CH 3: Ecosystem Ecology and Biomes

Ecosystem: a particular location on Earth distinguished by its particular mix of interacting biotic (living) and abiotic (non-living) components

Photosynthesis and Respiration

  • Producers: organisms that use the energy of the sun to produce usable forms of energy; also known as autotrophs

  • Consumers: organisms that obtain energy by feeding on other organisms, including both herbivores and carnivores; also known as heterotroph

  • Photosynthesis: producers use solar energy to convert carbon dioxide and water into glucose

  • Cellular Respiration: the process by which organisms convert glucose and oxygen into carbon dioxide, water, and energy in the form of ATP.

Trophic Levels, Food Chains, and Food Webs

  • Trophic levels: successive levels of organisms consuming one another

  • Food chain: sequence of consumption from producers through tertiary consumers

  • Food web: a complex network of interrelated food chains that illustrates how energy and nutrients flow through different organisms in an ecosystem.

  1. Producers

  2. Primary consumers (herbivores): plant and algae eating animals (e.g. zebras, grasshoppers, and tadpoles)

  3. Secondary consumers (carnivores): heterotrophs that obtain energy by eating other consumers (e.g. lions, hawks, and rattlesnakes)

  4. Tertiary consumers: carnivores that eat secondary consumers (e.g. bald eagles)

  • Scavengers: carnivores that consume dead animals

  • Detritivores: organisms that specialize in breaking down dead tissue and waste products into smaller particles

Ecosystem Productivity

  • Gross Primary productivity (GPP): the total amount of energy captured by producers through photosynthesis over a specific time period.

  • Net Primary Productivity (NPP): energy captured (GPP) minus the energy respired by producers

  • GPP is revenue while NPP is profit

Energy Transfer Efficiency and Trophic Pyramids

  • Energy in an ecosystem is measured in terms of biomass

    • Biomass: total mass of all living matter in a specific area; represented using a trophic pyramid

      • Standing Crop: amount of biomass present in an ecosystem at a given time

  • Ecological efficiency: the proportion f consumed energy that can be passed from one trophic level to another

  • Trophic Pyramid: representation of distribution of biomass among trophic levels

Matter Cycles

  • Biosphere: the global sum of all ecosystems, encompassing both terrestrial and aquatic environments.

  • Earth can be divided into four compartments: earth (soil and rock), water, and atmosphere, and living things

  • All matter cycles involve the movement of materials from one compartment to other compartments

Biogeochemical Cycles: the cycling of matter through the biosphere

  • Bio: life

  • Geo: earth

  • Chemical: matter

Hydrologic Cycle: The movement of water through the biosphere

Nitrogen Cycle: The process by which nitrogen is converted between its various chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems.

Carbon Cycle: The process involving the movement of carbon among the atmosphere, terrestrial organisms, and oceans, which plays a crucial role in regulating climate and supporting life.

Ecosystem and Disturbance

  • Disturbance: an event caused by physical, chemical , or biological agents that results in changes in population size or community composition

  • Natural ecosystem disturbances include hurricanes, ice storms, tsunamis, volcanic eruptions, and forest fires

  • Anthropogenic ecosystem disturbances include human settlements, agriculture, air and water pollution, and clear-cutting of forests, as well as strip mining

Resistance vs. Resilience

  • Resistance: a measure of how much disturbance an ecosystem can tolerate without significantly changing the flows of energy and matter

  • Resilience: the rate at which an ecosystem returns to its original state after a disturbance

Watershed Studies

  • Watershed: all of the land in a given landscape that drains into a particular stream, river, lake, or wetland

Weather: the short term, local conditions of the atmosphere (e.g. temperature, humidity, clouds, precipitation, wind speed, and atmospheric pressure)

Climate: average weather that occurs in a given region over a long period (typically several decades)

Earth’s Atmosphere

  • Troposphere: layer closest to Earth’s surface extending roughly 10 miles above Earth

  • Stratosphere: above the troposphere extending roughly 10-31 miles

Atmospheric Convection Currents

  • Density: less-dense air rises, denser air sinks

  • Water vapor capacity: warm air has a higher capacity for water vapor than cold air

  • Adiabatic Heating or Cooling

    • As air rises, it expands and cools adiabatically, leading to cloud formation and precipitation, while descending air compresses and warms, inhibiting cloud development.

  • Latent Heat Release: This process occurs when water vapor condenses into liquid water, releasing heat into the surrounding environment, which can further influence weather patterns and climate dynamics.

Earth’s Rotation and the Coriolis Effect

  • Coriolis Effect: the deflection of an object’s path due to Earth’s rotation

  • Prevailing winds are produced by a combo of atmospheric convection currents and the Coriolis effect

Ocean Currents

  • Driven by a combo of temp, gravity, prevailing winds, the Coriolis effect, and the locations of continents

  • Warm water expands and rises

  • Gyres: Large-scale circular ocean currents that are influenced by the Earth's wind patterns and rotation, resulting in the movement of water in a clockwise direction in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

  • Upwelling: The process where cold, nutrient-rich water rises to the surface, primarily driven by the action of winds and ocean currents, significantly enhances productivity in marine ecosystems.

