全球生態學 (Global Ecology)

鄭先祐 (Ayo)國立臺南大學 環境生態研究所 教授環境與生態學院 院長

Global Ecology and Human Ecology 2

目錄 Global Ecology 大氣層 (Atmospheric Envelope) Concepts El Nino and La Ninas ( 氣候變遷 ) 氮肥的增加 對生物多樣性的衝擊 溫室效應 臭氧層破洞

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圖 1. 從月球看地球。地球是一個多水的行星。(Apollo 12 於月球拍攝的照片 ) 。 (Fig. 23.1)

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Global Ecology

人在樹林中，只能看到樹木，沒有看到森林的全貌。

於 1968-70 年間，太空人將從太空拍攝地球的照片傳回地球，人類首次得以走到畫框外面而看到整個地球。

結果， 1970 年人們發起地球日 (Earth day) 。許多環保法令陸續頒布，關心全球環境的輿論興起，以及提出環境影響評估的要求。

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21st century

Peter Vitousek (1994) This is the first generation( 第一個世代 ) in

history with the tools to examine how humanity has changed the Earth.

This may be the last generation ( 最後一個世代 ) that has a chance to affect the course of those changes significantly.

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大氣層 (Atmospheric Envelope)

Exosphere ( 散逸層 )

Thermosphere ( 熱成層 )

Mesosphere ( 中間層 )

Stratosphere ( 平流層 )

Troposphere ( 對流層 )

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Green-house effect

倘若沒有陽光照射地球，地表的平均溫度約是 -18oC 。

目前平均是 15oC 。 提高約 33oC 的溫度。

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Greenhouse Effect ( 溫室效應 )

Heat is trapped near the earth’s surface by greenhouse gases: (Water Vapor, Carbon Dioxide, Methane,

Ozone, Nitrous Oxide, and CFC’s) Absorb infrared and reemit most back to

earth. 30 % Solar energy reflected back by clouds,

particulate matter, etc. 70 % Absorbed by atmosphere/surface.

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Essay 28.5 The greenhouse effect

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Essay 28.5 The greenhouse effect

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Greenhouse Effect

Fig. 23.2

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Concepts El Nino and La Ninas ( 氣候變遷 ) Human activity has greatly increased the quanti

ty of fixed nitrogen cycling( 氮循環的量 ) through the biosphere.

Rapid changes in global patterns of land use threaten biological diversity. ( 威脅生物多樣性 )

Human activity is increasing the atmospheric concentration of CO2, which may be increasing global temperatures. ( 溫室效應 )

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El Nino Southern Oscillation聖嬰 - 南方震盪

The name El Nino ( 聖嬰 ) originated when this climatic seemed limited to the west coast of South America. ( 南美洲的西部沿岸 ) During an El Nino, a warm current appears off the we

st coast of Peru ( 祕魯的西部沿岸 ), generally during the Christmas season( 聖誕節 ) .

The term Southern Oscillation refers to an oscillation in atmospheric pressure ( 氣壓 ) that extends across the Pacific Ocean( 太平洋區 ).

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歷史軌跡

Gilbert Walker( 英國數學家 ) ，印度天文觀測站主任 (1904) 。 印度於 1899-1900 發生乾旱而糧食欠收。 Walker 研析如何預測季節雨量。 Walker (1924) 發現太平洋的大氣壓與季節雨

量的關係。 東太平洋的氣壓下降，西太平洋的氣壓會上升。

反之，西太平洋的氣壓下降，會造成東太平洋的氣壓上升。 (southern oscillation)

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Southern oscillation index

Is determined by the difference in barometric pressure between Tahiti ( 大溪地 ) and Darwin, Australia ( 澳洲的達爾文港 ) (Fig. 23.4).

Walker noticed that low values of the index were associated with drought( 乾旱 ) in Australia( 澳洲 ), Indonesia( 印尼 ), India( 印度 ), and parts of Africa( 部分非洲 ).

Also suggested that winter temperatures in Canada ( 加拿大的冬天溫度 ) were somehow connected to the Southern Oscillation.

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Jacob Bjerknes (1966,1969)

A professor at the UCLA. El Nino – Southern Oscillation ( 相關

聯 ) Walker circulation (Fig. 23.5)

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Fig. 23.5 Walker circulation, El Nino, and La Nina.

