Choose three significantly different invasive species. For each, describe how it was introduced into the environment, the impact on the environment, and efforts that have been made to control or eradicate the species from that environment. For each species you choose, consider this: Have the efforts to control or eradicate the invasive species generally had a positive impact on the environment or a negative one? Explain.
What are some strategies used today in species conservation efforts?
What are some of the strengths and weaknesses of each strategy?
Use recent events to support your answer.
What factors contribute to deforestation, especially in developing countries?
What are some of the impacts of deforestation on the environment, the local populations, and the planet?
What are some of the strategies being used to address deforestation? To what extent are they working? Use recent examples to support your answer.
What are the basic strategies of forest management? Why is forest management necessary?
“Invasive species”—they may not sound very threatening, but these invaders, large and small, have devastating effects on wildlife.
Invasive species are among the leading threats to native wildlife. Approximately 42 percent of threatened or endangered species are at risk due to invasive species.
Human health and economies are also at risk from invasive species. The impacts of invasive species on our natural ecosystems and economy cost billions of dollars each year. Many of our commercial, agricultural, and recreational activities depend on healthy native ecosystems.
What Makes a Species “Invasive”?
An invasive species can be any kind of living organism—an amphibian (like the cane toad), plant, insect, fish, fungus, bacteria, or even an organism’s seeds or eggs—that is not native to an ecosystem and causes harm. They can harm the environment, the economy, or even human health. Species that grow and reproduce quickly, and spread aggressively, with potential to cause harm, are given the label “invasive.”
An invasive species does not have to come from another country. For example, lake trout are native to the Great Lakes, but are considered to be an invasive species in Yellowstone Lake in Wyoming because they compete with native cutthroat trout for habitat.
How Invasive Species Spread
Invasive species are primarily spread by human activities, often unintentionally. People, and the goods we use, travel around the world very quickly, and they often carry uninvited species with them. Ships can carry aquatic organisms in their ballast water, while smaller boats may carry them on their propellers. Insects can get into wood, shipping palettes, and crates that are shipped around the world. Some ornamental plants can escape into the wild and become invasive. And some invasive species are intentionally or accidentally released pets. For example, Burmese pythons are becoming a big problem in the Everglades.
In addition, higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species—such as garlic mustard, kudzu, and purple loosestrife—to move into new areas. Insect pest infestations will be more severe as pests such as mountain pine beetle are able to take advantage of drought-weakened plants