CHapter 12 geo quiz

Soil – Four Components

• Soil is made of minerals, organic matter (humus), air, and moisture
• All components are needed for healthy plant growth

Soil – Organic Matter & Bacteria

• Dead plants and animals decompose due to bacteria
• Decomposition releases nutrients into the soil
• Forms humus
• Humus gives soil a dark colour and fertility

Soil – Humus

• Made from decayed organic material
• Provides nutrients and moisture
• Helps improve soil fertility and structure

Soil – Air

• Plants need air around their roots
• Air spaces come from loose humus and soil organisms
• Worms and insects create air pockets by tunneling

Soil – Moisture

• Water dissolves nutrients for plants
• Absorbed through plant roots
• Needed for weathering and decomposition
• Essential for all living organisms

Soil Profile

• Layers of soil from top to bottom
• Includes A, B, C, and D horizons
• Each layer has different materials and functions

A Horizon (Topsoil)

• Top layer of soil
• Rich in humus and nutrients
• Dark brown or black
• Best layer for plant growth

B Horizon (Subsoil)

• Located below topsoil
• Contains minerals and some organic matter
• Lighter brown colour

C Horizon

• Contains mostly weathered rock and mineral fragments
• Slowly breaks down to form soil

D Horizon (Bedrock)

• Solid rock layer beneath soil
• Source of parent material

Topsoil Formation

• Minerals added from parent material below
• Organic matter added from surface above
• Forms very slowly over time

Topsoil Formation Rate

• Takes thousands of years to form
• Prairies: 40–100 cm in 6000–10000 years
• Forests: 15–25 cm in same time

Loam Soil

• Mixture of sand, silt, clay, and humus
• Best soil for plant growth
• Holds moisture but drains well

Natural Vegetation

• Plants that grow without human interference
• Depends on climate and soil conditions

Factors Affecting Vegetation

• Climate (temperature + precipitation)
• Soil quality
• Plants need heat and moisture to survive

Growing Conditions and Vegetation

• Warm + wet climates → large trees
• Cold or dry climates → grasses or small plants

Vegetation Regions in Canada

• Canada has 7 vegetation regions
• Main types: tundra, forest, grassland

Transition Zone

• Area where two vegetation regions gradually change
• No sudden boundary between regions

Human Impact on Vegetation

• Much natural vegetation has been cleared for farming and cities
• Human activity reduces natural ecosystems

Coniferous Trees

• Needle-leaved trees
• Usually evergreen (keep needles year-round)
• Adapted to cold climates and short growing seasons

Deciduous Trees

• Trees that lose leaves in the fall
• Prefer warmer climates and longer growing seasons