Question

27 the stability of ecosystems
key question: what factors contribute to ecosystem stability and how are diversity and ecosystem stability related?
ecosystem stability has long been a central principle in ecology. ecosystems maintain a state of equilibrium and high diversity without continual change in species composition, although they may change over geological time. after a disturbance, the community recovers, species reoccupy their positions,
ecosystem stability (community equilibrium) can be viewed from two perspectives: resistance, the ability to resist disturbance and remain unchanged, and resilience, the ability to recover from external disturbances.
communities most resistant to change typically have a large biotic structure (such as trees) with nutrients and energy stored in standing biomass. forest communities tend to be relatively resistant, withstanding local disturbances such as temperature changes, insect outbreaks, and drought. however they have low resilience and are slow to recover from major disturbances such as logging or widespread fire.
aquatic ecosystems, which lack large biomass stores are easily disturbed (low resistance) but tend to be highly resilient. the systems can be disturbed, e.g by pollutants or flooding, but will return to an equilibrium after the disturbance is removed.
biodiversity and stability are connected and higher diversity systems are generally more stable. there are a number of mechanisms proposed for this relationship. in a hypothetical system (right), variation in community biomass over time is reduced relative to the variation in individual species, creating an overall community stability. the more species are contributing, the more the overall variations are reduced.
the biodiversity of ecosystems at low latitudes is generally higher than that at high latitudes, where climates are harsher, niches are broader, and systems may be dependent on a small number of key species.

1. (a) what is meant by ecosystem stability?

(b) describe the components of ecosystem stability and why each of these components is important:

1. (a) describe the relationship between ecosystem stability and biodiversity:

(b) describe possible reasons for this relationship. use the graph above as evidence for your statement:

Explanation:

1. (a)

Ecosystem stability refers to the ability of an ecosystem to maintain a state of equilibrium. This means it resists disturbances (like small - scale environmental changes) and remains unchanged in terms of species composition and overall function to a large extent.

• Resistance:
• Explanation: The ability to resist disturbance.
• Importance: Allows the ecosystem to maintain its structure and function when faced with small - scale perturbations (e.g., a minor temperature change in a forest ecosystem where large trees with stored biomass can buffer the effect).
• Resilience:
• Explanation: The ability to recover from external disturbances.
• Importance: Ensures that after a major disturbance (such as a flood in an aquatic ecosystem), the ecosystem can return to its equilibrium state, continuing its ecological processes.

Higher biodiversity is generally associated with greater ecosystem stability. More diverse ecosystems (with a larger number of species) have a more complex web of interactions. This complexity makes the ecosystem less likely to be severely affected by the loss or fluctuation of a single species, as there are more species to fill ecological roles.

Answer:

Ecosystem stability is the ability of an ecosystem to maintain a state of equilibrium, resisting disturbance and remaining relatively unchanged in species composition and function.

1. (b)