food chain that takes into account the complexity of nature.

Ecosystem Productivity Gross primary productivity (GPP)- Is the assimilation of energy into biomass by autotrophs (Product of photosynthesis) Portion of this biomass is used by the autotrophs for their own metabolism by cellular respiration.

Ecosystem Productivity Net primary productivity (NPP)- The energy/biomass that remains after respiration (R) and is available by heterotrophs/consumers in that ecosystem NPP = GPP – R

Matter cycles through the biosphere Biogeochemical cycles- The movement of matter within and between ecosystems involving biological, geologic and chemical processes.

The Hydrologic Cycle The movement of water through the biosphere.

The Hydrologic Cycle Transpiration- The process where plants release water from their leaves into the atmosphere. Evapotranspiration- The combined amount of evaporation and transpiration. Runoff- When water moves across the land surface into streams and rivers, eventually reaching the ocean.

The Carbon Cycle

Carbon Cycle Large amounts of CO2 exchanged between atmosphere and ocean (balanced) Enters foodwebs via photosynthesis by algae Combine with calcium ions in water to form Calcium carbonate (limestone) forms sediment in bottom of ocean Organic carbon – not decomposed – fossil fuels

Carbon Cycle Human Impacts: Anthropogenic combustion of fossil fuels → Greenhouse Effect

Carbon Cycle Human Impacts: Tree Harvesting Large amounts of Carbon stored in the wood of the trees Cutting and burning – increases CO2 in atmosphere Decreases Biodiversity

The Nitrogen Cycle Nitrogen is an important component of: Amino acids which make up PROTEINS Component in nitrogenous bases of DNA and RNA (A,T,C, G)

The Nitrogen Cycle Mnemonic – FixNAAD ANPAN PROCESS PRODUCT Fix – N Fixation Ammonium (NH3 →NH4+) Nitrification Nitrates (NO2- → NO3-) Assimilation Proteins Ammonification Denitrification Nitrogen gas (N2)

The Nitrogen Cycle

The Nitrogen Cycle Human Impacts: ANTHROPOGENIC Nitrogen based fertilizers can cause environmental problems: Enters Surface Waters Enters Ground Water Air Pollutant Production, Transportation, Application

The Nitrogen Cycle Fertilizers enter Surface Waters: Nitrates (NO3-) repel negatively charged soil molecules → promotes LEECHING of nitrogen out of soil Increases Algal blooms Promotes eutrophication Dissolved oxygen depletion from decomposing bacteria Prevents sunlight from reaching submerged plants

The Nitrogen Cycle

The Nitrogen Cycle Results in Nitrate contamination of drinking water Fertilizers enter ground water: Results in Nitrate contamination of drinking water “Blue Baby Syndrome” (affects infants under 6 months of age) aka Methemoglobinemia The nitrate reacts with hemoglobin to form methemoglobin, which does not carry oxygen. the baby is suffocated

The Nitrogen Cycle Bacterial Decomposition of Fertilizer: NO3- → N2O → N2 Produces gas Nitrous Oxide (N2O) (aka laughing gas) NOT A LAUGHING MATTER THOUGH: N2O gas increases global warming N2O deplete ozone layer in atmosphere

The Nitrogen Cycle Production, Transportation, and Application of Fertilizers: Consumes fossil fuels – producing CO2 which increases global warming Increases habitat destruction during extraction of fossil fuels

The Nitrogen Cycle Increased Fertilizers can affect biodiversity in ecosystems: Plants that are adapted to low Nitrogen levels may be replaced by species that are adapted to living in soils with higher Nitrogen levels Lead to change in plant species in an ecosystem

The Phosphorus Cycle

The Phosphorus Cycle Phosphorus is major component of DNA, RNA, and ATP Limiting nutrient to plants (second to Nitrogen) on land and in water: On land – major source weathering of rocks In water – Not very soluble in water, most forms sediment at bottom of ocean Humans mine Phosphorus and add it as component in fertilizers NO ATMOSPHERIC FORM

The Phosphorus Cycle Excess Phosphorus PO4 -3 binds to positively charged minerals found in soil…does not leech out with water Very little Phosphorus available in aquatic ecosystems Causes Algal blooms Decomposition leads to depletion of dissolved oxygen (hypoxic conditions)

The Phosphorus Cycle Increased Phosphorus: can also alter plant communities Ex: Florida Everglades Cattails have replaced sawgrass Animals dependent on sawgrass are no longer favored in this ecosystem

The Phosphorus Cycle Two major sources of Phosphorus in Waterways: Fertilizers – runoff Detergents – discharge water from washing machines Due to Ecologic Dead Zones, Manufacturers stopped added phosphates to Laundry Detergents – 1994 Dishwashing Detergents - 2010

Systems A system is a set of interacting components connected in such a way that a change in one part affects one or more other parts of the system

A large system may contain many smaller systems within it. The boundaries of a system may be defined by the researchers point of view. The largest system that environmental science considers is Earth.

Systems Analysis Why is it important for environmental scientists to study whole systems rather than focusing on individual plants, animals, or abiotic components within a system? Studying systems allows scientists about complex relationships between organisms and their environment, but most importantly they can predict how changes in one part of the system will change the entire system.

Earth is a single interconnected system The story about the Gulf of Mexico’s “Dead Zone” shows how systems (Mississippi River and Gulf of Mexico) are interconnected

Open system- exchanges of matter or energy occur across system boundaries. Closed system- matter and energy exchanges across system boundaries do not occur.

System analysis shows how matter cycles and energy flows in the environment Earth is an open system with respect to energy. Solar radiation enters Earth’s atmosphere, and heat and reflected light leave it. Earth is essentially a closed system when it comes to matter. Due to Earth’s magnetic field only an insignificant amount of material enters and leaves the Earth system.

steady states Steady state- in a system, when input equals output it is said to be in a steady state.

steady states Negative feedback loops- when a system responds to change by returning to its original state, or at least by decreasing the rate at which the change is occurring. Positive feedback loops- when a system responds to change by increasing the rate at which the change is occurring.

Ecosystems Provide Valuable Services Intrinsic Value – Value independent of any benefit to humans. Ex: Moral value of an animal’s life. Can not be quantified. Instrumental Value – Provide goods and services that humans could not live without. Can be quantified, as it holds economic value to humans.

Instrumental Values of Ecosystems Provisions- Goods that humans can use directly. Ex: lumber, food crops, medicinal plants, etc. Regulating services- The service provided by natural systems that helps regulate environmental conditions. Ex: Tropical Rainforest and Oceans – absorb excess CO2. Support services- The support services that natural ecosystems provide such as pollination, natural filters and pest control. Cultural services- Ecosystems provide cultural or aesthetic benefits to many people. Resilience- Resilience of an ecosystem ensures that it will continue to provide benefits to humans. This greatly depends on species diversity.

Ecosystems respond to disturbance Disturbance- An event caused by physical, chemical or biological agents that results in changes in population size or community composition. Ex: Fire

Resistance versus Resilience Resistance- A measure of how much a disturbance can affect its flows of energy and matter. Resilience- The rate at which an ecosystem returns to its original state after a disturbance. Restoration ecology- A new scientific discipline that is interested in restoring damaged ecosystems Example: Florida Everglades – Restore water flow and nutrient inputs to historic levels to restore functions of this ecosystem. .

The Intermediate Disturbance Hypothesis The intermediate disturbance hypothesis- states that ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance levels.