Chapter 5

Climate and Terrestrial Biodiversity

CLIMATE: A BRIEF INTRODUCTION

• Weather • Climate - Latitude and elevation help

determine climate.• Warm front• Cold front• High pressure• Low pressure• Adiabatic cooling

FRONTS the movement of warm and cold masses of air creates

the weather, and when the two clash, it often rains. A warm front is defined as the transition zone where a

warm air mass is replacing a cold air mass. Warm fronts generally move from southwest to northeast and the air behind a warm front is warmer and more moist than the air ahead of it. When a warm front passes through, the air becomes noticeably warmer and more humid than it was before.

FRONTS

• A cold front is defined as the transition zone where a cold air mass is replacing a warmer air mass. Cold fronts generally move from northwest to southeast. The air behind a cold front is noticeably colder and drier than the air ahead of it. When a cold front passes through, temperatures can drop more than 15 degrees within the first hour.

FRONTS

PRESSURE SYSTEMS• The air associated with a high pressure system sinks

down from above and warms as it does so and is very stable.

• A high pressure system (anticyclone), is a system of closed isobars surrounding a region of relatively high pressure. When compared with low pressure systems, highs tend to cover a greater area, move more slowly and have a longer life.

• When the high pressure system is located over land the weather will be typically dry and free of cloud.

PRESSURE SYSTEMS

• A low pressure system (cyclone) develops where relatively warm air ascends from the Earth's surface. These are systems of closed isobars surrounding a region of relatively low pressure.

• As the rising air cools, clouds will begin to form. The instability of the air will produce quite large vertical development of cumuliform clouds with associated rain showers (such as cumulonimbus cloud).

Adiabatic Cooling

• Adiabatic cooling deals with the cooling of parcels of air as they rise, or are forced up, through the atmosphere.

Adiabatic cooling

Adiabatic cooling

Adiabatic cooling

Earth’s Current Climate Zones

Figure 5-2Figure 5-2

Solar Energy and Global Air Circulation: Distributing Heat

Climate is affected by:• 1) Uneven heating of

the earth’s surface• 2) Seasonal changes

in temperature and precipitation

• 3) Earth’s rotation• 4) Unique properties

of air & water

Figure 5-3Figure 5-3Diagram

Coriolis Effect• Deflection of air

due to the rotation of the earth & friction between air & Earth – less effect near the equator (fewer hurricanes within 5 degrees)

Figure 5-4Figure 5-4

Coriolis Effect

Trade Winds

Convection Currents

• Drive day-to-day weather patterns

• Rain-shadow Effect

Figure 5-5Figure 5-5

Convection Cells• Distribute heat &

moisture• 6 Vertical currents at

different latitudes : • Hadley Cell – 0 – 30

- tradewinds• Ferrel Cell – 30-60-

westerlies• Polar Cell- 60 – 90 -

easterliesFigure 5-6Figure 5-6

El Nino/ENSO• Equatorial winds weaken along

Eastern Pacific• Surface water warms• No upwelling• Increased flooding in e. Pacific• Drier western Pacific• Fewer Atlantic hurricanes

World Map

La Nina

• Exaggerated normal pattern• Cooler water than normal

along eastern Pacific• Drier eastern Pacific• Flooding along western

Pacific• More Atlantic hurricanes

Topography and Local Climate:Land Matters

• Rain Shadow effect• Microclimates (forests, cities)• Sea breezes• Land breezes

Figure 5-8Figure 5-8

BIOMES: CLIMATE AND LIFE ON LAND

• Biomes – large terrestrial regions characterized by similar climate, soil, plants, and animals.

• Latitude vs. altitude• Succulents• Evergreens• Deciduous plants• Coniferous plants

BIOMES: CLIMATE AND LIFE ON LAND

Figure 5-9Figure 5-9

BIOMES: CLIMATE AND LIFE ON LAND

• Biome type is determined by precipitation, temperature and soil type

Figure 5-10Figure 5-10

BIOMES: CLIMATE AND LIFE ON LAND

• Parallel changes occur in vegetation type occur when we travel from the equator to the poles or from lowlands to mountaintops.

Figure 5-11Figure 5-11

DESERT BIOMES

• 30% of Earth’s land• Evaporation exceeds precipitation.• Little vegetation.

– Found in tropical (Sahara), temperate (Mojave) and cold regions (Gobi).

• Succulent plants• Deep vs. widespread roots• Some plants secrete toxins into soil

(sagebrush)• Small animals

DESERT BIOMES

• Tropical, temperate and cold deserts.

Figure 5-12Figure 5-12

GRASSLANDS AND CHAPARRAL BIOMES

• Tropical grasslands (savannas)• Temperate grasslands (prairies)• Chaparral (Mediterranean, SoCal) • Wet/dry season• Many are fire-maintained (many plants

contain oils)

GRASSLANDS AND CHAPARRAL BIOMES

• Most grasslands have alkaline soil

• Temperate grasslands are nutrient-rich

Figure 5-14Figure 5-14

Polar Grasslands

• Tundra - covered with ice and snow except during a brief summer (permafrost)

• Seasonal wetlands • Lots of migratory

animals & mosquitoes

Figure 5-17Figure 5-17

Chaparral

• Moderate climate

• Dense thickets of spiny shrubs

• Subject to periodic fires

Figure 5-18Figure 5-18

FOREST BIOMES• Tropical rainforest• Tropical deciduous

forest• Temperate

deciduous forest• Temperate rain

forest• Coniferous forest

(boreal, taiga).Figure 5-19Figure 5-19

Tropical Rain Forest• Heavy rainfall • High biodiversity• Broadleaf

evergreens• Nutrient-poor soil• High decomposition

rate

Figure 5-20Figure 5-20

Temperate Deciduous Forest• Most of the trees

survive winter by dropping their leaves, which decay and produce a nutrient-rich soil

• Moderate rainfall

Figure 5-22Figure 5-22

Evergreen Coniferous Forests• Mostly cone-

bearing evergreen trees - keep their needles year-round

• Insulating factor - helps the trees survive long and cold winters

• Sheds snow

Figure 5-23Figure 5-23

Temperate Rain Forests

• Coastal areas (Calif., Oregon, Washington) - huge cone-bearing evergreen trees such as redwoods and Douglas fir

• Cool moist environmentFigure 5-24Figure 5-24

MOUNTAIN BIOMES• High-elevation

islands of biodiversity

• Snow-covered peaks - reflect solar radiation

• Release water to lower-elevation streams and ecosystems.

Figure 5-25Figure 5-25

Fig. 5-26, p. 123

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. 5-27, p. 123

Oil production and off-road vehicles in arctic tundra

Overgrazing by livestock

Release of CO2 to atmosphere from grassland burning

Conversion to cropland

Grasslands

Natural Capital Degradation

Fig. 5-28, p. 124

Clearing for agriculture, livestock grazing, timber, and urban development

Conversion of diverse forests to tree plantations

Damage from off-road vehicles

Natural Capital Degradation

Forests

Pollution of forest streams

Fig. 5-29, p. 124

Natural Capital Degradation

Mountains

Agriculture

Timber extraction

Mineral extraction

Hydroelectric dams and reservoirsIncreasing tourism

Urban air pollution

Increased ultraviolet radiationfrom ozone depletion

Soil damage from off-roadvehicles