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Leafy spurge seed pods build up pressure and explode, shooting seeds up to 15 feet away.

 
Exotic Species

Student Activities | Research and Links

Life out of Context

Some things just don't belong together: the square block in the round hole, a whale in the desert, a coconut palm atop an alpine peak, exotic species at the Great Sand Dunes.

Exotic species are animals or plants that have been introduced and which are nonnative to a particular ecosystem. Some of these species may cause heavy environmental damage and economic loss. Although not all invasive species are highly destructive, some may have 'weedy' characteristics, making them difficult to manage. Weedy species may quickly invade and disrupt the local ecology.

Exotic species artificially enter an ecosystem primarily through human means. Seeds may stick to clothing, to shoelaces or on a pet's fur. Seeds may travel in the soil on shoes or on tires. Other examples are blights and molds on infected nursery transplants. Once transplanted, spores blow off and infect nearby plant communities. Garden plants that are considered "pretty" or "fast-growing" may also escape cultivation and spread like wildfire into surrounding ecosystems. Since many people like to grow plants in their gardens that are not native to their areas or that spread really fast, gardeners must be especially careful not to let any of the more invasive plants spread outside the garden plot. Mustards (Brassicaceae) and composites (Asteraceae) are especially prone to escape gardens.

What is the problem at the Great Sand Dunes?

Exotic Plants

Invasive exotic plants are of great concern. Fortunately, at present, few nonnative plants have established themselves into the Great Sand Dunes' ecosystem. However, the park is downwind of a rather large agricultural area which has numerous weed problems. Among these are various species of knapweed, Canada thistle, leafy spurge and whitetop. The highly invasive tamarisk (or salt cedar) is also beginning to appear on the nearby landscape. The geography at Great Sand Dunes literally acts as a sand trap, not only for sand, but also for invasive plants' seeds.

	Exotic Species at Great Sand Dunes
	Present Concern				Potential for Concern
	Canada thistle (Cirsium arvense)				Tamarisk (Tamarix spp.)
	Leafy spurge (Euphorbia esula)				Musk thistle (Carduus nutans)
	White top (Cardaria spp.)				Plains cottonwood (Populus deltoides)
	Knapweed (Centaurea sp.)				Russian olive (Eleagnus angustifolia)
					Musk thistle weevil (Rhinocyllus conicus)

Exotic Animals

Currently, there is only one nonnative animal species that has park managers worried. This species of beetle in the weevil family, ironically, was introduced as a biological control method for the eradication of musk thistle on the west side of the San Luis Valley. While biological methods of controlling weeds are successful to some degree on certain nonnative plant species, they may be potentially destructive to closely-related native species. In this case, the musk thistle has relatives that are native to this area. Recent research has indicated that the weevil will establish itself on two species of native thistles, wavy-leaved thistle and Platte thistle, sometimes preferentially. As a result, the weevil can reduce these plants' fecundity or vigor, impacting their populations as a whole.

For the nature of Great Sand Dunes National Park and Preserve to remain a precious wonder, we must do our best to limit the spread of exotic species into the park. Special species of plants and animals abound and keeping them from being impacted through our neglect is a primary goal of park managers.

You can help by learning more about invasive species through the links below. Find out what action you can take to limit the spread of invasive species. Stock users can do their part by feeding and packing weed free hay when bringing stock to wild areas.

Student Activities

In the Land of Many Opportunists outdoor activity, learn how aggressive invasive exotic species take advantage of a wide range of resources in order to expand their range and compete in a nonnative habitat. And a fictitious cottonwood at Great Sand Dunes has been infected by numerous exotic species. Help restore the health of this micro-ecosystem in Following the Doctor's Orders.

Research Papers and Links

The PLANTS database
Natural history information on thousands of plants that occur within the United States.

Invasivespecies.gov
Comprehensive list of invasive species and management plans.

Colorado State University Cooperative Extension Fact Sheets
Download information on weed species and the learn about the types of management for each.

Invasive Weeds: What are they and Why should We Care About Them
Weeds booklet (PDF) for smaller children, presented by Los Angeles County Weed Management Area.

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