Biosphere Ecology

What Is Ecology?

• The scientific study of the interactions between organisms and their environments.
• Word derivation:
  • Oikos: home or household
  • Logos: to study
  • “To study home or household”
• The environment is made of two parts:
  • Abiotic (nonliving) components
    • Heat
    • Light
    • Water
    • Nutrients
  • Biotic (living) components

Hierarchy in the Study of Ecology

• Organismal ecology (parts of chapters 50 and 51)
  • Concerned with how individual organisms deal with their physical environment (abiotic environment)
  • Includes:
    • Behavioral adaptations
    • Physiological adaptations
    • Morphological adaptations
• Population ecology (chapter 52)
  • Concerned with groups of individuals of the same species living in the same geographical area
  • Mainly deals with factors that affect:
    • Population size
    • Population composition
• Community ecology (chapter 53)
  • Concerned with all organisms living in a particular area
  • Deals with a variety of different species and their interactions with one another, including:
    • Predation
    • Competition
    • Parasitism
    • Mutation
• Ecosystem ecology (chapter 54)
  • Concerned with the relationships between the organisms in a community and abiotic factors
  • Mainly deals with:
    • The flow of energy through the system
    • The cycling of chemicals
• Biosphere ecology (chapter 50)
  • Concerned with the global ecosystem
  • Deals with:
    • All the life on the planet
    • The physical environment (atmosphere, oceans, land, etc.)
  • The biosphere, a.k.a. “Biosphere 1,” is Earth.
  • Biosphere 2 is an experiment in Oracle, Arizona to recreate Earth's different ecosystems in one continuous structure.
    • Created by a Texas oil multimillionaire in the 1980s.
    • Was run until recently by Columbia University.
    • Its future is uncertain.

From The Marketing Den; from Wikipedia's Biosphere 2 article

Biosphere Overview

The biosphere consists of two primary parts:

• Abiotic factors, which influence the distribution of life on Earth.
• Biomes, the major types of ecosystems.
  • Terrestrial biomes:
    • Tropical forest
    • Savanna
    • Desert
    • Chaparral
    • Temperate grassland
    • Temperature deciduous forest
    • Coniferous forest (taiga)
    • Tundra
  • Aquatic biomes:
    • Freshwater:
      • Lakes
      • Rivers
    • Marine:
      • Estuaries
      • Coral reefs
      • Intertidal
      • Continental shelves
      • Oceanic pelagic
      • Abyssal zone

Abiotic Factors

Weather vs. Climate

• Weather refers to the short-term fluctuations of the following abiotic factors in a region over periods of hours or days:
  • Cloud cover
  • Humidity
  • Precipitation
  • Temperature
  • Wind
• Climate refers to the patterns of weather that prevail from year to year and even century to century in a particular region, and is primarily determined by the following abiotic factors:
  • Precipitation
  • Sunlight
  • Temperature
• Influence on organisms:
  • Weather can affect individual organisms.
  • Climate influences and limits the overall distribution of entire species.

Relating Climate and Biomes

• The distribution of biomes (major ecosystems) is strongly correlated with climate.
• Observe the distribution of biomes based on the climatograph (average annual temperature versus average annual precipitation).

Figure 50.3, page 1030, Campbell's Biology, 5th Edition

It's All About the Sun

• Solar energy is the primary controller of global climate patterns.
• The amount of solar energy depends on latitude.
  • Equator (0° latitude)
    • Most direct rays of sun
    • More solar energy per square meter than anywhere else on the planet over the course of a year
    • Hot climate
  • North and south poles (90° north latitude and 90° south latitude)
    • Most oblique rays of sun
    • Less solar energy per square meter than anywhere else on the planet over the course of a year
    • Cold climate

From a University of Wisconsin, Milwaukee lecture; from a Weber State University lecture; unknown source

Earth's Tilt, Solar Energy, and the Seasons

• The effect of the sun on the Earth is a bit more complicated than mentioned in the last section because the earth is tilted on its axis.
• The seasons are a result of the Earth's tilt on its axis.
  • Because of the tilt, different regions of the Earth receive different amounts of solar radiation throughout the year (as illustrated below).
• In December, sunlight reaches a greater area in the southern hemisphere than it does in the northern hemisphere.
  • This causes the southern hemisphere to be warmer than the northern hemisphere.
  • Therefore, it is summer in the southern hemisphere and winter in the northern hemisphere.
  • The reverse occurs six months later.

Unknown source; from zoomschool.com

Global Air Circulation, Precipitation, and Biomes

The Tropics and the Tropical Forest Biome

• Area on the Earth's surface between Tropic of Cancer (23° 26' 22" north latitude) and Tropic of Capricorn (23° 26' 22" south latitude).
• Receives more solar energy than any other part of the Earth.
  • Air is heated, expands, and therefore rises.
  • As the air rises it cools.
  • Cool air is able to hold less moisture than warm air, so clouds form and moisture is released.
• Thus, the tropics are the warmest and wettest part of the planet, year round.
• Trees require a lot of water to live, so this region predominantly consists of forests—hence the tropical forest biome.

