Chapter 5 Climate and Terrestrial Biodiversity A CLIMATE
Chapter 5 Climate and Terrestrial Biodiversity
A. CLIMATE: A BRIEF INTRODUCTION Weather is a local area’s short-term physical conditions such as temperature and precipitation. 2. Climate is a region’s average weather conditions over a long time. 1. a) Latitude and elevation help determine climate.
Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Parallels and Meridians Myneni Lecture 03: Rotating Sphere Jan-22 -07 (5 of 15) • From these concepts we can draw systematic set of coordinates on the earth’s surface called “Meridians and Parallels” Parallels -Parallel to one another - Intersect meridians at 90 -degree angles Meridians - Not parallel to one another - Intersect at the poles
Myneni Natural Environments: The Lecture 03: Rotating Sphere Atmosphere Jan-22 -07 GE 101 – Spring 2007 (6 of 15) Boston University Geographical Coordinate System: Latitude • From these sets of lines, we can define a “geographic coordinate system” based on the relation of our position on the globe to the fixed meridians and parallels Fixed Meridian Latitude Parallel Equator Latitude Position measured in degrees of arc (along a fixed meridian) from the Equator
Myneni Natural Environments: The Lecture 03: Rotating Sphere Atmosphere Jan-22 -07 GE 101 – Spring 2007 (7 of 15) Boston University Geographical Coordinate System: Longitude Meridian Fixed Parallel Prime Meridian Longitude Position measured in degrees of arc (along a fixed parallel) from a fixed meridian Called the “Prime Meridian” - passes through Greenwhich, England is defined as 0 -degrees longitude
Myneni Natural Environments: The Lecture 03: Rotating Sphere Atmosphere Jan-22 -07 GE 101 – Spring 2007 (8 of 15) Boston University Geographical Coordinate System: Example Location of point P is: 50 degrees North, 60 degrees West So P would be located…. ?
Animation: Climate and Ocean Currents Map PLAY ANIMATION
Animation: Air Circulation and Climate PLAY ANIMATION
3. Global air circulation is affected by the uneven heating of the earth’s surface by solar energy, seasonal changes in temperature and precipitation. a) Uneven heating indicates the equator is heated more than the poles Figure 5 -3
Video: Seasonal Variation PLAY VIDEO
Coriolis Effect 4. Global air circulation is affected by the rotation of the earth on its axis. a) Rotation results in the earth moving faster beneath air masses at the equator and slower at the poles Figure 5 -4
5. Properties of air, water, and land affect global air circulation Water evaporation sets up cyclical convection cells. b) These occur both vertically and from place to place. c) The result is an irregular distribution of climates and patterns of vegetation from pole to pole. a)
Convection Cells 6. Heat and moisture are distributed over the earth’s surface by vertical currents, which form six giant convection cells at different latitudes. Figure 5 -6
7. Ocean currents influence climate by distributing heat from place to place and mixing and distributing nutrients Differences in water density and heat create ocean currents that are warm/cold b) Currents, such as the Gulf Stream, redistribute absorbed solar heat from one place to another, influence vegetation and climate near coastal regions c) Currents also help mix ocean waters to distribute nutrients and dissolved oxygen needed for aquatic organisms a)
8. The Greenhouse effect refers to the change in thermal equilibrium temperature of our planet by the presence of gasses that absorbs infrared radiation. These gasses (water vapor, carbon dioxide, methane, and nitrous oxide) are known as greenhouse gasses. b) The earth would be a cold, mostly lifeless place without this effect a)
Animation: Greenhouse Effect PLAY ANIMATION
Animation: Increasing Greenhouse Gases PLAY ANIMATION
9. Global warming: a) Considerable scientific evidence and climate models indicate that large inputs of greenhouse gases from anthropogenic activities into the troposphere can enhance the natural greenhouse effect and change the earth’s climate in your lifetime. l Anthropogenic - caused or influenced by humans
10. Interactions between land oceans and disruptions of airflows by mountains and cities affect local climates. a) Various topographic features can create local and regional climates different from the general climate of a region.
