** ANSWER KEY **
Study Guide for Quiz 4: Ecosystem Services and Biodiversity
Warning: Long answers! Your answers don’t need to be as long as mine, but do read these, not only to check yours, but
also to deepen your understanding!! The quiz will be mostly multiple choice, but there will be at least one open-ended
where I will expect you to apply your knowledge.
Ecosystem Services
Define of Ecosystem: An ecosystem is a community of living organisms interacting with one another and with their physical
environment. Ecosystems include the nonliving (abiotic) factors as well, that is the physical and chemical components, such
as soils, water, and nutrients that support the organisms living within them, as well as all the interactions among all the
living and nonliving components.
Define of Ecosystem Services: Ecosystem Services are the processes by which the environment produces resources that we
want and need. Some are necessary for our survival. Some make our lives better.
Give six examples of Ecosystem Services:
Any 6 of these:
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moderate weather extremes and their impacts
disperse seeds
mitigate (lessen the frequency and severity of) drought and floods
protect people from the sun’s harmful ultraviolet rays
cycle and move nutrients
protect stream and river channels and coastal shores from erosion
detoxify and decompose wastes
control agricultural pests
maintain biodiversity
generate and preserve soils and renew their fertility
contribute to climate stability
purify the air and water
regulate disease carrying organisms
pollinate crops and natural vegetation
Natural ecosystems perform fundamental life-support functions upon which
human civilization depends. Unless human activities are carefully planned and managed, valuable ecosystems will continue to
be impaired or destroyed.
Why are Ecosystem Services important?
What do we mean when we say we are looking at costs and benefits? Whenever you are making decisions involving
the environment, you have to look at the costs, not only the actual dollar amount, but also any negative effects that
could result. You also need to look at the possible benefits, or the good things that would result. You need to weigh the
costs and benefits carefully when making a decision. You also need to make sure you look at long-term costs as well as
short-term costs. Some costs and benefits are more serious than others. It isn’t easy to do, but it is important.
Biodiversity
Define Biodiversity:
Biodiversity refers to the number of different species in an area.
What are the two types of value of biodiversity? Explain.
Biodiversity has both economic and ecological value.
By economic value, we mean value that can be translated to dollars and cents. We get many resources from the
environment, including food, water, oxygen, and raw materials for clothing, medicine, and other products. Ecosystems
also have value for recreation and tourism. In addition, we must consider the value of ecosystem services, some of
which our lives depend on. Many of these services would cost billions of dollars to replace artificially.
Biodiversity has ecological value because all the species in an ecosystem are connected and interrelated to one another.
Many species depend on one another for survival. Any change to one species impacts the entire ecosystem.
What are three factors that affect biodiversity in an ecosystem?
Three factors that affect biodiversity in an ecosystem are area, climate, and niche diversity.
Usually, a larger area supports more diversity. In general, the warmer the climate, the greater the diversity, but
precipitation is also a factor. Tropical, wet climates support the greatest biodiversity. Niche diversity means there are
many different types of places for organisms to live. (The book doesn’t say this, but it also means there are many
different “roles” for the organisms to fill.)
What is a keystone species?
A “keystone species” is a species that influences the survival of many other species in an ecosystem. Destroying a
keystone species would cause disastrous effects to the entire ecosystem.
What are the most diverse ecosystems in the world?
The most diverse ecosystems in the world are tropical rainforests. Coral reefs are the second-most diverse ecosystems in
the world.
Describe four human actions that threaten biodiversity? Which is the worst one?
The absolute worst human action which threatens biodiversity is habitat destruction. Every time people build towns,
subdivisions, farms, etc., they are destroying natural habitat. Almost as bad is habitat fragmentation, which is breaking
up habitats into small, isolated pieces, or fragments.
Other human actions which reduce biodiversity are poaching, pollution, and introducing exotic species.
Poaching means illegal hunting, fishing, and harvesting. Any illegal activity that harms, kills, or removes an organism
from its natural habitat is considered poaching.
The book doesn’t say this, but legal hunting, fishing, and harvesting can also harm biodiversity when people take too
much. This could be thought of as overhunting, overfishing, and overharvesting. If we remove more organisms than can
be replaced through natural reproduction, the population is doomed to decrease and eventually die out.
Pollution can harm organisms even if it is far away. Harmful substances can be introduced into the water, air, and soil.
These pollutants can weaken organisms, cause birth defects, and even kill them outright.
Exotic species are species that are introduced by human action into a new environment where they did not originally
occur. These species often do very well in the new environment, much to the detriment of the native species. There are
many, many examples where the exotic species becomes invasive – meaning that, much like an invading army, it “takes
over” and crowds out and/or out-competes the native species, thus reducing the biodiversity and harming the
ecosystem.
Explain three ways to protect biodiversity.
Three ways humans can protect biodiversity are captive breeding, laws and treaties, and habitat preservation.
Captive breeding is the mating of animals in zoos and wildlife preserves. It is hoped that these animals will eventually be
released into the wild.
Laws and treaties protecting wildlife, such as The Endangered Species Act and the Convention on International trade in
endangered Species (CITES), are sometimes difficult to enforce, but have helped many endangered species to recover.
The most important thing people can do to protect biodiversity is to preserve habitats by setting them aside and
protecting them from development.
Compare and contrast extinct, endangered, and threatened species.
All of these terms are adjectives used to describe the status of a species. An extinct species is one which has been
completely wiped out. This means there are no longer any surviving individuals of that particular species. Extinct is
forever. Once a species is extinct, it can never be brought back. You may have heard of talk of cloning extinct animals,
but even if this is eventually possible, these animals will never be exactly like the originals. It’s not the same as bringing
back the species. It is natural and normal for species to become extinct, but human action has greatly accelerated (sped
up) the rate of extinction. There isn’t time for new species to arise to take the place of extinct species, as happens
naturally. Right now our planet is experiencing an extinction crisis!
Endangered and threatened are similar terms because in both these cases, there are still living individuals of the species
and there is still hope for their recovery. However, the populations of these particular species are low enough to raise
concern. Endangered species have such a low population that they are in danger of becoming extinct in the near future.
Threatened species are species that are not quite that low, but almost. They are in danger of becoming endangered!
It is too late to save extinct species, but people can take steps to help threatened and endangered species recover.
How is biodiversity related to ecosystem services?
This was a “thinking” question!
As you have learned, we need ecosystem services to survive! Ecosystems which are missing species have a lower
biodiversity. If they are missing components, they do not function as well as they normally would, which results in a
reduction and even loss of the crucial ecosystem services they provide.
Applying Concepts: Purple Loosestrife is a pretty, purple flowering plant that is not native to North America. People
introduced it here because it is so pretty. The purple loosestrife grew very well, spreading all over wetlands in the
country, so that in some areas where there were once many different kinds of plants, there is now a veritable sea of
purple. This plant “out-competes” the native wetland plants and “takes over” wherever it is introduced. How has this
plant affected biodiversity?
Purple loosestrife is an example of an exotic species, which is one of the four main threats to biodiversity. Because these
plants do so well, they are taking over native wetlands. There is more and more purple loosestrife, but fewer and fewer
of the native plants, such as cattails. Fewer different types of plants means lower biodiversity.
Did you know that cattails are a protected species? If you go to the Celery Farm, look for the sign that says it is illegal to
pick them! One of the reasons why they need to be protected tis that the invasive purple loosestrife has caused a
decrease in native cattails!
If you want to read more about the Celery Farm and its battle against purple loosestrife, check out this link:
http://celeryfarm.net/2010/07/fighting-loosestrife-one-leaf-at-a-time.html
“Sea” of purple loosestrife:
Cattails: