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Chapter 5

Chapter 5.docx

Environmental Studies
Course Code
ENV 1101
Sonia Wesche

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Chapter 5: Earth Systems and Ecosystems Ecology
The Nature of Environmental Systems:
- Systems are networks of interacting components that generally involve feedback loops,
show dynamic equilibrium, and result in emergent properties
- Earth’s natural systems are complex, so environmental scientists often take a holistic
approach to studying environmental systems
- Because environmental systems overlap and interact, one’s delineation of systems
depends on the questions in which one is interested
Plate Tectonics and the Rock Cycle:
- Matter is cycled within the lithosphere, and rocks transform from one type to another
- Plate tectonics is a fundamental system that produces earthquakes and volcanoes and
guides Earth’s physical geography
Ecosystems and how living and nonliving entities interact in ecosystem-level ecology
- Ecosystems consist of all organisms and non living entities that occur and interact in a
particular are at the same time
- Energy flows in one direction through ecosystems whereas matter is recycled
- Energy is converted to biomass, and ecosystems vary in their productivity
- Input of nutrients can boot productivity, but an excess of nutrients can alter ecosystems in
ways that cause severe ecological and economic consequences
Fundamentals of Landscape Ecology:
- Landscape ecology studies how landscape structure influences organisms
- Landscapes consist of patches spatially arrayed in a mosaic. Organism’s dependent n
certain types of patches may occur in metapopulations.
- Remote sensing technology and GIS are assisting the use of landscape ecology in
conservation and regional planning
Water, Carbon, nitrogen, and Phosphorus Cycle through the Environment:
- Water moves widely through the environment in the hydrologic cycle
- Most carbon is contained in sedimentary rock
- Substantial amounts of carbon also occur in the oceans and in soil
- Carbon flux between organisms and the atmosphere occurs via photosynthesis and
- Nitrogen is a vital nutrient for plant growth. Most nitrogen is in the atmosphere, so it
must be “fixed” by specialized bacteria or lightning before plants can use it
- Phosphorus is most abundant in sedimentary rock, with substantial amounts in soil and
the oceans. Phosphorus has no appreciable atmospheric pool. It is a key nutrient for plant
- Humans are causing substantial impacts to Earth’ biogeochemical cycles. These impacts
include: shifting carbon from fossil fuel reservoirs into the atmosphere, shifting nitrogen
from the atmosphere to the plant’s surface and depleting groundwater supplies, among
many others.
Open Systems: a system that exchanges energy, matter, and information with other systems
Closed Systems: a system that is self-contained with regard to exchanges of matter with its
surroundings. Scientists may treat a system as closed to simplify some question they are
investigating, but no natural system is truly closed
Feedback loop: a circular process in which a system’s output serves as input to that same system
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