Climate and Terrestrial Biodiversity

Biodiversity and Climate •  Different climates lead to different communities of organisms, especially vegetation. •  As you move from the equator to the poles the amount of biodiversity decreases.

Latitude

Biodiversity and Climate •  Weather is a local area’s short-term physical conditions such as temperature and precipitation. •  Climate is a region’s average weather conditions over a long time.

Earth’s Current Climate Zones

Figure 5-2

Climate

•  An area's climate is determined mostly by: •  solar radiation, •  earth’s rotation •  global patterns of air and water movement •  gases in the atmosphere •  earth’s surface features.

Solar Radiation •  Due to the tilt of the earth’s axis, the earth is warmed unevenly making the tropics hot and the polar regions cold •  As the earth revolves around the sun the tilt also causes season changes in temperature and precipitation Figure 5-3

The Sun’s rays strike the equator directly twice a year: 12 hours of daylight and 12 hours of darkness March Equinox – March 20th or 21st September Equinox – September 22nd or 23rd June Solstice – June 20th or 21st – Sun directly above the Tropic of Cancer (23.5° N latitude) – the longest day in the northern hemisphere December Solstice – December 21st or 22nd – Sun directly over the Tropic of Capricorn (23.5° S latitude) – the shortest day in the northern hemisphere

Convection Currents •  Heat from the sun evaporates ocean water and transfers heat from the ocean to the atmosphere creating convection cells that move heat and water from one area to another (adiabatic cooling and heating)

Figure 5-5

Convection Cells •  The result of the Coriolis effect is six giant convection cells at different latitudes forming large terrestrial regions characterized by similar climate, soil, plants and animals

(Biomes) Figure 5-6

Fig. 7-8, p. 146

Polar Tundra Subpolar

Coniferous forest

Temperate

Hot

Desert Deciduous forest

Grassland Chaparral

Tropical Desert

Rain forest

Tropical seasonal forest

Savanna Scrubland

Fig. 7-10, p. 147

Earth’s Rotation

•  The largest input of solar energy occurs at the equator. As this air is heated it rises and moves toward the poles. However, the earth’s rotation deflects the movement of the air over different parts of the earth. This creates global patterns of prevailing winds that help distribute heat and moisture in the atmosphere. Figure 5-4

The winds are deflected to the right in the northern hemisphere and to the left in the southern hemisphere in what is called the Coriolis effect.

Ocean Currents: Distributing Heat and Nutrients •  Heat and differences in water density create warm an cold ocean currents. •  Prevailing winds and irregularly shaped continents interrupt these currents and cause them to flow in roughly circular patterns between the continents •  Creates a connected loop of deep and shallow ocean currents which act like a giant conveyor belt and redistribute heat received by the sun (especially along the coast)

Fig. 7-2, p. 142

Greenhouse Gases Warm the Lower Atmosphere •  Greenhouse gases –  H2O –  CO2 –  CH4 –  N2O

allow mostly visible light and some infra red radiation and some UV radiation from the sun to pass through the atmosphere

•  Greenhouse effect – long wave length infra red radiation (heat) rises to the lower atmosphere

Flow of Energy to and from the Earth

The Earth’s Surface Features Affect Local Climates •  Rain Shadow Effect – Mountains-interrupt flow of prevailing winds and movement of storm

The Earth’s Surface Features Affect Local Climates •  Heat Island Effect – Cities- bricks, concrete, asphalt absorb and hold heat and buildings block wind flow. Causing higher temperatures and lower wind speeds

The Earth’s Surface Features Affect Local Climates •  World’s oceans and large lakes moderate weather and climate •  Heat is absorbed and released more slowly by water than by land. Creates land and sea breezes

ENSO •  A periodic (3-7 years) reversal in the surface (wind and water) currents in the tropical Pacific Ocean 1.  Trade winds near South America weaken 2.  Warm equatorial water from the western Pacific moves eastward to toward the west coast of South America 3.  #2 suppresses upwelling of the coast of Peru (decreased productivity!) 4.  Results in extremely rainy weather along the coast of South America and Southwestern US and extremely dry weather in Australia and SE Asia (affects most of the world)

DESERT BIOMES •  Deserts are areas where evaporation exceeds precipitation. •  Deserts have little precipitation and little vegetation. –  Found in tropical, temperate and polar regions.

