Chapter 4 – Instructor’s Manual 19
Ecology and Geology
Learning Objectives
After reading and studying this chapter, students should
▪ Know some of the basic concepts of ecology and linkages to geology
▪ Understand the importance of relationships between geology and biodiversity
▪ Know what factors increase or decrease biodiversity
▪ Know what human domination of ecosystems is and how we can reduce the human
footprint on the environment
▪ Know why we need an appropriate environmental ethic on a time scale relevant to
people today
▪ Know what ecological restoration and the processes of restoration are
Chapter Summary
This chapter focuses on the principles of ecology, linkages between geology and ecology, and the
nature of human impacts on ecosystems. The chapter opens with a basic discussion of ecosystems
and ecological concepts. Subsequent sections address ecological processes, biodiversity, specific
case studies related to geology-ecology interactions, and human impacts on ecosystems. The chapter
closes with a discussion of strategies and examples of ecological restoration.
Chapter Outline
I. Ecology for Geologists: Basic Terms
A. Ecology
1. Ecology is the study of controls over the distribution and abundance of living things
3. Related terms
a. species: a group of individuals capable of interbreeding
b. population: a group of individuals of the same species living in the same area
c. ecological community: a group of populations of different species living in the same area
with varying degrees of interaction with each other
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Ecology and Geology
g. exotic species: brought into an area or region by humans for a variety of purposes or as
i. biota: all organisms living in an area or region up to and including the entire Earth
B. What is an ecosystem and how does it work?
1. An ecosystem is an ecological community and its nonliving environment in which energy
flows and chemicals cycle
3. Two main processes are energy flow and chemical cycling
5. Types include indigenous, natural, human-modified, human-made
C. Natural service functions of ecosystems
1. Definition: processes of ecosystems responsible for producing clean water and air, and
mixtures of plants and animals necessary for our survival
2. Natural service functions include buffering of landsliding and flooding processes
3. Humans often interfere with those natural service functions
II. Geology and Biodiversity
A. Biodiversity
2. Species richness vs. species evenness
B. Biodiversity of trees in North America and Europe
2. North American trees could disperse southward during ice ages because mountain ranges are
oriented north-south
3. European trees were trapped between ice sheet and east-west trending mountain ranges
C. Community effects and keystone species: how are these concepts related to geology?
2. Links between geology and keystone species help maintain ecosystems and biodiversity
D. Stream processes and ecology: story of mountain streams, elk, and wolves in Yellowstone
National Park
1. Mountain streams are complex systems of rock, water, and biota
3. Reintroduction of wolves kept elk out of stream environments, and stream channels
recovered
4. Wolves are a keystone species
E. Coastal geology, kelp, urchins, and sea otters
1. Southern California kelp forests depend on rocky platform environments
3. Sea urchins break through kelp holdfasts and cause kelp to float and die
5. Reintroduction of sea otters leads to return of kelp
6. Sea otters are a keystone species
F. Factors that increase or decrease biodiversity
1. Primary concern is species richness, and genetic diversity is also important
G. What factors increase biodiversity?
1. Diverse habitat with many potential niches
3. Presence of harsh environments may host specialized species that increase diversity at a
regional scale
4. Relatively constant environmental factors such as temperature, precipitation, and elevation
6. An environment that is highly modified by life
7. Geology, which affects ecosystem function and process from small- to continental-scale
environments
H. What factors decrease biodiversity?
1. Presence of extreme environments
2. Extreme disturbance, or very frequent disturbance such as regional-scale fires, storms, or
volcanic activity that catastrophically disrupt ecosystems
3. Transformation of the land, which fragments ecosystems
4. Presence of environmental stresses, such as pollution
6. Introduction of exotic, intrusive species
7. Presence of mountain ranges that block or restrict migration of plants and animals
I. Human domination of ecosystems
1. Human domination has caused disastrous conditions in some areas
3. The extinction event of the last 2000 years has featured rates of extinction much higher than
would be expected
J. The golden rule of the environment: a geologic perspective all about timing
1. Gould advocated consideration of both geologic time and human time
2. Humans need to develop a more compatible relationship with Earth
K. What can we do to reduce the human footprint on the environment?
2. Manage populations and resources more effectively
4. Develop a moral responsibility to manage ecosystems better
III. Ecological Restoration
A. Definition
1. The process of altering a site or area with the objective of reestablishing indigenous,
historical ecosystems
B. Examples
1. River restoration for fish and other wildlife habitat
2. Dam removal to reunite fragmented river ecosystems (see A Closer Look: Restoration of the
Kissimmee River)
3. Floodplain restoration to improve ecological function
5. Beach and coastal sand dune restoration to prevent erosion and improve wildlife habitat (see
6. Restoration of endangered species habitat
8. Restoring habitat for native species and wildlife impacted by clearcut logging
C. Objectives of restoration
Ecology and Geology
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1. Common objective is to change a degraded ecosystem so that it resembles a less human-
2. Alternate definition is the process of deliberately modifying a site or area to compensate for
environmental degradation caused by humans
3. A practical approach to restoration is to attempt to transform the present ecosystems and
4. Consideration must be given to the “Big Three” major factors, including hydrologic process,
soil and rock, and vegetation
5. There is feedback between the goals and scientific endpoints
a. scientific endpoints are a consequence of goals
b. if endpoint is unreachable, goals should be reconsidered
D. Restoration is a negotiated process
2. Those doing the restoration work
3. Scientists making recommendations, gathering data, and analyzing results
Answers to Review Questions and Critical Thinking Questions
Review Questions
Chapter 4 – Instructor’s Manual 23
Critical Thinking Questions
1. An answer to the question should address linkages between the biota and the geological
environment and a discussion of which factor is the primary factor in determining ecosystem