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THE BIOSPHERE
CHAPTER 34
Topics
•The biosphere
•Ocean and freshwater ecosystems
•Biomes – Biomes Project Handout
LEARNING OUTCOMES
WEEK 12
 What are the components of the biosphere?
 Influence of climate on communities; the ocean and its
communities; adaptation to the environment.
 Freshwater ecosystems and the distribution of biomes.
 Tropical forests and the logging controversy.
 Other biomes.
ECOLOGISTS STUDY HOW ORGANISMS INTERACT
WITH THEIR ENVIRONMENT AT SEVERAL LEVELS
 Ecologists study environmental interactions at several
levels:
 Organism-how one kind of organism meets challenges of
environment. E.g. adaptation of a clam to extreme
temperatures.
 Population-an interbreeding group of individuals
belonging to same species and living in same geographic
area. E.g. study of growth rate in clams living near the
hydrothermal vent.
 Community-all the organisms (all populations of different
species) that inhabit a particular area. E.g. all organisms
found near the hydrothermal vent. More focus on
interactions e.g. predator-prey.
 Ecosystem-includes all life forms in a certain area and all
the non-living factors as well.

Abiotic components-non-living component of the ecosystem
e.g. temperature, water, air.

Biotic component-living component of the biological
community; e.g competition, predation.
THE BIOSPHERE IS THE TOTAL OF ALL OF EARTH’S
ECOSYSTEMS
 Biosphere-the global ecosystem-sum of all the planet’s
ecosystems. Most complex level in ecology.
 Features of biosphere:
 It’s self-contained except deriving energy for
photosynthesizers from sunlight.
 Its patchy e.g. distribution of continents and oceans.
PHYSICAL AND CHEMICAL FACTORS INFLUENCE LIFE
IN THE BIOSPHERE
 Solar energy-powers nearly all terrestrial and shallowwater ecosystems. E.g. photosynthesis.
 Water-essential to all life. E.g. Organisms have ways of
preventing drying out in terrestrial ecosystems-cuticle.
 Temperature-important effect on metabolism. E.g.
adaptations to live outside the normal body temperature;
resistant enzymes.
 Wind-reason for patchiness in ecosystems.
 Other abiotic factors-soil structure, pH, nutrient,
unpredictable disturbances (fire, hurricanes etc).
ORGANISMS ARE ADAPTED TO ABIOTIC AND BIOTIC
FACTORS BY NATURAL SELECTION
 Organism’s ability to survive and reproduce in a particular
environment is a result of natural selection.
 A species is present in a location due to 2 reasons:
 The species evolved in that location.
 The species got dispersed to this location and it could
survive there.
REGIONAL CLIMATE INFLUENCES THE DISTRIBUTION OF
BIOLOGICAL COMMUNITIES
Solar radiation varies with latitude
 Doldrum-an area of calm or
PREVAILING WIND
very light winds near the equator,PATTERNS
caused by rising warm air.
 Trade winds-the movement of
air in the tropics. Blow from east
to west.
 Prevailing winds-major global
air movements that result from
the combined effects of the
rising and falling of air masses
and Earth’s rotation.
 Because Earth is spherical, its
surface moves faster at the
equator than at other latitudes.
OCEANIC ZONES
OCEANIC COMMUNITIES & ZONES
• Estuary-area where a freshwater stream or river merges
with the ocean. Most productive biome.
• Wetland-ecosystem that is intermediate between an aquatic
ecosystem and a terrestrial one. Usually has soil saturated
with water, either periodically or permanently.
• Intertidal-where water meets land. Area is flooded by high
tides then left dry at low tides every 12 hours.
 Pelagic zone-open ocean; communities of highly motile
animals e.g. fish, squids.
 Phytoplankton-diverse algae and cyanobacteria drift
passively in the pelagic zone. Ocean’s major
photosynthesizers.
 Zooplankton-animals that drift in pelagic zone and most
float. Consume phytoplankton.
 Benthic zone-seafloor.
 Photic zone-small portion of ocean water and bottom into
which light penetrates and in which photosynthesis occurs.
 Aphotic zone-under photic zone; dark region. Most extensive
part of the biosphere.
 Continental shelves-submerged parts of the continents.
 Coral reefs-found in warm tropical waters above continental
shelf. Dominated by hard skeletal structures secreted
primarily by cnidarians.
FRESHWATER BIOMES INCLUDE LAKES, PONDS,
RIVERS, STREAMS AND WETLANDS
 Light has significant effect on freshwater biomes.
 Temperature also has profound effect on freshwater
communities.
 Many lakes and ponds are affected by large inputs of nitrogen
and phosphorus from sewage runoff and fertilizers from
agriculture.
 Wetlands are the richest of biomes in terms of species
diversity.
 Their ecological and economic value has led to protection
and restoration of wetlands.
TERRESTRIAL BIOMES REFLECT REGIONAL VARIATIONS
IN CLIMATE
Arctic
North America
Europe
Asia
Africa
South America
Oceania

A type of biological community not a specific assemblage
of species characterizes each biome. E.g. organisms adapted
to arid conditions will be found in desert areas.

