Ecology and the Biosphere
Ecology: the scientific study of organisms and the environment Multi-dimensional: biology, chemistry, physics, geology Main Thrust of All Ecology – Address Environmental Issues - “Precautionary Principle”
Types of Ecology: Move from the smaller to the greater - hierarchy Organismal: How does an organism meets it needs in the environment? Population: How many organisms live in an area? Community: How do different populations interact? – predator/prey, competition Ecosystem: How do the abiotic factors affect the community? Landscape: How do different ecosystems interact with one another? Biosphere: How does the planet function?
Two basic components of all levels: Biotic – living components - animals, plants, fungus, bacteria, protists Abiotic – non-living components - water, light, altitude, nutrients, temperature, wind, altitude Together these two components determine the biogeography in the biome. Biogeography – location of species in the environment
Biogeography Provides a good starting point for understanding what limits the geographic distribution of species Species absent because Yes No Dispersal limits distribution? Behavior limits distribution? Biotic factors (other species) limit distribution? Abiotic factors limit distribution? Area inaccessible or insufficient time Habitat selection Predation, parasitism, competition, disease Water Oxygen Salinity pH Soil nutrients, etc. Temperature Light Soil structure Fire Moisture, etc. Chemical factors Physical Figure 50.6
1. Dispersal and Distribution: how few and far between? Changes in Dispersal and Distribution: - Natural Range becomes too small or there is a shift in movement of the organism - Species Transplants – exotic species EX: Kudzu
2. Behavior and Habitat Selection – Why does an organism live in a specific area when it could live in another location? 3. Biotic Factors: Other species interaction - due to the presence or absence of another species - symbiosis, competition, mutualism, prey predation
4. Abiotic Factors: Temperature: usually a function of the ability of an organism to maintain homeostasis in the optimal range of its enzymes Water: Sunlight: base energy source for all trophic levels Wind
Rocks and Soils – affects plant distribution which determines animal populations Climate: Prevailing weather conditions in the environments – mainly determined by temperature, water, sunlight and wind
Factors Affecting Climate: Sunlight – amount and intensity is determined by latitude and tilt of earths axis - determines how directly the sun’s rays strike the earth – more direct = higher amounts of energy – Pg 1088
LALITUDINAL VARIATION IN SUNLIGHT INTENSITY Low angle of incoming sunlight Sunlight directly overhead North Pole 60N 30N Tropic of Cancer 0 (equator) 30S 60S Atmosphere LALITUDINAL VARIATION IN SUNLIGHT INTENSITY Tropic of Capricorn South pole
2. Global Air Circulation: Moist air near the ground is heated causing it to rise Ascending moist air cools resulting in condensation of the water High, cool, dry air descends drying out the land it hits Result of pattern: areas of wet and dry Areas of descending air = deserts Areas of rising air = Rain fall
GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS Descending dry air absorbs moisture Ascending moist air releases 30 23.5 0 Arid zone Tropics 60N 30N 0 (equator) 30S 60S GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS
3. Bodies of Water: High specific heat of water allows for climate regulation Water absorbs and releases heat more slowly than land keeping areas near large bodies of water more moderate Oceans currents move warm and cool water which then heats and cools the air causing wind patterns and climate differentials Ex: England is farther north than New England but the UK is warmer because of warm ocean currents that pass by it. New England is brushed by a cold ocean current from Greenland making its climate cooler.
Cooler air sinks over water. 3 Air cools at high elevation. 2 1 Warm air over land rises. 4 Cool air over water moves inland, replacing rising warm air over land.
