Course Outline 

Invasive Species  

	Activity 1: War on Weeds Activity 2: English Ivy

Background Information
Biodiversity is simply the variety of life in an area. It includes all types of plants, animals, fungi, and microorganisms. A wide variety of organisms are necessary to maintain a healthy ecosystem and most organisms in an ecosystem are dependant on each other (interdependence). According to the Sierra Club, 'the "ecological services" provided by biodiversity include the supply of oxygen to the atmosphere, water purification, the prevention of floods and soil erosion, nutrient recycling, and pollination. Nearly half of all medicines used today originally came from wild organisms.' (http://www.sierraclub.ca/national/biodiv/biodiv/biodiv.html)

Biodiversity is currently being reduced by a number of human activities including agriculture, development, and the introduction of non-native species. Non-native species are plant or animal species that do not naturally occur in an area. These might be introduced by a number of different means. Some, such as Kudzu and English Ivy, are brought to an area as landscape plants. Others, such as cheat grass, were brought to western regions to help feed cattle. Still others come to an area without knowledge of people, as did the zebra mussel, which colonized ships and eventually overran the great lakes.

Organisms compete for resources in the ecosystem. Some of these resources include nutrients, space, water, and sunlight for plants. When non-native species are introduced into an ecosystem, they often don't have any natural predators or diseases and thus there is nothing to control their spread. When climatic conditions are right for them, they tend to out compete native species, taking more of the resources for themselves and leading to a decrease in diversity.

Go to Activity 1: War on Weeds >>