Unit 2 Living World

4 Ecosystem

10 Total Points Possible?

(a)?Describe the climate you might expect to find on your trip to the tropical rainforest.?

(i) 2 point maximum. 1 point for correct information about temperature and 1 point for correct information about precipitation.?

Possible answers might include the following points:

The temperature is warm to hot and varies little throughout the year. Air is humid because of the large amount of rainfall and warm air temperature.?Precipitation is evenly distributed throughout the year with the water cycle repeating often.

(ii) Describe what type of vegetation is found in a tropical rainforest.

2 points maximum. 1 point for description of trees found in the tropical rainforest and 1 point for description of plants.?

Possible answers might include the following point:

The length of sunlight is about 12 hours per day?(because of the location near the equator), resulting in a high amount of photosynthetic activity and a great amount of plant life.?

Rainforests are the most productive and most complex ecosystems on Earth.?Biotic diversity is high. Rainforests cover less than 2% of Earth’s surface but are home to 50-70% of all plant and animal life-forms on Earth.?

The shrub layer has the densest plant growth. It?contains shrubs and ferns and other plants that need less light. Saplings of emergents and canopy trees can also be found here. The forest floor is usually dark and damp.?

(iii) Describe what you would expect the soil quality to be like in the tropical rainforest.?

1 point possible

Possible answers might include the following points:

Tropical soils are often several yards (meters) deep, but the soils are often strongly leached, with large amounts of nutrients and minerals being removed from the subsoils. Over many millions of years, this leaching has?left most of the soils lacking many of the fundamental nutrients needed by the aboveground vegetation.

(b)?Describe one water quality test that your class might want to do and why you chose that test.

2 points possible. Choice of water test and reason(s) for?choosing it must be related to conditions in or around Lake Gatún.?

Possible answers might include the following points:?

■ With an increased rate of deforestation, the turbidity of water bodies around the forested areas can increase as the main purpose of tree roots is to anchor the soil particles together. When the trees are removed, the soil?particles become loose and soil erosion can increase because of increased surface runoff. As a result, these soil particles are washed into the surrounding water bodies.?

■ Turbidity affects water quality by increasing soil?particulates in the water. As a consequence, light does not penetrate through the water and aquatic plants at the bottom of the rivers cannot survive as they are unable to photosynthesize. This affects the entire food web.

(c)?

(i)?Describe deforestation and its effects on the hydrologic?cycle in the tropical rainforest.

2 points possible. 1 point maximum for the correct?definition of “deforestation” and 1 point maximum for one?effect of deforestation on the hydrologic cycle in the tropical rainforest.

Possible answers might include the following points:

■ Deforestation is the cutting down and removal of all or?most of the trees in a forest area.

■ Deforestation affects the amount of water in the soil and?groundwater, thus affecting the recharge of aquifers and the moisture in the atmosphere.

■ Deforestation increases surface water runoff, which can?contribute to flash flooding and extreme floods.

(ii)?Describe one cause of deforestation in the Amazon basin.?

1 point possible for a correct cause of deforestation.

Possible answers might include the following points:?

■ Clearing of land for agricultural purposes (e.g.,?soybeans, cattle, coconuts, oranges, coffee, and palm oil). Eighty percent of land clearing is used for raising cattle.?

■ Clearing of land for roads, timber harvesting, etc.

5 Biogeochemical Cycle