Soil Dynamics and Ecosystem Processes

Soil Evolution and Degradation

Soils evolve while newly forming soils are simultaneously destroyed due to erosion. There are two primary scenarios:

• Scenario 1: If predominant soil-forming processes lead to thicker soils, though not indefinitely. In the upper layers, plant debris accumulates, and decomposers are active. In the lower layers, bedrock breaks down, even at significant depths.
• Scenario 2: If soil erosion predominantly causes thickness loss, the parent rock may become exposed, initiating the soil formation process anew.

Human Impact on Soil Degradation

Soils are degraded and destroyed by various human activities that decrease their quality and fertility:

1. Deforestation or Forest Clearing: For timber or agriculture, which significantly facilitates erosion.
2. Crop Overexploitation: Impoverishes the soil, often leading to excessive fertilizer use that contaminates the soil.
3. Overgrazing: Leaves the soil unprotected and vulnerable to erosion.

Ecosystem Matter and Energy Flow

Matter circulates in a loop within an ecosystem:

• Matter Flow: Inorganic matter becomes organic through producers. This organic matter is then consumed by herbivores and subsequently transformed by decomposers (from rotting dead matter) back into inorganic forms, which producers then reuse.
• Energy Flow: Energy originates from the sun, and plants transform it into chemical energy stored in organic compounds. As energy moves from one trophic level to another, it is released through respiration and dissipates into the environment as heat. Ultimately, all chemical energy is transformed into heat energy.

Measuring Ecosystem Energy

Energy in an ecosystem can be measured in the following ways:

1. Biomass: The total amount of organic matter present in an individual, or at a specific trophic level within an ecosystem. It is typically measured in grams, kilograms, or tonnes per unit of surface area or time.
2. Production: The increase in biomass per unit of time.
   • Net Primary Production: The increase in biomass of producers.
   • Net Secondary Production: The increase in consumer biomass.
   • Net Ecosystem Production: The overall increase in biomass within an entire ecosystem over a given period.

Ecosystem Periodic Changes

Organisms and ecosystems exhibit various periodic rhythms:

1. Daily Rhythms: Organisms alter their periods of rest and activity depending on the time of day. These can be diurnal (daytime), nocturnal (nighttime), or crepuscular (dawn/dusk).
2. Seasonal Rhythms: Behavior adapts to the changing seasons, such as leaf drop in deciduous trees or the timing of flowering in plants.
3. Tidal Rhythms: Changes in sea water levels due to tides significantly affect coastal organisms and their behaviors.