■ Supporting (e.g., nutrient cycles and crop pollination)
■ Cultural (e.g., spiritual and recreational benefits)Ecosystem Service Benefit
Moderation of weather extremes
(e.g., flooding) and their impact
by floodplains absorbing excess
water– Reduces property damage
– Saves lives
– Reduces insurance costs
– Helps to protect native habitatsFormation of new soil and the
renewal of soil fertility– Reduces the need for fertilizer
– Allows for greater crop yields,
which can feed more peopleKeeping pest populations in
balance through natural predators– Keeps food prices lower
– Reduces the need for pesticides
– Regulated in ecosystems
through the actions of predators
and parasites as well as by the
defense mechanisms of their
prey (e.g., birds and bats that
eat insects)LAW OF TOLERANCE
Earth’s ecosystems are affected by both biotic (living) and abiotic (nonliving)
factors, and are regulated by the Law of Tolerance, which states that the
existence, abundance, and distribution of species depends on the tolerance level
of each species to both physical and chemical factors. The abundance or
distribution of an organism can be controlled by certain factors (e.g., the
climatic, topographic, and biological requirements of plants and animals) where
levels of these exceed the maximum or minimum limits of tolerance of that
organism.
Limiting Factors
A limiting factor is any abiotic factor that limits or prevents the growth of a
population. Limiting factors in terrestrial ecosystems may include the level of
soil nutrients, the amount of water, light, and/or temperature. In aquatic
ecosystems, major limiting factors may include the pH of the water, light, the
amount of dissolved oxygen, and/or salinity.