The Dynamics of Weathering, Soil, and Ecosystems

Weathering Processes

Physical or Mechanical Weathering

• Temperature Changes: Rocks expand when heated and shrink when cooled.
• Frost Wedging (Gelification): The breakdown of rocks caused by the expansion of water as it freezes into ice.

Chemical Weathering

This process is common in humid climates.

• Oxidation: Iron, one of the most common chemical elements in nature, is part of many minerals and rocks and reacts with oxygen.
• Solution: Some rocks and minerals, like salt (halite), dissolve easily in water.

Soil Formation and Composition

Soil is formed by the weathering of rocks, caused by water, air, and living organisms.

• Allochthonous: Originates in a place other than its current site and has been transported by a geological agent.
• Autochthonous (Indigenous): Originates in the same place where it is found.

Soil Horizons

• Horizon O: A very thin layer consisting of partially decomposed and unaltered organic matter.
• Horizon A: Dark-colored, rich in humus and plant roots.
• Horizon B: Lighter in color, poor in humus, and has few roots.
• Horizon C: Contains abundant coarse rock fragments. Below this horizon is the bedrock.

Soil Types

• Sandy Soil: Predominantly large-sized particles.
• Clay Soil: Dominated by very fine particles.
• Loam Soil: A balance between coarse and fine particles.

Soil Degradation and Protection

Causes of Degradation

• Deforestation
• Over-cultivation
• Overgrazing

Soil Protection Methods

• Avoid overexploitation.
• Practice contour plowing (do not make furrows down the slope).
• Reforestation.

Ecosystem Fundamentals

An ecosystem is a system naturally formed by a group of living organisms (biocenosis) and the physical environment (biotope) in which they relate.

• Biocenosis: The set of organisms of all species (plant, animal, etc.) in an area.
• Biotope: An area of uniform environmental conditions providing a living space for a specific set of flora and fauna.
• Ecosphere: The global ecosystem of the Earth.

Ecosystem Components

• Abiotic: Components that are non-living or not derived from living beings.
• Biotic: Components that are living or derived from living beings.

Adaptation is a physiological trait or behavioral process of an organism that has evolved over a period through natural selection in such a way that it increases its long-term expectations to reproduce successfully.

Trophic Levels and Energy Flow

Producers

These are autotrophs, such as plants and algae, that produce their own food.

Consumers

These are heterotrophs that obtain energy by feeding on other organisms.

• Primary Consumers: Herbivores that feed on producers.
• Secondary Consumers: Carnivores that eat herbivores.
• Tertiary Consumers: Carnivores that eat other carnivores.

Decomposers

Organisms that feed on dead organic matter from the environment.

Food Chains and Food Webs

• Food Chain: A linear series of organisms in which each individual feeds on the one preceding it.
• Food Web: The entire network of interconnected food chains that form an ecosystem.