4. Mountains: Increase in altitude causes for cooler temperatures and greater wind - 6oC for every 1000 m - matches the decline in temperature as you move north by 880 km South sides (in northern hemisphere) receive more sun. Windward sides receive more moisture than the leeward side – wind causes air to rise up and cool and drop its moisture – as it passes over the top of the mountain, the eastern side is hit by dry air Rain Shadow - deserts are often found on the leeward side of very high mountain ranges
Figure 50.12 As moist air moves in 1 off the Pacific Ocean and Farther inland, precipitation increases again as the air moves up and over higher mountains. Some of the world’s deepest snow packs occur here. Figure 50.12 3 On the eastern side of the Sierra Nevada, there is little precipitation. As a result of this rain shadow, much of central Nevada is desert. As moist air moves in off the Pacific Ocean and encounters the westernmost mountains, it flows upward, cools at higher altitudes, and drops a large amount of water. The world’s tallest trees, the coastal redwoods, thrive here. 1 2 East Pacific Ocean Wind direction Coast Range Sierra Nevada
5. Seasonality: changes in the angle of the sun on the earth due to the rotation of the earth around the sun – due to tilt of Earth’s axis changes in solar intensity cause for cooler and warmer seasons – changes in temperature alter ocean currents and thus wind currents changes the distribution of nutrients in the water which affects life cycles of organisms in the oceans can also result in changes in weather patterns (Ex: Hurricanes)
SEASONAL VARIATION IN SUNLIGHT INTENSITY June solstice: Northern Hemisphere tilts toward sun; summer begins in Northern Hemisphere; winter begins in Southern Hemisphere. March equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight and 12 hours of darkness. 60N 30N 0 (equator) 30S Constant tilt of 23.5 September equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight and 12 hours of darkness. December solstice: Northern Hemisphere tilts away from sun; winter begins in Northern Hemisphere; summer begins in Southern Hemisphere. SEASONAL VARIATION IN SUNLIGHT INTENSITY
Seasonal Changes on Lake Stratification - called Turn Over – Pg 1091 - Based on Thermal Stratification of Water Layers Winter: Coldest at Top of Water – decomposition of detritus in the benthic layer occurs – nutrient levels increase on the bottom of the lake
In spring, as the sun melts the ice, the surface water warms to 4°C and sinks below the cooler layers immediately below, eliminating the thermal stratification. Spring winds mix the water to great depth, bringing oxygen (O2) to the bottom waters (see graphs) and nutrients to the surface. 2 In winter, the coldest water in the lake (0°C) lies just below the surface ice; water is progressively warmer at deeper levels of the lake, typically 4–5°C at the bottom. 1 In autumn, as surface water cools rapidly, it sinks below the underlying layers, remixing the water until the surface begins to freeze and the winter temperature profile is reestablished. 4 In summer, the lake regains a distinctive thermal profile, with warm surface water separated from cold bottom water by a narrow vertical zone of rapid temperature change, called a thermocline. 3 Winter Spring High Medium Low O2 concentration O2 (mg/L) Lake depth (m) 8 12 16 24 Autumn Summer 4C 4 2 0 6 8 18 20 22 5 Thermocline
Spring: Surface Heats to 4oC – becomes more dense than the slightly cooler layers and all the water mixes causing the loss of thermal stratification – Wind also causes the water to move and mix – Oxygen is brought to the bottom of the lake and nutrients at the bottom are brought to the top – increased solar radiation gives energy to the producers (algae and plants) that use the nutrients to grow
In spring, as the sun melts the ice, the surface water warms to 4°C and sinks below the cooler layers immediately below, eliminating the thermal stratification. Spring winds mix the water to great depth, bringing oxygen (O2) to the bottom waters (see graphs) and nutrients to the surface. 2 In winter, the coldest water in the lake (0°C) lies just below the surface ice; water is progressively warmer at deeper levels of the lake, typically 4–5°C at the bottom. 1 In autumn, as surface water cools rapidly, it sinks below the underlying layers, remixing the water until the surface begins to freeze and the winter temperature profile is reestablished. 4 In summer, the lake regains a distinctive thermal profile, with warm surface water separated from cold bottom water by a narrow vertical zone of rapid temperature change, called a thermocline. 3 Winter Spring High Medium Low O2 concentration O2 (mg/L) Lake depth (m) 8 12 16 24 Autumn Summer 4C 4 2 0 6 8 18 20 22 5 Thermocline
Summer – Thermal Stratification is reestablished by the heating of the surface of the water cooler water sinks to the bottom of the lake – lots of growth in the photic layer of the lake – dead things move to the benthic layer