•  Desert plants have adaptations that help them stay cool and get enough water.

DESERT BIOMES •  Variations in annual temperature (red) and precipitation (blue) in tropical, temperate and cold deserts.

Figure 5-12

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Tropical Desert

Fig. 5-12a, p. 109

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Temperate Desert

Fig. 5-12b, p. 109

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Polar Desert

Fig. 5-12c, p. 109

DESERT BIOMES •  The flora and fauna in desert ecosystems adapt to their environment through their behavior and physiology.

Figure 5-13

GRASSLANDS AND CHAPARRAL BIOMES •  Variations in annual temperature (red) and precipitation (blue).

Figure 5-14

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Tropical grassland (savanna)

Fig. 5-14a, p. 112

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Temperate grassland

Fig. 5-14b, p. 112

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Polar grassland (arctic tundra)

Fig. 5-14c, p. 112

GRASSLANDS AND CHAPARRAL BIOMES •  Grasslands (prairies) occur in areas too moist for desert and too dry for forests. •  Savannas are tropical grasslands with scattered tree and herds of hoofed animals.

Temperate Grasslands Ø The cold winters and hot dry summers have deep and fertile soil that make them ideal for growing crops and grazing cattle.

Figure 5-15

Temperate Grasslands •  Temperate tallgrass prairie ecosystem in North America.

Figure 5-16

Polar Grasslands Ø Polar grasslands are covered with ice and snow except during a brief summer.

Figure 5-17

Chaparral •  Chaparral has a moderate climate but its dense thickets of spiny shrubs are subject to periodic fires.

Figure 5-18

FOREST BIOMES •  Variations in annual temperature (red) and precipitation (blue) in tropical, temperate, and polar forests.

Figure 5-19

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Tropical rain forest

Fig. 5-19a, p. 116

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Temperate deciduous forest

Fig. 5-19b, p. 116

Freezing point

Month

Mean monthly precipitation (mm)

Mean monthly temperature (°C)

Polar evergreen coniferous forest (boreal forest, taiga)

Fig. 5-19c, p. 116

FOREST BIOMES

•  Forests have enough precipitation to support stands of trees and are found in tropical, temperate, and polar regions.

Tropical Rain Forest •  Tropical rain forests have heavy rainfall and a rich diversity of species. –  Found near the equator. –  Have year-round uniformity warm temperatures and high humidity. Figure 5-20

Tropical Rain Forest

•  Filling such niches enables species to avoid or minimize competition and coexist Figure 5-21

Temperate Deciduous Forest •  Most of the trees survive winter by dropping their leaves, which decay and produce a nutrient-rich soil.

Figure 5-22

Evergreen Coniferous Forests •  Consist mostly of cone-bearing evergreen trees that keep their needles yearround to help the trees survive long and cold winters.

Figure 5-23

Temperate Rain Forests

•  Coastal areas support huge conebearing evergreen trees such as redwoods and Douglas fir in a cool moist environment. Figure 5-24

MOUNTAIN BIOMES •  High-elevation islands of biodiversity •  Often have snowcovered peaks that reflect solar radiation and gradually release water to lowerelevation streams and ecosystems. Figure 5-25

HUMAN IMPACTS ON TERRESTRIAL BIOMES •  Human activities have damaged or disturbed more than half of the world’s terrestrial ecosystems. •  Humans have had a number of specific harmful effects on the world’s deserts, grasslands, forests, and mountains.

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 CO2 to atmosphere from grassland burning

Overgrazing by livestock

Oil production and off-road 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