Chapter 8 Ecosystem services
Introduction
8-1 Material cycling and energy flow
8-2 Ecosystem services
8-3 The relation between ecosystem services and intensity of use
8-4 The fallacy that economic supply and demand protect natural resources from overexploitation
Introduction
1.
Renewable resources vs. waste (fig. 8.1)
2.
Ecosystem services depends on two parts: material cycling and energy flow
3.
Overexploitation: take too much from ecosystems and damage ecosystem
8-1 Material cycling and energy flow
1.
Production (fig. 8.2)
(1) Photosynthesis: joins carbon into the carbon chains based on sunlight
(2) Biological production or primary production: the growth of the plants
2.
Consumption
(1) Use the carbon chains in their food
(2) Respiration: carbon chains are broken apart and release energy
3.
Material cycling
(1) Nutrient cycling of production and consumption
(2) Consumers: herbivores, predator, scavengers, parasites, pathogens
(3) Decomposers: release any mineral nutrients into the environment
4.
The laws of thermodynamics
(1) Energy forms: radiation, chemical, mechanical, electrical, nuclear, heat
(2) First law of thermodynamics: energy can never be created or destroyed, but it can be transformed from one form into another
(3) Second law of thermodynamics: whenever energy is converted from one form to another, some of the energy becomes low-level heat. (fig. 8.3)
(4) High-level energy transfer to low-level heat (fig. 8.4)
5.
A metaphor for material cycling and energy flow in ecosystems
(1) A pot of water on a stove (fig. 8.5)
(2) High-level energy → cycling (water self-organization) → low-level heat
6.
Energy flow in ecosystems
(1) Net primary production (carbon chains): photosynthesis – respiration
(2) Consumer eat high-level energy (carbon chains) and release low-level heat

(3) Food chain efficiency: 10-50% (fig. 8.6) (fig. 8.7)
(4) Eventually converted to low-level heat, as infrared radiation (fig. 8.8)
(5) Human energy: labor, mechanized energy, chemical fertilizer,
(6) Modern agriculture, most of human energy inputs come from petroleum
8-2 Ecosystem services
1.
How dependent humans are on the functioning of parts of the ecosystem (fig. 8.9)
2.
Two essential services: renewable resources and purification
8-3 The relation between ecosystem services and intensity of use
1.
Relation between ecosystem services and intensity of use (fig. 8.10)
2.
Overexploitation: deplete the ecosystems natural capital
3.
Ecosystem services may disappear if the intensity of use is excessive
(1) Human-induced succession, desertification, … (fig. 8.11)
(2) Salinization: irrigation in arid regions and makes the soil toxic for crop
(3) River purification decline
(4) Evaluation and monitoring overexploitation, precautionary principle
8-4 The fallacy that economic supply and demand protect natural resources from overexploitation
1.
Invisible hand of supply and demand protects renewable resources from overexploitation (fig. 8.12)
2.
Fallacy: switch from one stability domain to another (fig. 6.6)
3.
Irreversible: forest clear-cut → soil erosion → grass or desert
4.
Irreversible: forest road → farming in hillslope