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Notes to Instructors
Chapter 56 Conservation Biology and Restoration Ecology
What is the focus of this activity?
Many species of both plants and animals are rapidly going extinct as a result of habitat
What is this particular activity designed to do?
Activity 56.1 What factors can affect the survival of a species or community?
Students are asked to consider and integrate a wide range of principles to address
questions in conservation biology.
Answers
Activity 56.1 What factors can affect the survival of a species
or community?
Making decisions to preserve communities requires an understanding and integration of
many factors. Assume you work for the U.S. government and manage a large national
You have asked your staff to do an analysis of two possible methods for implementing
the plan:
Proposal I: Split the million acres into two parcels of a half million acres each and
allow the foresters to harvest all trees on one of these parcels.
Proposal II: Divide the million-acre tract into 50 parcels of 10,000 acres each and
allow the foresters to cut half the trees in each parcel.
1. List some of the ecological advantages and disadvantages of each proposal.
Notes to Instructors 377
378 Activity 56.1
Proposal I Proposal II
Advantages Disadvantages Advantages Disadvantages
• Fewer roads would
be needed.
• The regeneration
rate for trees would
• All cut areas would
be closer to seed
• There would be
more roads and
2. Given the following characteristics of various animal species described below, which
of the forestry-cutting proposals would be more likely to ensure continued success
of each animal species? Explain your answers.
a. C. arnivora is a secondary and occasionally a tertiary consumer or carnivore.
Behaviorally, it roams over about 20 square miles of “home range” in search of
food—for example, rabbits (herbivores) and foxes (carnivores).
One square mile contains 2.8 ⫻107square feet; 20 square miles contains
b. R. odentia is a small rodentlike herbivore that exists in small numbers in the
forest. Its preferred food and habitat are found along the edges of the forest and
are composed primarily of herbaceous (nonwoody) annual plants which produce
tender shoots in the spring and plentiful seeds later in the year.
Proposal II would produce more edge habitat than proposal I. If the success of
c. P. redatoria is a predatory bird which feeds on small rodents and occasionally on
snakes and other reptiles. It can range over large distances looking for food. It
nests in hollows that occur naturally in a particular species of tree. These hollows
are not found in trees under 20 years of age but are commonly found in trees
40 years and older.
If we assume that 40-year-old trees are randomly distributed throughout the
3. Conservation biologists have debated extensively which is better: many, small
reserves or a few large ones.
a. What types of factors should be considered in making judgments about size and
location of reserves?
What is better will vary from species to species. Some species roam over wide
Activity 56.1 379
b. Some ecologists argue that we should be concerned about preserving the largest
number of species. Others argue that we should be most concerned with saving
those species judged to be of unusual importance. Develop an argument to
support one of these viewpoints. Your argument should be based on our existing
understanding of biology in general and ecology in particular.
Many logical arguments can be proposed. In developing your argument, you
4. Based on your answers to questions 1–3, which of the proposals for removing half a
million acres from the national forest in question 1 would you recommend? Explain
your reasoning.
Again, a number of possible arguments can be developed to support either proposal I
380 Activity 56.1
