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Range expansions of non-native species: recognizing problem plants in Alaska Matthew L. Carlson, Lindsey Flagstad, Helen Cortés-Burns Alaska Natural Heritage Program & Biological Sciences Department, UAA [email protected] Outline 1. Retrospective: Distinguishing non-native species movements • Background • Guidelines • Remaining problem taxa 2. Prospective: Evaluating potential for future problem movements • Background • Recommendations Natural and Human-caused species movement Plant species’ distributions change naturally over time – Species originate in one place, their range expands, then contracts Suitable Habitat Range of Species Natural and Human-caused species movement – Movement and establishment is a function of 1. Availability and degree of suitable habitat 2. Dispersal potential 3. Number of propagules (Hultén’s “centrants” and “radiants”) Natural and Human-caused species movement Natural movements of species are insignificant relative to current movements facilitated by people – – – – Current movements of species is 100 to 1000 X times the background rate (Gaston et al. 2003) 400,000 species moved by humans, most in last 200 years (Pimentel 2001) Native species & ecosystem services are at risk Globalization of floras as well as economies Natural and Human-caused species movement Distinguishing natural from anthropogenicassisted dispersal is usually easy – Examples of Vicia cracca, Crepis tectorum, Polygonum cuspidatum… Sometimes it isn’t so easy – Example of Rorippa curvisiliqua Rorippa curvisiliqua distribution (GBIF) Natural and Human-caused species movement Distinguishing natural vs. anthropogenic-assisted migration (See Bennett 2006. SIBERIAN WILD RYE (ELYMUS SIBIRICUS L., POACEAE) IN WESTERN NORTH AMERICA: NATIVE OR INTRODUCED? BOTANICAL ELECTRONIC NEWS 366.) 1. 2. 3. 4. What does the literature suggest? Are the earliest collections at locations of high-use or agricultural stations? Are the collections in disturbed habitats? Does genetic data indicate AK populations are a subset of total variation? Expectation for recent dispersal Are some populations of big leaf lupine native to Alaska? – M. Duffy Natural and Human-caused species movement Distinguishing natural vs. anthropogenic-assisted migration Questionable taxa • Artemisia dracunculus • Lupinus polyphyllus • Phalaris arundinacea – some genotypes may be native (genetic work underway) • Erysimum cheiranthoides (“apparently indigenous in some areas” – Rollins; one subspecies native to Alaska – Hulten; introduced – Al-Shehbaz) • Potentilla norvegica (“probably native and introduced” - Hulten) • Others… Natural and human-caused Distinguishing natural vs. anthropogenic-assisted migration • What do we do with anthropogenic-assisted migrations within Alaska? e.g., Raspberries in Glacier Bay Lepidium densiflorum along right-of-ways across Alaska? Sitka spruce in the Aleutians from 1800s and WWII plantings? Pinus contorta var. latifolia on the Kenai? Alden & Bruce 1989 Part II: Future movements - Distinguishing Problem Species Premise 1: Ecological and economic damage is not the same for all non-native species Vs. Part II: Future movements - Distinguishing Problem Species Vs. At any one time, impact to an area for a species is a function of: 1. Pound for pound ecological impact 2. Pounds (Invasiveness rankings attempt to distinguish potential levels of ecological damage - http://akweeds.uaa.alaska.edu/akweeds_ranking_page.htm) Pound for pound variation in impact Hypothetical example of two species Total Ecological Impact Distinguishing Problem Species Ecological and economic damage is not the same for all non-native species v Total Amount (biomass/area) Distinguishing Problem Species Ecological and economic damage is not the same for all non-native species Assuming all species have same impact/mass… Ecological Impact • Expansion rate (Δabundance/year) Distinguishing Problem Species Premise 2: Assuming two species have the same per unit mass ecological impact, we should control: 1. The species with the lowest current amount, 2. The greatest potential amount, and 3. Greatest expansion rate of expansion Distinguishing Problem Species 1. Identifying new arrivals Management is most effective for new arrivals Theoretically easy to do • Simply survey the whole state every year • (Confirm the species’ introduction to the state is most likely due to people) • Share data – make the results available AKEPIC CNIPM DNR, Division of Agriculture Distinguishing Problem Species Recommendations for determining lowest current amount? (survey data, e.g., AKEPIC & EDDMapS) Hieracium aurantiacum - AKEPIC • • Hieracium pilosella - AKEPIC How do we determine potential area occupied? How do we determine rate of expansion? Distinguishing Problem Species 2. Recommendation for determine potential area occupied? 1. Habitat niche modeling (e.g., Bella et al. in prep.) 2. In general, species with known wide ecological tolerances and similar habitats/climates to Alaska Cirsium arvense – MaxEnt output Distinguishing Problem Species 3. How do we determine how quickly they can expand across potentially suitable habitat? Distinguishing Problem Species Expansion Rates of Invasive Species Expansion speed Dispersal Area occupied Seed Density 1. Availability and degree of suitable habitat 2. Dispersal potential Distance 3. Demography: (# of propagules/time) “Once intermediate to high densities are reached the rate of spread is accelerated” (Humston et al. 2005) Population Size or Area Occupied Is there a way to identify plants that can expand more rapidly? Only a fraction of introduced species establish and cause significant problems Saturation (“Naturalization”) Colonization Establishment Time Distinguishing Problem Species Three example expansions: 1. Examples of what doesn’t appear to be spreading quickly here: Raphanus sativus Raphanus sativus Raphanus sativus 1941-1968 2001-2009 Distinguishing Problem Species Three example expansions: Examples of Crepis tectorum – quick off the starting blocks Crepis tectorum 1941-1968 Crepis tectorum 2001-2009 Distinguishing Problem Species Three example expansions: Example of Prunus: Still geographically restricted, but expanding into many different habitat types (black spruce to krummholtz) (Caragana in Fairbanks) Birch-spruce forests Subalpine 2009 floodplains Distinguishing Problem Species Recommendation of An Epidemiological Approach: 1. Number of records increases rapidly (relative to total weed records collected at that time) 2. Records appear in distant areas 3. Records in new habitat types Distinguishing Problem Species 3. Those likely to expand? Can we use information on its past or current behavior to anticipate the future? • Observed lack of expansion does not mean it will not occur • • e.g., Starlings (unsuccessful in 1870s), reed canarygrass in Alaska However, current aggressive behavior does suggest future problems Distinguishing Problem Species 3. Those likely to expand? • Those species that have expanded rapidly elsewhere in similar ecosystems • • For example, Japanese knotweeds (Polygonum cuspidatum, P. × bohemicum, P. sacchilense) have spread throughout Scandinavia Or that have wide native distributions in similar habitats (e.g., Leucanthemum vulgare) Distinguishing Problem Species 3. Those likely to expand? How much habitat is available and how continuous the is the habitat? Are there major gaps in habitat? Distinguishing Problem Species 3. Those likely to expand? What is the reproductive capacity? Does the species have the capacity for long-distance dispersal? Recap and Recommendations Native-introduced status is well accepted for most plants in Alaska – Some research is warranted for a handful of species Predicting rapidly expanding plants should involve multiple approaches 1. Change in number and locations of records 2. We should be cautious in assuming plants that aren’t rapidly expanding cannot 3. Examine dispersal capacity and seed production Recap and Recommendations Statewide management will greatly benefit if all parties agree with control priorities We should develop an acceptable statewide prioritization system • • Invasive Plants of Alaska Prioritization Tool A system that incorporates invasiveness ranks and distributional data and species with a higher probability of establishing quickly