Environmental Problems, Their Causes, and Sustainability 1

Natural Capital DegradationGrasslandstorrents of water pour off the unprotected burned hillsidesto flood lowland areas. Bottom line. Chaparral hasagreat climate but is a risky place to live.Conversion of savanna andtemperate grassland to croplandRelease of CO 2 to atmospherefrom burning and conversion ofgrassland to croplandOvergrazing of tropical andtemperate grasslands bylivestockDamage to fragile arctic tundraby oil production, air and waterpollution, and off-road vehiclesFigure 6-27 Natural capital degradation: major human impactson the world’s grasslands.use nutrients released by the fire. New shrubs growquickly and crowd out the grasses.People like living in this biome because of its favorableclimate. But those living in chaparral assumethe high risk of losing their homes and possibly theirlives to frequent fires and mudslides.Some people in southern California learned thislesson in the fall of 2003 when fires raging throughchaparral areas destroyed several thousand homes andkilled 20 people. After fires often comes the hazard offlooding and mudslides; when heavy rains come, great6-6 FOREST BIOMESWhat Are the Major Types of Forests? Hot,Mild, and ColdForests have enough precipitation to supportstands of trees and are found in tropical, temperate,and polar regions.Undisturbed areas with moderate to high average annualprecipitation tend to be covered with forest,which contains various species of trees and smallerforms of vegetation. The three main types of forest—tropical, temperate, and boreal (polar)—result fromcombinations of this precipitation level and variousaverage temperatures (Figures 6-16 and 6-28). Take aclose look at the graphs in Figure 6-28.What Are Tropical Rain Forests? Centersof BiodiversityThese forests have heavy rainfall on most days andhave a diversity of life forms occupying a varietyof specialized niches in distinct layers.Tropical rain forests are found near the equator, wherehot, moisture-laden air rises and dumps its moisture(Figure 6-10). Trace the nutrient flows and energytransfers in Figure 6-29. These forests have a warm annualmean temperature (which varies little either dailyor seasonally), high humidity, and heavy rainfall almostdaily (Figure 6-28, left).Mean monthly temperature°C °F in. mm100 1535375309014 35025 8013 32520 7012 30015 6011 27510 5010 2505 409 2250 308 200–5 32°F Freezing point207 175–10–15106 150–20 05 125–25 –104 100–30–35–40–45–20–30–40–5032107550250JanFebMarAprMayJunJulAugSepOctNovDecMonthsTropical rain forest(Manaus, Brazil)Mean monthly precipitationMean monthly temperature°C °F in. mm100 1535375309014 35025 8013 32520 7012 30015 6011 27510 5010 2505 409 2250 308 200–5 32°F Freezing point207 175–10–15106 150–20 05 125–25 –104 100–30–35–40–45–20–30–40–5032107550250JanFebMarAprMayJunJulAugSepOctNovDecMonthsTemperate deciduous forest(Nashville, Tennessee)Figure 6-28 Climate graphs showing typical variations in annual temperature (the graphed line) and precipitation(the shaded area on the graph) in tropical, temperate, and polar forests.Mean monthly precipitationMean monthly temperature°C °F in. mm100 153537530 9014 35025 8013 32520 7012 30015 6011 27510 5010 2505 409 2250 308 200–532°F207 175–10Freezing point–15106 150–20 05 125–25 –104 100–30 –203 75–35–40–45–30–40–5021050250JanFebMarAprMayJunJulAugSepOctNovDecMonthsPolar evergreen coniferous forest(boreal forest, taiga)(Moscow, Russia)Mean monthly precipitation120 CHAPTER 6 Climate and Terrestrial Biodiversity