Figures 50.6(a), page 1032 Campbell's Biology, 5th Edition; unknown source; figure 50.16(a), page 1044, Campbell's Biology, 5th Edition

The Desert Biome

• Tropical air continues to rise near the equator.
  • This displaces the older air, which is pushed away from the equator toward the poles (either northward or southward).
• At about 30° north latitude and 30° south latitude, this air has cooled, its density increases, and it begins to sink.
  • As it sinks, this air warms (because air closer to the Earth's surface is warmer due to solar radiation).
  • Warm air is able to hold more moisture than cold air, so clouds do not form.
• Thus, around 30° north latitude and 30° south latitude global climate is dry and hot.
• Most large deserts are found close to these latitudes.

Unknown sources; Figure 50.16(c), page 1045, Campbell's Biology, 5th Edition

Air Circulation Cells

• The air that descends at 30° north latitude and 30° south latitude returns towards the equator, forming two air circulation cells:
  • One between the equator and 30° N
  • One between the equator and 30° S
• Two more pairs of air circulation cells exist (each pair has one in the north and one in the south):
  • Between 30° and 60° (north and south)
  • Between 60° and 90° (north and south)

Unknown sources

The Coniferous Forest Biome (Taiga)

• At 60° latitude (north and south) air rises again.
  • Rising air results in cloud formation and the release of moisture.
  • Large trees, such as conifers, require a large amount of rainfall to live.
• Therefore, around 60° latitude (north and south) is where the largest expanses of coniferous forests are found on Earth.
  • Since there are no large landmasses around 60° S, the coniferous forest biome is mainly found in the northern hemisphere.
  • The northern coniferous forest biome is also called the taiga.

Figure 50.16(g), page 1047, Campbell's Biology, 5th Edition

The North and South Poles

• At 90° latitude (north and south) air sinks again.
  • This sinking air warms due to the solar radiation on the Earth's surface.
  • This warming is relative to the air above it, which is very, very cold!
  • This warmer air is able to hold more moisture than cold air, so clouds don't form and very little precipitation occurs.
• Effect on terrestrial life:
  • There is no land at the north pole, so it is not an issue for terrestrial life there!
  • Antarctica is the landmass at the south pole.
    • Because Antarctica receives little solar energy, it is very cold.
    • Because air is sinking, Antarctica receives little moisture and is a desert.
    • The annual precipitation at the south pole is two inches (the same as the Sahara!).

From unicycling.org

Complications in the Expected Global Climate Pattern

• If the Earth's surface were uniform, then climate zones would occur in bands corresponding to latitude as explained in the previous slides.
• However, the interactions of the irregularly shaped continents with the oceans alter the global climate pattern.
  • This is due to water's high specific heat (from hydrogen bonding), which causes it to heat and cool much more slowly than land.
• Variation in elevation on continents further complicates this situation.
  • As elevation increases, the atmosphere becomes thinner and retains less heat.
  • Temperature drops approximately 3.5 °F for every 1000 feet elevation gain.
  • This explains why snow-capped mountains are found in the tropics.
    • Example: Mt. Kilimanjaro in Tanzania is 3° south of the equator and is covered by glaciers!

Unknown sources

The Rainshadow: How Mountains Modify Rainfall Patterns

• Average rainfall tends to be greater on the windward side of a mountain range.
  • When water-laden air is forced to rise as it meets a mountain, it cools.
  • Cooling reduces the air’s ability to retain water, and the water condenses as rain or snow on the windward side of the mountain.
• As air descends on the far side (leeward side) of the mountain, it warms, absorbing more water, creating a local dry area.
• This dry area is called a rain shadow.
• Yearly rainfall data across the Santa Cruz Mountains:

  Santa Cruz

  31 inches

  Ben Lomond

  48 inches

  San Jose

  15 inches (we are in the rain shadow!)

• This same rainfall pattern can be observed across the Sierra Nevada Mountains.
  • Evidence of this rainfall pattern is the plant life.
  • Think about the wonderful forests you drive through on your way to Tahoe—evidence of much precipitation.
  • The east side of the Sierras is in the rain shadow, so it is a dry desert with very little plant life.

Figure 56.7, Purves's Life: The Science of Biology, 7th Edition

Terrestrial Biomes

Low Latitudes

• Tropical forests
  • Climate: high temperature, heavy rainfall
  • Vegetation: tall trees, epiphytes (plants which grow on other plants; they do not need soil), vines
  • Example: Amazon Rainforest
• Savanna
  • Climate: high temperatures, heavy rainfall for a few months each year, followed by many months of no rain
  • Vegetation: grassland with scattered trees
  • Example: the most famous savanna is in east Africa where large African mammals live.
  • Can be thought of as “tropical grasslands” because the savanna is basically found within the tropics.

