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UNIT 2: ECOLOGYTHE BIOSPHERE
Apollo 8 December 24, 1968
“Ecology”?
= The study of interactions among organisms and between organisms and their environment
Levels of Ecology:
SpeciesPopulations
Communities
Ecosystems
BiomesBiosphere
Put these in order (smallest largest)
Biosphere8km Up11km Down
At the core of every organism’s interaction with the environment is its need for energy to power life’s processes
The flow of energy through an ecosystem is one of the most important factors that determines the system’s capacity to sustain life
“Autotrophs” “Heterotrophs”
MainSource
Autotrophs/ Producers (Photosynthetic and Chemosynthetic)
Heterotrophs/Consumers (Herb-/Carn-/Omn-ivores and Decomposers)
Energy flows through an ecosystem in one direction, Sun or Inorganic compounds Autotrophs (producers) Heterotrophs (consumers)
Food Chains = a series of steps in which organisms transfer energy by eating and being eaten
Trophic Levels = each step in a food chain or food web
Food Webs = links all the food chains in an ecosystem together
Producers?First Order/Primary Consumers?Second Order/Secondary Consumers?Third Order/Tertiary Consumers?Fourth Order/Quaternary Consumers?
Ecological Pyramid = a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web
Energy Pyramids = represents the amount of energy that is transferred from one trophic level to the next
Only about 10% of the energy available within one trophic level is transferred to the next
What happens to the rest?Life Processes and Heat
Biomass Pyramids = represent the amount of potential food that is available for each trophic level in an ecosystem
Biomass is usually expressed in terms of grams of organic (living) matter per unit area
Pyramid of Numbers = represents the numbers of individual organisms at each trophic level in an ecosystem
Cycles
Don’t just need energy!
What else is needed?
More than 95% of the body is made up of just four elements: oxygen, carbon, hydrogen, and nitrogen
Biogeochemical Cycles
Organisms don’t “use-up” matter,they “transform” it
The Water Cycle
The Carbon CycleNutrient Cycles
The Nitrogen CycleProteins
Nitrogen Fixation
78%
The Phosphorous CycleDNA/ RNA/ ATP
Doesn’t enter the atmosphere
Primary Productivity = the rate at which organic matter is created by producers
Limiting Nutrient = a nutrient that is scarce or cycle slowly
Oceans = Nitrogen
UNIT 2: ECOLOGYECOSYSTEMS
ANDCOMMUNITIES
1. The Role of the Climate2. What Shapes an Ecosystem?3. Biomes4. Aquatic Ecosystems
1. THE ROLE OF CLIMATE
• What is Climate?
• The Greenhouse Effect
• The Effect of Latitude on Climate
• Heat Transport in the Biosphere
What is Climate?
Weather = the day-to-day conditionof Earth’s atmosphere at a particulartime and place.
Climate = the average, year-after-year conditions of temperature and precipitation in a particular region.
What factors affect the climate?
The Greenhouse EffectGreenhouse Effect = the natural situation in which heat is retained by greenhouse gases (warming effect)
Carbon dioxide, methane, water vapor, and a few other atmospheric gases
Earth would be 30o C cooler than it is today if these gases weren’t present
The Effect of Latitude on ClimateEarth’s 23.5o tilt on its axis causes different parts of Earth to receive different angles of solar radiation
This results in a difference in heat distribution with latitude
Three Main Climate Zones
Temperate Zones = sit between the polar and tropical zones
Tropical Zones = between 23.5o North and 23.5o South of the Equator
Polar Zones = between 66.5o and 90o North and South latitudes
PolarZones
Low Angle SunlightCold
TemperateZones
SeasonalChanging Angle
TropicalZones
Direct AngleConstant
Warm “Rises”Pole-ward
Cold “Sinks”Equator-ward
The unequal heating of Earth’s surface drives winds and ocean currents, which transport heat throughout the biosphere