於反聖嬰時期，太平洋的暴風會向西移動。

於聖嬰時期，暴風會向東移動。

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El Nino and La Ninas

During El Nino, 太平洋東邊的熱帶海面溫度會比平常高，氣

壓則會比較低。 如此會增加太平洋東部的暴風 (Promotes th

e formation of storms) 因此，增加東太平洋的雨量，減少西太平洋地區

的雨量。 La Ninas, 相反的情況。

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El Nino and Marine Populations

平常，南美洲西海岸海面的水溫都比較低 低的海面水溫，是來自海面下的湧升流。

當聖嬰時期，海面的水溫上升。 海面下的湧生流停止，減少營養的供應 ( 湧升

流帶來的 ) ，因此減少浮游植物的產量。

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El Nino and Marine Populations

於聖嬰時期，海面的水溫明顯的上升

於非聖嬰時期，海面的水溫比較冷。

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El Nino and Great Salt Lake

Strong El-Nino of 1982-83 was source of many storms deep into interior of N. America. Increased precipitation with Great Salt Lake b

asin. 1983-87 lake rose 3.7 m.

Wurtsbaugh and Smith Berry found lake salinity dropped by 50 g/l and the lake was invaded by predaceous insect Trichocorixa verticalis.

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El Nino and Great Salt Lake

Predator reduced population of brine shrimp from 12,000 to 74 per m3. Phytoplankton biomass increased

significantly. By 1990, lake level fell 2.8 m, and salinity

returned to 100 g/l. All ecosystem changes were reversed.

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El Nino and Kangaroo Populations

Red Kangaroo (Macropus rufus) occupies most of Australia’s semiarid interior.

During wet period with plenty of food, females will simultaneously have a baby following, a younger offspring in the pouch, and an embryo waiting to enter the pouch.

Under marginal conditions, most young die soon after leaving the pouch.

If food becomes scarce, females stop lactating and young die in embryo stage.

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El Nino and Kangaroo Populations

Kangaroos breed quickly and young enter the pouch within 60 days of onset of significant rainfall.

By reproducing large numbers of offspring under favorable conditions, kangaroos increase the number of adults that will face El Nino induced droughts.

Cairns and Grigg found a tight coupling of M. rufus populations to El Nino.

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Human Activity and Global Nitrogen Cycle

As human civilization developed intensive agriculture and industrial processes, we began to manipulate nitrogen cycle on massive scale. Vitousek

N - fixing bacteria/plants 100 Tg/yr Marine environments 5-20 Tg/yr Lightning 10 Tg/yr Human sources 130 Tg/yr

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Tropical Deforestation

Support at least half of earth’s species. Skole and Tucker reported tropical forest

s occur in 73 countries and once covered 11,610,360 km2. Brazil contains 1/3 of total.

Highest deforestation rate. Estimated by 1978, 78,000 km2 deforested. Annual rate of deforestation 1978-1988 was

15,000 km2.

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Tropical Deforestation

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Edge Effects and Tropical Deforestation

When a forest fragment is isolated due to cutting, its edge is exposed to greater amounts of solar radiation and wind. Physical environment along forest edges is

hotter and drier and solar intensity is higher. Fragmentation decreases diversity of many

animal groups.

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Edge Effects and Tropical Deforestation

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Human Influence on Atmospheric Composition

Record of atmospheric composition during last 160,000 years was extracted from ice cores in Greenland and Iceland. Samples of atmosphere trapped in ice.

Core indicated two very large fluctuations in atmospheric CO2 concentrations.

140,000 years ago. 13,000 years ago.

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Fig. 23.21

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Human Influence on Atmospheric Composition

Periods of low CO2 correspond to low temperatures experienced during ice ages, while high levels correspond to interglacial periods.

During 19th and 20th centuries, concentration of atmospheric CO2 increased dramatically.

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If greenhouse gases continue to rise at the current rate, between 2030 and 2050, the average temperature on Earth will rise by about 1.5oC to 10oC.

If the temperature should rise 4oC, these scientists forecast massive changes in weather and ocean currents.

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Human Influence on Atmospheric Composition

Fossil fuel burning alone produces more than enough CO2 (5,600 Tg/yr) to account for recent atmospheric concentrations (3,500 Tg/yr).

Three major periods of interruptions: World War I Great Depression World War II

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Depletion and Recovery of the Ozone Layer

In 1985, British Antarctic Survey discovered major reduction in atmospheric ozone. Attention focused on stopping

chlorofluorocarbons (CFCs). 1987 Montreal Protocol

Largest hole to date in 2000. 2003 saw first reported evidence the ozone

layer is recovering.

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