Ecosystems (生態系統).pptVIP

Chapter 54 Ecosystems (生態系統) Key Concepts Concept 54.1: Ecosystem ecology emphasizes energy flow and chemical cycling (生態系統強調能量流通與化學循環) Concept 54.2: Physical and chemical factors limit primary production in ecosystems (物理與化學因子限制生態系統的初級生產量) Concept 54.3: Energy transfer between trophic levels is usually less than 20% efficient (不同食性階層的能量轉移效率低於20%) Concept 54.4: Biological and geochemical processes move nutrients between organic and inorganic parts of the ecosystem (生物與地質化學過程生態系統有機與無機間的營養) Concept 54.5: The human population is disrupting chemical cycles throughout the biosphere (人類族群破壞生物圈的化學循環) Overview: Ecosystems, Energy, and Matter An ecosystem consists of all the organisms living in a community As well as all the abiotic factors with which they interact Ecosystems can range from a microcosm, such as an aquarium to a large area such as a lake or forest Regardless of an ecosystem’s size Its dynamics involve two main processes: energy flow and chemical cycling Energy flows through ecosystems While matter cycles within them Concept 54.1: Ecosystem ecology emphasizes energy flow and chemical cycling Ecosystem ecologists view ecosystems As transformers of energy and processors of matter Ecosystems and Physical Laws The laws of physics and chemistry apply to ecosystems Particularly in regard to the flow of energy Energy is conserved But degraded to heat during ecosystem processes Trophic Relationships Energy and nutrients pass from primary producers (autotrophs) To primary consumers (herbivores) and then to secondary consumers (carnivores) Energy flows through an ecosystem Entering as light and exiting as heat Nutrients cycle within an ecosystem Decomposition Decomposition Connects all trophic levels Detritivores, mainly bacteria and fungi, recycle essential chemical elements By decomposing organic material and returning elements to inorganic reservoirs Concept 54.2: Physical and chemical factors limit primary production in ecosystems Primary production in an ecosystem