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Skaneateles Conservation Area/Invasive species/Pyrus calleryana

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Pyrus calleryana (Callery pear) tree near the fishing pond at the Skaneateles Conservation Area, Oct. 16, 2015.

Pyrus calleryana (Callery pear)

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The Callery pear (Pyrus calleryana), including its 'Bradford' cultivar, is now listed as highly invasive in New York State.[1] There is a single known Callery pear present at the SCA near the fishing pond. It appears to have been planted sometime around 2003, shortly after the pond was expanded. This tree has not been removed (as of Sep. 12, 2021). It does not appear to be spreading at this time but there is evidence that the species is rapidly becoming invasive in much of its horticultural range in at least the eastern United States.[2][3]

  1. ↑ New York State Invasive Species Tiers: Pyrus calleryana. 2021 New York Natural Heritage Program
  2. ↑ Michael A. Vincent (2005). "On the Spread and Current Distribution of Pyrus calleryana in the United States." Castanea, 70(1): 20–31.
  3. ↑ Rick Rojas (2021). "A Tree That Was Once the Suburban Ideal Has Morphed Into an Unstoppable Villain." The New York Times.

Observations of Pyrus calleryana (Callery pear) at the SCA

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The following photographs and corresponding iNaturalist observations of 119793-Pyrus-calleryana were made at or very near the Skaneateles Conservation Area. Click on images to enlarge and read details on Wikimedia Commons or on the "Pyrus calleryana iNat obs" links to view the corresponding observations at iNaturalist.

  • Pyrus calleryana, Skaneateles Conservation Area, 16 Oct 2015. iNat obs
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  • Pyrus calleryana, Skaneateles Conservation Area, 10 Nov 2018. iNat obs
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Invasiveness ranking for Pyrus calleryana (Callery pear)

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The 2008 assessment gave Pyrus calleryana a score of 54/83 = 65.06%, which gave it a New York invasiveness rank of Moderate.[1]

As of 2021, the New York Natural Heritage Program gives Pyrus calleryana a New York invasiveness rank of High and places it in State Tier 4 and Finger Lakes Tier 4.[2]

Pyrus calleryana is not yet regulated by New York State law.[3]

Callery pear is present and listed as a Tier 4 invasive plant in the Finger Lakes PRISM.[4]

1. Ecological impact (13/20)

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1.1. Impact on Natural Ecosystem Processes and System-Wide Parameters: Unknown (U)

  • As of 2008, analysis of herbarium specimens indicated a recent shift from the lag-phase to the spreading phase of this species, so the ecosystem-level effects have yet to be examined.[5][6][7]

1.2. Impact on Natural Community Structure: Significant impact in at least one layer (7/10)

  • Recent field observation have shown this species to be rapidly invading fields, thus creating a canopy layer where one was absent.[5][7]
  • Once established Callery pear forms dense thickets that push out other plants including native species that can’t tolerate the deep shade or compete with pear for water, soil and space. [8]

1.3. Impact on Natural Community Composition: Influences community composition (3/10)

  • Definitely out-competes with native spp. in areas where it invades.[5][7]

1.4. Impact on other species or species groups: Minor impact (3/10)

2. Biological characteristics and dispersal ability (19/22)

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2.1. Mode and rate of reproduction ()

2.2 Innate potential for long-distance dispersal: ()

2.3. Potential to be spread by human activities: ()

2.4. Characteristics that increase competitive advantage: ()

2.5. Growth vigor: ()

2.6. Germination/Regeneration: ()

2.7. Other species in the genus invasive in New York or elsewhere: ()

3. Ecological amplitude and distribution (15/21)

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3.1. Density of stands in natural areas in the northeastern USA and eastern Canada:

3.2. Number of habitats the species may invade:

3.3. Role of disturbance in establishment:

3.4. Climate in native range:

3.5. Current introduced distribution in the northeastern USA and eastern Canada:

3.6. Current introduced distribution of the species in natural areas in the 8 NY PRISMs:

4. Difficulty of control (7/10)

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4.1. Seed banks:

4.2. Vegetative regeneration:

4.3. Level of effort required:

References for invasiveness ranking

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  1. ↑ M.J. Jordan, G. Moore & T.W. Weldy (2008). Invasiveness ranking system for non-native plants of New York. Unpublished. The Nature Conservancy, Cold Spring Harbor, NY; Brooklyn Botanic Garden, Brooklyn, NY; The Nature Conservancy, Albany, NY. Pyrus calleryana assessed by Steve Glenn, Gerry Moore, November 19, 2008.
  2. ↑ New York State Invasive Species Tiers: Pyrus calleryana. 2021 New York Natural Heritage Program
  3. ↑ New York Codes, Rules and Regulations, Title 6 Section 575.4 - Regulated invasive species
  4. ↑ Finger Lakes Partnership for Regional Invasive Species Management (PRISM) (2021). Callery Pear.
  5. ↑ a b c Michael A. Vincent (2005). "On the Spread and Current Distribution of Pyrus calleryana in the United States." Castanea, 70(1): 20–31.
  6. ↑ Brooklyn Botanic Garden Plant Information Records System: Pyrus calleryana
  7. ↑ a b c Theresa M. Culley, Nicole A. Hardiman (2007). "The Beginning of a New Invasive Plant: A History of the Ornamental Callery Pear in the United States." BioScience, 57(11): 956–964
  8. ↑ National Park Service & U.S. Fish and Wildlife Service (2010). "Callery Pear." Plant Invaders of Mid-Atlantic Natural Areas. 4th ed.
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