[BIO 1306] Ch56_Lecture

[BIO 1306] Ch56_Lecture - 56 Ecosystems and Global Ecology...

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56 Ecosystems and Global Ecology
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56 Ecosystems and Global Ecology 56.1 What Are the Compartments of the Global Ecosystem? 56.2 How Does Energy Flow Through the Global Ecosystem? 56.3 How Do Materials Cycle Through the Global Ecosystem? 56.4 What Services Do Ecosystems Provide? 56.5 What Options Exist to Manage Ecosystems Sustainably?
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56.1 What Are the Compartments of the Global Ecosystem? Earth is a closed system with respect to matter, but open with respect to energy. Energy from the sun, and from radioactive decay that melts the magma in the Earth’s interior, drive the processes that move materials around the planet. Many of these processes are cyclic.
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Figure 56.1 The Global Ecosystem’s Compartments are Connected by the Flow of Elements
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56.1 What Are the Compartments of the Global Ecosystem? Earth is an unusual planet. Among its unusual features: Life, oceans, moderate surface temperature, continental drift, a large moon. The moon stabilizes the tilt of Earth on its axis. The degree of tilt strongly influences climate. It also produces tides, and slows Earth’s rotation.
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56.1 What Are the Compartments of the Global Ecosystem? The physical environment can be divided into four compartments: oceans, freshwaters, atmosphere, and land. The compartments and the types of organisms living in them are very different.
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56.1 What Are the Compartments of the Global Ecosystem? Oceans Over very long time scales, most materials that cycle through the four compartments end up in the oceans. Oceans exchange materials with the atmosphere only at their surface, respond slowly to inputs, receive material from land in river runoff, and mix slowly.
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56.1 What Are the Compartments of the Global Ecosystem? Materials from other compartments sink to the ocean floor and remain for millions of years, until being uplifted by mountain-building events. Upwelling zones occur where offshore winds push water away from shore. Cold bottom-water that moves up is nutrient-rich and supports a high photosynthesis rate. Most fisheries are in upwelling zones.
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Figure 56.2 Zones of Upwelling are Productive
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56.1 What Are the Compartments of the Global Ecosystem? Fresh waters Rivers, lakes, groundwater (water in soils and rocks). Water moves rapidly through this compartment. Mineral nutrients enter through weathering of rock. In lakes, nutrients taken up by aquatic organisms end up as part of the sediments.
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Surface waters of lakes become depleted in nutrients, bottom-water becomes depleted in oxygen. Turnover , or mixing, reverses this process. Wind can cause mixing; in deep lakes, turnover is controlled by temperature. In summer, surface waters warm, and the
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This note was uploaded on 04/08/2008 for the course BIO 1306 taught by Professor Adair,tamarah during the Spring '08 term at Baylor.

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[BIO 1306] Ch56_Lecture - 56 Ecosystems and Global Ecology...

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