Schematic plots for hypothetical changes in temperature. Climate change alters the occurrence of extreme events in

various ways depending on how the probability distribution changes.

In a warming world, will more weather records be broken? Daily high or low temperatures?

Leaf litter on the forest floor-source of vital nutrients for the living plants.

Soil formation

Profile of mature soil whose structure developed over thousands of years.

Vegetation boundaries in Alaska, with taiga forest changing to tundra-note the treeline where forests end part way up the slopes of mountains.

Vegetation Boundaries

Soil Erosion

Agricultural practices have not stopped erosion here in Kenya where cropping on steep terrain has led to gullying. Similar extensive cropping and grazing have led to desertification.

Acid Rain Attacks Fragile Forests

Pollution from nearby factories create acid rain leading to needle loss and tree mortality in the Black Forest of SW Germany.

Soil Erosion During Dust Bowl of the 1930s

Large dust storm buries town of Springfield in eastern Colorado during height of the Dust Bowl of the 1930s. Although conservation practices were soon adopted, dust storms returned in the 1950s and again in the late 1970s.

Sustainable Development

which the World Commission on Environment and Development defines as “development

that meets the needs of the present without compromising the ability of future

generations to meet their own needs.”

Problems that need to be addressed to conserve our flora and fauna:• population• poverty

Unit 24: Biogeographic Processes

Life and death in the African savanna—here, vultures feast on an elephant carcass in Kenya.

OBJECTIVES• Discuss the processes of photosynthesis

and respiration and relate them to climatic controls• Introduce the concept of ecosystems and

highlight the important energy flows within ecosystems• Outline the factors influencing the

geographic dispersal of plant and animal species within the biosphere

Evolution of Life on Earth

The development of the Earth’s biosphere-the time scale of life.

Tropical Rainforest

Tropical rainforest displays a nearly continuous canopy of green made up of tall trees competing for sunlight, here in eastern Bolivia.

Net Primary Productivity (NPP)

Global distribution of annual productivity (in grams per square meter of dry biomass matter). Note the highest productivity tends to be in tropical rainforests.

Ecosystem Food Chains

While energy flows through an ecosystem, matter cycles through the trophic levels to decomposers, where matter breaks down and is available for plants.

A pond is a self-contained ecosystem.

Energy flows and matter cycles through the ecosystem pictured here in Britain’s Lake Country.

Pyramid of Mass

Since only about 10% of energy produced in the form of food is passed from one trophic level to the next higher, the higher trophic level animals must harvest large numbers of lower trophic level species.

Plant Successions

An idealized sequence of plant succession in which a lake is eventually colonized by shrubs and trees.

Secondary Plant Succession

An increase in stored energy is typical of a secondary plant succession, which may involve a period of a century or more to reach a climax community.

Tolerance Limits

The Law of Tolerance states that a species is limited geographically by its range of tolerance to local environmental factors. Species with wide ranges of tolerance to most factors will be widespread.

Geographic Dispersal Influenced by Landforms

Zones of vegetation and animal life on the flanks of Mount Kenya in E. Africa along the equator.

Competition between sage and grasses

Along the N. California coast, steep terrain and thin soils favor sagebrush over grasses in this Mediterranean climate.

Invasive Species

Predator-prey relationships keep ecosystem species in balance. Introducing species that have no natural predator often leads to overpopulation and ecosystem collapse.

Endangered Endemic Species

Global distribution of biodiversity “hot spots.” These areas contain high concentrations of endemic species threatened by humans.

Unit 25: The Global Distribution of Plants

Montane forest in East Africa’s Chyulu Hills, where elevation and moisture combine to sustain luxuriant flora amid steppe and savanna.

OBJECTIVES

• Explain the use of biomes to map global patterns of vegetation, and the factors that differentiate major biomes• Briefly survey the principal terrestrial

biomes

Global Biomes

Global distribution of the principal terrestrial biomes.

Distribution of natural vegetation in North America.

Vegetation distribution by latitude, altitude

Vegetation changes with latitude and altitude. The temperature, which affects vegetation, decreases with increasing latitude and altitude.

Distribution of Terrestrial Biomes

A general distribution of major terrestrial biomes arranged according to increasing aridity and latitude (decreasing temperature).

Tropical Savanna

East African savanna supports large animal population with abundant grasses and sparse trees like this acacia.

Desert Biome

Even this poor soil and scant rainfall can support a wide range of plant and animal species here in the Arizona desert.

Temperate Grassland Biome

One of the remaining natural tallgrass regions, the Oklahoma’s Tallgrass Prairie Reserve contains diverse prairie grasses.

Temperate Deciduous Forest Biome

Deciduous broadleaf trees showing off fall colors in the Vermont Green Mountains National Forest.

Temperate Evergreen Forest Biome

Lush, old growth Douglas fir forest in the U.S. Pacific NW

Mediterranean Scrub BiomeItaly’s Amalfi coast, south of Naples, shows the co-existence of human occupation amid Mediterranean vegetation clinging onto the steep slopes.

Northern Coniferous Forest Biome

A river meanders across a taiga (snowforest) landscape east of the Ural Mountains in Siberia. What season is it?