chap. 3 energy in ecological systems (ii) 鄭先祐 (ayo) 國立台南大學 環境與生態學院...
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Chap. 3 Energy in Ecological Systems (II)
鄭先祐 (Ayo)
國立台南大學 環境與生態學院
2008 年 2 月至 6 月
3. energy in ecological systems (part II) 2
Energy in Ecological systems
1. The Laws of Thermodynamics ( 熱力學定律 )
2. Solar radiation and the energy environment
3. Concept of productivity
4. Energy partitioning in food chains and food webs
5. Energy quality: eMergy
6. Metabolism and size of individuals: the ¾ power principle
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Energy in Ecological systems
7. Complexity theory, energetics of scale, and the law of diminishing returns
8. Concepts of carrying capacity and sustainability
9. Net energy concept10.An energy-based classification of
ecosystems11.Energy future12.Energy and money
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5 Energy Quality: eMergy
Energy quality,能量不能僅有量的大小，亦有品質的好壞。同
量但不同形式的能量，其作功的能力大不相同，也就是品質各不相同。並不是所有每 1 卡能量都具有同樣的品質。
eMergy (embodied energy), as the sum of the available energy already us
ed directly or indirectly to create a service or product.
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Fig. 3-25. Diagram showing how increasing energy concentration (quality) accompanies decreasing energy quality.
3. energy in ecological systems (part II) 6
Fig. 3-25. Diagram showing how increasing energy concentration (quality) accompanies decreasing energy quality.
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Table 3-10
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6 Metabolism and Size of Individuals: The ¾ Power Principle
The ¾ Power Principlethe rate of metabolism in individual animals te
nds to increase as the ¾ power of their body weight.
Fig. 3-26. Relationships between (A) respiration and body weight and (B) respiration per unit weight and total body mass.
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7 Complexity Theory, Energetics of Scale, and the Law of Diminishing
Returns
Law of diminishing returns when maintenance energy costs balance the
available energy, the theoretical maximum size or carrying capacity has been reached, beyond which decreasing returns of scale set in
C = N(N-1)/2
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8 Concepts of Carrying Capacity and Sustainability
Carrying capacity ( 承載量 )Maximum carrying capacityOptimum carrying capacityEconomic carrying capacity (economic welfar
e threshold)
Maximum sustained yield (optimum density)
3. energy in ecological systems (part II) 11Fig. 3-27. Carrying capacity in relation to sigmoid population growth. (A) Growth curve
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Fig. 3-27. Carrying capacity in relation to sigmoid population growth. (B) change in growth curve depending on population size.
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Concept of sustainability
Sustain = to keep in existence + to support + to maintain + to supply
Sustainability = maintaining natural capital and resources
3. energy in ecological systems (part II) 14Fig. 3-28. Trends in the gross national product (GNP) index and the index of sustainable economic welfare (ISEW) in the US.
3. energy in ecological systems (part II) 15Fig. 3-29. Energy-generating windmills in eastern Germany.
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9 Net Energy Concept
Fig. 3-30. Concept of net energy.
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10 An Energy-Based Classification of Ecosystems Four classes of ecosystems
1. Natural, unsubsidized solar-powered ecosystems
2. Natural, solar-powered ecosystems subsidized by other natural energies.
3. Human-subsidized solar-powered ecosystems
4. Fuel-powered, urban-industrial techno-ecosystems
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Table 3-11
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11 Energy Futures
Energy 1. Age of muscle power
2. Age of fossil fuels
3. Age of atomic energy
Future: solar energy and fuel-cell (hydrogen) Ocean thermal energy conversion (OTEC)
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Peaceful uses of atomic energy
At the first international conference (Geneva in 1955), the chair of the conference, Homi J. Bhabha of India, described three ages of humanikind.
Bhabha believed the coming of the atomic age would close the gap between rich and poor nations.
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3. energy in ecological systems (part II) 22
12 Energy and Money
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Fig. 3-31. Energy flow model of an estuarine ecosystem harvested for seafood.
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圖 8 傳統的經濟活動。海灣區對人類的實際價值至少是此區生產的魚獲量價值的十倍。紅色線表示能量的循流；
淡藍色線表示貨幣之流通。
海洋生態體系
物質循環
能量循流
太陽
捕魚活動
人力、漁具、漁船、能量
海產市場
經濟學 生態學
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3. energy in ecological systems (part II) 27
圖 9 人類的能源支持體系。由人工和農業生態系來的能量，貨幣流通大致配合能量的循流；但是從自然態系而來的能量，並無貨幣配合。紅色線表示能量的循流；淡藍色線表示貨幣之流通。
科技系統
農林漁牧生態系
自然生態系
世界經濟
化石燃料
太陽能
能源 能量轉換 能量享用
3. energy in ecological systems (part II) 28
經濟生產 消費
景觀、環境&
物種的舒適 廢物的化解自然資源
生態功能
東西與服務
勞工
資源流動
殘餘廢棄
舒適服務
狹窄觀點
寬廣觀點
殘餘廢棄物
圖 3. 經濟的狹窄觀點和寬廣觀點。傳統經濟學理是立基於狹窄觀點，新寬廣觀點認識到自然生態環境對經濟活動所提供的價值。基本內容摘譯自： Young(1992) ， p.10， Figure 1.4 。
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