In spring, as the sun melts the ice, the surface water warms to 4°C and sinks below the cooler layers immediately below, eliminating the thermal stratification. Spring winds mix the water to great depth, bringing oxygen (O2) to the bottom waters (see graphs) and nutrients to the surface. 2 In winter, the coldest water in the lake (0°C) lies just below the surface ice; water is progressively warmer at deeper levels of the lake, typically 4–5°C at the bottom. 1 In autumn, as surface water cools rapidly, it sinks below the underlying layers, remixing the water until the surface begins to freeze and the winter temperature profile is reestablished. 4 In summer, the lake regains a distinctive thermal profile, with warm surface water separated from cold bottom water by a narrow vertical zone of rapid temperature change, called a thermocline. 3 Winter Spring High Medium Low O2 concentration O2 (mg/L) Lake depth (m) 8 12 16 24 Autumn Summer 4C 4 2 0 6 8 18 20 22 5 Thermocline
Autumn – water cools to the same temperature so the thermal stratification is once again removed until the winter profile is reestablished – oxygen is brought to the bottom of the lake – more decomposition can occur
In spring, as the sun melts the ice, the surface water warms to 4°C and sinks below the cooler layers immediately below, eliminating the thermal stratification. Spring winds mix the water to great depth, bringing oxygen (O2) to the bottom waters (see graphs) and nutrients to the surface. 2 In winter, the coldest water in the lake (0°C) lies just below the surface ice; water is progressively warmer at deeper levels of the lake, typically 4–5°C at the bottom. 1 In autumn, as surface water cools rapidly, it sinks below the underlying layers, remixing the water until the surface begins to freeze and the winter temperature profile is reestablished. 4 In summer, the lake regains a distinctive thermal profile, with warm surface water separated from cold bottom water by a narrow vertical zone of rapid temperature change, called a thermocline. 3 Winter Spring High Medium Low O2 concentration O2 (mg/L) Lake depth (m) 8 12 16 24 Autumn Summer 4C 4 2 0 6 8 18 20 22 5 Thermocline
6. Microclimates: protected areas in a larger climate that make for different smaller climates – Ex: Shade of a tree, under a log Variations in the abiotic factors result in different types of regions called biomes. Each biome has a specific type of climate which results in a particular type of organismal community.
BIOMES Two Basic Types of Biomes: Aquatic and Terrestrial Aquatic Biomes: Fresh water: less than 1% salt concentration Marine: about 3% salt concentration About 75% of planet’s surface - affect climate and rainfall - photosynthetic organisms provide most of the oxygen in the atmosphere and are responsible for capturing CO2
30N Tropic of Cancer Equator 30S Continental shelf Lakes Coral reefs Rivers Oceanic pelagic zone Estuaries Intertidal zone Abyssal zone (below oceanic pelagic zone) Key Tropic of Capricorn
Basic Structure of Aquatic Biomes: Photic Zone: Depth that light penetrates the water and allows for photosynthesis Aphotic Zone: too little light to allow for photosynthesis Benthic Zone: bottom substrate – made of soil, living organisms, decaying matter (detritus) Benthic Zone: Bottom Pelagic Zone: Open water that is above the benthic zone Thermocline: thin layer that separates the thermally stratified layers of warm water and cold water
(b) Intertidal zone Neritic zone Oceanic zone Littoral zone Marine zonation. Like lakes, the marine environment is generally classified on the basis of light penetration (photic and aphotic zones), distance from shore and water depth (intertidal, neritic, and oceanic zones), and whether it is open water (pelagic zone) or bottom (benthic and abyssal zones). Zonation in a lake. The lake environment is generally classified on the basis of three physical criteria: light penetration (photic and aphotic zones), distance from shore and water depth (littoral and limnetic zones), and whether it is open water (pelagic zone) or bottom (benthic zone). (a) Littoral zone Limnetic zone Photic zone Benthic zone Aphotic zone Pelagic zone Intertidal zone Neritic zone Oceanic zone 200 m Continental shelf Pelagic zone 2,500–6,000 m Abyssal zone (deepest regions of ocean floor) (b)
Lakes: Littoral Zone: Shallows – growth of plants in the benthic layer Limnetic Zone: Deep areas – plants can’t grow in the benthic zone because it is in the aphotic zone Oceans: Intertidal Zone: Area of vast change due to the presence of water during the high tide and lack of water during the low tide – leads to the generation of tide pools and communities of organisms that are adapted to daily changes in temperature, salt and tidal change Neritic Zone: Constantly covered with water, but still near the shore Oceanic Zone: Deep parts Abyssal: Deepest zone of oceans
