Ecosystems and Biomes Study Guide

Ecosystems

  • Ecosystem encompasses:
    • Atmosphere
    • Ecosphere
    • Hydrosphere
    • Biosphere
    • Lithosphere

Lecture Outline

  • Climate and the Ecosystem
  • Solar Radiation
  • Global Wind Circulation

Biomes

  • Terrestrial Ecosystems
    • Tundra
    • Forests
    • Shrublands
    • Grasslands
    • Deserts
  • Aquatic Ecosystems
    • Life Zones
    • Lakes
    • Estuaries
    • Seashores
    • Oceans

Climate and the Biosphere

  • Climate: Prevailing weather conditions in a region.
  • Determined primarily by temperature and precipitation.
  • Rotation and annual revolution of the Earth.
  • Influenced by various factors including latitude, tilt of the earth’s axis, and topography.
  • Effects of solar radiation.
  • Spherical earth.
  • Rotation and path of the earth around the sun.

Solar Radiation - Climate

  • Solar Radiation along with the tilt of the Earth result in seasons.
  • Equator receives a consistent amount of sun throughout the year, resulting in minimal seasonal changes.
  • Air rises at the equator and again at 60 degrees.
  • Rising air cools and loses moisture, leading to rain.
  • At 30 degrees, air descends, warms, and collects moisture, leading to dry areas.

Distribution of Solar Energy

  • Winter solstice: Northern Hemisphere tilts away from the sun in December.
  • Vernal equinox: Sun aims directly at the equator in March.
  • Summer solstice: Northern Hemisphere tilts toward the sun in June.
  • Autumnal equinox: Sun aims directly at the equator in September.

Global Wind Circulation

  • Westerlies at 60°N and 60°S.
  • Northeast trade winds at 30°N.
  • Southeast trade winds at 30°S.
  • Equatorial doldrums at 0°.
  • Ascending moist air cools and loses moisture.
  • Descending dry air warms and retains moisture.

Rain Shadow

  • Occurs with a coastal mountain range.
    • Windward side: Winds rise and cool, releasing moisture resulting in dense vegetation.
    • Leeward side: Air descends, warms, and absorbs moisture, leading to evaporation of existing water and rare rainfall (rain shadow effect).

Monsoon

  • Air over lands heats and rises, drawing in cool air from the ocean.
  • Rising air loses moisture, resulting in tremendous rain.

Ocean Currents

  • Water warms more slowly and holds heat longer than air.
  • Water moderates temperatures near land.
  • Gulf Stream off the coast of NC brings warm water and agreeable temperatures.

Terrestrial Communities

  • Biomes are a particular mix of plants and animals adapted to living under certain environmental conditions.
  • Delineated by climate and tend to repeat wherever temperature and precipitation are the same.
  • Precipitation is very important.
  • Latitude: Distance from the equator, farther away = cooler.
  • Altitude: Distance from sea level, farther away = cooler.

Deserts

  • Major deserts are located at 30º latitude.

Forests

  • Forests are located around 60° latitude.

Tundra

  • Arctic tundra encircles Earth just south of ice-covered polar seas in the Northern Hemisphere.
  • Long cold winter and short summers.
  • Poor soil, short growing season, little precipitation = no trees.
  • Roots cannot penetrate permafrost.
  • Few animals year-round- very harsh winter.

Coniferous Forests

  • Taiga typifies coniferous forest with cone-bearing trees; aka Boreal forest.
  • Trees are well adapted to cold with needle-like leaves to withstand snow and thick bark.
  • Short wet summer, long cold winters.
  • Limited understory/ not plant heavy; short growing season, so smaller plants.

Temperate Rain Forest

  • Northwest US, winds blow inland off the Pacific.
  • Winds hit mountain range, cool and rise, lose moisture.
  • Evergreen forest, redwoods.
  • Temperate = more moderate temperatures.

Temperate Deciduous Forests

  • Found south of taiga in eastern North America, eastern Asia, and much of Europe.
  • Four well-defined seasons with long growing seasons.
  • Deciduous trees lose leaves.
  • Ground-life is plentiful –gets sunlight and has fertile soil.
  • Amphibians and reptiles because more temperate climate.

Tropical Forests

  • Found in equatorial regions.
  • Abundant rainfall avg 74 inches (NC avg - 37 inches).
  • Most animals live in trees arboreal abundant insects, primates, amphibians, reptiles, birds.
  • Epiphytes (plants without roots), lianas (woody vines) common.
  • Soils are nutrient-poor - Rapid recycling of nutrients.
  • Slash & burn agriculture successful but destructive.
  • Little light reaches forest floor; trees often have buttress roots (anchorage).