How are Biomes named?
1. Climatic features
2. Predominant vegetation
3. Microorganisms
4. Animals adapted to that environment

Distribution of biomes depends on:
1. Climate
2. Temperature
3. Rainfall
TROPICAL FOREST BIOME
What are the characteristic
conditions?
TROPICAL FOREST BIOME
 Tropical forests-occur in equatorial areas where
temperature is warm and days are 11-12hours long yearround.
 Rainfall quite variable and determines the vegetation that
grows.
 Most complex of all biomes having enormous numbers of
different species.
 Vertical stratification provides many different habitats.
 Different strata:






Upper canopy.
Lower-tree layer.
Shrub.
Ground layer of herbaceous plants.
Forest floor (litter layer).
Root layer.
 Animal communities: monkeys, birds, snakes, and bats.
 Soils are poor because high temperatures and rainfall lead to
rapid decomposition and recycling rather than build up of
organic material.
 Human impact on tropical forests is a great concern:
 Clear forest for timber.
 Burn forest.
 Farm forest than abandon it.
 Mining.
 Recovery of rainforest very slow due to nutrient-poor soil.
 Consequences of deforestation:
 Lose species and productivity.
 Degradation of soil and water resources.
 Fragmentation of landscape.
 Hindrance to regulation of climate and cycles of nutrients
and water and gases.
SAVANNAS
GRASSLANDS WITH SCATTERED
What are ARE
the characteristic
TREES conditions?
SAVANNAS ARE GRASSLANDS WITH SCATTERED TREES
 Savanna-biome dominated by grasses and scattered trees.
 Central South America, central and South Africa.
 Simple in structure c.f. tropical forests.
 Frequent fires (human activity and lightning) and grazing
animals inhibit further invasion by trees.
 Dominant plants are fire adapted.
 Dominant animals-insects, mice. Moles, squirrels, worms,
giraffes, zebras, cheetahs, lions.
DESERTS ARE DEFINED BY THEIR DRYNESS
What are the characteristic
conditions?
DESERTS ARE DEFINED BY THEIR DRYNESS
 Deserts-driest of all terrestrial biomes, characterized by low and
unpredictable rainfall.
 Both cold and hot deserts.
 Sahara desert, Kalahari in Africa.
 Plant community-cacti and deep-rooted shrubs.
 Periods of rainfall followed by blooms of annual plant.
 Animal community-seed-eating ants, birds and rodents. Also
lizards, snakes and hawks.
What are the characteristic
SPINY SHRUBS DOMINATE THE CHAPARRAL
conditions?
SPINY SHRUBS DOMINATE THE CHAPARRAL
 Chaparral-region of dense, spiny shrubs with tough,
evergreen leaves.
 Occurs in midlatitudinal coastal areas.
 Plant community-perennial shrubs and annual plants.
 Requires fires for long-term maintenance.
 Animal community-deer, fruit-eating birds, seed-eating
rodents, lizards and snakes.
TEMPERATE GRASSLANDS
What are the characteristic
conditions?
TEMPERATE GRASSLANDS
 Temperate grasslands-share characteristics of tropical
savannas, but they are mostly treeless, except along rivers or
streams.
 Found in regions of relatively cold winter temperatures.
 Keys to the persistence of most grasslands are seasonal
drought, fires and grazing by large animals all of which
inhabit the growth of woody plants.
 Animal community-pronghorn, zebras, horses, sheep.
 Amount of rainfall influences height of vegetation.
DECIDUOUS TREES DOMINATE TEMPERATE FORESTS
What are the characteristic
conditions?
 Temperate deciduous forests-grow throughout
midlatitudinal regions where there is sufficient moisture to
support growth of large trees.
 Broadleaf, deciduous trees (oak, maple) characterize this
biome.
 Temperatures range from very cold in winter to very hot
during summer.
 Rainfall is relatively high annually.
 Soil is rich in organic and inorganic nutrients.
 Animal community-birds, foxes, black bears, mice, squirrels.
CONIFEROUS FORESTS ARE OFTEN DOMINATED BY A
What
the characteristic
FEWare
SPECIES
OF TREES
conditions?
CONIFEROUS FORESTS ARE OFTEN DOMINATED BY A FEW
SPECIES OF TREES
 Coniferous trees-forests with cone-bearing evergreen
trees such as spruce, pine, fir and hemlock.
 Found at cool, high elevations in more temperate
latitudes.
 Soil usually nutrient-poor, thin and acidic.
 Conifers with fire-resistant cones and seeds colonize
recently burned areas.
 Animal community-squirrels, grizzly bears, wolves,
migratory birds.
LONG, BITTER-COLD WINTERS CHARACTERIZE THE
What are the characteristic
TUNDRA
conditions?
LONG, BITTER-COLD WINTERS CHARACTERIZE THE
TUNDRA
 Tundra-biome at the northernmost limits of plant growth
and at high altitudes, characterized by dwarf woody shrubs,
grasses, mosses and lichens.
 Climate is often extremely cold with little light for long
periods of time.
 Absence of trees due to cold air, high winds and permafrost
(soil or rock < 0oC).
 Animals survive by good insulation-rodents, foxes, and
insects.