(b) Intertidal zone Neritic zone Oceanic zone Littoral zone Marine zonation. Like lakes, the marine environment is generally classified on the basis of light penetration (photic and aphotic zones), distance from shore and water depth (intertidal, neritic, and oceanic zones), and whether it is open water (pelagic zone) or bottom (benthic and abyssal zones). Zonation in a lake. The lake environment is generally classified on the basis of three physical criteria: light penetration (photic and aphotic zones), distance from shore and water depth (littoral and limnetic zones), and whether it is open water (pelagic zone) or bottom (benthic zone). (a) Littoral zone Limnetic zone Photic zone Benthic zone Aphotic zone Pelagic zone Intertidal zone Neritic zone Oceanic zone 200 m Continental shelf Pelagic zone 2,500–6,000 m Abyssal zone (deepest regions of ocean floor) (b)
Types Of Aquatic Biomes 1. Lakes: Oligotrophic: nutrient poor and oxygen rich – clear and pristine Eutrophic: nutrient rich and oxygen poor (in winter and in the aphotic zone) - abundance of nutrients allows for the growth of producers which sets up the lake to have a large biological load (decreases oxygen) Mesotrophic: an oligotrophic lake undergoing eutrophication Eutrophication: influx of nutrients into an oligotrophic lake allows it to become eutrophic
Lakes LAKES Figure 50.17 An oligotrophic lake in Grand Teton, Wyoming A eutrophic lake in Okavango delta, Botswana LAKES Lakes Figure 50.17
2. Wetlands – marshes and swamps – high diversity and production Figure 50.17 WETLANDS Okefenokee National Wetland Reserve in Georgia
3. Streams and Rivers – streams – faster, more oxygen Figure 50.17 A headwater stream in the Great Smoky Mountains The Mississippi River far form its headwaters
4. Estuaries – rivers meet the sea – fresh and salt water mix Figure 50.17 An estuary in a low coastal plain of Georgia ESTUARIES
5. Intertidal Zones – high tide, low tide – turbulent and changing Figure 50.17 INTERTIDAL ZONES Rocky intertidal zone on the Oregon coast
6. Oceanic Pelagic Biome – open ocean – most productive due to size Figure 50.17 Open ocean off the island of Hawaii OCEANIC PELAGIC BIOME
7. Coral Reefs – tropical rain forest of ocean Figure 50.17 A coral reef in the Red Sea CORAL REEFS
8. Marine Benthic Zone – deep bottom Figure 50.17 A deep-sea hydrothermal vent community MARINE BENTHIC ZONE
Terrestrial Biomes 30N Tropic of Cancer Equator Capricorn 30S Key Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Tundra High mountains Polar ice
Terrestrial Biomes Climograph: compares temperature and rainfall to indicate the areas of different biomes NOTE: there is variation in each zone and some biomes overlap
Climograph Desert Temperate grassland Tropical forest Temperate broadleaf forest Coniferous Arctic and alpine tundra Annual mean precipitation (cm) Annual mean temperature (ºC) 100 200 300 400 30 15 15
Ecotone: area of integration of one biome into another – not a sharp division, but a gradual movement from one type to another Characteristics: Named for major climate characteristics and predominant vegetation. Biological Species: Those adapted to that particular area. Some species are very specific to one biome while others may move freely between biomes.
Vertical Stratification: Canopy – upper portions of forested biomes Low tree stratum – smaller trees Shrub Under story Ground Story – herbaceous plants Forest Floor – leaf litter Root Layer Sub-soil Stratification provides different areas for plants and animals to live and obtain nutrients. Allows for less competition by portioning resources into specific niches.
Periodic Disturbances: Change of weather, fire, volcanoes, hurricanes. All can alter the climate and may actually be necessary for maintaining the biome. Ex. Fire
1. Tropical Forest – diverse – lots of rain – nutrient poor soil A tropical rain forest in Borneo Figure 50.20 Tropical forest
2. Desert – less than 30 cm rain Figure 50.20 DESERT The Sonoran Desert in southern Arizona
3. Savanna – grasslands with trees – Lion King – fire dependent A typical savanna in Kenya Figure 50.20
An area of chaparral in California 4. Chaparral – hot in summer, cold in winter – waxy leaves – fire dependent CHAPARRAL An area of chaparral in California Chaparral Figure 50.20
Sheyenne National Grassland in North Dakota 5. Temperate Grassland – um, grass – fire dependent – rich soils agriculture Sheyenne National Grassland in North Dakota Figure 50.20 TEMPERATE GRASSLAND
6. Coniferous Forest – pine forests – cold, northerly – acidic soil Rocky Mountain National Park in Colorado CONIFEROUS FOREST Figure 50.20
7. Temperate Broadleaf Forest – you live here Great Smoky Mountains National Park in North Carolina Temperate broadleaf forest Figure 50.20
Denali National Park, Alaska, in autumn 8. Tundra – no trees, lichens as primary producers – permafrost – reindeer and Santa TUNDRA Figure 50.20 Denali National Park, Alaska, in autumn