Biomes and Population Ecology Notes Unit 8 lecture 1

Overview of Biomes

• Definition: Biomes are the largest ecological groups that categorize environments based on weather patterns, particularly temperature and precipitation.
• Biosphere: Encompasses all living things on Earth, with biomes existing beneath this level.

Key Characteristics of Biomes

• Temperature and Precipitation: Two critical factors shared among biomes that influence their ecosystems.
• Tropical Forests: High temperatures with significant variability in precipitation; typically the most rain.
• Temperate Broadleaf and Northern Coniferous Forests: Can receive rainfall comparable to tropical forests, but generally less precipitation overall.
• Grasslands and Tundras: Include temperate grasslands, deserts, polar ice, and alpine tundra, which can have low precipitation levels similar to deserts.
• Climate Overlap: Many biomes exhibit overlaps in temperature and precipitation; eg. deserts can appear in both temperate and tropical regions.

Specific Biomes

• Tropical Rainforests: Located in the tropic band (between the Tropic of Capricorn and Tropic of Cancer), characterized by high rainfall and temperature.
• Subtropical Regions: Areas slightly north or south of the tropics, such as parts of South Florida.
• Grasslands: Comprise temperate grasslands (prairies, pampas) distinguished from tropical grasslands (savanna).
  • Savanna: Tropical grassland, notably in Africa.
• Chaparral: Coastal areas with dry conditions characterized by bushy vegetation, common in regions noted for wine production.
• Tundra: Characterized by permafrost; includes Arctic tundra (northern) and alpine tundra (mountains). Sometimes termed deserts due to low precipitation.

Adaptations in Biomes

• Vegetation: Adaptations like CAM plants that conserve water in deserts; waxy surfaces in cacti to reduce moisture loss.
• Animal Adaptations: Species like kangaroo rats obtain water metabolically; camels store fats in humps.

Climate Change and Biome Transformation

• Desertification: Can occur when environments like grasslands experience reduced rainfall and become deserts.
• Deforestation Impact: Cutting down rainforests leads to decreased rainfall due to reduced transpiration, escalating desertification processes.
• Global Issues: The effects of climate change have significant implications for preserving environments and preventing biome shifts.

Population Ecology (Chapter 53)

• Importance: Focuses on populations of a single species in relation to their environment, studying dynamics like density, distribution, age structure.

Key Concepts in Population Ecology

• Population: A group of individuals of the same species living in a defined area.
• Density and Dispersion:
  • Density: Number of individuals per unit area or volume.
  • Dispersion: Patterns of spacing (e.g., uniform, clumped, random).
• Demographics: Statistics related to population dynamics—birth rates, death rates, migration.
• Cohorts: Groups followed for studying survival statistics.

Population Dynamics and Methods

• Capture-Recapture Technique: Method for estimating populations by marking a sample and calculating the total based on re-sampling.
• Life Tables: Provide age-specific survival and reproduction statistics, indicating trends like longevity differences between sexes.

Population Influences

• Birth and death rates are primary influences on population size, along with immigration and emigration.
• Environmental and social factors can influence how individuals in a population are distributed—resource availability and territoriality are significant factors.

Case Studies: Mule Deer and Other Populations

• Examples from field studies demonstrate practical applications of population ecology, such as the use of radio collars to monitor deer movement and behaviors.

Summary of Important Points

• Biomes are defined largely by temperature and precipitation patterns.
• The study of population ecology is vital to understanding dynamics affecting species and their environments.
• Climate change poses a threat to the integrity of biomes, emphasizing the need for conservation efforts to maintain ecological stability and diversity.