Climate and Biodiversity Notes

Climate and Biodiversity

Factors Influencing Climate

  • Climate is the general pattern of atmospheric conditions in an area over decades or longer, while weather refers to temperature, precipitation, wind speed, and cloud cover over hours to days.
  • Key factors determining an area’s climate include:
    • Incoming solar energy
    • The earth’s rotation
    • Global patterns of air and water movement
    • Gases in the atmosphere
    • The earth’s surface features
  • Ocean currents, prevailing winds, and the Earth's rotation redistribute heat from the sun through surface and deep currents.
  • Air circulation patterns are influenced by uneven heating of the earth’s surface, the earth’s rotation, and the properties of air, water, and land.
  • El Niño-Southern Oscillation (ENSO)
    • Occurs every few years
    • Prevailing winds in the tropical Pacific Ocean change direction
    • Affects much of earth’s weather for 1-2 years
  • Greenhouse gases warm the lower atmosphere:
    • H2O (water vapor)
    • CO2 (carbon dioxide)
    • CH4 (methane)
    • N2O (nitrous oxide)
    • The natural greenhouse effect keeps the earth habitable.
    • Human activities enhance global warming.
  • Mountains interrupt the flow of prevailing winds, causing the rain shadow effect, where most precipitation falls on the windward side, leading to deserts on the leeward side.
  • Cities create microclimates.

Climate and Biomes

  • Differences in average annual precipitation and temperature lead to the formation of tropical, temperate, and cold deserts, grasslands, and forests, largely determining their locations.
  • Biomes are large land regions with specific climate and dominant plant life and are not uniform but a mosaic of patches that change with latitude and elevation.

Major Types of Biomes

  • Deserts
    • Annual precipitation is low and scattered.
    • Types: Tropical, temperate, and cold deserts
    • Deserts are fragile ecosystems.
  • Grasslands
    • Occur in interior continents, too moist for deserts and too dry for forests
    • Types: Tropical (savanna), temperate, and cold (arctic tundra)
  • Tropical Grassland (Savanna)
    • Grazing and browsing animals are common.
  • Temperate Grassland (Prairie)
    • Cold winters and hot, dry summers
    • Tall-grass and short-grass prairies
    • Often converted to farmland
  • Cold Grassland (Arctic Tundra)
    • Plants grow close to the ground to conserve heat.
    • Most growth occurs in the short summer.
    • Animals have thick fur.
    • Permafrost: Underground soil that stays frozen
    • Alpine tundra: Above the tree line in mountains
  • Forests
    • Lands dominated by trees
    • Types: Tropical, temperate, and cold (northern coniferous and boreal)

Types of Forests

  • Tropical Rain Forests
    • Hot and high moisture
    • Stratification of specialized plant and animal niches
    • Rapid recycling of scarce soil nutrients
  • Temperate Deciduous Forests
    • Cooler temperature and less moisture
    • Broad-leaf deciduous trees
    • Slow rate of decomposition
  • Evergreen Coniferous Forests
    • Cold winters
    • Few species of cone-bearing trees
    • Slow decomposition
    • Coastal coniferous forest, temperate rain forests are found in scattered coastal regions.

Mountains

  • Steep, high elevation lands contain a majority of the world’s forests.
  • Act as islands of biodiversity with habitats for endemic species.
  • Help regulate the earth’s climate.
  • Major storehouses of water with a significant role in the hydrologic cycle.

Human Impact on Terrestrial Ecosystems

  • Human activities are disrupting ecosystem and economic services provided by many of earth’s deserts, grasslands, forests, and mountains.
  • About 60% of the world’s major terrestrial ecosystems are being degraded.
  • The human ecological footprint is spreading across the globe.
  • Examples of Major Human Impacts on Terrestrial Ecosystems:
    • Deserts: Large desert cities; destruction of soil and underground habitat; depletion of groundwater; soil damage from off-road vehicles.
    • Grasslands: Conversion to cropland; release of CO_2 to atmosphere from burning grassland; overgrazing by livestock; damage from off-road vehicles.
    • Forests: Clearing for agriculture, livestock grazing, and timber; conversion of diverse forests to tree plantations; air pollution; land disturbance and pollution from mineral extraction.
    • Mountains: Agriculture; timber and mineral extraction; hydroelectric dams and reservoirs; air pollution; soil damage from off-road vehicles.

Biome Changes

  • Biomes are not fixed; they change as the climate changes.
  • Human activities are likely to affect biome placement in the future.

Three Big Ideas

  • Differences in climate largely determine the types and locations of the earth’s deserts, grasslands, and forests.
  • The earth’s terrestrial systems provide important ecological and economic services.
  • Human activities are degrading and disrupting many of the ecological and economic services provided by the earth’s terrestrial ecosystems.
  • Climate plays a key role in determining the nature of terrestrial ecosystems which helps distribute heat from solar energy and recycle the earth’s nutrients