LOW PRESSURE Cool, dry air HIGH PRESSURE Heat released radiates to space Condensation Falls, is compressed, warms and precipitation Rises, expands, cools Warm, dry air Hot, wet air Flows toward low pressure, picks up moisture and heat HIGH Moist surface warmed PRESSURE by sun LOW PRESSURE Fig. 5 -5, p. 103
The rainshadow effect, where an air mass moves inland from an ocean, reaches a mountain range, and as the air is forced to rise, it cools and loses moisture on the windward side. 12. The leeward side of the mountain will be drier due to the loss of moisture on the windward side 13. Bricks, asphalt and other building materials create distinct microclimates in cities that are warmer, have more haze and smog and lower wind speeds than the countryside around them 11.
Prevailing winds pick up moisture from an ocean. On the windward side of a mountain range, air rises, cools, and releases moisture. On the leeward side of the mountain range, air descends, warms, and Releases little moisture. Dry habitats Moist habitats Fig. 5 -8, p. 105
Animation: Coastal Breezes PLAY ANIMATION
Animation: Upwelling Along Western Coasts PLAY ANIMATION
B. Biomes: climate and life on land 1. Different climates lead to different communities of organisms, especially vegetation. Biomes – large terrestrial regions characterized by similar climate, soil, plants, and animals. b) Each biome contains many ecosystems whose communities have adapted to differences in climate, soil, and other environmental factors. a)
2. Biome type is determined by precipitation, temperature and soil type Figure 5 -10
Animation: Biomes Map PLAY ANIMATION
3. Parallel changes occur in vegetation type occur when we travel from the equator to the poles or from lowlands to mountaintops. Figure 5 -11
C. DESERT BIOMES 1. Deserts areas where evaporation exceeds precipitation. a) 2. The largest ones are found in the interior of continents Deserts have little precipitation and little vegetation. Found in tropical, temperate and polar regions. Tropical deserts are hot, with few plants, rocks and sand c) Temperate deserts have plants that are widely spaced, mostly drought-resistant shrubs, cacti/succulents d) Polar deserts have cold winters, warm summers with low rainfall a) b)
Freezing point Month Mean monthly precipitation (mm) Mean monthly temperature ( C) Tropical Desert Fig. 5 -12 a, p. 109
Freezing point Month Mean monthly precipitation (mm) Mean monthly temperature ( C) Temperate Desert Fig. 5 -12 b, p. 109
Freezing point Month Mean monthly precipitation (mm) Mean monthly temperature (°C) Polar Desert Fig. 5 -12 c, p. 109
3. Desert plants have adaptations that help them stay cool and get enough water. Plants may have no leaves, they store water in fleshy tissue, and open pores to have gas exchange only at night b) Evergreen plants have thick, waxy leaves to reduce evapotranspiration c) Annuals store biomass in seeds that may be dormant for years a) 4. Desert ecosystems are fragile and take a long time to recover from disturbances due to slow plant growth, low species diversity, slow nutrient cycling, and lack of water
Video: Desertification in China PLAY VIDEO l From ABC News, Environmental Science in the Headlines, 2005 DVD.
D. Grassland Chaparral Biomes 1. Grasslands have enough precipitation support grasses but not enough to support large stands of trees They persist because of seasonal drought b) The three main types of grasslands are tropical, temperate, and polar a)
Savannas are tropical grasslands with scattered trees and enormous herds of hoofed animals a) A savanna usually has warm temperatures yearround, two long dry seasons with much rain the rest of the year Tropical grassland (savanna) Freezing point Month Mean monthly precipitation (mm) Mean monthly temperature ( C) 2. Fig. 5 -14 a, p. 112
b) Temperate grasslands with cold winters and hot and dry summers have deep and fertile soils that make them ideal for growing crops and grazing cattle Temperate grassland Freezing point Month Fig. 5 -14 b, p. 112 Mean monthly precipitation (mm) Mean monthly temperature ( C) 3. Competition for plant materials has been minimized due to specialized eating habits
3. Temperate grasslands with cold winters and hot and dry summers have deep and fertile soils that make them ideal for growing crops and grazing cattle a) b) c) d) e) Rain falls unevenly throughout the year Natural grasses are adapted to fire Soil held in place by network of intertwined root Humans have used these lands to raise cattle and crops because it is easily plowed Plowing makes soil vulnerable to erosion and blowing
Animation: Prairie Food Web PLAY ANIMATION
