Humans & Ecosystems

What services do ecosystems provide?

How do humans affect ecosystems?

The Human System

This graph shows how much grain it takes to make one pound of each kind of meat.

If we did not eat beef then we could feed 3 times as many people on Earth.

The Human System

Violations of the First Principle of Ecosystem Sustainability

• Excessive use of fossil fuels.• Feeding largely on the third trophic level.• Use of coal or nuclear power.• Use of agricultural land to produce meats.

Violations of the Second Principle of Ecosystem Sustainability

• Lack of recycling.• Excessive use of fertilizers.• Destruction of tropical rain forests.• Nutrient overcharge into aquatic ecosystems.• Production and use of nonbiodegradable

compounds.

Ecosystems respond to Disturbance

Disturbance

An event caused by physical, chemical or biological agents that results in changes in population size or community composition

Watershed Studies

• Watershed • All of an area of land in a given landscape that

drains into a specific stream, river, lake or wetland or larger body of water.

Resistance v. Resilience

• Resistance is a measure of how much a disturbance can affect its flow of energy and matter

• Resilience the rate at which an ecosystem returns to its original state after a disturbance

• Restoration Ecology is a new scientific discipline that is interested in restoring damages ecosystems.

Intermediate disturbance hypothesis

• Ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance levels.

• WHY????

Ecosystems provide valuable services

Instrumental Services:• Provisions are goods that humans can use

directly. (examples?)• Regulating services provided by natural systems

help regulate environmental conditions. (examples?)

• Support systems are services that natural systems provide (e.g. pollination, natural filters, pest control)

Ecosystem Services and Functions

Gas, climate and water regulationWater supplyErosion controlSoil formationPollinationBiological control

Ecosystem Services and Functions

Food productionRecreationRaw materialsNutrient cyclingWaste treatment

Intrinsic Values of Ecosystems

• The Resilience of an ecosystem ensures that it will continue to provide benefits to humans—but this depends greatly on species diversity

• Cultural Services are part of the aesthetic benefits to many people. (examples??)