The nature and complexity of ecosystem functioning and global biodiversity

Ecosystem Functioning

The processes and interactions occuring within an ecosystem such as energy flow, nutrient cycling, and biomass production.

Biomass

The measurement of the amount of energy stored as living matter present in an ecosystem.

Measurement: Grams of energy/m2/yr

Nutrient Cycling

A pathway by which the chemicals move through both the biotic and abiotic aspects of an ecosystem.

-The circulation of nutrients within ecosystems via biogeochemical processes is crucial to the maintanence of stability and productivity of ecosystems and the recycling of essential elements.

Ecosystem

A biological community of interacting biotic and abiotic factors.

Energy Flows

One-direction flow of energy starting with sunlight.

Decomposers

Organisms that break down the dead remains of other organic matter.

Food Chain

A linear sequence of organisms through which nutrients and energy is transferred to organisms up in the heirarchy.

Trophic Levels

The hierarchical levels of the food chain through which energy flows from primary producers to primary consumers, secondary consumers and producers.

Food Web

A representation of the feeding relationships within a community.

Energy Flow in Ecosystems

As energy flows through the trophic levels 90% of it is lost to the atmosphere in the form of heat or for playing important roles in other crucial processes and the other 10% is transferred to the next trophic level.

Human Impacts on the Nutrient Cycle

Human activities can disrupt the biogeochemical processes leading to issues like Eutrophication.

Example:

The Sahel region of Africa is undergoing significant desertification, marked by expanding desert conditions, vegetation loss, soil degradation, and reduced ecosystem productivity. Key factors include overgrazing, deforestation, drought, and unsustainable land-use practices.

Bioaccumulation

The accumulation of non-biodigradable, toxic substances.

Eutrophication

The death of aquatic flora and fauna due to algae growth in waterways from fertilisers.

Heterotroph

An organism obtaining energy from what it consumes; also called a consumer; herbivores, carnivores, omnivores, and decomposers.

Autotroph

Independant feeders that convert inorganic matter into organic compounds.

Dynamic Equilibrium in Ecosystems

The balance between opposing forces where overall stability is maintained despite the occurrance of changes. The balance between vulnerability and resilience.

E.g. Coral reefs maintaining dynamic equilibrium by balancing coral growth and erosion. Disturbances such as climate change and pollution disrupt this balance, therefore leading to instability within the system.

Vulnerability

The extent to which an ecosystem is prone to harm as a result of external pressures like human

Resilience

An ecosystem's capability to recover from these negative selection pressures while maintaining its essential functions and structures.

Determining Vulnerability (BEL)

1. Location

- Proximity to pressures.

- e.g. coral reefs near urban areas are more vulnerable to pollution.

2. Extent

- The size of the ecosystem.

- Larger ecosystems may contain more internal diversity to buffer disturbances.

Feedback Loops

The affect of a causal relationship between two or more processes in nature. It is caused by one process giving rise to another, then causing the original process to accelerate or diminish.

Positive Feedback Loops

Positive feedback loops enhance or amplify changes; this tends to move a system away from its equilibrium state and make it more unstable.

Example

- Deforestation leaving to a loss of vegetation.

Negative Feedback Loops

A feedback loop in which a system responds to a change by returning to its original state, or by decreasing the rate at which the change is occurring.