Chapter 5 Ecosystem Organization
Introduction
5-1 Coadaptation
5-2 Ecosystem design
5-3 Ecosystem homeostasis
5-4 Comparison of natural, agricultural and urban ecosystems
5-5 Landscape mosaics
Introduction
1. Food web: they all fit together functionally with two reasons:
(1) The community assembly process is able to select from a pool of species.
(2) It selects only species that fit into the existing web.
2. Three major kinds of ecosystems: natural, agricultural and urban ecosystems
3. Landscape mosaic: hierarchical patchwork of smaller ecosystems in landscapes
5-1 Coadaptation
1. Emergent properties of ecosystem: coadaptation and coevolution.
(1) Coadaptation: (fitting together) is a consequence of coevolution (changing
together).
(2) Coadaptation between predator and prey is an evolutionary game that never
ends just for survive. Coexistence is built into the game.
2. Symbiosis: completely cooperative relationships (共存共榮)
3. Symbiosis vs. coexistence
5-2 Ecosystem design
1. Coadaptation and community assembly are the source of nature’s design for
ecosystems.
2. Ecosystems vs. television sets:
(1) Similar:
a. selection of parts that function together
(2) Different:
b. limited by the actions of other components.
a. ecosystems have a higher level of duplication (copies)
b. ecosystems have ability to change as circumstance demands.
5-3 Ecosystem homeostasis
1. Ecosystem homeostasis vs. individual homeostasis
2. Ecosystem state: usually remains within the stability domain
3. Gaia hypothesis: concept of ecosystem homeostasis. “life on Earth maintains the
Earth’s climate and atmospheric composition at an optimum for life”
4. Daisy World: three kinds of flowers: white, grey and dark color (fig. 5.1)
5-4 Comparison of natural, agricultural and urban ecosystems
1. Natural ecosystems
(1) Formed entirely by coevolution, coadaptation and community assembly.
(2) Self-organizing, self-sufficient and self-sustaining.
(3) Inputs and outputs are small (fig. 5.2)
2. Agricultural ecosystems
(1) Domesticated plants or animals to produce food, fiber or fuel
(2) Combination of design by people and nature. Not self-sustaining
(3) Human input: machinery, fertilizers, pesticides, irrigation …(fig. 5.3)
(4) Traditional agricultural ecosystems vs. modern agricultural ecosystems
(5) Polyculture (mixed cropping); organic farming (free of toxic chemicals)
3. Urban ecosystems
(1) Human-made structure; not self-sustaining; large input and output (fig. 5.3, 4)
(2) Population between industrialized and developing countries (fig. 5.5)
5-5 Landscape mosaics
1. Landscape mosaic (fig. 5.6, 7)
2. Every ecosystem is an ecological island because it is surrounded by other
ecosystems.
3. Landscape mosaics have their own self-organizing process. Ex: water from forest
to rice field.
4. Spatial hierarchies: (fig. 5.8)
5. City’s zone of influence: serves as a source of labor, fuel, food, water and building
materials for the city.