Heat Transport in the Biosphere
Winds Ocean Currents
Ocean Currents contribute for same reasonsMountains and the ”Rain Shadow” Effect
2. WHAT SHAPES AN ECOSYSTEM?
• Biotic and Abiotic Factors
• The Niche
• Community Interactions
• Ecological Succession
Biotic and Abiotic FactorsBiotic Factors = the biological influences on organisms within an ecosystem Abiotic Factors = physical, or nonliving factors that shape ecosystems
Determine the survival and growth of an organisms and the productivity of the ecosystem in which the organism lives
Habitat = the area where an organism lives (includes both biotic and abiotic factors)
The NicheNiche = the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
Community InteractionsCommunity interactions can powerfully affect an ecosystem
Competition occurs when organisms of the same or different species attempt to use an ecological “resource” in the same place at the same time
Often results in a winner and a loser (fails to survive)
1. Competition
Competitive Exclusion Principle = no two species can occupy the same niche in the same habitat at the same time
CEP is a fundamental rule in ecology
Predation = an interaction in which one organism captures and feeds on another organism (predator/ prey)
2. Predation
Symbiosis = any relationship in which two species live closely together (“living together”)
3. Symbiosis
A. MutualismB. CommensalismC. Parasitism
A. Mutualism = both species benefit from the relationship
B. Commensalism = one member benefits and the other is neither helped nor harmed
C. Parasitism = one organism lives on or inside another organism (the host) and harms it
Ecosystems and communities are always changing (abruptly or gradually) in response to natural or human disturbances
Ecological Succession = this series of predictable changes that occurs in a community over time
Ecological Succession
Lowered to 8,363 ft
Summit = 9,677 ft
Mt. St. Helens May 1980
As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community
Primary Succession = succession (on land) that occurs on surfaces where no soil exists (volcanic eruptions, glaciers, etc.)
Pioneer Species = the first species to populate the area
Lichen = a symbiotic relationship between a fungus and an algae (protist)
Enchanted Rock (Fredericksburg)
Secondary Succession = succession that occurs when a disturbance of some kind changes an existing community without removing the soil
Succession can even occur at the bottom of the oceans
3. BIOMES
• Biomes and Climate
• The Major Biomes
• Other Land Areas
Ecologists group Earth’s diverse environments into biomes
Biome = a complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals
World’s Major Biomes:-Tropical Rain Forest-Tropical Dry Forest-Tropical Savanna-Desert-Temperate Grassland-Temperate Woodland and Shrubland-Temperate Forest-Northwestern Coniferous Forest-Boreal Forest
-Tundra
Each of these biomes is defined by a unique set of abiotic factors – particularly climate- and a characteristic assemblage of plants and animals
Adaptations Tolerance
Microclimate = the climate in a small area that differs from the climate around it
The climate of a region is an important factor in determining which organisms can survive there
Some areas of land on Earth do not fall neatly into the major biome categories
Mountain Ranges
Abiotic and biotic conditions vary with elevation
Polar Ice Caps
North Polar Region (thinner ice)South Polar Region (thicker ice)
4. AQUATIC ECOSYSTEMS
DepthFlowTempChemistry of Water
Impacted by:
Freshwater Ecosystems3% of World’s Surface Water
Standing-Water
Flowing-Water
Flowing-Water Ecosystems:(Rivers, Steams, Creeks, and Brooks)
Typically originate in mountains or hills, often springing from an underground water source
Plenty of dissolved oxygen but little plant life
As the water flows downhill, sediments build up and enable plants to establish themselves
Farther downstream, the water may meander more slowly through flat areas
Standing-Water Ecosystems: Lakes and ponds
In addition to the net flow of water in and out of these systems, there is usually water circulating (turning-over) within them
This circulation helps to distribute heat, oxygen, and nutrients
Phytoplankton = single-celled algae supported by nutrients in the water
Zooplankton = planktonic animals that feed on the phytoplankton
Plankton = tiny, free-floating or weakly swimming organisms that live in both fresh/saltwater
Freshwater Wetlands:
Wetland = an ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year
“Biodiversity”
Bog
Swamp
Marsh
Estuaries = are wetlands formed where rivers meet the sea
Estuaries
fresh water and salt water (brackish) Affected by the ocean tides
HighProductivity
Detritus = is made up of tiny pieces of organic material that provide food for organisms at the base of the estuary’s food web
Photosynthesis(200 meters)
Chemosynthesis
“Coastal Zone” “Open Ocean”
Coral Reefs Exists in warm, shallow water of tropical coastal oceans
Among the most diverse and productive environments on Earth
Named for the coral animals whose hard, calcium carbonate skeletons make up their primary structure (Coral)
Symbiotic relationship with Algae
Algae: PhotosynthesisCoral: Waste