Question

27 the stability of ecosystems
key question what factors contribute to ecosystem stability
and how are stability and biodiversity related?
ecosystem stability has two central principles: resistance,
the ability of an ecosystem to maintain equilibrium and high biodiversity
without continual change in species composition, and resilience,
they may change over geological time. after a disturbance,
the community recovers (community resilience) and may or may not
reoccupy their positions.
ecosystem stability (community resilience) can be viewed
from two perspectives: resistance, the ability to resist
change when faced with external disturbances, and resilience, the
ability to recover from a disturbance.
communities most resistant to change typically have a large
biotic structure (such as trees) with nutrients and biomass
stored in standing biomass. forest ecosystems tend to be
relatively resistant to natural and man - made disturbances such as
seasonal 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 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
reasons 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 its structure and function over time, and to resist and recover from disturbances.

(b) The components of ecosystem stability are resistance (ability to resist change), resilience (ability to recover from change), and equilibrium (a state of balance). Resistance helps the ecosystem withstand short - term disturbances, resilience allows it to bounce back after being disturbed, and equilibrium provides a baseline state for the ecosystem.

1. (a) Ecosystem stability and biodiversity are positively correlated. Higher biodiversity generally leads to greater ecosystem stability.

(b) The graph shows that in a more diverse community (with multiple species like A, B, C), the overall community biomass is more stable over time compared to individual species. This is because different species may respond differently to disturbances, and their combined presence buffers the overall ecosystem against changes.

Answer:

1. (a) The ability of an ecosystem to maintain structure and function over time and resist/recover from disturbances.

(b) Resistance: Resist change, important for withstanding short - term disturbances. Resilience: Recover from change, allows bounce - back after disturbance. Equilibrium: State of balance, provides baseline.

1. (a) Higher biodiversity generally leads to greater ecosystem stability.

(b) The graph shows more diverse communities have more stable community biomass as different species buffer against changes.