Biology 2014-2015

Sec. 6-2 Renewable and Nonrenewable Resources
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Classifying Resources

¨       Environmental goods and services may be classified as either renewable or nonrenewable.

¨       A renewable resource can regenerate if it is alive, or can be replenished by biochemical cycles if they are nonliving.

Ø       A tree is an example of a renewable resource, because a new tree can grow in place of an old tree that dies or is cut down.

¨       A renewable resource is not necessarily unlimited.

¨       Fresh water can easily become limited by drought or overuse.

Ø       A nonrenewable resource is one that cannot be replenished by natural processes.

Ø       Fossil fuels-coal, oil, and natural gas are nonrenewable resources.  When they are depleted, they are gone forever.

 

Sustainable Development

¨       Sustainable development is a way of using natural resources without depleting them, and providing for human needs without causing long-term environmental harm.

¨       Human activities can affect the quality and supply of renewable resources such as land, forests, fisheries, air, and fresh water.

¨       Sustainable strategies must enable people to live comfortably and improve their situation.

¨       The use of insects to control insect pests is one such strategy.  This may help farmers reduce the use of pesticides.

 

Land Resources

¨       Land is a resource that provides space for human communities and raw materials for industry.

¨       Land also includes the soils in which crops are grown.

¨       The most fertile soil is in the uppermost layer called topsoil.

¨       Such soil is produced by long-term interactions between the soil and plants growing in it.

¨       Plowing the land removes the roots that hold the soil in place.

¨       Soil erosion is the wearing away of surface soil by water and wind.

Ø       The Midwest loses roughly 47 metric tons of topsoil per hectare every year!

¨       In dry climates, a combination of farming, overgrazing, and drought has turned once productive areas into deserts a process called desertification.

¨       There are a variety of sustainable-development practices that guard against these problems.

Ø       Contour plowing, in which fields are plowed across the slope of the land to reduce erosion.

Ø       Leaving the stems and roots of the previous year’s crop in place to help hold the soil.

Ø       Planting a field with rye rather than leaving it unprotected from erosion.

 

Forest Resources

Ø       Forests have been called the “lungs of the Earth” because they remove carbon dioxide and produce oxygen.

Ø       Forests provide:

Ø       Wood for homes, paper, fuel

Ø       Store nutrients

Ø       Provide habitats and food for organisms

Ø       Moderate climate

Ø       Limit soil erosion

Ø       Protect freshwater supplies

 

¨       Worldwide, about half of the area originally covered by forests and woodlands has been cleared.

¨       Only about one-fifth of the world’s original old-growth forests remain.

¨       Deforestation or the loss of forests can lead to severe erosion as soil is exposed to heavy rains.

¨       Erosion can wash away nutrients in the topsoil.

¨       Grazing or plowing after deforestation can change local soils and microclimates that may prevent regrowth of trees.

¨       There are a variety of sustainable-development strategies for forest management:

Ø       Mature trees are harvested selectively to promote growth of younger trees and promote the forest ecosystem.

Ø       Foresters plant, manage, harvest, and replant tree farms.

Ø       Tree geneticists are also breeding new, faster-growing tree varieties that produce high quality wood.

 

Fishery Resources

Ø       Fishes and other animals that live in water are a valuable source of food for humanity.

 

Overfishing

¨       Overfishing, or harvesting fish faster than they can be replaced by reproduction, greatly reduced the amount of fish in parts of the world’s ocean.

¨       From 1950-1990, the world fish catch grew from 19 million tons to more than 90 million tons.

¨       By the early 1990’s, populations of cod and haddock had dropped so low that researchers thought these fish might disappear.

¨       The declining fish populations are an example of the “tragedy of commons”.

¨       “Tragedy of commons” is when people from several countries take advantage of a resource but no one takes responsibility for maintaining it.

 

 

 

Sustainable Development

Ø       Because of the declining fisheries, the U.S. National Marine Fisheries Service created guidelines for United States commercial fishing.

Ø       The guideline specified how many fish, and of what size, could be caught in various parts of the oceans.

¨       The regulations are helping fish populations to recover.

¨       Unfortunately, it caused loss of jobs in the short term, but will protect the fishing industry for the future.

 

Aquaculture

Ø       Aquaculture is the raising of aquatic animals for human consumption.

Ø       It also helps to sustain fish resources.

Ø       If it is not managed properly, aquaculture can pollute water and damage aquatic ecosystems.

 

Air Resources

¨       Air is a resource that affects people’s health and it’s quality remains a challenge for modern society.

¨       Smog is a mixture of chemicals that occurs as a gray-brown haze in the atmosphere.

¨       Smog is due to automobile exhaust and industrial emissions.

¨       Smog is considered a pollutant.

¨       A pollutant is a harmful material that can enter the biosphere through land, air, or water.

¨       The burning of fossil fuels can release pollutants into the atmosphere.

¨       Toxic chemicals are nitrates, sulfates, and particulates which are microscopic particles of ash and dust.

¨       Most industries have to control their emissions from factory smokestacks.

¨       Strict automobile emission standards and clean-air regulations have greatly improved air quality in U.S. cities.

¨       The release of nitrogen and sulfur compounds into the atmosphere when combined with water vapor form strong acids.

¨       When acid rain falls, it can kill plants and change the chemistry of soils and standing-water ecosystems.

 

Freshwater Resources

¨       Americans use billions of liters of freshwater daily for drinking and washing to watering crops and making steel.

¨       Pollution threatens water supplies in several ways.

Ø       Improperly discarded chemicals can enter streams and rivers.

Ø       Waste discarded on land can seep through soil and enter groundwater.

Ø       Domestic sewage (sinks and toilets) which contain nitrogen can encourage growth of algae and bacteria in aquatic habitats.

Ø       Sewage containing microorganisms can spread disease among humans and animals.

¨       One way of ensuring the sustainable use of water resources is to protect the natural systems involved in the water cycle.

Ø       Wetlands help to purify the water passing through them.  Densely growing plants filter certain pollutants out of the water.

Ø       Forests and other vegetation help to purify the water that seeps into the ground.

¨       Water conservation is becoming an increasingly important aspect of sustainable development.

¨       More than three quarters of all water consumed is used in agriculture.

Ø       An example of conservation would be to use drip irrigation which delivers water directly to plant roots.  This reduces the amount of water lost through evaporation.