Figure 50.16(a) and 50.16(b), page 1044, Campbell's Biology, 5th Edition

Mid Latitudes

• Deserts
  • Climate: low rainfall, high temperature (although there are some cold deserts)
  • Vegetation: adaptations to reduce water loss: leathery leaves, reduced leaf size or no leaves, etc.
  • Examples: Mojave Desert, Great Basin (between the Sierra Nevada and the Rockies)
• Chaparral
  • Climate: think California! Cool rainy winters with hot, dry summers
  • Vegetation: low-growing shrubs, trees with tough evergreen leaves; adapted for periodic fires
  • Examples: California and countries surrounding the Mediterranean Sea
• Temperate grassland
  • Climate: hot summers, cold winters; less precipitation than the tropical savanna
  • Vegetation: grasses
  • Example: North American Prairie
• Temperate deciduous forest
  • Climate: warm summers, cold winters; enough precipitation to support trees
  • Vegetation: deciduous trees (trees which lose their leaves in the fall)
  • Example: forests of the eastern U.S.

Figure 50.16(c), 50.16(d), 50.16(e), 50.16(f), pages 1045 and 1046, Campbell's Biology, 5th Edition

Mid-to-High Latitudes

• Coniferous forest
  • Climate: long, cold winters, short summers; precipitation is in the form of snow (enough to support trees)
  • Vegetation: cone-bearing trees (evergreen trees)
  • Example: forests across Canada
    • The northern coniferous forest is also known as the taiga, and is the largest terrestrial biome on the planet!
• Tundra
  • Climate: long, cold winters, very short summers; the ground freezes in the winter, and the top few inches thaw during the summer, but the rest remains permanently frozen all year (hence the name “permafrost”)
  • Vegetation: grasses and low lying shrubs
  • Example: Alaskan tundra

Figure 50.16(g) and 50.16(h), page 1047, Campbell's Biology, 5th Edition

In Your Backyard

• In terms of biomes, changes in elevation generally mimic changes in latitude.
• Precipitation and temperature are the two main determiners of ecosystems (biomes), and precipitation and temperature can change with elevation just as they change with latitude!
• Example:
  • Next time you drive from here to Lake Tahoe look out the window and imagine you are driving toward the North Pole.
  • If you continue your trip to the top of the ski lifts at your favorite resort, then you have taken the trip from the chaparral to the tundra!

Unknown source

Aquatic Biomes

• Two broad categories exist based on the salt concentration:
  • Freshwater biomes
    • Salt concentrations of less than 1 % (not “salty”)
    • Cover 2.5 % of the Earth's surface.
    • Major freshwater biomes: lakes and rivers.
  • Marine biomes
    • Salt concentrations of 3 % (“salty”)
    • Cover 75 % of the Earth's surface!
    • Major biomes in the oceans: intertidal zones, coral reefs, oceanic pelagic, benthos
• Estuary biomes: where freshwater and marine meet
  • Salt concentration varies daily and yearly depending on rainfall and tides.
  • Local example: Elkhorn slough

Unknown sources

Their Different Zones

Zonation in aquatic biomes is determined by three different physical parameters. There is some overlap in this naming system.

1. Penetration of light
   • Photic zone: light
   • Aphotic zone: no light
2. Distance from shore
   • Freshwater
     • Littoral: near shore (rooted and floating aquatic plants exist)
     • Limnetic: away from the shore, in the photic zone
   • Marine
     • Intertidal: region between high and low tides (zone where we go “tide pooling”)
     • Neritic: region over continental shelf
       • Average distance from shore is about 40 miles.
       • Continental shelf ends at about a depth of 660 feet.
     • Oceanic: region beyond the continental shelf
3. Open water or bottom
   • Freshwater
     • Limnetic zone: region in deeper water, away from the shore, where there is light
     • Profundal zone: region in deeper water, away from the shore, where there is no light; synonymous with the aphotic zone
     • Benthic zone: bottom of a lake from shoreline to shoreline
   • Marine
     • Pelagic zone: open ocean of any depth
     • Benthic zone: bottom of the seafloor
   • Abyssal zone: exceptionally deep regions of the ocean

Figures 50.10 and 50.13, pages 1036 and 1039, Campbell's Biology, 5th Edition

Freshwater: the Lake Biome

Classification of lakes is done by their production of organic matter.

• Oligotrophic lakes
  • Word derivation:
    • Oligo: few, little
    • Trophic: food
    • “Little food”
  • These lakes do not produce much organic matter.
  • They are generally nutrient-poor.
  • They have deep, clear, cold water.
  • Example: Lake Tahoe
• Eutrophic lakes
  • Word derivation:
    • Eu: good
    • Trophic: food
    • “Good food”
  • These lakes produce a lot of organic matter.
  • They are nutrient-rich (from runoff into the lake).
  • They are shallow and murky.
  • Example: Vasona Lake

Unknown sources