2 Tragedy of the commonsEnglish villagers grazed their cattle on shared pasture lands called commons.Sometimes there were more cattle than the pastures could hold.Pastures were overused.Overgrazing pastures damaged the land so bad that the pastures could no longer support cattle.Ecologists called this the “tragedy of the commons”.
3 Classifying Resources Environmental goods and services may be classified as renewable and nonrenewable.Renewable resources – regenerate if they are alive or can be replenished by biogeochemical cycles if they are non-living. Examples – fresh water, trees, pastureNonrenewable resources – cannot be regenerated by natural processes. Examples – coal, oil and natural gas take too long to form
4 Sustainable Development Human activities can affect the quality and supply of renewable resources such as land, forests, fisheries, air and fresh water.Sustainable development is the way of using natural resources without depleting them and of providing for human needs without causing long-term environmental harm.
5 Land ResourcesLand provides space for human communities and raw materials for industry.Soil can be a renewable resource if used properly and damaged if mismanaged.Fertile soils consist of good topsoil, sand, clay and rock particles.Good topsoil absorbs and retains moisture and lets excess water to drain.
6 Land ResourcesPlowing the land removes the roots that hold the soil in place.Soil erosion is increased.A combination of farming, overgrazing, and drought has turned fertile soils into deserts – termed desertification
7 Sustainable development practices to preserve land resources Farming practices like contour plowing reduces soil erosion.Leaving stems and roots of previous crops to hold the soil in place.Planting a field with rye to protect the soil from erosion.
8 Forest ResourcesForests are important for the products they produce and the ecological functions they perform.Use wood for heating and cooking“Lungs of the earth” – they remove carbon dioxide and produce oxygenStore nutrients and provide habitatsModerate climate and limit soil erosion
9 Forest Resources Can be considered renewable resources Northeastern forests have been logged at least once before.Northwestern forests (old growth forests) are non-renewable since it takes many centuries to produce old-growth forests
10 Forest Resources Effects of Deforestation – the loss of forests Severe erosion since soil is exposed to runoffErosion washes away nutrients in the soilGrazing or plowing can cause permanent changes to soils that can prevent the regrowth of trees
11 Forest ResourcesForest Management strategies for sustainable developmentSelective cutting of trees to promote growth of younger trees to preserve the forest ecosystem.Plant, manage, harvest, and replant tree farmsGeneticists are breeding new, faster-growing tree varieties for high quality wood
12 Fishery Resources Fish and other animals are a valuable food source OverfishingHarvesting of fish faster than they can replace by reproductionA true “tragedy of the commons”
13 Fishing Resources Sustainable development US National Marine Fisheries Service created guidelines for commercial fishing.Regulations help fish populations to recoverSpecified how many fish and what size could be caught in various parts of the oceans.
14 Fishery Resources Aquaculture The raising of aquatic animals for human consumptionCould pollute water and damage aquatic ecosystems
15 Air Resources Air is a common resource that we all use. Smog is a mixture of chemicals that occurs as a gray-brown haze in the atmosphere.Smog is considered to be a pollutant.Pollutants are harmful materials that can enter the biosphere through the land, air, or water.
16 Air ResourcesThe burning of fossil fuels can release pollutants that can cause smog and other problems in the atmosphere such as nitrogen and sulfur compounds.If these compounds combine with water, then acid rain is formed.Acid rain can kill plants by damaging their leaves and changing the chemistry of soils and standing water ecosystems.
17 Freshwater ResourcesWater is a renewable resource but is in a limited supply.Pollution threatens waters in many ways;Discarded chemicals get into waterwaysSewage can get into the soils