Polar grasslands are covered with ice and snow except during a brief summer a) Most growth occurs within 6 -8 weeks of summer during the long hours of daylight Polar grassland (arctic tundra) Freezing point Month Mean monthly precipitation (mm) Mean monthly temperature ( C) 4. Fig. 5 -14 c, p. 112
Permafrost is a permanently frozen layer of soil when water freezes c) Tundra is waterlogged during summer, with hordes of insects d) Global warming is causing some parts of the permafrost in parts of Alaska to melt b)
Chaparral 5. Chaparral has a moderate climate but its dense thickets of spiny shrubs are subject to periodic fires. Figure 5 -18
5. Chaparral has a moderate climate but its dense thickets of spiny shrubs are subject to periodic fires. Chaparral or temperate shrubland is found in coastal areas that border deserts b) The winter rainy season is longer than in desert, fog during spring/fall reduces evaporation c) Chaparral is adapted to occasional fires d) Humans like the climate of this biome, but risk losing homes to fire a)
E. Forest Biomes 2. Forests have enough precipitation to support stands of trees and are found in tropical, temperate, and polar regions Tropical rain forests have heavy rainfall and a rich diversity of species Tropical rain forest Freezing point Month Mean monthly precipitation (mm) Mean monthly temperature ( C) 1. Fig. 5 -19 a, p. 116
E. Forest Biomes Forests have enough precipitation to support stands of trees and are found in tropical, temperate, and polar regions 2. Tropical rain forests have heavy rainfall and a rich diversity of species a) Tropical rain forests are near the equator, and have hot humid conditions. b) Dominant plants are broadleaf evergreens with shallow roots c) Tropical forests cover about 2% of the land surface, but are habitats for about half the terrestrial species of earth. d) Most nutrients are stored in trees, vines and other plants. 1.
Animation: Rainforest Food Web PLAY ANIMATION
Temperate deciduous forests grow in areas with moderate average temperatures, abundant rainfall and long, warm summers. Mean monthly precipitation (mm) Temperate deciduous forest Most of the trees in these forests survive winter by dropping their leaves, which decay and produce nutrient-rich soil b) Broadleaf, deciduous trees dominate this Freezing point biome c) More sunlight penetrates the canopy so there is richer diversity of ground level plant life d) smaller mammals are now often the. Month dominant species a) Mean monthly temperature ( C) 3. Fig. 5 -19 b, p. 116
Evergreen coniferous forests or boreal forests are located in areas just south of arctic tundra around the northern subarctic regions of the earth These forests consist mostly of cone-bearing Polar evergreen coniferous forest evergreen trees that keep their needles year(boreal forest, taiga) round b) Decomposition is slow because of low Freezing temperatures, waxy narrow leaves and point high soil acidity c) Year-round residents include bears, wolves, moose, lynx and many burrowing rodent Month species a) Mean monthly precipitation (mm) Mean monthly temperature ( C) 4. Fig. 5 -19 c, p. 116
Temperate Rain Forests 5. Coastal areas support huge cone-bearing evergreen trees such as redwoods and Douglas fir in a cool moist environment. Figure 5 -24
E. MOUNTAIN BIOMES High-elevation islands of biodiversity 2. Often have snow-covered peaks that reflect solar radiation and gradually release water to lowerelevation streams and ecosystems. 3. Mountains play a major role in the hydrologic cycle 1.
F. HUMAN IMPACTS ON TERRESTRIAL BIOMES Human activities have damaged or disturbed more than half of the world’s terrestrial ecosystems. 2. Humans have had a number of specific harmful effects on the world’s deserts, grasslands, forests, and mountains. 1.
Natural Capital Degradation Desert Large desert cities Soil destruction by off-road vehicles Soil salinization from irrigation Depletion of groundwater Land disturbance and pollution from mineral extraction Fig. 5 -26, p. 123
Natural Capital Degradation Grasslands Conversion to cropland Release of CO 2 to atmosphere from grassland burning Overgrazing by livestock Oil production and offroad vehicles in arctic tundra Fig. 5 -27, p. 123
Natural Capital Degradation Forests Clearing for agriculture, livestock grazing, timber, and urban development Conversion of diverse forests to tree plantations Damage from off-road vehicles Pollution of forest streams Fig. 5 -28, p. 124
Natural Capital Degradation Mountains Agriculture Timber extraction Mineral extraction Hydroelectric dams and reservoirs Increasing tourism Urban air pollution Increased ultraviolet radiation from ozone depletion Soil damage from off-road vehicles Fig. 5 -29, p. 124
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