Terrestrial and Aquatic Biomes

Terrestrial Biomes

  • Chapter 23 focuses on terrestrial biomes.

Reminders

  • Lecture assignment 9 and makeup lecture assignment are due on Friday.
  • An issue with images in assignment 9 has been resolved.
  • The final exam is on Thursday, May 8 at 2:00 PM.
  • There's one lab assignment remaining, and students are advised to do a careful job.

Types of Terrestrial Biomes

  • The distribution of terrestrial biomes is influenced by mean annual temperature and precipitation.
  • Examples include tropical rain forests, temperate rain forests, tropical seasonal forests, temperate forests, thorn forests (savanna), woodlands, thorn scrub (grassland), taiga, shrubland, tundra, and desert.
  • Temperature ranges from Tropical to Subtropical, Warm temperate, Cold temperate, and Arctic-Alpine.

Temperate Shrublands in Mediterranean Climates

  • Also called chaparral.
  • Dominated or codominated by shrubs.
  • Characterized by sclerophyllous trees and shrubs.
  • Cool ocean currents circulating offshore result in mild, rainy winters and hot, dry summers.

Sclerophyllous Vegetation

  • Sclerophyllous vegetation has adaptations to reduce water loss during the summer period.
  • These adaptations include small leaves, thickened cuticles, glandular hairs, and sunken stomata.

Shrubland Characteristics

  • Shrubland soils are generally deficient in nutrients.
  • Ecosystem productivity varies with annual precipitation and severity of the summer drought.
  • Temperature range, precipitation, and fire are key factors.

Temperate Broadleaf Forest

  • Found in midlatitudes.
  • Temperature varies seasonally.
  • High precipitation (2.5-5ft) is necessary to support large trees.
  • Deciduous trees drop leaves based on temperature.
  • Net Primary Productivity (NPP) is influenced by temperature and the length of the growing season.

Temperate Broadleaf Forest Characteristics

  • Heavy leaf litter supports many soil invertebrates.
  • Mammals undergo hibernation.
  • Many bird species migrate south for winter.
  • Virtually all the original temperate broadleaf forests in North America were cut for the logging industry (building materials) and cleared for agriculture or development.

Coniferous Forest (Taiga, Boreal Forest)

  • Located in the Northern Hemisphere.
  • Dominated by cone-bearing evergreen trees.
  • Lower precipitation and colder temperatures.
  • High seasonal variation.
  • Largest terrestrial biome on Earth.

Coniferous Forest (Taiga, Boreal Forest) Characteristics

  • Low Net Primary Productivity (NPP) is limited by low nutrients, cooler temperatures, and a short growing season.
  • Boreal species are well adapted to fire, which is a source of regeneration.
  • Litter input is low, but decomposition is slow.

Tundra

  • Frozen plain with permafrost (permanently frozen soil layer).
  • Located at the highest latitudes of the Northern Hemisphere.
  • Two types:
    • Tundra: up to 100 percent plant cover and wet to moist soils.
    • Polar desert: less than 5 percent plant cover and dry soil.
  • Vegetation includes grasses, moss, lichen, and small shrubs or trees.

Tundra Animal Species

  • Animal species diversity in the tundra is low.
  • Example: musk ox.

Alpine Tundra

  • Found on very high mountaintops at all latitudes, including the tropics.
  • High winds and cold temperatures create alpine tundra.
  • Similar to arctic tundra, but no permafrost.
  • Strong winds, snow, cold, and widely fluctuating temperatures.

Polar Ice

  • Covers the land north of the arctic tundra and Antarctica.
  • Only a small portion is free of ice or snow, even in summer.
  • Some life exists, but not as diverse as other biomes.

Aquatic Biomes

Overview

  • Chapter 24 focuses on aquatic biomes.

Types of Aquatic Biomes

  • Freshwater biomes:
    • Salt concentration of <1%.
    • Include lakes, streams, rivers, and wetlands.
  • Brackish water / Estuaries:
    • Where rivers and oceans meet.
  • Marine biomes:
    • Salt concentration around ~3%.
    • Open-water vs. coastal: oceans, intertidal zones, coral reefs.

Aquatic Ecosystems and the Water Cycle

  • All aquatic ecosystems are linked directly or indirectly as parts of the hydrological (water) cycle.
  • Includes precipitation, lakes, streams, wetlands, beaches, rivers, estuaries, and salt marshes.

Freshwater Biomes

  • Comprise 0.01% of Earth’s water.
  • Home to 6% of all described species.
  • Used by humans for drinking water, crop irrigation, sanitation, and industry.
  • Two groups:
    • Standing water (lentic): lakes and ponds.
    • Flowing water (lotic): rivers and streams.

Lake Origins and Characteristics

  • Origins:
    • Glacial erosion and deposition.
    • Sediment and debris damming up water.
    • Shifts in the Earth’s crust.
    • Beaver dams, human-created dams.
  • Important physical characteristics:
    • Dissolved oxygen.
    • Temperature.
    • Light: Light is increasingly attenuated with water depth.