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(c) An increase in species richness would increase primary (d) An increase in species richness would be more likely
productivity in an ecosystem, because fewer species to recover from disruptions, because more individuals
will be present to compete with one another. would be present to reproduce.
Free-Response Question
Researchers set out to determine if there is a relationship (a) Using the data in the table , identify the species rich-
between climate warming in the tundra and biodiversity. ness of mosses at an elevation of 1200 meters. (1 pt.)
They collected species richness data for groups of vegetation (b) Describe the general relationship between species
.
at three different elevations in Denali National Park in Alaska. richness and elevation for the data in Table 1 (1 pt.)
Their findings are listed in the table below. (c) Describe how climate warming would affect the
species richness in the tundra ecosystem. (1 pt.)
(d) Explain why ecosystems with higher species richness
Species richness of vegetation in denali National are better able to recover from disturbances. (2 pts.)
(e) For the researchers’ experiment described above,

Park study area
(i) identify the independent variable in the inves-
Total richness at elevation tigation. (1 pt.)
Species type 300 meters 700 meters 1200 meters (ii) describe a research question for the investiga-
tion. (1 pt.)
Vascular Plants 153 217 276 (iii) identify one variable that would have been held

Mosses 133 170 196 constant in the investigation. (1 pt.)

Lichens 82 126 191 (f ) Another research team looks at the study data and predicts
that an elevation of zero meters would be most affected
(Data from https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ by climate warming, and species richness would be low-
ecs2.1848)
est. Make a claim to support or refute the researcher’s

prediction, and justify the claim using evidence. (2 pts.)

Module 9

Unit 2 8 9 10 11 12 13 14

Ecosystem Services

In the previous module, we examined how biodiversity exists Learning Goals
at different scales and how maintaining high biodiversity
helps populations, species, and ecosystems resist the harmful After reading this module you should be able to
impacts of environmental stressors. A critical question that

environmental scientists investigate is whether the planet’s 9-1 explain the four categories of ecosystem
natural life-support systems are being degraded by stressors services.
caused by human activities. Ecosystems provide ecosystem

,
services which are the processes by which life-supporting 9-2 describe how human activities can disrupt
resources such as clean water, timber, fisheries, and agri- ecosystem services.
cultural crops are produced. Ecosystem services may bene-
fit people directly, for example by providing the food that is unable to provide the same services such as water purifi-
we eat or the water that we drink. They may also benefit
us indirectly, for example by providing a diversity of condi- cation or produce the same goods such as fruit or firewood.
tions, nutrients, and species, all of which make the ecosys-
tem healthier for all organisms, including humans. Although Ecosystem services The processes by which life-supporting
we often take a healthy ecosystem for granted, we tend to resources such as clean water, timber, fisheries, and
agricultural crops are produced.

notice when an ecosystem is degraded or stressed because it

ModUle 9 ■ Ecosystem Services 105
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Copyright © Bedford, Freeman & Worth Publishers.
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