  • Thermohaline Circulation: A large-scale ocean circulation pattern driven by differences in water temperature and salinity, which plays a crucial role in regulating global climate and transporting nutrients across the world's oceans.

El Nino

  • Southern Oscillation ENSO

  • Every 3-7 years, Earth’s atmosphere and ocean surface currents interact in the tropical Pacific Ocean to reverse direction

La Nina

  • Opposite weather patterns compared to El Niño, such as increased rainfall in the western Pacific and drought conditions in the eastern regions.

Robert Harding Whittaker (1920-1980)

  • American Ecologist

  • Cornell University

Biomes: Large geographic regions on Earth with a unique climate, plants (flora), and animals (fauna) that are adapted to those specific conditions

Tundra

  • Cold, treeless biome with low-growing vegetation

  • Soil is completely frozen in winter

  • Short, four month growing season

  • Permafrost: underlying subsoil is permanently frozen

Boreal Forest

  • Sometimes called Taiga

  • Mostly coniferous (cone-bearing) evergreen trees

  • Found between about 50 and 60 degrees North in Europe, Russia, and N. America

  • Plant growth more constrained by low temp than precipitation

  • Soil id nutrient-poor due to slow decomposition

Temperate Rainforest

  • Moderate temps and high precipitation

  • Coastal biome ocean currents moderate temp fluctuations and provide water vapor

  • 12 month growing season where winters are rainy and summers are foggy

  • Mild temps and high precipitation supports growth of huge trees

Temperate Seasonal Forest

  • Receive over 1 meter (39 inches) of precipitation annually

  • Found in the Eastern U.S., Japan, China, Europe, Chile, and Eastern Australia

  • Dominated by broadleaf deciduous trees such as beech, male, oak, and hickory

  • Warmer temps = more decomposition so soils generally contain more nutrients than those of boreal forests

Woodland/Shrubland

  • Mediterranean Climate

  • Hot, dry summers and mild, rainy winters

  • 12 month growing season but plant growth constrained by low summer precipitation cool winter temperatures

  • Plants of this biome are well adapted to both fire and drought

Temperate Grassland/Cold Desert

  • Great plains of N. America, S. America, Central Asia, and Eastern Europe

  • Cold, harsh, winters and hot, dry, summers

  • Dominated by grasses and non-woody flowering adapted to wildfires and frequent grazing

Tropical Rainforest

  • Located between 20 degrees north and south of the equator

  • Central and S. America, Africa, SE Asia, and NE Australia

  • Frequent rainfall, warm and wet with steady temps

  • More biodiversity than any other terrestrial biome (2/3rds of Earth’s terrestrial species)

Tropical Seasonal Forest/Savanna

  • Warm temps and distinct wet and dry seasons

  • Central America, Atlantic coast of S. America, southern Asia, in NW Australia, sub-Saharan Africa

  • Fairly fertile soil but low precipitation constraints plant growth

  • Grasses and scattered deciduous trees are common

Subtropical Desert

  • 30 degrees N and S with hot temps and extremely dry conditions

  • Mojave Desert in SW U.S., Sahara, Middle East, Great Victoria Desert of Australia

  • Cacti, euphroes, and succulent plants

Aquatic Biomes

  • Categorized by salinity, depth, and water flow

  • Lakes and Ponds

    • Littoral Zone: the shallow area of soil and water near the shore where algae and emergent plants grow

    • Limnetic Zone: open water, where rooted plants can no longer survive. Phytoplankton are the only photosynthetic organisms. This zone extends to as deep as sunlight can penetrate

    • Profundal Zone: the zone where sunlight cannot penetrate and therefore producers cannot survive

    • Benthic Zone: muddy bottom of a lake or pond beneath the limnetic and profundal zone

Salt Marshes: one of the world’s most productive biomes

Mangrove Swamps

  • Found along tropical and subtropical coasts and contain trees whose roots are submerged in water

  • Mangrove trees are salt tolerant and help protect the coastlines from erosion and storm damage

Intertidal Zone

  • Narrow band of coastline that exists between the levels of high ride and low tide

  • Waves that crash onto the shore in this biome can make it a challenge for organisms to hold on and not get washed away

Coral Reefs

  • Found in warm, shallow water beyond the shoreline

  • Earth’s most diverse marine biome

  • Found in water that is relatively poor in nutrients and food; depends on coral-algae mutualism

  • Coral bleaching: when the algae inside the coral dies due to combo of disease and environmental change

The Open Ocean

  • The depth that light can penetrate in the open ocean is dependent on the amount of sediment and algae suspended in the water

  • Photic Zone: the zone that receives enough light to allow photosynthesis to occur

  • Aphotic Zone: the deeper water that lacks sufficient light for photosynthesis

  • Chemosynthesis: the process that occurs in the aphotic zone when some species of bacteria use methane and hydrogen sulfide to generate energy