Page 122 - Environment: The Science Behind the Stories

Group of organism Percentage of total Number of species Percentage of total Annual economic
introduced introduced annual costs costs
Plants 50.0 25,000 27.2
Microbes 40.0 20.2
Arthropods 9.0 15.7
Fish 0.28 4.2
Birds 0.19 1.5 $1.9 billion
Mollusks 0.18 1.7
Reptiles and amphibians 0.11 0.009
Mammals 0.04 20 29.4 $37.5 billion
TOTAL 100 50,000 100 $127.4 billion
Source: Pimentel, D., R. Zuniga, and D. Morrison, 2005. Update on the environmental and economic costs associated with alien-invasive species
in the United States. Ecological Economics 52: 273–288.

1. Of the 50,000 species introduced into the United States, the costs documented by Pimentel and his colleagues.
half are plants. Describe two ways in which non-native What steps can we—farmers, governments, and all of us
plants might be brought to a new environment. How as a society—take to minimize the impacts of invasive
might we help prevent non-native plants from establishing species on crops?
in new areas and posing threats to native communities? 3. How might your own behavior influence the influx and
2. Organisms that damage crop plants are the most costly ecological impacts of non-native species like those listed
of introduced species. Weeds, pathogenic microbes, and above? Name three things you could personally do to
arthropods that attack crops together account for half of help reduce the impacts of invasive species.

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