Definitions for invasive plants

1. Definitions for invasive plants • People use different words for invasive species • Alien Exotic • Invasive Non-indigenous • Imported Weedy • Introduced Non-native • Immigrant Colonizer • Naturalized

2. Definitions for invasive plants • LEGAL DEFINITIONS • State: NRS 555 • “Noxious weed” means any species of plant which is, or is likely to be, detrimental or destructive and difficult to control or eradicate. • Federal: Plant Protection Act of 2000 • Noxious weed means any plant or plant product that can directly or indirectly injure or cause damage to crops (including nursery stock or plant products), livestock, poultry, or other interests of agriculture, irrigation, navigation, the natural resources of the United States, the public health, or the environment. • Federal: Executive Order 13112 • “Alien species” means, with respect to a particular ecosystem, any species … that is not native to that ecosystem • (e) “Introduction” means intentional or unintentional escape, release…of a species…as a result of human activity • (f) “Invasive species” means an alien species whose introduction does or is likely to do harm to public health

3. Definitions for invasive plants • ECOLOGICAL DEFINITIONS • (1) Nevada’s Coordinated Invasive Weed Strategy • Noxious weeds are “species of plants that cause disease or are injurious to crops, livestock or land, and thus are detrimental to agriculture, commerce or public health” • Invasive weeds often share characteristics such as • Highly competitive Cause environmental degradation • Exotic Easily spread • Highly aggressive Are difficult to control • Cause economic loss Augment wildfires • “Species of concern” are species that have potential to cause greatest impact on Nevada’s ecosystem and economic well being • (2) The Nature Conservancy • Invasive species are: • Spread from human settings into wild • Once wild, continue to reproduce • Displace native species; reduces biodiversity • Usually non-native

4. Definitions for invasive plants • ECOLOGICAL DEFINITIONS • (3) Davis & Thompson (2000) • 8 ways to be a colonizer, but only 2 ways to be an invader • Dispersal: Short Long • Uniqueness: Common Novel Common Novel • Impact: Small Great Small Great Small Great Small Great • SC SC NNC NIC SC SC NNC NIC

5. Definitions for invasive plants ECOLOGICAL DEFINITIONS ( (4) Richardson et al. (2000) Alien plants = plant taxa in a given area whose presence is due to intentional or accidental introduction as a result of human activity Casual alien plants = alien plants that flourish but do not form self-replacing populations. Continued presence depends on re-introductions. Naturalized plants = alien plants that reproduce consistently and sustain populations over many life cycles without direct intervention by humans Invasive plants = naturalized plants that produce reproductive offspring (often in large numbers) at considerable distance from parent plants >100m & <50 years for seed dispersing species >6 m & >3 years for vegetatively reproducing species Weeds = plants that grow in sites where they are not wanted; usually have economic or environmental effects Transformers = subset of invasive plants that change ecosystems

6. How are they located? • Eyewitness account • Darwin in 1833 during trip through the Argentinean pampas • “… very many (probably several hundred) square miles are covered by one mass of these prickly [variegated thistle] plants, and are impenetrable to man or beast. Over the undulating plains, where these great beds grow, nothing else can now live.”

13. Remote sensing Satellite imagery: spectral signatures (from Eric Peterson, NV Natural Heritage Program, http://heritage.nv.gov/reports.htm)

14. Remote sensing Bromus tectorum greens up early

15. Remote sensing Bromus tectorum greens up early, and also senesces early compared to native species

16. Fall Winter Spring Summer N D O A M J F A M S J J Remote sensing From a spectral perspective

17. Fall Winter Spring Summer N D O A M J F A M S J J Peak greenness Min. greenness Remote sensing From a spectral perspective

18. Fall Winter Spring Summer N D O A M J F A M S J J Peak greenness Min. greenness Remote sensing From a spectral perspective NDVI = greenness index based on chlorophyll reflectance in infrared relative to red.

19. Fall Winter Spring Summer N D O A M J F A M S J J Peak greenness Min. greenness Remote sensing From a spectral perspective NDVI = greenness index based on chlorophyll reflectance in infrared relative to red. Does change in NDVI (ΔNDVI) correspond with Bromus abundance?

20. Remote sensing Imagery from Landsat 5; 8 scenes over Owyhee Uplands from 2 times during year

21. Remote sensing But also need ground truthed data

22. Relative ΔNDVI Measured Bromus cover Remote sensing Ground trutheddata: 262 training plots

23. Remote sensing • Ground truthed data: 262 training plots plus 75 validation plots • 9.7% error for validation plots

24. Remote sensing Map of Bromus tectorum abundance in Owyhee Uplands

25. Remote sensing Invasive annual grasses across entire state