34_Lecture

Chapter 34: The Biosphere: An Introduction to Earth’s Diverse Environments

Big Ideas

• The biosphere encompasses Earth’s diverse environments.

• Key topics include:

  • Aquatic biomes

  • Terrestrial biomes

Introduction

• Environmental concerns are pressing issues today.

• Essential questions include:

  • How can we manage Earth’s resources to meet current needs without compromising resources for future generations?

34.1: Ecology Basics

• Ecology is the scientific study of organism-environment interactions.

• Organisms are influenced by many variables categorized as:

  1. Biotic Factors: Living organisms in an environment.

  2. Abiotic Factors: Non-living components (physical and chemical factors).

• An organism’s habitat is characterized by both biotic and abiotic factors.

Levels of Ecological Study

• Ecologists study interactions at various levels:

  • Organism Level: Focuses on individual species.

  • Population Level: Examines groups of the same species.

  • Community Level: Studies interactions between different species.

  • Ecosystem Level: Involves energy and chemical cycles between biotic and abiotic components.

  • Landscape Level: Considers arrays of ecosystems from an aerial perspective.

The Biosphere

• The biosphere extends from several kilometers above the Earth to ocean depths and includes all areas inhabited by life.

34.2: Ecology and Environmental Problems

• Human activities, especially chemical use, impact all aspects of the biosphere, including air, water, and living organisms.

• DDT (dichloro-diphenyl-trichloroethane):

  • An insecticide used against crop and disease-carrying mosquitoes, initially thought to be harmless to vertebrates.

  • By the late 1950s, its residues raised consumer concerns and ecological debates.

34.3: Abiotic Influences on Life

• Key abiotic factors include:

  • Energy source (solar energy)

  • Temperature

  • Water availability

  • Inorganic nutrients

  • Other factors (oxygen levels, currents, salinity for aquatic life; wind and fire for terrestrial life).

• Hydrothermal vents showcase ecosystems existing without sunlight, utilizing inorganic chemicals for energy.

Climate Effects on Terrestrial Communities

• The global climate is mainly dictated by solar energy and Earth's movement.

• Solar radiation directly influences temperature and precipitation patterns, resulting in differences between equatorial and polar latitudes.

• Seasonal variations are caused by Earth's tilt and orbit around the sun.

34.8: Terrestrial Biomes

• Nine major types of biomes based on predominant vegetation and climate:

  1. Tropical Forests: Complex ecosystems with rich biodiversity near the equator.

  2. Savannas: Grasslands with scattered trees and seasonal rainfall.

  3. Deserts: Characterized by minimal rainfall and extreme temperatures, experiencing desertification.

  4. Chaparral: Shrubland with periodic fires and distinct seasonal climates.

  5. Temperate Grasslands: Dominated by grasses and found in regions with cold winters.

  6. Temperate Broadleaf Forests: Require moisture for large tree growth, seasonal changes with leaf drop.

  7. Coniferous Forests (Taiga): Characterized by long, cold winters and short wet summers.

  8. Tundra: Treeless, features permafrost, and limited precipitation.

  9. Polar Ice: Covers high latitude areas with extremely cold temperatures and low precipitation.

Global Water Cycle

• Ecological subdivisions like biomes interconnect through nutrient and water cycles.

• Human actions directly influence these cycles:

  • Deforestation limits moisture vapor, impacting local climates.

  • Over-extraction of groundwater affects evaporation and land humidity.

Summary Objectives

• Define and distinguish ecosystem levels and components.

• Explain the impact of human activities on environmental conditions.

• Analyze abiotic factors influencing biotic life in various biomes.

• Describe specific adaptations of organisms like pronghorns for survival in their environments.

• Illustrate the connections between aquatic and terrestrial biomes through the global water cycle.