Introduction to Landscape Architecture: Plants, Soils, and Ecosystem Services

1. Key Historical Dates and Concepts

  • Humus: The rich organic soil layer created by decaying plant material that recycles essential nutrients back into the ecosystem.

  • Agriculture Timeline: Developed around 12 000 years ago12\,000\text{ years ago}, shifting humans from passive gatherers to active stewards of the landscape.

  • Mayan Agricultural Collapse: Used raised fields, canals, and ditches; declined between 800 CE800\text{ CE} and 1000 CE1000\text{ CE} due to over-farming, deforestation, soil erosion, and severe drought.

2. Key Biological Processes

  • Photosynthesis Process: Chlorophyll captures solar energy to convert carbon dioxide (CO<em>2CO<em>2) into nutrients while producing oxygen (O</em>2O</em>2).

  • Marine Photosynthesis: Phytoplankton, cyanobacteria, seaweed, and algae generate 50%50\% of Earth's oxygen supply.

  • Transpiration: Movement of water absorbed by roots, transported upward via xylem, and released as vapor through leaf pores called stomata.

3. Scientific Naming Rules

  • Binomial Nomenclature: Two-part Latin naming system made of:

    1. Genus (capitalized)

    2. Specific Epithet (lowercase)

  • Test Examples:

    • White Oak (Quercus alba): Quercus = Genus, alba = Specific epithet (meaning white).

    • Venus Flytrap (Dionaea muscipula): Translates to "goddess mousetrap".

4. Plant Categorization

  • 5 Main Structural Groups: Trees, shrubs, vines, herbaceous plants, and ground covers.

  • Foliage Types: Evergreen (retains foliage year-round) vs. Deciduous (drops foliage seasonally).

5. Environmental Stats and Phytoremediation

  • Urban Heat Island Effects: Tree shade and evapotranspiration lower surface temperatures by 20 to 45∘F20\text{ to }45^\circ\text{F} and ambient air temperatures by 4 to 9∘F4\text{ to }9^\circ\text{F}.

  • Pollution Stats: U.S. urban trees remove approximately 822 000 tons822\,000\text{ tons} of air pollution annually.

  • Phytoremediation Agents and Targets:

    • Indian Mustard: Removes heavy metals (lead, cadmium, zinc, mercury, copper).

    • Willow Trees: Cleans heavy metals and diesel-contaminated soil in wetlands.

    • Poplar Trees: Decomposes organic pollutants and petroleum hydrocarbons.

    • Indian Grass: Breaks down pesticides, herbicides, and petroleum contaminants.

    • Sunflowers: Extracts heavy metals and radioactive pollutants.