Chapter 5
Terrestrial Environment

Links for Enrichment and Further Learning

• Global Leaf Area index Data - Oak Ridge National Laboratory
• Tropical Rain forests: the understory

Study Questions / Quiz Prep. (Consult Required Reading and lecture notes for answers.)

1. The amount of light at any depth in the canopy is a function of....
2. In determining light absorption by the canopy, using just the NUMBER of leaves is not always realistic. Why?
3. What is the mathematical expression for the Leaf Area Index?
4. Give a verbal statement that describes the meaning of the Leaf Area Index.
5. Calculate thje Leaf Area Index for the following:

6. Which situation lets in the most light from above?
7. Which situation lets in the least light from above?
8. The higher the leaf area index above any surface, the _______________ the quantity of light reaching the surface.
9. Refer to the below picture. Which leaf receives the greater amount of sunlight?
   
10. Refer to the picture above. At mid-day in summer, which leaf will lose less water from evaporation?
11. Refer to Figure 5.6 on page 90. In which season is sunlight intensity greatest?
12. Refer to Figure 5.6 on page 90. In which season is the forest floor exposed to the greatest PAR?
13. Refer to Figure 5.6 on page 90. In which season is the forest floor exposed to the least PAR?
14. Which five factors influence soil formation?
15. List the five horizon layers described in Figure 5.9 on page 94.
16. Be able to recognize A and B horizons in photos of soil profiles.
17. Why are topsoil layers ('A' horizon) often so thin in the tropical rain forest?

Light scattering in a mixed forest. Most sunlight is captured by tall trees. Plants below receive filtered light, ambient skylight, and occasional streams of light breaking through the canopy cover.

A forest floor, shaded heavily by the treetop canopy.

Light scattering in a meadow. Compared to a forest, more light reaches the ground here.

A meadow.

A method for determining the leaf area index. The higher the index, the less light reaches below.

Leaf angle can influence the quantity of intercepted light.

Leaves of a live oak. Note that many of the leaf surfaces have a vertical component to their orientation.

Light intensity at various heights above the forest floor, at various seasons.

A forest in winter. Note that in the absence of leaves, more sunlight strikes the forest floor. But in winter, sunlight is less intense (lower in the sky), and days are shorter.

Soil Horizon diagram.

Soil horizons.

Deep soils of North American coastal flatlands. Note the thick, dark A horizon.	Thin soils of the tropical rain forest. Difficult to find an A horizon in this profile mainly consisting of subsoil layers. High nutrient demand by plants rapidly withdraws nutrients from the soil. High rainfall washes topsoil away.