2. The use of native vegetation in Xeriscaping creates habitat for native wildlife while reducing the risk of invasion Greg Cronin University of Colorado at Denver and Health Sciences Center March 8, 2007

3. Some Goals of Xeriscaping Water conservation –Less human consumption means more water for aquatic ecosystems –Saves money Beautiful, fun landscaping Wildlife Conservation –Providing habitat for native species –Preventing the introduction of exotic species

4. Native to Balkans A hybrid, but most daylilies originate in Asia. None are native to NA.

5. Exotic Species - What are they? They are species that have been transplanted, usually with human ’ s help, to habitats outside their normal range, regardless of political boundaries. –These include plants, animals, fungi, bacteria, protists, and viruses –Some are obvious (purple loosestrife, zebra mussels, kudzu), but most probably go undetected (many microbes, and colonists that do not successfully invade) –They can have beneficial (biocontrol agents) and/or negative impacts on communities. An introduced species can become a resource for some natives, or an enemy of others –Most countries have on the order of 100's to 10,000 exotic species –Often reach nuisance abundance Exotic Species is the #2 reason for our current biodiversity crisis, after habitat loss

6. Invasion Process Species Elsewhere Introduced Established Invasive In Pathway e.g. imported for trade Reproducing Ecological &/or Economic impacts

7. How do Exotics Occur? Natural –plate tectonics. Mixing of marsupial and placental mammals 3 mya –migrations Human-aided –Accidentals –Waterways –Hitchhikers (on clothing or shoes) –Ballast water - zebra mussels –Wooden crates –Imported fruits, vegetables, soils –Failed quarantines –Intentionals Citizens/uncontrolled releases –Released pets –Ornamental plants Government releases/ ” controlled releases ” –Game fishes –Food resource (Nile perch) –Biocontrol agents

8. Risks Posed - Plants Availability of known invasives –45% of US restricted plants available over web Misidentifications –40% of Linnean names incorrect –Ambiguous common names

9. Effects of exotics Allowed success of European imperialism –Disease Black and brown rats killed 30-40% of Europeans in 1500's HIV Ebola Costly/Economics Costs the USA $137 billion/yr Foot and mouth disease cost Britain $30 billion EO 13112, National Invasive Species Council

10. Ecosystem Costs of Exotic Species second most detrimental factor on biodiversity, after habitat loss –Species extinctions via predation –Brown tree snake wiped out 10 of 13 native birds on Guam, 6 of 12 native lizards, and 2 of 3 native bats –Nile perch in Lake Victoria has extirpated half of the endemic cichlid species –Pet cats/feral cats –Sea lamprey - destroyed 97% of lake trout in 21 years –Effects via competition/ecosystem change: –Tamarisk/Salt Cedar

11. State of understanding of biological invasions (not very good) Paul Ehrlich “ ecologists can make some powerful and wide-ranging predictions about invasions...On the other hand, ecologists cannot accurately predict the results of a single invasion or introduction event ”. Depends on complex interactions between the species and community, which are difficult enough to understand in isolation

12. What percentage of colonists successfully invade? Over-representation of organisms that are easy to observe Most unsuccessful colonists go unobserved In biological control cases, overrepresentation of species likely to be successful Probably from 1-40%

13. What communities are susceptible to invasion? Islands (biologically “ unsophisticated ” communities) Early successional/Disturbed Climactically matched with exotic ’ s home habitat (global warming will result in range expansions) Absence of predators (islands) Predators both make it difficult for species to invade AND May make it easier for some species to invade by minimizing competition

14. Invasions of Nonnative Species Most permanent form of pollution Summary of why species invade successfully –most invaders fail to establish –major community effects occur most often in low-diversity systems –species must have appropriate physiological and morphological adaptations to invade successfully –invaders are more likely to become established in disturbed systems –even stable systems can be vulnerable to invasion –the greater the number of invaders and the number of invasions, the greater the probability of successful invasions –species that have a history of prior invasions are likely to invade successfully again

15. Common Invasive Species in Colorado European Starling English House Sparrow Eastern Fox Squirrel Bull Frog Leafy spurge Russian knapweed Diffuse knapweed Spotted knapweed Musk thistle Canada thistle Field bindweed Purple loosestrife Perennial pepperweed Hoary cress Yellow toadflax Dalmatian toadflax Russian Olive Salt cedar

16. Reducing The Impacts Species Elsewhere Introduced Established Invasive × Invasion Steps Options Prevention – exclude species of concern Insure no propagules can escape cultivation Rapid response - eliminate populations while small Mitigate damage, control spread, eradicate if possible Effective? Yes Unlikely Unlikely – requires surveys and funds on hand Eradication usually impossible, control is expensive

17. Reducing The Impacts Species Elsewhere Introduced Established Invasive × Invasion Steps Options Prevention – exclude species of concern Insure no propagules can escape cultivation Rapid response - eliminate populations while small Mitigate damage, control spread, eradicate if possible Effective? Yes Unlikely Unlikely – requires surveys and funds on hand Eradication usually impossible, control is expensive

18. Reducing The Impacts Species Elsewhere Introduced Established Invasive × Invasion Steps Options Prevention – exclude species of concern Insure no propagules can escape cultivation Rapid response - eliminate populations while small Mitigate damage, control spread, eradicate if possible Effective? Yes Unlikely Unlikely – requires surveys and funds on hand Eradication usually impossible, control is expensive

19. Reducing The Impacts Species Elsewhere Introduced Established Invasive Invasion Steps Options Prevention – exclude species of concern Insure no propagules can escape cultivation Rapid response - eliminate populations while small Mitigate damage, control spread, eradicate if possible Effective? Yes Unlikely Unlikely – requires surveys and funds on hand Eradication usually impossible, control is expensive

20. Native Alternatives Resources –Colorado Native Plants Society http://conps.org/conps.html –Denver Botanic Gardens http://www.botanicgardens.org/pageinpage/home.cfm –Native Plant Master Program (CSU) http://www.coopext.colostate.edu/jeffco/natural/native.htm http://ww14.co.jefferson.co.us/coopext/slideshow.do –National Invasive Species Information Center http://www.invasivespeciesinfo.gov/

21. By promoting native vegetation, We provide habitat for native species –Habitat loss is the #1 cause of extinction We reduce the chance of introducing invasive species –Exotic species is the #2 cause of extinction Better safe than sorry