CHAPTER 34 The Biosphere: An Introduction to Earth's Diverse Environments Modules 34.1 – 34.6

A Mysterious Giant of the Deep Ecology is the scientific study of the interactions of organisms with their environment The ocean is Earth’s largest and least explored ecosystem Recent explorations of the deep sea have brought previously unknown species to light, such as this “mystery squid”

Deep-sea submersibles like Alvin allow the exploration of the deep sea It can accommodate a pilot and two other people It is equipped with instruments to view and sample the ocean at depths of up to 2,500m

Scientists have found seafloor life whose ultimate energy source is not sunlight, but energy that comes from the interior of the planet This energy is emitted from hydrothermal vents near the edges of Earth’s crustal plates

Many animals thrive in the extreme environment around hydrothermal vents Tube worms were unknown to science until hydrothermal vents were explored They live on energy extracted from chemicals by bacteria

34.1 Ecologists study how organisms interact with their environment at several levels Ecologists study environmental interactions at the organism, population, community, and ecosystem levels These clams that live near an ocean vent constitute a population Figure 34.1

Hierarchy Review Organism level – individual organisms interact with aspects of immediate surroundings Population level – focus on functioning among all the members of an interbreeding group and its environment Communities – focus on all the organisms of all species and their interactions within one particular area

Ecosystem level – adds nonliving factors (abiotic components) to the the relationship among living factors (biotic components)

Organisms are affected by their environment Ecosystem interactions involve living (biotic) communities and nonliving (abiotic) components Abiotic components include energy, nutrients, gases, and water Organisms are affected by their environment But their presence and activities often change the environment they inhabit

34.2 The biosphere is the total of all of Earth's ecosystems The global ecosystem is called the biosphere It is the sum of all the Earth's ecosystems The biosphere is the most complex level in ecology Figure 34.2A

Biosphere includes atmosphere to an altitude of a few kilometers, the land to a soil depth of a few meters, all lakes and streams, and the ocean to a depth of several kilometers Biosphere is isolated by space

The biosphere is self-contained except for energy obtained from the sun and heat lost to space Patchiness characterizes the biosphere Patchiness occurs in the distribution of deserts, grasslands, forests, and lakes At each level patchiness is is a result of habitats (places where organisms live) Each habitat has a unique community of species Figure 34.2B

34.3 Connection: Environmental problems reveal the limits of the biosphere Human activities affect all parts of the biosphere Effects of technology: chemicals for agriculture (fertilizer/pesticides) major environmental impacts Rachel Carson – DDT  bald eagles ** Carson data from Rosalie Edge (plug for Rosenberg’s aunt’s book – “Hawk of Mercy” Environmental degradation, famine, species endangerment, and extinction all tied to human activities, including land misuse, expanding human population, incursions into natural habitats, and poisoning of soil and water by toxic wastes

Rachel Carson was one of the first to perceive the global dangers of pesticide abuse Carson documented her concerns in the 1962 book Silent Spring This book played a key role in the awakening of environmental awareness Figure 34.3

Biosphere Influences

34.4 Physical and chemical factors influence life in the biosphere The most important abiotic factors that determine the biosphere's structure and dynamics include Solar energy – powers terrestrial and shallow water ecosystems Exception are the chemoautotrophs Availability of light is critical factor affecting distribution of photosynthetic organisms and their dependents Water – essential to all life In aquatic environments, water balance must be maintained in diverse ionic concentrations. In terrestrial environments, water must be conserved.

Temperature – affects rate of metabolism and the functioning of enzymes Metabolism typically between 0’ C and 50’ C Soil structure, pH, nutrient content are important factors for plants. Oxygen not limiting for terrestrial, but typically for aquatic Fire and other catastrophes are infrequent and unpredictable in most ecosystems Fire’s importance for the grasslands Wind – brings nutrients to some organisms, but causes damage, increases evaporation and lowers effective temperatures.

Disturbances such as fires, hurricanes, and volcanic eruptions are also abiotic factors Figure 34.4

Natural selection adapts organisms to abiotic and biotic factors 34.5 Organisms are adapted to abiotic and biotic factors by natural selection The presence and success of a species in a particular place depends upon its ability to adapt Natural selection adapts organisms to abiotic and biotic factors Biotic factors include predation and competition Figure 34.5

Evolution and Ecology Species exist due to evolution or dispersion Unique adaptations to environment allow survival Pronghorn designed for conditions on the plains of North America. Move to forests, will not survive Abiotic conditions Daily/seasonal temperature fluctuations Aridity Wind Pronghorn with coat of hollow hairs and gets water from diet Biotic conditions Diet – coarse grasses/woody shrubs Predators – Wolves, coyotes, cougars Adaptive teeth for chewing and ruminant digestive system and speed/endurance, camouflaged, good eye sight, live in herds

34.6 Regional climate influences the distribution of biological communities Climate often determines the distribution of communities Earth's global climate patterns are largely determined by the input of solar energy and the planet's movement in space

Most climatic variations are due to the uneven heating of Earth's surface This is a result of the variation in solar radiation at different latitudes North Pole 60º N Low angle of incoming sunlight 30º N Tropic of Cancer Sunlight directly overhead 0º (equator) Tropic of Capricorn 30º S Low angle of incoming sunlight 60º S Atmosphere South Pole Figure 34.6A

The seasons of the year result from the permanent tilt of the plant on its axis as it orbits the sun MARCH EQUINOX (equator faces sun directly) JUNE SOLSTICE (Northern Hemisphere tilts toward sun) DECEMBER SOLSTICE (Northern Hemisphere tilts away from sun) SEPTEMBER EQUINOX Figure 34.6B

The tropics experience the greatest annual input and least seasonal variation in solar radiation The direct intense solar radiation near the equator has an impact on the global patterns of rainfall and winds

moist air releases moisture Ascending moist air releases moisture Descending dry air absorbs moisture Descending dry air absorbs moisture Trade winds Trade winds Doldrums 0º 23.5º 23.5º 30º 30º TROPICS TEMPERATE ZONE TEMPERATE ZONE Figure 34.6C

Warm, moist air at the equator rises As the air rises, it cools and releases much of its water content This results in the abundant precipitation typical of most tropical regions After losing their moisture over equatorial zones, high altitude air masses spread away from the equator

They cool and descend again at latitudes of about 30° north and south This explains the locations of the world's great deserts As the dry air descends, some of it spreads back toward the equator This creates the cooling trade winds that dominate the tropics

Temperate zones are located between the tropics and the Arctic Circle in the north and the Antarctic Circle in the south They have seasonal variations in climate The temperatures are more moderate than in the tropic or polar regions

Prevailing winds result from the combined effects of the rising and falling of air masses and Earth's rotation In the tropics, Earth's rapidly moving surface deflects vertically circulating air, making the winds blow from east to west In temperate zones, the slower-moving surface produces the westerlies, winds that blow from west to east Figure 34.6D

Ocean currents have a profound effect on regional climates by warming or cooling coastal areas They are created by winds, planet rotation, unequal heating of surface waters, and the locations and shapes of continents

Local high temperatures for August 6, 2000, in Southern California Fresno 100º 40 miles Death Valley 119º Bakersfield 100º Pacific Ocean Burbank 90º Santa Barbara 73º San Bernardino 100º Key Riverside 96º Los Angeles (Airport) 75º 70s (ºF) Santa Ana 84º Palm Springs 106º 80s 90s 100s 110s San Diego 72º Figure 34.6E

Landforms, such as mountains, can affect local climate East Wind direction Pacific Ocean Cascade Range Coast Range Figure 34.6F