Tropical Deciduous Forest

  • Have seasons.
  • Trees are deciduous.

Shrublands

  • Tend to occur along coasts that have hot, dry summers and cool, wet winters.
  • Shrubs adapted to withstand arid conditions.
  • Dense shrubland in California known as chaparral – fire is frequent.

Grasslands

  • Occur where annual rainfall is greater than 25 cm, but generally insufficient to support trees.
  • Good soil (decomp of grasses).
  • Herbivores common.
  • Sometimes droughts, occasional fire.
  • Grasses well adapted to changing environment.
    • Temperate Grasslands – Bitter cold winter, hot dry summers; prairies we also use for farmland.
    • Savannas – Cool dry winter, hot rainy summer, few trees.

Deserts

  • Usually found at latitudes of about 30 degrees in both north and south hemispheres – descending wind.
  • Types: hot/dry, semi-arid, coastal, cold.
  • Annual rainfall less than 25 cm (9 inches).
  • Large temperature differential between day and night.
  • Burrowing, nocturnal animals.
  • Succulent plants, plants with quick life cycles.
  • Poor soil – no organics, but lots of minerals.
  • Lots of evaporation.

Aquatic Ecosystems

  • Saltwater vs freshwater systems
    • Wetlands
    • Marshes
    • Swamps
    • Estuaries
    • Lakes
    • Coastal Ecosystems
    • Ocean

Wetlands

  • Wetlands –wet most of the year.
    • Marshes - grasses.
    • Swamps – trees or woody plants.
    • Bogs – nutrient poor, water from precip  cranberry bogs.
    • Estuaries.

Estuary

  • Saltwater, freshwater mix.
  • Many organisms reproduce here.
  • Productivity = tropical rain forest.
  • Wetlands:
    • Nutrient trap.
    • Filter/purify water.
    • Absorb storm water.

Estuaries

  • Partially enclosed bodies of water where freshwater and seawater meet and mix.
  • Organisms must be able to adapt to changing salinity.
  • Estimated over half of all marine fishes require development in estuaries.

Lakes

  • Bodies of water classified by nutrient status.
    • Oligotrophic - Nutrient-poor.
    • Eutrophic - Nutrient-rich.
  • Lake Stratification
    • In temperate zones, deep lakes are stratified in the summer and winter.
    • Spring and Fall winds cause overturn –mixing of nutrients from the bottom and temperature is uniform. During winter and summer, the bottom layer is different temp.

Oligotrophic vs Eutrophic Lake

  • Oligotrophic – nutrient poor, deep, cold; low productivity (few plants). Nutrients from detritus (decaying material that falls in –leaves, etc).
  • Eutrophic – nutrient rich, shallow, warmer, many plants; subject to run-off and pollution.

Aquatic Life Zones

  • Plankton
    • Important community in BOTH fresh water and salt water.
      • Phytoplankton - Algae.
      • Zooplankton - Animals.
  • Life Zones
    • Littoral zone - Closest to shore, many insects, small fish, etc. Plants rooted to the bottom.
    • Limnetic zone – Open sunlit areas.
    • Profundal zone - Below light penetration –no lite, no photosynthesis.
    • Benthic zone – Soil mucky bottom, bacteria plentiful, area of decomp.

Seashores

  • Intertidal zone lies between high and low water marks (= littoral zone of lake).
  • Rocky Shores
    • Many attached organisms.
    • Littoral zone of rocky beach divided into subzones.
  • Sandy beach
    • No attachment sites available.
    • Nearly all permanent residents dwell underground.

Marine Environment

  • Pelagic – water.
    • Neritic – over continental shelf.
    • Oceanic - open water.
  • Euphotic – portion of both that light penetrates.
  • Mesopelagic – no light.

Oceans

  • Pelagic Division- water= Neritic + Oceanic.
    • Neritic Province – area over continental shelf.
      • High concentration of organisms due to sunlight penetration and supply of inorganic nutrients.
      • Include Coral Reefs.
    • Oceanic Province
      • Lacks inorganic nutrients – large organisms, low productivity.
      • Does not have high concentration of phytoplankton.
      • Text uses Euphotic zone – light penetrates.
  • Benthic Division
    • Includes organisms that live on or in:
      • Continental Shelf (sublittoral zone)
      • Continental Slope (bathyal zone)
      • Abyssal Plain (Abyssal zone)
    • Organisms are dependent on debris sinking down from above.